'Unleaded' For G/A..?? [Archive]

LeadSled

2nd Aug 2013, 06:17

Creamie,
I've just learned something new, I didn't need to modify all those Jag cylinder heads to run on unleaded, and the blokes who supplied the new valve seats and valves (of clearly different material to older exhaust valves) was obviously deluded by Jaguar supplying these new p/ns for "unleaded" conversion.
It was all a big con!!
Likewise, those very real examples of "hammered" valve seats I have seen are nothing to do with running unleaded, but the problem mysteriously does not reoccur if we modify the cylinder heads with the new exhaust valves and valve seats.

From a BP data sheet.
UNLEADED WILL NOT HARM YOUR ENGINE
Unleaded Petrol is perfectly suitable for those engines capable of converting from Leaded to Unleaded. These engines do not require lead for exhaust valve seat lubrication and are satisfied by the lower octane of Regular Unleaded Petrol. Old leaded engines not on this list either require lead for valve seat lubrication or require a higher octane fuel.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CDYQFjAB&url=http%3A%2F%2Fwww.bp.com%2Fliveassets%2Fbp_internet%2Faus tralia%2Fcorporate_australia%2FSTAGING%2Flocal_assets%2Fdown loads_pdfs%2Ff%2FFuel_news_FN_facts_about_leaded_unleaded.pd f&ei=3Ez7UbmxDtDrlAXnyYHgCA&usg=AFQjCNFX_5-n4ScZ96SPTxj37LYLdFgKSQ&bvm=bv.50165853,d.dGIhttp://

Another con job by the RACQ:

Unleaded Petrol and Pre-1986 Cars | Motoring | RACQ (http://www.racq.com.au/motoring/cars/car_advice/car_fact_sheets/unleaded_petrol_and_pre-1986_cars)

Now, perhaps, we could start a discussion on flame propagation rates of burning, versus pre-ignition versus detonation and the significance of differing octane ratings, and the contributions of various components of the typical leaded and unleaded fuels, and the effects of different fuel air ratios. (ie What does 100/130 for an aviation fuel mean).
Oh Boy, this takes me right back to the test engine for determining octane ratings we had in the basement of the old Engineering School at Sydney Uni. --- that WAS a long tome ago --- but, mysteriously, the ASTM D 910 Aviation Gasoline specification for leaded, of the present day, looks remarkably like the one we had then??

Tootle pip!!

Creampuff

2nd Aug 2013, 06:25

Yes: It was indeed, and continues to be, all a big con.

From the inestimable John Deakin’s must-read article: Lead in the Hogwash http://www.avweb.com/news/pelican/182149-1.html:First, a few of the OWTs...

Lead Myths

•Lead does NOT "cushion" or "lubricate" valves. There is nothing in the serious literature, and no known scientific data to support this notion. If you know of something, please write. I said DATA, not some mechanic or overhauler mouthing this decades-old gossip. Remember, EVERYONE once "knew" the world was flat (and some still believe it). I do have one report that high-output marine engines had some valve problems when switched from mogas to unleaded fuels, but that same report said that hardened valve seats took care of that problem.

•Lead has no effect on the BTUs or "power" in the fuel. "Octane rating" has very little effect on BTUs or "power," and what effect it has is in the wrong direction. The more the fuel components are processed to raise the octane, the less "power" the fuel will produce. But the effect is almost negligible. The same "power" is generated by a gallon of 80/87, 91/96, 100LL, or the old 115/145, with or without lead. (What DOES change is the required timing for different fuels. Hold that thought. Timing is that all-important measure of when the spark lights off in relation to top-dead-center piston position.)

•Lead does NOT cause valves to run cooler or hotter. Lead does NOT prevent (or cause) "valve recession."

•Finally, EGT has little or no effect on valve temperature. Most of the heat comes from the very high combustion temperatures during the combustion event, 3,000 degrees Fahrenheit or more, and most of that heat is transferred to the cylinder, and the cooling fins. EGT shows the temperature of exhaust gas after the exhaust valve opens, by which time a great deal of the heat has been dissipated.

I know of NO known reliable DATA to support any of these notions, other than the well-meaning folks who happen to believe them, having heard them repeated over and over for decades. As I mentioned, there is some good data that refutes them, if you'll look.

Just for one example, the FAA ran a twin with flat sixes for several hundred hours, one engine running 100LL, and the other side with unleaded fuel. Then they tore both engines down and used some custom-built instrumentation to measure the valve wear. The lead did no good, at all. That's pretty good data, but I'd like to see more of it. Well done, FAA!

If any of you have scientific evidence for any of these, PLEASE point it out. I am NOT talking about "My mechanic says," or "everyone knows," I'm talking about published, scientific data by reputable people, who know what they're talking about.

At this point, let me point out that in the 30s and 40s, all the best and the brightest engineers were working with recips, and virtually everything we know about them comes from that era. Those people were ENGINEERS in the classic mold, and knew their stuff. What they did with primitive tools is astounding, and just about everything we're re-learning today was known then! Starting in the 50s, all the "best and brightest" gravitated to turbines, and it wasn't long before the general attitude was, "recips are dead." The old knowledge and "corporate memory" died, the marketing folks took over at Lycoming and Continental, and today we see the results. There may be a few real engineers left, but I don't see much evidence of that at the factories. The result is that most technical information coming from "the big two" is either intellectually dishonest, or solidly based on pure ignorance. There is NO curiosity left, and warranties are often worthless. The basic engines are usually excellent, having been originally designed by the engineers of yesteryear, but what the factories have done to them is pathetic.
…
If lead doesn't add power, what does it do? Like "octane," lead ALLOWS a higher power SETTING without detonation. The primary means of accomplishing this is in simply reducing the speed of combustion. By reducing the speed of the flame front, it takes longer to reach maximum pressure, and thus that max pressure occurs later, after top dead center. Can you spell T-I-M-I-N-G, again? … :ok:

LeadSled

2nd Aug 2013, 06:41

Creamie,

I have the greatest of respect for John Deacon, but nobody is always correct about everything, unless you want to believe that "big oil" and "big auto" ran a con job on exhaust valves world wide.

What would the motive have been, unleaded was a done deal. Why would OEMs now be offering cylinder kits "suitable" for unleaded, if any of the P/Ns could run on unleaded for a normal overhaul life --- another big con job???

That FAA tests proved no change as described by Deacon, (you are a lawyer) didn't disprove the problem with exhaust valves and seats, because there is no information about the material used in the valves and valve seats of the "test" engines.

I have considerable experience with "old" auto engines, particularly Jaguar XK series --- it is quite remarkable how rapidly old material seats "hammered" or recessed withing a few thousand miles with unleaded. Equally, such problems ceased when we rebuilt heads with Jaguar supplied replacement seats and valves.

Old Holden "grey" motors were a particular problem, the early "Holden" 5L and the 350 Chev derived engines of the era also suffered, even with "lead substitute" additives.

This isn't my imagination, it is all a matter of records.

Tootle pip!!

dubbleyew eight

2nd Aug 2013, 06:42

TetraEthyl Lead was determined by experimentation as the best of 16,000 substances tried as a detonation inhibitor. it was significantly better than the next best substance.

described in "Engines & Enterprise, the life and work of Sir Harry Ricardo" by John Reynolds. published by Haynes Publishing as book H4516.
ISBN 978 1 84425 516 0
Library of Congress card No. 2008922573

a very interesting read.

"moreover, in 1926 two scientists working for General Motors in the USA, Charles Kettering and Thomas Midgeley, discovered the use of tetraethyl lead as an additive had a remarkable effect in reducing the tendency of petroleum fuels to detonate"

LeadSled

2nd Aug 2013, 06:58

dubbleyew8,
An equally good read:
"I Kept No Diary" by Air Commodore Rod Banks.
Banks was an Australian who was the youngest naval commander in WW1 -- of an armed sand barge patrolling the Suez Canal.

During the 20s/30s he worked for International Octel Inc, who "invented" Tetra Ethyl Lead as a petrol additive, selling it around Europe. He became a fuel expert, and was responsible for the "bug juice"mixtures used in a number of Schneider Trophy contenders, particularly Italian and British.

That was all about octane ratings, whatever the additives, the wear reduction properties of "lead" were a useful side effect.

By WW11, he was called up, in the RAF, worked for Beaverbrooke, and played a central role in making one single gasoline the standard for everything gasoline before D-Day.

There is a very interesting story of an airlift of valves from US to UK in the weeks before D-Day, it was found that a lot of British MT was not compatible with the available petrol, thousands of vehicles had to have new valves fitted -- one GMC has valves of the right stem diameter, wrong head, so there was a frantic effort to re-machine the heads to the right size and fit them before D-Day. Maybe a bit off thread, but all about compatibility of materials and fuels.

Tootle pip!!

Creampuff

2nd Aug 2013, 07:11

Leaddie: I don’t understand how you can still get the guy’s name wrong, when it’s stated in this thread. Be that as it may ….

DATA me ol’ prune. DATA? :ugh:

Wally Mk2

2nd Aug 2013, 07:14

......where's JABBA?:ok:
Come on Jabba we won't bite:-)
He'll set us all straight, that guy knows way too much about recip donks:E

Lead is a good lubricant, used on door hinges as well:-)

Wmk2

OpsNormal

2nd Aug 2013, 07:22

Creampuff, are you actually aware that valves rotate slowly as they work (otherwise you could make them square, triangular or any other shape you like that would increase valve seat area to get more charge in and out), which is one of the reasons they need some form of deposit regularly being put on the valve face or it will dig itself into the valve seat as there is nothing to stop complete metal to metal contact and galling from the rotating valve as it closes. BTW, your link is broken/not copied correctly and I suspect they would ignore this one small fact as it doesn't suit their argument.

You may wish to expand your understanding further with this from Shell: Avgas Facts and Future (http://www.shell.com/global/products-services/solutions-for-businesses/aviation/aeroshell/knowledge-centre/technical-talk/techart12-30071515.html) which touches on a couple of reasons why some older designed engines will not cope with unleaded fuels that do not have any form of additive in them that protects the valves and their very soft seats. This issue does not affect ALL engines, just a few with certain composition seat inserts.

I respect your superior intellect and intimate knowlege of legal circles and regs etc, however you're well wide of the mark on this one. The last thing I wish to do is enter into a piddling contest but this issue does only effect a small percentage of engines but what it ultimately means is that someone may have to spend $$$$ on designing and certifying new seat inserts that will work well and stay in situ (think expansion rates) - or that will spell the end of the effective life for those engines.

