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rutan around
28th Nov 2013, 22:10
In recent years I have been led to believe TCM was dragged kicking and screaming into the 21st century and that their injector nozzles whilst slightly inferior to the GAMIs were at least balanced to meet the different fuel requirements of the individual cylinders.
This belief was strengthened when I noticed each nozzle was numbered 1-6 and installed in the corresponding cylinder. What I didn't notice was that part numbers after the 6 different first digits are all the same.
Shock horror. I've now discovered that all 6 nozzles have identical sized bores and all flow the same rate. No wonder I couldn't lean my new IO- 520 properly.

I've now been informed that while TCM do make balanced injectors for some IO-550s they don't bother with IO-520s
If there are still any troglodytes out there that don't believe 520's need balanced injectors I have a set of TCM injectors hardly used - cheap.http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/evil.gif

I'm now wondering how many other owners and LAMEs believed TCMs numbered injectors meant they were balanced .
Cheers RA

Walter Atkinson
28th Nov 2013, 23:23
Both standard and "balanced" injectors are available form TCM for the 520 and 550. About 30% of the balanced injectors are "balanced." TCM cannot tweak them to be balanced like GAMI can on theirs. Comparing TCM's "balanced" injectors to GAMIjectors is a very poor comparison.

If, OTOH, you get lucky and get a good set of TCM balanced injectors… good for you.

Jabawocky
28th Nov 2013, 23:23
I'm now wondering how many other owners and LAMEs believed TCMs numbered injectors meant they were balanced .

In my experience, they all believe they are the factory tuned (GAMI like) injectors.

One CMI (TCM) employee admitted that their injectors are balanced……they weigh exactly the same amount. :ouch: Probably true.

RU, as you should know, ;) , the only way to ensure you have balanced F/A ratio's is to do each engine in its own airframe and do the work. CMI are not able to do that nor could they on 3000+ engines a year.

This is part of the reason GAMI have such a good business. They do what others can't.

So the answer for you is order a set of GAMI's and then do the GAMI lean test to verify they are within acceptable limits.

The number of LAME's and engine builders in Australia that I can be sure have the understanding of all this is able to be counted on my fingers (no thumbs required) so the chances you have a LAME that understands all this is highly unlikely.

Review your online course subscription for fuel air ratio analysyis :ok:

ForkTailedDrKiller
29th Nov 2013, 00:46
The Fork Tailed Dr Killer has a newly installed factory-reman IO520. Hope to fly it next week.

I am under no illusions that its injectors are anything more than .................... just injectors!

Dr :8

Wally Mk2
29th Nov 2013, 02:13
.................sheeze Dr how long has that V-tail been languishing at the back of the hanger for?:)


Wmk2

ForkTailedDrKiller
29th Nov 2013, 02:21
3.5 yrs Wally! Long story!

But almost restored to her former glory.

Praise the Lord and clear the airways! The Fork-tailed Dr Killer is about to fly again! :E

Dr :8

PinkusDickus
29th Nov 2013, 03:26
And will we see any pictures of the beast?

VH-XXX
29th Nov 2013, 03:36
And will we see any pictures of the beast?

Jabba usually posts some good pics from behind the Bo because it's always in front of him. Expect to see some of those.

ForkTailedDrKiller
29th Nov 2013, 06:16
PinkDick, at risk of drifting this thread any further, this would be the BEST picture by far that I have of the Forktailed Dr Killer!

http://www.fototime.com/DBE5F4FFEF39198/standard.jpg

The old donk had Gamis but IMO was never quite happy LOP.

Dr :8

rutan around
29th Nov 2013, 06:32
RU, as you should know, http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/wink2.gif , the only way to ensure you have balanced F/A ratio's is to do each engine in its own airframe and do the work.

That's right. rub it in Jabba. http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/boohoo.gif I bought an Australian overhauled exchange IO-520.
Fitting GAMI injectors was discussed but as I was having new fuel components from TCM fitted and TCM nozzles came with the kit I decided they would be ok. Lending strength to this decision was the good experience I'd had with my last engine which had TCM injectors.It was very smooth.
After reading Walters post I realize I was just lucky last time.

TCM -CMI should lift their game. They put out a handbook that condones running their engines on the edge of disaster based on a CHT reading from only one cylinder and an EGT reading which is the average of three cylinders. All this when they know their temperatures are all over the place due to their failure to rectify known design faults. :ugh:They treat us like mugs because they know that cylinder failure is a gradual event that normally occurs outside of warranty and if earlier it's the pilots fault anyway.
When the revolution comes CEOs from companies that overcharge and under deliver will be first up against the wall.:D
Cheers RA

Walter Atkinson
29th Nov 2013, 23:27
**TCM -CMI should lift their game. They put out a handbook that condones running their engines on the edge of disaster based on a CHT reading from only one cylinder and an EGT reading which is the average of three cylinders. All this when they know their temperatures are all over the place due to their failure to rectify known design faults. They treat us like mugs because they know that cylinder failure is a gradual event that normally occurs outside of warranty and if earlier it's the pilots fault anyway.**

To be fair, those recommendations do not come from TCM/CMI, but from the airframe OEM.

I do hear what you say, however.

Old Akro
2nd Dec 2013, 01:53
Shock horror. I've now discovered that all 6 nozzles have identical sized bores and all flow the same rate.