Regards,

OpsN.

LeadSled

2nd Aug 2013, 07:31

I don’t understand how you can still get the guy’s name wrong

Creamie,
Easy, and if I recall correctly, this is not the first time I have made that mistake, and you have picked me up. It's all because I have an acquaintance called Deacon. I promise to try harder.

As to data, what data would you like. The problem of exhaust valve seats v. unleaded fuels or not an urban myth. As far as I an concerned, my own personal experience over quite a number of engines is enough for me.

If it really is a huge con. job, it is one of the most successful and enduring of all time. The 1986 lists of vehicles came from the vehicle manufacturer's themselves, on what basis they separated valve/valve seat suitability in various models for unleaded operation without modification I do not know, but I doubt they plucked it out of thin air --- not after their experiences with Ralph Nader.
If all they wanted to do was sell new cars, why did some offer conversion kits of one kind or another (ie: Jaguar selling valves and seats made of the same material as later generation -post mid 1980 - production)
In Australia, NSW DMT/RTA (or their predecessor?) NRMA, RACQ, RVAC etc were all suckered in, amazing!!

Tootle pip!!

dubbleyew eight

2nd Aug 2013, 07:47

Wow: We may have discovered a new OWT!

I have to ask. whats an OWT!

OpsNormal

2nd Aug 2013, 08:09

OWT= Old Wives Tale.

sms777

2nd Aug 2013, 08:11

Ok.....The solution is.... install hardened valve seats and if you want to go the whole hog...buy a set of stainless valves. In an automotive engine costs about a grand plus labour of remove and replace cylinder head(s).
I can't see why it would be more complicated in an aero engine not counting CASA's involvement. :ooh:

Oracle1

2nd Aug 2013, 08:15

I found this idea interesting,

an old composite oxy bottle and some CNG and off we go, would fit perfect in the belly of a 206

wonder what it will do to temps

what say Jaba?

Natural Gas-Powered Airplane - YouTube

Jabawocky

2nd Aug 2013, 08:41

Righto you lot, spend two days away from pprune and look what happens.

Facts.
TEL does only one thing, Creamie is 100% correct. End of discussion.

Leadsled,
That FAA tests proved no change as described by Deacon, (you are a lawyer) didn't disprove the problem with exhaust valves and seats, because there is no information about the material used in the valves and valve seats of the "test" engines.
TCM and Lycoming have ALWAYS used hardened seats. The problems that started the old wives tales you are reciting stem back to the days when Ag operators in the USA were suffering fuel prices going up and up, they went to UL fuel, and before long they were having problems, so they correctly aligned the sudden spike in valve problems with running unleaded fuel. Therefore the LEAD was protecting the valves. This was a 100% correct OBSERVATION and a 100% incorrect CAUSATION.

The issue was the LATENCY of the fuel. Nothing more and nothing less. The solution was knock off a few degrees of timing and all was good again, happily burning bog standard unleaded.

Now the old Holden engines, they had what? Cast Iron heads and the valve seats were machined into the heads, they were not the fancy seats used in modern engines or the same kind that were used for decades in Aviation Piston engines. Big difference. So the lack of Octane rating and thus the difference in latency mean the peak pressure happens at a different interval, and you should see the results on the Dyno when sampling ICP's at 50khz.

You can come see this in Sydney in November if you like. We do several runs, and we use Mogas ordinary premium unleaded.

Basically as best I can tell from scanning Creamie's posts is his are the only ones 100% correct so far. :D Not bad for a dumbs lawyer :ok:

So, lets just move onto the bottom line, a 100% drop in replacement for Leaded Avgas. It needs to be unleaded, it needs to be suitable not just for low compression O-320's but also High compression turbo charged engines, and even more so, those on big blowers, C414's, 421's Chieftans and Nevergo's etc.

It also needs to be 100% mixable as the fleet and the fuel outlets need to "change over" without penalty. It also must be compatible with not only new materials but old in service materials.

It must have equal or better vapour pressure properties.

It must also be able to be produced in most decent refineries with no significant cost increase.

I only know of one of these fuels anywhere in the world, having given in the taste test so to speak, seen the data test reports and watched it in action on a TN IO550, I can tell you it is the answer.

It is ready now, just needs some more time for paperwork and an industry to take it up when the FAA give the FLEET WIDE STC approval.

Hows that sound.

Ohh and by the way all those big old radials can have the Hi-Blower unleashed again on this stuff. It out-performs 100LL and the old purple stuff you might remember Leadslead. :ok:

Here is the data sheet.
http://i849.photobucket.com/albums/ab58/jaba430/G100UL2020R20plus20M20over2022020at20105pt206.jpg

dubbleyew eight

2nd Aug 2013, 09:01

Facts.
TEL does only one thing, Creamie is 100% correct. End of discussion.

he is correct but he obviously has never looked into an exhaust pipe.
for avgas with TEL
correct mix burns light grey.
lean mix burns white and rich mix burns dark grey.

go fly a real aeroplane and take a bloody look!

LeadSled

2nd Aug 2013, 09:32

Facts.
TEL does only one thing, Creamie is 100% correct. End of discussion.

Jaba,
With all due respect, bollox.TCM and Lycoming have ALWAYS used hardened seats

izzatso, perhaps you could explain why I have been supplied with two separate P/Ns for Conti. cylinder kits, the difference being the exhaust valves and valve seat, maybe somebody in AU has some very, very old stock??

Tootle pip!!

dubbleyew eight

2nd Aug 2013, 10:05

leadie he is correct in that it was only intended to do one thing.

he is wrong about it being the only effect though. the muck in the burnt mixture really does slow valve seat recession in unhardened valve seats.
that is a well documented and experienced fact.

it also changes colour according to the mix.
40 years ago we used to check the tuning adjustment of the car by taking it for a run around the block. after a few miles the exhaust colour would confirm or otherwise whether the tune was ok. same for aircraft.

it also makes you clean out the lead nodules from spark plugs on a reasonably regular basis thereby increasing your opportunities for dropping them.
(I was once asked, almost as an exam question, what is the corner of a hangar for? answer; somewhere to kick dropped spark plugs so that you cant find them.)

Volumex

2nd Aug 2013, 10:08

So what do we need to do to get G100UL certified by CASA?
Would they accept the flight test reports of the flights that were witnessed by the FAA?

dubbleyew eight

2nd Aug 2013, 10:26

we went from having multiple grades of avgas to all using just one (100/130) not because of CASA but because the fuel companies stopped making them.

I would suggest that the first task is to find a company prepared to produce and distribute it.
the engines were originally certified by the FAA so once they certify the fuel blend it should be an easy rubber stamp exercise for CASA.

Wally Mk2

2nd Aug 2013, 10:59

"88" I reckon no fuel Co maker/distributor would make a specialist type fuel (as that's where all leaded fuel is heading) as there wouldn't be the volume there for them to produce it never lone market it to a dieing sector as GA, simply no money in it or a decent return on outlay.
GA in the not to distant future will only be for the elite with money to burn.

It's my understand that lead or fuel with a higher octane rating has a direct effect on ignition timing & therefor performance, sure did in motor vehicles of yesteryear. If you put 'std' fuel in a car that was tuned for 'super' it pinged it's head off at the std BTDC timing (usually around 6 deg's) so you had to back off the dissy 'till it stopped pinging & the result was a slug! Can't see the Aero engines being any diff but am here to learn from the "Master Jabba":ok:

Wmk2

Jabawocky

2nd Aug 2013, 11:19

Leadsled, I would love you to show me the data to prove your claim but two different part umbers does not mean that they were not changed somewhat over the years, different manufacture is not uncommon, but they have always had a hardened seat because they were ALWAYS aluminium heads.

So please, don't be sucked in any longer.

W8......no I was correct entirely, the muck in the burnt mixture really does slow valve seat recession in unhardened valve seats.

Right observation.....WRONG causation. Did you not read about the ag guys, latency etc. :ugh: Go do the study. I am not paid to do this, and I do not do this for kicks, but FFS, the OWTs are hard enough to kill off as it is, so please be careful with the beliefs of OWT's.

As we say, Data is no weapon against the warm fuzzy feeling of a deeply held superstition.

Jabawocky

2nd Aug 2013, 11:21

Vex
So what do we need to do to get G100UL certified by CASA?
Would they accept the flight test reports of the flights that were witnessed by the FAA?

Fleet wide STC ...... problem solved. CASA do not need to do anything, which is just as well :}

Jabawocky

2nd Aug 2013, 12:20

Wally, on the topic of timing you can only reduce the timing so much, and in high compression engines the timing is retarded enough already.

Also on the larger high output engines there is a very thin line. Advance the timing, and you get into detonation margin, or into light detonation. The Chieftain engine is a classic example. they live there all the time. So you cant advance, but you ca't retard.

If you do retard the timing the problem is you run into TIT problems as the EGT goes up.

It is all about latency of the fuel.

Anyone interested in learning about this.... it takes more thna an internet post. Advanced Pilot (http://www.advancedpilot.com/livecourse-au.html) Ask Volumex and creamie :ok:

RatsoreA

2nd Aug 2013, 13:14

Excuse my ignorance, but where exactly is the TIT measured from (sensor placement) in the average engine(s), and what is the average reading in cruise, and what info does it give you that the EGT/CHT/oil temp/oil press combo can't give you?

Ex FSO GRIFFO

2nd Aug 2013, 14:18

**** Me Guys & Gals,.....

Oi dinna wanna start WW3.....

T'was just a discussion on feckin' FUEL ....FCSs....

Now..... Exhaust valves at the ready...GO!

:p

LeadSled

2nd Aug 2013, 15:44

--- but they have always had a hardened seat because they were ALWAYS aluminium heads.Jaba,
Please go back and read what I have already posted --- all the Jaguar cylinder heads are aluminium --- that didn't automatically make the valve seats "hardened".

Are you really suggesting that Jaguar (and others) went to all the trouble of changing the material in production heads post the mid-'80's, and went to the trouble of producing valves and seats for retrofitting --- if there was no need?? As has already been mentioned, changing valve guide material is part of the above unleaded conversion.

TEL isn't always good, how many of you can remember the new heads we had to fit to Gypsy Majors, to cope with "high octane" leaded fuel.

As I said before, while I have the greatest of respect for the efforts of Pelicans Perch, in making know, in present times, what many of us have always known about the operation of piston engines. How do you think the Qantas "double daylight" services in the Catalina's made the range they did --- in fact, they very carefully operated right on peak CHT, to get every last drop of power out of the available fuel.

What we do have now, in little engines, that make it easier, are Gamijectors and good multi-point EGT or CHT --- but little else has changed in the last 70 or so years. The physics and chemistry certainly haven't changed.

Tootle pip!!

PS: Having been an operator of reasonably high performance car and bike engines, and aeroplane engines, since the late '1950's, and originally having an engineering background, I have not been sucked into anything.

Jabawocky

2nd Aug 2013, 21:05

Leadie, I have no idea what think Jaguar did with their heads, and frankly it has little to do with this debate. Lead does nothing to the valve or seats that cushions or protects. Perhaps they always had hardened valve seats ;) Yes even back in the 1940's Leadie, the early XK120's etc, all had hardened valve seats. Here is what one Jaguar specialist has to say on the topic.The fitting of an electronic 'U' box from AJ6 engineering is another good solution if your engine tends to 'ping' on unleaded fuel. Don't have an 'unleaded cylinder head conversion' unless you are overhauling the head anyway. If you want to give money away we can suggest a very good charity.

The key issue was ignition timing, why? Latency, it has nothing to do with lead as a lubricant, because it is not.

In latter years the XJS series in particular (have a friend who is an XJS fanatic) the biggest issue was valve seats dropping. This is entirely an overheating issue. End of story.

You have just proven this concept to yourself with the following statement.
TEL isn't always good, how many of you can remember the new heads we had to fit to Gypsy Majors, to cope with "high octane" leaded fuel.

TEL is never good for the engine. Why do you think they add in Bromine? Well to scavenge the lead after it finished with the latency issue they want it out! The result is Lead Oxybromide which is a salt. And when has a salt of anything made an excellent lubricant or any other active ingredient that is good for the internals of an engine? Besides that salt is gaseous and expelled at all but idling temperatures where a small amount can settle out in a cold engine. Once hot enough they are gone. Even the ATSB were fooled by OWT's on this one.

So for the punters reading this;
1. How does TEL (not lead) in fuel lubricate the valve stems on the inlet or exhaust valve when it does not come in contact with either? And if it were to come in contact say through worn guides? The fuel is a solvent on the inlet side and that makes a poor lubricant, and under the suction of the intake stroke it would not get sucked into the valve guide anyway. Myth Busted.

Now lets look at the exhaust valve, it is closed during all but the expelling of hot exhaust gas, which now contains a compound called Lead Oxybromide. If that gets into the valve guide, the guides will really wear fast, and then the valve rattles around and wears it more and before long you have a valve failure. Sound familiar?

2. The reason engines designed to run on higher octane (not leaded because they need the octane not the lead) when run on ordinary ULP had valve issues was that of Internal Cylinder pressures. The problem is the latency of the fuel, the time it takes for the fuel to burn and the pressure in the cylinder to rise. If this happens quicker, after the spark event, the gas expansion occurs sooner and with the piston rising this happens in a progressively smaller chamber. So what follows is a much higher peak pressure. This does not generate more HP by the way as much of the extra pressure generated goes into doing the compressive effort in the other cylinders, and the peak is now closer to TDC than before, thus less Torque is generated by the crank angle being less, and less torque means less power at any given RPM.

With all that understood, these higher pressures, much higher, and the resulting higher temperatures were the reason for valve recession and valve jobs. The solution in many cases was simply back off the timing to compensate for the latency. A premium unleaded PULP of a similar octane and latency will run an "old school" engine just fine and it will run longer on the PULP because it has less deposits. Just as pointed out above with the Tiger Moth engines. My race car engine has SOFT cast iron heads an no problems on PULP, because it was timed right, the compression ratio was right, the cooling was right....heck I even put the thing together myself! That was the biggest risk!

Some years ago the FAA tested side by side a twin with one engine on AVGAS and one on unleaded, and they ran it for several hundered hours. What a surprise, two identical engines and one had more wear and degradation than the other. You can guess which one was the healthier one.

The only reason we have the lead fuel is to have a latency suitable for high HP engines so that they can have sufficient detonation margin without suffering a loss of performance. When you see a Chieftan engine run on PULP you soon realise you can extract a lot of HP out of it without an issue, but you simply can't extract full rated power out of it without it detonating to the point where it is dangerous. If you cure the detonation, you don't get the power. And all the piston twin pilots will tell you that they need every pony they can get to meet the minimum certification single engine performance numbers as it is. So either you have a fuel that works, or planes are grounded. It is that simple. And they burn the most volume of the fuel so if you ground them, AVGAS or an UL version of it disappears anyway.

Tiger Moths and O-320's and other low compression engines have STC's for low octane fuel, and they are best run on it. IF you can. Rotax actually specify more frequent oil changes is Avgas is used. You are better without the lead.

Bottom line is there is no hard data to prove leaded fuel has any benefit other than latency and if there was I am sure we would have found it by now. Smarter folk than I have never found it because it does not exist. there are plenty of superstitions that are tightly held onto though.

Jabawocky

2nd Aug 2013, 21:15

Leadsled,
How do you think the Qantas "double daylight" services in the Catalina's made the range they did --- in fact, they very carefully operated right on peak CHT, to get every last drop of power out of the available fuel.

I would like to see the data for that ;), as the scientific fact is to get the very last drop of range/fuel they did not operate at peak CHT or peak EGT. They would have had to operate at BSFCmin. And that is way LOP. And far from peak CHT. If they ran at peak CHT, it was because they had no way of telling BMEP or EGT, and that I can believe. So if that was the case what they did was sub-optimal but they knew no better.

To get the most or peak power, they would have operated at a setting that was around 75dF ROP. The peak CHT would have been fractionally less, and maybe that is what they did, but it would have been sub-optimal. Perhaps on those aircraft they could not define the difference. I assume they did not measure BMEP either like in the Connie or other big R3350 installs.

If you have the manuals for these particular operations I would happily study them and compare it to the R3350 which was carefully operated with BMEP, because back then they did not have EGT instruments like we do now.

This is major thread drift....sorry :sad:

OZBUSDRIVER

2nd Aug 2013, 21:41

161octane:eek::eek::ok:

Does this mean I will once again hear the noise of a Merlin at full song? I am getting all wet just thinking about it.

Old Akro

2nd Aug 2013, 22:26

There is been a fact based discussion about this on AVWEB for a year or more. Its a complex issue. Many GA engines could switch tomorrow. The main problem is the slowness of the US labs in testing fuels. Its been the subject of debate in congress. Other engines will never run on unleaded fuel and if you read the documents put out on this subject by both lycoming & Continental they concede that it would mean the retirement of many aircraft - including my Seneca. It got quite a bit of attention when a fringe group in California started a court case seeking the immediate ban on the sale of AVGAS

While admire John Deakin, lets just remind ourselves of his qualifications. Engine calibration is the single most difficult part of vehicle development and experienced engine calibrators are highly sought after globally. The number of good ones in Australia could be counted on the fingers of one hand. The best guys work for Ricardo, AVL or FEV. There are even fewer fuel technologists.

If you want to understand this, then get do a paper search on places like the library of Ricardo engineers, The SAE and the NASA Langley library.

Creampuff

2nd Aug 2013, 22:43

I am perpetually fascinated by the propensity of highly intelligent people to confuse correlation for causation.

When the traffic lights turn green, the cars start moving. Therefore, the green light causes the cars to move …

The lack of lead does not cause the problems that people keep citing. The detonation does.

If you take the lead out, the combustion event happen more quickly, moving the peak pressure point closer to TDC and increasing the absolute peak pressure. It’s not the ‘removal’ of the ‘valve lubrication’ or ‘valve cooling’ that’s causing the problems: it’s the advance in the PPP and the increase in the PP caused by the quicker combustion in the absence of the lead.

You can create exactly the same problems by advancing the timing. Leave the lead in, and slowly advance the timing to e.g. 30 degrees BTDC instead of 22 and see what happens (not on my engine, please). (Hmmmm, perhaps the magneto timing is lubricating the valves :confused: )

You can take the lead out and make the problems go away by retarding the timing. (Therefore, the magneto timing is definitely lubricating the valves :ok:) But if you do that, you’ll create other problems.

When GAMI gets G100UL certified, no doubt the received wisdom will become that the secret herbs and spices are 'lubricating the valves'. :D

Oracle1

2nd Aug 2013, 23:15

Having seen the inside of a Rotax that has been run on Avgas I can tell you that is is a serious contaminant within the engine. It leaves a paste of abrasive which cloggs the internals and the first thing that happens is the starter system which uses fine springs to disconnect the starter as the engine fires fails. I can tell if a rotax has been running Avgas just by looking at the oil, you can see the lead suspended in it.

In my 0-300 D I am convinced that the lead actually DAMAGES valves. Because it is a low compression engine the heads do not get hot enough to scavenge the lead. It actually forms deposits under the valve seat causing leakage and the valve starts to burn.

Wally Mk2

2nd Aug 2013, 23:32

'Griffo' you have created a monster here buddy!:)

Wmk2

Aussie Bob

2nd Aug 2013, 23:43

Well, from this thread I am convinced enough to go out and purchase a Peterson STC for my Scout. Then I can legally run PULP mogas. I can't currently get lean of peak cause she misses too much and doesn't really sound well. My multi point thingie Jabba convinced me was a good idea is still in the mail.

So perhaps someone could tell me, do I treat PULP like avgas? Do I lean as aggressively? Do I just fly and hope for the best. Given the nature of the machine I am seldom above 3000, but occasionally (like when over water) I like to climb up to the 9500 range of nose bleeding altitude.

Oracle1

2nd Aug 2013, 23:50

Install the engine monitor ASAP then you will know exactly what is going on. Best investment for the health of your engine!

Creampuff

3rd Aug 2013, 00:00

Oracle: Your earlier observation about the damage done by lead is spot on. As John Deakin has observed:Lead is not "good" for an engine, IT IS HARMFUL to engines. But if you want high performance from an engine, it is the least toxic of the presently known chemical additives that will allow high power without detonation.AB: Successful LOP operations do not depend on the fuel you use. Successful LOP operations are about getting each cylinder to reach peak at the same point as the others.

Once you get your multi-point thingy, you will be able to work out why your engine is behaving the way it is, and what to do to run it LOP (on either ULP or 100LL or (hopefully soon) G100UL). :ok:

Shagpile

3rd Aug 2013, 00:14

So how would PULP go with electronic ignition?

Reading the lightspeed FAQ, it looks like it does the same timing as mags at full power and as you reduce map (and rpm), it advances the timing to achieve peak power.

So advancing timing = bad for unleaded yes?

I wish gami would hurry up and get their prism onto the market.

General Aviation Modifications, Inc. (http://www.gami.com/prism/prism.php)

Creampuff

3rd Aug 2013, 00:33

Not quite. Advancing the timing too far is always bad, irrespective of what fuel you are using. It's just that, all other things being equal, the timing of an engine running on fuel that does not have a latency addititive (like lead) will not be able to be advanced as far as it would if it were running of fuel with a latency additive.

The lack of latency addititive in the fuel has an effect equivalent to advancing the timing, because the combustion event happens quicker which means the PPP happens sooner. If you advance the timing, the spark starts sooner, which means the PPP happens correspondingly sooner.

That's why PRISM, so far as I understand it, has senors to detect detonation.

Old Akro

3rd Aug 2013, 02:15

Not quite. Advancing the timing too far is always bad, irrespective of what fuel you are using.

I could take you next door and show you engines running happily with over 40 deg advance. Its a far more complex issue that involves variables RPM, load, mixture, type of fuel, cyl head design, spark plug location, intake design.

Its a complex issue, which is why engine calibrators are paid lots of money and headhunted from company to company around the world.

Thee is nothing wrong with leaded AVGAS. I was used for decades -= and in engines far more highly stressed than the GA fleet. Many race car engines still use it.

Old Akro

3rd Aug 2013, 02:18

I should add that AVGAS is also made to a tight spec. Australia has amongst the most lax fuel standard in the world. Unless you buy refined in Australia Shell, BP, Mobil or Caltex (While you can), then its a Russian roulette of imported fuel.

dubbleyew eight

3rd Aug 2013, 02:21

sorry to drift this a bit but I needed the sleep.

wallymk2 made a pessimistic prediction that there would be a difficulty in getting anyone to make G100UL and distribute it (in Australia).

throughout the centre of Australia there is OPAL. the low aromatic fuel created to foil the petrol sniffing kids. I havent seen or burnt the stuff myself but I believe it to be in wide distribution in the "centre".
by all accounts OPAL is just avgas without the tetraethyl lead in it.

if OPAL was replaced by G100UL the combined volume may just make the stuff a viable fuel for someone like AirBP.

certainly hope so.

Shagpile

3rd Aug 2013, 02:26

You can take the lead out and make the problems go away by retarding the timing. (Therefore, the magneto timing is definitely lubricating the valves ) But if you do that, you’ll create other problems.

Forgive my ignorance but what problems does retarding the timing make? Jaba mentioned hotter egt but I'm not following why...

Jabawocky

3rd Aug 2013, 02:35

Akro, the 40 degrees advance is probably happening on engines at 5000+ RPM if I were to bet on it ;) So lets not confuse the issue.

We have aeroplanes, with props (yeah wally props are for boats:} ) and those props want to turn at 2500+/- 10% so that has pretty much fixed the speed/advance thing.

The next issue is how much HP do we want? The engine designer starts with this, works out a BMEP and peak pressure and starts designing back from there.

So the relevance of what happens next door while technically interesting only has the science in common, the application of it for your average Chieftan or 414 is different.

I should add that AVGAS is also made to a tight spec.
Not really, the spec on making AVGAS is not that tight at all and BP98 would be a tighter spec. One of my flying buddies here at YCAB actually fiddles the knobs on the fuel factory and is paid a heap to do it, nice job, but the production of AVGAS makes him laugh compared to other fuels when it comes to spec. It has to meet certain specifications, but that is about it. Quality control after that is where the expense comes from.

Jabawocky

3rd Aug 2013, 02:43

W8

Sorry the G100UL will not replace OPAL. The kind of compound that makes G100UL work is definately not going to be suitable for that target market. The compound is called :oh:

Hope you understand :ok:

dubbleyew eight

3rd Aug 2013, 02:55

The compound is called

Hope you understand

:p ...so if it isnt suitable for breathing uncombusted, why is it going to be suitable for breathing once it is combusted?

are we going to see a disaster in the making like one of the current additives in unleaded that is yet to have a bacteria evolve that can break it down in the environment? serious question actually. we do need exhaust products to be biodegradable.

Jabawocky

3rd Aug 2013, 03:09

Shagie,

Forgive my ignorance but what problems does retarding the timing make? Jaba mentioned hotter egt but I'm not following why...

Well it works to a point but you can't have a fixed spark engine retarded all the way back far enough to erode the detonation issue without turning it into a problem for many engines.

The big engines already run in the 20-25 BTDC range, and they run two plugs. In terms of flame fronts that is twice as much as the car engine Old Akro refers to above. So when you consider a Turbo 540/550 engine at say 22d BTDC, it is already in its sweet spot full rich, so if you advance or retard the timing by say 3 degrees, it will lose HP.

As a by product, if you advance the timing, EGT will drop and CHT will go up. If you retard the timing the CHT will drop b the EGT will go up. We want less CHT and hence more detonation marging but we have a Turbine that has a limit of say 1650dF. So we are caught in a small window of reality physics. The lower compression TC engines (compared to 8.5:1 in say a TN) will always have higher EGT to begin with so the have less of a window.

Now if you get in your trusty C414 or a pressurised Baron or 402 and retard the timing enough to un on ordinary UL, life might be fine when running really rich or very LOP but the TIT will be on the limit and you can't use a mixture in-between, but you are OK because the power loss is only 30HP or there about, but what about when you have to shut one down or it does it for you :uhoh: Does a sizeable ROD concern anyone?

So in essence, changing the spark timing matters, there is only a small range of timing values that are useful on a fixed speed engine, and that is around 20-25 and at high powers you can't have more, although you can have a bit more when running well LOP or at low powers, but you need to take off first!

That help?

Jabawocky

3rd Aug 2013, 03:19

W8

I can't reveal any more but the compound blended with an existing high octane unleaded base stock is very readily available in refineries now and is no more a problem than anything else. It is made from the same basic elements of the periodic table that most other petroleum products have.

It is incredibly common. But I would not pour it on my corn flakes as much as I would any other petroleum product.:ok:

dubbleyew eight

3rd Aug 2013, 03:21

It is incredibly common. But I would not pour it on my corn flakes as much as I would any other petroleum product.

so it is not whiskey or beer. bugger :}

Old Akro

3rd Aug 2013, 03:38

BP98 would be a tighter spec

BP Kwinana is one of 3 BP refineries in the world that will meet the California fuel specs. It is the best fuel. It used to go into short supply every now and then because BP would sell a few tanker loads to California when the spot market price was right.

Although, my engine tuning mates get the best power from the United Racing fuel. We used to use AvgAS in the rally car until we turned to Philip racing fuel in pursuit of more power. I think it cost us $15 / litre and I haven't rallied for over 10 years.

Don't confuse company specs with Govt. specs. Australia has only had a National fuel spec for a handful of years.

Walter Atkinson

3rd Aug 2013, 04:24

A few things that ARE in harmony with the laws of physics:

1) Lead does NOT slow the burn rate of avgas. It increases the latency, which is the time it takes for the flame front to become organized after the spark event. This is why it suppresses detonation. After the flame front is organized the flame front moves at the same speed with or without the lead.

2) The iso-octane study done by the FAA took two NEW engines, one on the right, one on the left in a twin. One engine was run on 100LL; the other on 100 octane (iso-octane) with no lead. After several hundred hours, there was NO difference in the wear patterns in the two engines. NONE. This proved that lead had no effect on wear or exhaust valve life or performance. Lead is NOT needed in ANY way to help valves. Period. Parade Rest. It is used ONLY to widen the detonation margin.

3) The reasons seats were changed in auto engines when unleaded fuel came about was that the existing seats were not hard (like aircraft engines have always had). These issues are not in any way applicable to aircraft engines.

4) 100 octane unleaded fuel performs exactly like 100LL. Why? If you remove the lead in 100LL it is not 100 octane.

5) John Deakin is right. Everything he says about this topic is in harmony with Taylor, Haywood, and all other known sources of DATA, including the most advanced engine test facility in the world.

6) Many SAE papers on the topic of the effects of lead in combustion are flawed in that the studies did not control for internal cylinder pressures (which ARE the cause of the observed problems).

7) Healthy exhaust stains are a very, very light tan (almost whitish) because this indicates that the engine is being run at BSFC(min) mixtures (LOP).

I have data to support all of the above. I have been showing it during the APS classes for over a decade to thousands of pilots, mechanics, OEM engineers and combustion engineers from the engine manufacturers. Not once has anyone taken issue with the hard data or presented any contrarian data.

If you have any contrarian data (respectfully, no opinions, please) I would deeply appreciate seeing it.

If you would like to see this data, we will be presenting it in Ada, Oklahoma in October and Sidney in November (I think it's November--can't recall at this instant).

It seems as though everyone has an opinion on this topic, but it is worth remembering that the data has no opinion. It is what it is.

dubbleyew eight

3rd Aug 2013, 04:41

it may not seem it but I have no problems with decisions based on data.

Healthy exhaust stains are a ...

which fuel are you talking about???

100 octane unleaded fuel performs exactly...

octane rating is the detonation characteristic. octane rating has no effect on the energy released by the fuel which is about the same in all the petrols.

in all of this we still only have engines using about 25% of the energy and dumping out the exhaust 75% of the energy unused as waste heat.
it would be really lovely if people would see the big picture and engineer fuels that led to more thermally efficient engines.

now what I really wanted to do was ask a question.
80/87 avgas ran perfectly using REM40E massive electrode plugs.
the same engine will run 100/130 avgas quite well using REM38E plugs.
what plug is going to be needed for G100UL if it becomes widespread?

Old Akro

3rd Aug 2013, 04:45

Healthy exhaust stains are a very, very light tan (almost whitish)

Walter, correct me if I'm wrong, but this colour is only true for leaded fuel. Alas, you'll never see a road car with this colour exhaust any more.

When I was young I used to tune Weber carburettors by plug cuts and the looking at the colour of spark plug insulators. Many of the drag racing guys still do.

Checkboard

3rd Aug 2013, 12:12

TEL is never good for the engine. Why do you think they add in Bromine? Well to scavenge the lead after it finished with the latency issue they want it out! The result is Lead Oxybromide which is a salt.

Lead Oxybromide is a thing now? ;)

In my opinion, the ATSB has taken junk science, pure speculation and profound ignorance to levels seldom before seen. They have not only perpetuated "Old Wives' Tales," but they have invented a few new ones. I'm afraid we'll be hearing about "lead oxybromide deposits" for all eternity. As best I can tell, that term seems to have been INVENTED in this accident report. (Try a search on the Internet for "lead oxybromide"!)

Ultralights

3rd Aug 2013, 12:33

Walter, correct me if I'm wrong, but this colour is only true for leaded fuel. Alas, you'll never see a road car with this colour exhaust any more.
this could be the result of the catalytic converter, the exhaust residue colour of my 912ULS is a light brown colour.. and can also be seen as a very light brown staining on the bottom of the aircraft in a few spots. easy to clean off fortunately.

A Squared

3rd Aug 2013, 14:19

Ohh and by the way all those big old radials can have the Hi-Blower unleashed again on this stuff. It out-performs 100LL and the old purple stuff you might remember Leadslead.

Not true. Hi blower had nothing to do with higher power settings. On the DC-6* (R-2800-CB16 and CB17) high blower resulted in lower power and was not permitted at takeoff power (except above 10,000 ft, and at a greatly reduced MAP, RPM and Power output) Hi-Blower was there to take over in climb and cruise when the low blower ran out of steam at altitude. You'd reach WOT at climb MAP at about 12-13,000 ft in low blower.

*Which I flew for 8 years in all 3 seats

Jabawocky

3rd Aug 2013, 23:12

A Squared

Correct, and that was my mistake, the Connie runs reduced MP of 52" on 100LL :ok:

There must be a warbird or something like a T28 that runs a reduced supercharger setting that I am confusing it with. That will bug me all day now.

Thanks for pulling me up on that.

Jabawocky

3rd Aug 2013, 23:32

what plug is going to be needed for G100UL if it becomes widespread?

As best I can tell you will change nothing in the plugs. I do not know this for certain but as I understand it, the test flying has all been done with a standard engine and plugs in both planes. Walter will probably confirm this if he wanders into this thread again.

Checkers..... good catch! I meant to write Lead Bromide. Spend so much time time taking the you know what out of a famous report I end up repeating it. It would appear there is such a thing, (lead (II) oxybromide Pb3O2Br2) but we should be calling it Lead Bromide (PbBr2).

My bad again :oh:

Dexta

3rd Aug 2013, 23:36

What I want to know is... I have a O320-E2D running on PULP98 (with appropriate STC);
1. The STC (petersen) states to run a tank of AVGAS every 70-75 hours. I think it says because of the valves. Now this has been proved wrong, should I still do this to observe the requirements of the STC or not bother any more?
2. I only have a single CHT & EGT, I can lean it out to I get an RPM drop, which corresponds to roughly peak EGT. I run the engine around 70-75% power (2500 RPM @ 2500', 2600 RPM @ 5000', 2650 @ 9000') this is as per the Cessna manual. Now the manual was written for 80/87 AVGAS, can I assume PULP98 is close enough as to not make any difference, or should I do something different?
3. Re spark plugs, I am using REM38E, should I change to a different plug or not?
P. S. The engine appears to be running fine, CHT's around 350F in cruise, 400F in long climb (full rich), 30 litres an hour.

Walter Atkinson

3rd Aug 2013, 23:36

The G100UL fuel will run with the 38 heat range plugs just fine. It will also run fine on RGB29 plugs. The heat range was upped to burn off deposits. If one runs the mixture appropriately LOP, the cooler plugs will stay clean. Cooler plugs are less prone to cracking ceramics and leading to pre-ignition.

Walter Atkinson

3rd Aug 2013, 23:39

Exhaust stain color in autos is affected by the catalytic converters. The exhaust deposit color in aviation engines is a result of mixture more so than anything else.

Walter Atkinson

3rd Aug 2013, 23:44

There are a lot of OWTs about needing lead in the fuel to coat or cushion valves. ALL of these OWTs have been debunked. There is no science to suggest that the Peterson STC accomplishes anything by running a tank of 100LL every so often. It doesn't hurt, but it doesn't help, either.

Walter Atkinson

3rd Aug 2013, 23:48

BTW, there is mounting data that running the coolest plug possible (that does not foul) is a good idea. If you run LOP, you can run a much cooler plug since it will not be fouling anyway!! We have had good service running NA and turbo engines on RGB29 and even 27 plugs as long as the engines are run LOP. If you are a ROP operator, you will probably find that the cooler heat range plugs will be fouling. The higher the heat range, the greater the possibility of pre-ignition from a damaged plug.

dubbleyew eight

4th Aug 2013, 02:20

walter that all sounds good.
I'm just about to buy a new drum of avgas.
can we get a drum of G100UL to try yet?

I think it was the antarctic ice bubble samples that proved conclusively that there was no lead in the atmosphere until we started using tetraethyl lead in fuels. we can fix that.

Jabawocky

4th Aug 2013, 07:51

W8,

No the G100UL is not in production yet. There is an enormous effort being made to have the FAA certification done by the end of the year but it could take longer. Avgas will be around a little while longer although if Shell in Geelong shut the refinery, we will be left with BP Kwinana and Singapore. :uhoh:

So the sooner the better for us I reckon.

dubbleyew eight

4th Aug 2013, 08:11

ok we'll wait.

(but stuff me if we can use 91 octane ordinary motor fuel without problem let's get a move along.)

A Squared

4th Aug 2013, 11:32

the Connie runs reduced MP of 52" on 100LL

Yes, we ran at a max of 59.5"Hg for a wet takeoff with 100LL vs. 62" for an additional 100 hp/eng. if we had 108/135

Andy_RR

4th Aug 2013, 12:59

What's this latency of which the knowledgeable speak?

I've seen my fair share of indicator diagrams and destroyed enough pistons and barrels with knock in my life developing engines, but I've never come across the term.

Somebody care to explain?

Flying Binghi

4th Aug 2013, 13:30

via dubbleyew eight:

...I think it was the antarctic ice bubble samples that proved conclusively that there was no lead in the atmosphere until we started using tetraethyl lead in fuels. we can fix that.

I'd like to see a reference for that dubbleyew eight.

Considering volcanoes emit lead to the atmosphere i wonders how none were found in the Antarctic ice record. Perhaps volcanoes are new to Antarctica...

.

dubbleyew eight

4th Aug 2013, 13:58

my father warned me about people ruining good arguments by insisting on facts.:E

it was a comment by one of the climate wallahs during a documentary.
it was on the telly. they wouldnt lie to us would they.:oh:

le Pingouin

4th Aug 2013, 14:27

People far over-estimate volcanic contributions and far under-estimate human contributions.

Volcanic: 1200 tons Pb per year

Natural soil dust: 1400 tons Pb per year

Industrial: ~300,000 tons Pb per year

Magnitude of lead flux to the atmosphere from volcanoes (http://adsabs.harvard.edu/abs/1987GeCoA..51..675P)

Over-estimating volcanic activity leads to people swallowing this whopper:

When the volcano, Mt Pinatubo, erupted in the Philippines in 1991, it spewed out more greenhouse gases into the atmosphere than the entire human race had emitted in its entire YEARS on earth

The reality is Mt Pinatubo: 0.05Gt CO2, human activity: 30Gt per year.

Flying Binghi

4th Aug 2013, 15:03

via le Pingouin:

...Over-estimating volcanic activity leads to people swallowing this whopper:

When the volcano, Mt Pinatubo, erupted in the Philippines in 1991, it spewed out more greenhouse gases into the atmosphere than the entire human race had emitted in its entire YEARS on earth

The reality is Mt Pinatubo: 0.05Gt CO2, human activity: 30Gt per year.

News to me. le pingouin, atmospheric CO2 levels have been fairly well documented of late. Seems to me the increase of CO2 is all due to humans. Considering the atmosphere is still in a CO2 deprived state (plants grow better, need less water and produce more food at 1,200 ppm) i think we need to release a lot more yet.

Moving on...

via le pingouin:
...Volcanic: 1200 tons Pb per year. Natural soil dust: 1400 tons Pb per year.
Industrial: ~300,000 tons Pb per year...

For the discussion we'll run with those figures :)

Now, le pingouin. How much lead is used in Australia's avgas every year ?

.

A Squared

4th Aug 2013, 15:55

Now, le pingouin. How much lead is used in Australia's avgas every year ?

Your question got me curious.

Without spending a lot of time double-checking numbers the internet told me that 100LL contains 2 grams of TEL per US gallon. And the the US Avgas consumption (yes I know you asked about Australia) is 186,000,000 US gallons/year so that gives 372 tonne of TEL. According to my poorly remembered chemistry, Lead is 78% of the mass of TEL, so that would be 290 tonne of lead. Not as much as volcanoes, but not vanishingly insignificant either.

As far as Australia itself, one source I saw put AU avgas sales at about 80Ml/yr or about 21,000,000 US gal, which is about 11 percent of the US consumption, so that suggests roughly 31 tonne of lead for Australia.

le Pingouin

4th Aug 2013, 15:55

In 2010-2011 we produced 91Ml of AVGAS

http://www.bree.gov.au/documents/publications/energy-in-aust/energy-in-australia-2012.pdf

Doesn't break it down into type so pluck 0.7g/l Pb (from BP product handbook)

Yields ~60t Pb.

I think you'll find your claim about more food and less water at 1200ppm is rather less straightforward than you think.

Old Akro

4th Aug 2013, 22:21

Doesn't break it down into type so pluck 0.7g/l Pb (from BP product handbook)

This is pretty easy to get this from the oil company TDS

Shell 0.55 g/l
Mobil 0.53 g/l max
BP 0.52 g/l

This reduces your figure from 60t to 47t.

The consumption figure for the US is about 360t of lead. (186,000,000 gallons = 707,000,000 litres).

60t vs 360t is too high a %. I would expect that Australia should be about 10% of the US. But, the figure you quoted was production and not consumption. Consumption figures are readily available from the Petroleum institute or the ABS, but I've run out of time.

I also question your earlier figure of ~300,000 tonnes of lead per year going into the atmosphere. This would represent around 10% of total lead production.

rutan around

5th Aug 2013, 03:42

Andy RR
I had the good fortune to attend a GAMI forum with George Braly in Oshkosh on Friday. What TEL does is delay the start of fast burning of fuel at the spark event (thus making peak cylinder pressure occur where it's easier on the engine somewhere after TDC. Peak pressure is lower but occurs where it's mechanically more effective.) It also slows down the start of pinging because it takes a while for the pinging fire to get its act together in the presence of TEL. Once the fire gets going leaded fuel burns just as fast as unleaded. It's similar to burning large green wood piles. They take a bit to get going but once they do they burn hot and fast. This slow start is called "latency"
JABBA
Same forum. G100 UL is now approved as a drop-in fuel for all aircraft using 100 LL. Now all they need is for someone to start making it. Probable scenario is a state by state roll out. Greens or Govt will apply pressure and a state, perhaps California will outlaw unleaded. Before whenever a push came FAA pulled the safety card and said there was no known replacement. Well now there is.
All
I've seen the best and the worst over here. Innovation and lateral thinking in aviation everywhere. (They are too numerous list here.)
I've also seen Australia under Tony Abbot . The richest country in the world has beggars in the street (many ex military), a v--e--r--y s--l--o--w internet and in some populous places non existant and a crap hospital system. The wages are very low for people in semi and unskilled jobs and the unions have been legislated almost out of existence so there is no effective voice to fight unfair practices.
On a brighter note the Americans we've met have been very friendly and helpful.
Cheers RA

OZBUSDRIVER

5th Aug 2013, 08:20

RA....you been sniffing the product?

Jabawocky

5th Aug 2013, 11:11

I have....literally and it smells like ... :oh:

;)

rutan around

5th Aug 2013, 12:41

Oz
If I was sniffing I'd choose mo-gas . $3.64 per US gallon here in Oshkosh.Even I could support a habit at that price.http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/evil.gif
RA

le Pingouin

5th Aug 2013, 13:53

Akro, those figures you mention are for LL. Is that all you can buy these days? Serious question as I'm not a pilot. It was only a quick and dirty calculation to answer a question - production was the figure I found so I used it.

As to the 300,000t, it's quite probably a little dated - feel free to read the source paper or find alternate data :)

dubbleyew eight

5th Aug 2013, 14:19

rutan around you havent seen australia under tony abbot at all.

postscript.
if you mean that america is like australia will be under tony abbot then that is nonsense.
there is actually a study out there that shows that more people commit suicide under a liberal government than under labor governments. the study is a fact.
however I have had the experience of being in the welfare system under John Howard and under Labor. in my experience the welfare system actually worked better under John Howard than it has since. the government was managing the books and the money that the current government is wasting on interest payments was available to pay the welfare system.
the suicide statistics are because some people cannot handle the freedom to get out there and achieve and they feel abandoned. freedom isnt welcomed by some people.
you are sprouting bulls**t mate.

Walter Atkinson

5th Aug 2013, 16:06

Latency: the time period between the ignition event and the formation of a flame front.

This is why differing fuels will have differing EGTs and CHTs when used in the same engine. The G100UL has a latency very, very close to 100LL so there will be no need to change the timing on the engines. It is a drop-in replacement for 100LL and can be mixed with 100LL during a transition to unleaded fuel. And, it requires no special handling as 100LL does.

Knowing the latency of the fuel is important in the calculation of where the ignition event is engineered so as to produce the peak combustion pressure at about 15-16dAFTDC where the con rod-crank geometry transfers the most mechanical power from the chemical reaction inside the combustion chamber to the crankshaft.

Old Akro

5th Aug 2013, 21:42

those figures you mention are for LL. Is that all you can buy these days?

100 LL is the only AVGAS you have been able to buy for maybe 20 years. Suggest you research a little better.

Dexta

5th Aug 2013, 23:22

100 LL is the only AVGAS you have been able to buy for maybe 20 years. Suggest you research a little better.

I'm afraid not, we can only get 100/130 "Green" AVGAS supplied to us. This is the BP AVGAS and has about 50% more lead (0.85g/L as opposed to 0.56g/L for 100LL). We have been told by our supplier that the central and western states gets the 100/130, while the eastern states gets the 100LL. This has been confirmed by the fact that certain aircraft at Parafield are only certified for 100LL and they have to truck the 100LL from Victoria because they cannot get it from the Birkenhead depot.

Old Akro

5th Aug 2013, 23:32

Dexta

I'm stunned. Its been a while since I landed at Parafield, but at Adelaide International I only have the option of 100LL. Same at Port Pirie, Port Augusta, Whyalla, Olympic Dam, Coober Pedy, Murray Bridge, Waikerie, William Creek, Ceduna, Mt Gambier, Kangaroo Island. I think that's the total of My SA experience.

Creampuff

6th Aug 2013, 00:09

It's interesting to review the AVGAS MSDSs on BP Australia's website.

There are three.

One of them is for '100', and it says the colour is 'green'.

The others are for '100LL', and they say the colour is 'blue' (but each of these has different benzene levels than the other).

Perhaps BPA is still producing green (as well as LL blue). :confused:

OZBUSDRIVER

6th Aug 2013, 00:34

I am getting confused with the terms in this discussion. Latency? Time between spark and start of flame front????

See if I have this right, in a perfect stoiciometric mixture of avgas and air in a confined space at normal ATM. A spark is introduced resulting in a flame front propagating evenly in all directions at about the local speed of sound...340m/s.

if I increase the pressure in said closed vessel to a point where said stoic mixture ignition event turns from a nice steady 340m/s to a point where mixture begins to spontaneously ignite in front of the flame front increasing pressure and causing a supersonic 2000m/s shock wave induced detonation.

...adding TEL to this mixture keeps the stoic mixture happy to keep burning nicely at said higher pressure....where does latency come in? The ignition event occurs the flame propagates at the instant of the spark.

If you change the stoic mixture to one of NitroMethane and air under even higher compression...the flame front is happy to burn along at a sedate 100m/s...hence the need to run three times the advance in spark timing. 60+degrees advance....latency?...or just where you have to ignite the stuff to get peak pressure at the right point ATDC?

Happy for a link on "latency"

Creampuff

6th Aug 2013, 00:41

As Walter Atkinson said, latency "is the time it takes for the flame front to become organized after the spark event. ... After the flame front is organized the flame front moves at the same speed with or without the lead." :ok:

owen meaney

6th Aug 2013, 01:39

...... flame front moves at the same speed with or without the lead."
Are you sure about this?

OZBUSDRIVER

6th Aug 2013, 01:42

It makes sense that way...but....TEL keeps acting as a chemicals reaction within the flame front to "steady" the reaction..or, at least the way I think it goes.

100/130 will still detonate in a high compression, highly loaded up performance engine....thats when you need to think about changing to burning alcohol instead of drinking it....sorry for the thread drift.:\

rutan around

6th Aug 2013, 04:49

Oz
Normal flame front is no where near the speed of sound. A quick calculation will show you that even if you don't believe the data produced by others. Based on a IO 520 engine with a 4" stroke and a 5.25" bore operating at 2400 RPM and set to fire at 22 degrees of crank angle BTDC so the fuel burn finishes around 14 degrees ATDC. the following can be calculated.

The fuel burn lasts for 36 degrees of crank rotation. At 2400 RPM the crank rotates 40 times / second and one rotation (360 degrees ) takes 0.025 seconds. This means the fuel burn takes 0.0025 seconds. With both plugs firing each flame front only has to travel about half the the piston/ bore diameter ie 2.625" or 0.06667 metres .Using only my I- phone here on the shores of Lake Superior I make that 26. 67 m/sec or 96 kilometers/hr average.
Remember also that even in the best of engines the fuel air mix is far from homogenous. Pinging starts randomly in places where the temp and mixture most favor auto ignition. The TEL delays any auto ignition event from getting properly started . If an event does get going properly no amount of TEL will stop it.
Cheers RA

Flying Binghi

6th Aug 2013, 12:48

OK, seems there is somewhere from 36 to 47 tonnes annual use of lead in Oz avgas. For the exercise perhaps we can go worst case and use 47 tonnes.

What happens to it ? i guess it does its job and flows thru the engine and out to the atmosphere.

I see a comment on the lead accumulating in the engine oil. What percentage of the 47 tonnes of lead get changed out via the 25 hour oil changes. 5%, 20%, 50% ??? ...lets say two tonnes stay in the oil.

When the remaining 45 tonnes makes it out the exorst pipe, do this 'emitted' lead do the dust trick and float around for months at a time finnally settling somewhere mid Pacific ocean. Or do the heavy lead just fall to the ground in a matter of days ? Probably a bit of both.

Lets keep it a really bad worst case. Forty tonnes of lead gets put out over Oz. How bigs Oz... about 8,000,000 square kilometres. Where do avgas burning aircraft fly in Oz - from servicing remote Aboriginal communities to doing mail runs around regional centres to the local flying school. Just about every where. So its fairly evenly spread, though lead do accumulate, or so they say.

Now, i got straight F's in maths for the short time i were at school so yer better check me. Lets see, 45,000kg divided by eight million square km = .005625 Hmmm... bit hard to comprehend that amount over a square km, perhaps we need to work it to a square metre: .005625 divided by 1,000,000 = :ooh: Fleck ! me calculator caint work it out. Not enuf decimal place zero's.

...Anyway, there is an easier way to think about it. Next time yer open the box containing the latest wiz bang gadget from China - take a wiff, yer probably just got more lead inta yer in one go then a life time of sniffing avgas will do for ya.

Lead in avgas - Much ado about nothing...:hmm:

.

dubbleyew eight

6th Aug 2013, 14:56

you can look at lead dispersal another way.

if I take 23litres of avgas that is 23,000cc of avgas. I then spread it over 222km it ends up being a thread about 12lb fishing line. (I did work it out once quite accurately, but I forget the specifics) so of that 5% is lead.

5/8ths of stuff all really so go flying.

Old Akro

6th Aug 2013, 22:34

Next time yer open the box containing the latest wiz bang gadget from China - take a wiff, yer probably just got more lead inta yer in one go then a life time of sniffing avgas will do for ya.

From memory, lead-acid batteries are the major user of lead (over 50% I think) but paint is still maybe second or third.

Lead from car batteries / wheel weights has one of the highest recycling rate of any material (presumably behind metals like gold & silver!!).

Shagpile

7th Aug 2013, 06:59

What about when you inhale a nice dose of avgas burning in the morning wave...

Or get it all over your hands doing a fuel drain.

dubbleyew eight

7th Aug 2013, 08:16

shagpile have you ever felt stupid?
well it's the lead.
it was first noticed in japanese school kids who lived in heavily polluted city areas when leaded fuel was all the go. the lead diminished their intellect.
if you ever feel clumsy or bang your thumb with a hammer.
it's the lead.
if you ever wonder why people are so stupid at times.
it's the lead.

:E:E:E

seriously avgas is not harmful unless you get a really good dose into the lungs. then it'll kill you quick. read the materials data sheet.
if you are worried about the smelly hands nick into the loo and wash them.

Oracle1

7th Aug 2013, 08:36

Who's worried about getting avgas on them? I bathe in the stuff accompanied by Methyl Ethyl Ketone and a healthy dose of toluene. I find Kerosene better in warmer weather.

Shagpile

7th Aug 2013, 09:29

Haha I bet it's great for you.

Considering shift work is a known carcinogen (source: Dr Karl), I'm going to go with AVGAS is ******* bad for you.

Oracle1

7th Aug 2013, 09:43

I was being facetious I have an intolerance to hydrocarbon fume, gives me sinus infections.

To many paint jobs on other people's aircraft

glad rag

7th Aug 2013, 10:22

Bunch of Jessies.

I run a small engined "component doner vehicle" with a highly tuned to the 1.6 cvh, mass flowed head, high lift rally cam, twin 40's etc and add

http://tetraboost.com/

http://tetraboost.com/info/dosage/

to run at about 103-104 octane.

Helps that it's rear engined mind, :oh:

Flying Binghi

7th Aug 2013, 11:24

...What about when you inhale a nice dose of avgas burning in the morning wave......

Funny yer should mention "morning wave". Sea water contains three times the safe lead limit of the World Health Organisation (WHO) - Don't swim in it.
Spray from ocean waves produces atmospheric lead and is the cause of higher then normal soil lead levels near beaches. Breath deep next time yer at the beach, part of that beach smell is the aroma of lead..:ooh: ....Oh, and don't eat any sea food, its full of lead.

============================================

Excess lead is well proven to be harmful to health. Though excess of many things can be harmful. In Oz there have been some cases of excess lead recorded eg, lead mining areas and some oyster beds.

How much is to much lead ? The large scale experiment has already been done in Oz. Any 70+ year old Australian who were born in Oz has lived from childhood through the high leaded car fuels and leaded smog city hazes of old. They've played as children in lead dusted playgrounds, lived in heavy lead painted houses and drank water from leaded water tanks and probably chewed on a few lead toy soldiers. Probably had some lead shot at em as well.

Seems to me the 70+ crew did OK, supposed 'high' lead levels and all...:)

.

le Pingouin

7th Aug 2013, 13:48

It's still a serious problem in places like Port Pirie. Don't know where you're getting your seawater from Binghi but I suggest you stop using lead cups to collect the samples.

Flying Binghi

8th Aug 2013, 01:50

via le Pingouin:
It's still a serious problem in places like Port Pirie. Don't know where you're getting your seawater from Binghi but I suggest you stop using lead cups to collect the samples.

Now who'da thunk there were lead in sea spray...

le Pingouin, as dubbleyew eight discovered with Antarctic volcanoes, it depends where you hold your cup to do the testing..:)

There is believed to be over 20,000 active undersea volcanoes. There are unknown countless numbers of hydrothermal vents and undersea freshwater springs. All these volcanoes, vents and springs put out varying amounts of lead.

In the Australian context, rivers, lakes and springs naturally have varying lead levels. Bush fires produce natural lead emissions. Dust storms spread natural lead about. Even crops take up natural lead from the soil. All in all we is figuratively swimming in natural lead. (Edit just for le pengouin: dust storms, bush fires... But the science says our atmospheric lead levels are... When/Where did they hold out the testing 'cup' ?)

So, point be-laboured, with natural lead all round us yer can see that avgas adds about .000000000000005 % of sweet eef all to the Oz lead levels..;)

.

kabukiman

8th Aug 2013, 02:29

has anyone converted an aero engine to LPG? :p

rutan around

8th Aug 2013, 10:49

has anyone converted an aero engine to LPG? http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/tongue.gif
Yes. There was one at Oshkosh. A cub or something similar. It had a LPG tank under it, shaped something like a cessna206 baggage pod. Looked a bit draggy but I suppose that could be improved later once the concept of using gas was proved to operate safely.

rutan around

8th Aug 2013, 11:19

Edit for previous post. I don't know if the Cub was using LPG or if it was LNG. LNG would make more sense for a number of reasons that I don't have time to list just now.

Jabawocky

8th Aug 2013, 11:57

RA....how hard is it to carry around enough BTU's to equal a Bonanza or C210:E and 300L? Not likely to be easy I would think?

Worse still how about a canard machine :sad:

A Squared

8th Aug 2013, 12:13

It was a Husky (http://www.avweb.com/avwebflash/news/Aviat-Husky-Runs-On-Natural-Gas220307-1.html). Burned Compressed Natural Gas.

rutan around

8th Aug 2013, 12:24

Jabba
I have a mental picture of a RV-10 with two LNG tanks and looking something a C206 on floats.
I meant LNG is a better choice than LPG.
Off to Niagara Falls. In Aus we occasionally see someone driving on the wrong side of the road. Over here there are bloody thousands of them. http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/confused.gif

haydnc

24th Oct 2013, 10:43

Regarding a low compression engine aero engine, operating at reduced power (cruse) is there a problem running BP89 straight from the bowser? What if it is blended with some 100LL?

Is it a false economy economy to pay half the price of Avgas but only find it has to be paid for it in the long run (maintenance)?

What about the current cessna etc fleet STC'd for MOGAS that 'appear' to be operating engines on MOGAS without problems?

dubbleyew eight

24th Oct 2013, 11:02

I was flying my O-200 yesterday on 91 octane BP unleaded and was marvelling at just how well it was running on the car fuel.

the O-200 was designed for 80/87 so feeding it 91 hasn't hurt it.

Jabawocky

25th Oct 2013, 00:37

W8,

That is fine for the O-200 except the O200-D, but be careful with unleaded fuels and gum build up. Olefins in the fuel are a problem and ask me how quick I can strip and clean the 3 x dual throat carbies on a Yamaha V6 Outboard and reinstall, all thanks to the poor quality of regular mogas.

To answer Haydens question, the truth of the matter is most low power engines will run at low power on most fuels, however in an aircraft and in particular the IO engines, vapour pressure is a more serious issue than detonation margin. There is not enough control to categorically say use mogas. I will not use anything but avgas in my engine until there is a drop in AVGAS replacement. BP98 and Caltex 98 are probably as good as you will get but there is always some doubt.

Hot day in mid summer, hot fuel in wings, and climb to high levels to escape the heat and turbulence in any low wing aeroplane and you will see the issue of vapour lock running on Avgas. Mogas is not anything like the same in Reid Vapour Pressure terms. Avgas spec is 5.5-7.1PSI and mogas is usually well over 10.

As for the Octane rating, BP98 is a RON number and is about an 88MON (compared to 100-102MON for avgas).

Now do not get me wrong, unleaded avgas will be the best thing since sliced bread when it is available. TBO's will likely be 50% higher, Lycoming offer this in Europe to operators of the 94MON ULP, and the quality of the fuel in terms of an aviation grade unleaded will be such that all the random issues of mogas will not apply.

The solution is not far away, and it will change the way we maintain engines just like the changes ULP made to cars. This WILL be a good thing. Just wait a short while. ( I know thats been said before)

I have just spent 8 days straight at the pointy end of this (and my head hurts) so believe me when I say hang in there for not much longer.

dubbleyew eight

25th Oct 2013, 00:56

I wish, I wish people would take the TCP/IP route and not the Posix route to getting the fuel out there.
TCP/IP was the upstart that worked twice as fast as Posix and it almost went viral in some computing environments because the increased speed fixed network problems.

stuff the wait for certification.
sneak some out the back door so we can try it.
if I can use 91 without noticing the difference the newer fuel can only be better.

CASA you slow plodding elephant get the bloody lead out!

Jabawocky

25th Oct 2013, 02:14

W8,

If only it were that simple, and CASA would only slow it down.

You would probably not have any significant benefit from the aviation UL fuel in the O-200 other than less risks from mogas and varying fuel quality.

The final solution is a fuel spec that can be a drop in replacement, no difference to the pilot, the engine, the airframe, is able to blend in any ratio with existing avgas (critical for the changeover period) and still meet spec, and it needs to be fleet wide so at any one pump you can feed everything from the O-200 to a TIO540 or a R3350.

So far there is a fuel that will do this, and it is in the process of getting all the approvals. On the time scale of aviation.....not long to go, I hope!

It might breath a bit of life into GA. :ok:

OZBUSDRIVER

25th Oct 2013, 04:13

Jaba, hope springs eternal....if there is a need, would not mind tying up selling the stuff to normal servo's. Petrol heads will make the demand happen quicker than aviation....especially if it is way past 97RON!

Andy_RR

25th Oct 2013, 05:58

The solution is not far away, and it will change the way we maintain engines just like the changes ULP made to cars.

G100UL or 100SF?

sprocket check

25th Oct 2013, 08:50

Here's an interesting breakdown:

AVWEB (http://www.avweb.com/news/features/fuel_projects_stc_faa_avgas_epa_100ll_208068-1.html)

Jabawocky

25th Oct 2013, 09:19

Andy, it could be either, but only one requires no modifications and is drop in (fleet wide). One is able to be produced readily at just about any decent refinery the other is not.

Time will tell but which horse would you put money on? ;)

Andy_RR

26th Oct 2013, 06:51

Jaba, how is G100UL more "drop-in" than 100SF? (I'm assuming you're alluding to this, based on your connections to various folk over yonder place)

Jabawocky

26th Oct 2013, 08:10

Andy, I was being rather broad sweeping in my statement and not singling out any particular option for special treatment, however over the last 10 years there have been hundreds of fuel options tested by the FAA. Very few came even close and then the issue is that for any fuel to be a drop in replacement without hardware changes it needs to be not just an equivalent octane rating. A lot more to it.

What is critical besides the required performance parameters and material compatibility is that you can swap from one to the other and blend them in any ratio in the wing or the FBO tanks. Anything else than complete 'blendability' with existing 100LL is not going to work for the period of time it takes to change over. This is no easy task, and if it was easy, it would have been done long ago.

In summary any replacement for 100LL needs to be;
1. MON99.6 and supercharge rich rating of 130, or higher.
2. RVP of 5.5-7.1 PSI
3. Must not require modification to the aircraft/engine (read certification)
4. Must not have a derating of HP, most twins would be grounded if so
5. Needs to produced in sufficient volume to be rolled out across the USA, Canada, Brazil, Australia, Europe etc.

There are lots of other complex issues. In my opinion, so far only one ticks all the boxes, and that is based on a lot of recent research, more than I ever did at Uni :O My head hurts!

Old Akro

27th Oct 2013, 00:07

fuel options tested by the FAA.

The FAA is not the testing authority. Its ATSM International who have been criticised by the US Senate for their slowness.

There is an existing alternative to AVGAS for a large number of aircraft. Its called MOGAS. It seems to me that most carburetted single engined aircraft have a MOGAS STC available:

Petersen Aviation | Auto Fuel STC (http://www.autofuelstc.com/)

If we really wanted to get at the root of this issue, we'd look to the regulators that make transporting, storing and dispensing fuel for aviation many times harder than fuel for other vehicles.

Jabawocky

27th Oct 2013, 06:18

Akro, I beg to differ on this one. FAA at there engine test facility are the ones who had done significant testing, the last lot was about 30 odd of the leading brews over the last ten years.

ASTM are an industry body or association if you will. Big difference to what they actually do to what you are suggesting.

There may be MOAGS options for some, but the big users are the big engines and they can't have it. Its that simple. Two fuels on the field will not happen, or not very often.

Walter Atkinson

27th Oct 2013, 18:15

***If we really wanted to get at the root of this issue, we'd look to the regulators that make transporting, storing and dispensing fuel for aviation many times harder than fuel for other vehicles.***

You cannot mix AVgas and other fuels because of the lead. THAT is the reason it costs more to transport.

BTW, if we rely on Mogas to be the replacement, GA is DEAD. The engines that use 75% of the fuel cannot use Mogas.

If any fuel results in the derating of the engines it will mean the death of the twin fleet.

The ONLY answer that can save GA will have to be a drop-in replacement for 100LL, blendable with 100LL at any and all concentrations until the conversion to the new fuel is complete, is transparent to the operator, and keeps all engines operating without ANY modification. Any other notion is destined to failure. There is only one fuel that satisfies all of those requirements which is anywhere close to certification or is being tested in significant quantities by an independent source. Oh, and it can be made by a significant number of refineries--in short order.

Old Akro

27th Oct 2013, 22:13

You cannot mix AVgas and other fuels because of the lead.

I think that's regulatory, not technical. Which would be my point.

Regarding the ATSM, there has been extensive coverage in Avweb on this issue and if I recall properly there has been criticism of the ATSB for delaying the testing of alternate fuels in the US Senate.

Old Akro

27th Oct 2013, 22:29

Open Avweb today and what do I see?

Mogas: The Great Missed Opportunity - AVweb Insider Article (http://www.avweb.com/blogs/insider/Mogas-The-Great-Missed-Opportunity-220693-1.html)

Jabawocky

27th Oct 2013, 22:53

There may be criticism, but ATSM is not there to solve the problem as I see it. ASTM is and industry association which feathers its own nest in order to stay relevant. That is not a slagging off but a bit like "Standards Australia".

It is up to industry to solve the problem and then ASTM to peer review and publish a Standard or cookbook recipe page for the rest of industry to work to.

As Walter will no doubt confirm, not everything that gets printed in AvWeb is wholly reflective of the bottom line.

Walter Atkinson

27th Oct 2013, 23:30

I have the greatest respect for Paul Bertorelli and have considered him a friend for a couple of decades.

He knows that Mogas cannot and will not replace 100LL nor is that the point of his article. The point is that, yes, most of the low-use, low power, recreational pilots out there can continue to use Mogas as they have for a looong time…. BUT it will not work in the working fleet of high performance singles and twins. He has seen the data on the detonation margins on these fuels and he knows that it simply will not work in the high-powered engines without derating them--and that will kill the working twin fleet instantly. All sources seem to agree on that issue.

There is no Mogas formulation that can be the answer as a 100LL replacement. That's the science. Period. Parade rest.

In the current or foreseeable economical situation FBOs cannot afford the infrastructure of two gasoline products. It's NOT going to happen. We need ONE fuel that will service the entire fleet and allow profitability for the FBOs. If the Mogas crowd wants to continue to use it, fine… they can continue to haul it to the airport like I did for years.

100LL is going to go away and it should. We need a drop-in unleaded replacement to help GA survive--NOW. Without it, GA is dead. It may die anyway.

Based on what I know of the G100UL fuel under development, I doubt it will be priced much differently than 100LL--certainly not significantly higher. Based on what I know of Swift fuel it cannot be mass-produced as easily or economically.

FokkerInYour12

28th Oct 2013, 01:32

According to:
http://www.lycoming.com/Portals/0/Upload/SI1070S%20Specified%20Fuels.pdf
most low powered Lycoming aircraft engines (O-235, O-290, O-320, O-360 and most injected versions of the above) can use 93 "AKI" fuel. There are also a few other additional specifications relating to vapour pressure and oxygenate content.

AKI = (RON + MON)/2

From the regular fuels available in Australia from my brief research
Unleaded 91 RON = 87 AKI - ie unsuitable
"Premium" unleaded 95 RON = 90-91 AKI - ie unsuitable
Premium unleaded 98 RON = 93-94 AKI - quite possibly suitable

So there is some possible respite for flying schools with these fuel types... Of course, we need a new fuel truck and tank to handle it... which would possibly chew up all of the savings.

Lycoming's service instruction has this information though:

Automotive*ground*transportation*fuels*available*direct*to*c onsumers*(e.g.*“pump*gas”)*usually*do*not*have*labels*with*s ufficient*information*to*identify*compliance*with*the*requir ements*in Table*2.*While*indicated*octane*is*generally* necessary*for*display* at*retail*points*of*sale,*octane*rating*methods,* fuel* vapor* pressure,* oxygenate* content* and* ethanol* content* can* vary* widely* and* are*generally*known*only*at*the*wholesale*terminal.

(sorry about the *s - a copy and paste from a PDF).

Current average price for 98 RON in Perth is $1.60
AVGAS at Jandakot is $2.16

Old Akro

28th Oct 2013, 02:54

BUT it will not work in the working fleet of high performance singles and twins.

Correct! With only a couple of exceptions there are no MOGAS STC's for injected engines. And the engine I care most about (TSIO 360) is one of the most problematic. It is conceivable that Seneca's / Turbo Arrows / Turbo Mooneys become unusable.

However, 91 RON MOGAS STC's are currently available for the majority of Cessna and Piper singles and a bunch of Bo's. Collectively, C150, C172, C182, PA28's would represent (In Australia) about 20% of the fleet by numbers and probably much greater in terms of fuel consumed because this is the training fleet.

These aircraft could run on MOGAS within weeks. But why hasn't made any significant penetration? Because no-one has the dual pumps (80/87 & 100/130) that they used to and the unduly arduous regulations for aviation fuel handling make it not worth airports investing the money in additional pumps for MOGAS. This will be an impediment to the introduction of 100LL replacement fuels also.

Andy_RR

28th Oct 2013, 03:44

so, these big twins can't take a lower RON/MON/AKI fuel because they're highly boosted etc etc etc...

...however, if you look at the FAR's you have to, by regulation, run the engines extremely rich to leave a huge knock margin because noone really knows if the engines are going to knock or not under all circumstances.

Now, if you adopt UL fuel of any sort, suddenly, closed-loop fuelling control becomes possible, and with wide-band lambda/oxygen sensors, you can run rich and still be in control - i.e. you no longer need enormously wide margins to allow for component and calibration tolerances. You would have to change the FAR's to allow this though - a legal problem more than a technical challenge.

Add to this some closed-loop knock control and you could readily run within a gnat's cock of the knock limit all the time.

This should allow either an improved CR or a reduced fuel AKI rating (or both) for the same power. Not only that, but its highly likely your fuel consumption for the same power will drop usefully.

I'm guessing that this might be what Lycoming have achieved with their iE2 system, expensive and complicated as it is. I have no idea how successful they have been with it though. Is anyone out there running one?

Old Akro

28th Oct 2013, 03:51

AndyRR

I would love to have a go at that. A Motec system would be relatively cheap and sensational. Half the problems with converting to alternate fuels is the fuel handling. If you could use modern solid state fuel pumps it would be so much better. But just thinking about the grief you'd get from CASA makes my head hurt.

Jabawocky

28th Oct 2013, 05:09

Geez if it was all that simple.....somebody may have done it by now ;)

Andy, you are onto some of it and yes the GAMI PRISM system will help but there is more to it than that.

I have seen PRISM working on the Dyno, and it works very well at killing off detonation however on premium car gas it works, but not all mogas. This requires pressure sensors not the conventional auto acoustic sensors. Again not that simple.

The problem then is of derating the engine due to massive retardation. The piston twin feet can't cop that, they struggle as it is.

The solution is to build a fuel that works, supply it via a tight quality control delivery service and all is good in the world. This discussion is likely to be very different in a years time.:ok:

I'm guessing that this might be what Lycoming have achieved with their iE2 system, expensive and complicated as it is. I have no idea how successful they have been with it though. Is anyone out there running one?
The problem is their sensors can't handle the leaded fuel, and once that is gone it will be a perfect power plant, and a LOP one at that ;) Mike Kraft (Lycoming)is very keen to see this happen and publicly says so.

Andy_RR

28th Oct 2013, 07:27

Yes, I agree that it isn't simple. I'm not suggesting it is, but it is possible!

I'm sure that PRISM is a great thing too (the GAMI one, not the NSA version!), but from what I see, it still is only manipulating ignition angle with no control over air-fuel ratio. The two are/need to be very closely related if you want to reduce your margins to nothing. Also, while it's nice to measure cylinder pressure for knock estimation, it's not the only method out there. Spark ionization can yield some good results and piezo-acoustic knock sensors are also far from useless old-tech.

And as for de-rating, well engines are derated with altitude, temperature and condition all the time, only we have at best a few rules-of-thumb methods to predict and deal with it. At least a FADEC-type system could give you an accurate and real-time power prediction to give you a go-no-go decision point for the take-off roll. Such a system could also include a fuel quality warning based on ground run-up data.

I think GA would be better learning to adapt to an automotive gasoline standard that would be mandated at some known future point rather than waiting for another expensive, low-volume, silver-bullet fuel to arrive.