I'm not a major fan of Continental mainly because their QC is so bad. Walter knows much more than probably any of us (or all combined), but there is no mystery about aircraft injection. Its what is colloquially called "piss & dribble". The injectors are pretty much brass fittings with a hole that sprays fuel continuously. This is nowhere near car injectors which spray a timed jet of fuel at the optimal part of the cycle - aircraft injectors emit a constant stream of fuel regardless of whether the valve is open or not. The amount of fuel depends on the fuel pressure & hole size. Full stop. Its not much more technical than punching a hole in the bottom of a can and letting fuel pour out.

The diameter of the hole and the surface finish of the hole are critical to the amount of fuel dispensed. A score from the tool machining the hole can affect the fuel flow. With all due respect, you are unlikely to be able to measure the bores with the required accuracy to tell a difference. If you wanted to have a go at looking for differences you should try jerry rigging a flow bench with a fuel pump and a safe-ish fluid, maybe diesel. It won't be completely accurate, but should show a difference when you time a measured amount squirting into a bucket.

All this means that manufacturing quality is critical, which is where Continental fails & GAMI wins.

The other issue is that the design of the Continental intake tubes is from somewhere around the Jurassic era. The lack of any hint of attempt to create tuned length intake runners, similar length intake runners, smooth intake runners, matched plenum tube volumes or apply any scientific design means that the fuel charge is not even from cylinder to cylinder. Tuned injectors is really code for delivering different fuel quantities to different intake runners in an attempt to get each cylinder to receive the same amount of charge (fuel/ air mixture).

If this was a car engine and didn't have the certification issues of aircraft, there would be some guys making replacement intake manifolds by now.

5-in-50
2nd Dec 2013, 08:18
Do you think there is much of a future in piston engine R&D, or is turbine the way of the future?

Howard Hughes
2nd Dec 2013, 08:52
Praise the Lord and clear the airways! The Fork-tailed Dr Killer is about to fly again!
It's been so long, I'm surprised 'the Doctor' hasn't died of old age before the V-tail had a chance to get him! ;)

ForkTailedDrKiller
2nd Dec 2013, 09:18
Quote:
Praise the Lord and clear the airways! The Fork-tailed Dr Killer is about to fly again!
It's been so long, I'm surprised 'the Doctor' hasn't died of old age before the V-tail had a chance to get him! http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/wink2.gif

Was starting to look a bit that way Howard but I have a few good years left in me yet! :E

I had a dream the other night: - test flight of the FTDK - EFATO - put it down wheels up off the end of 01 - walked away unhurt! :ok:

Dr :8

Hasherucf
2nd Dec 2013, 10:25
I wonder how many of you guys have used a portaflow test box to adjust fuel flows. Drain lines to analog gauges and compare between that and the test box.Found the portaflow box fantastic when I can source one, especially on Turbo charged engines.

Walter Atkinson
2nd Dec 2013, 17:34
Old Acro:

Essentially, you are correct, but it may interest you to know that TCM created a pulse injector system more than 40 years ago. It worked. They discovered that at the rpms and power settings these engines operate, it showed little to no improvement over the constant flow nozzles… but with much more cost and complexity, so the project was scuttled.

It is easy to throw stones at TCM about the "old technology" but in many cases the "old technology" is still better than anything available "for the aircraft application."

There is nothing, and I mean NOTHING that has come out of the auto industry that can compete with the TCM or Lycoming engines at the power settings we consider "normal." According to one engine test engineer in Detroit, if the best engine test facilities in Detroit run their best auto engine at 75-80% power, they can only get about 300 hours out of them. If it were easy, everyone would finish the 24 hours of LeMans. Not all even make it 24 hours at the same powers we ask of our aircraft engines every flight.

It's worth pondering.

PhillC
2nd Dec 2013, 20:24
Do you think there is much of a future in piston engine R&D....?

Yes, but perhaps not Avgas burning piston engines. Mogas and diesel applications still have plenty of scope for R&D.

Jabawocky
2nd Dec 2013, 23:50
I am not so sure. The laws of physics apply the same now as they did before, and Diesel and low octane mogas struggle to provide sufficient power, efficiency and light weight.

These are three things a GA plane needs, and so far JetA burning diesel and turbine do not tick all the boxes. Nor can low compression mogas burning.

As Walter has mentioned above, these old technology engines still lead by a long way when you boil down the hard facts of what a GA plane needs. When you look at it, this is why we have had piston high octane burners for so long.

Invent a few new laws of physics, and it may be different.

Old Akro
3rd Dec 2013, 00:12
Just remind me - How many companies have gone broke chasing the lure of JetA-1 powered piston aircraft engines?

In Europe (for cars) the pendulum is swinging back from diesel to petrol cars. It is believed that petrol engines can be ultimately more efficient than diesel. A lot of development work is now being done on small capacity (sub 1.5 litre) turbocharged petrol engines.

Aussie Bob
3rd Dec 2013, 09:11
Just remind me - How many companies have gone broke chasing the lure of JetA-1 powered piston aircraft engines?

Also, how many companies have gone broke trying to better the avgas burners we are currently using. Pretty neat thing my O360.

rutan around
4th Dec 2013, 19:17
Do you think there is much of a future in piston engine R&D,
Before companies pour money into R&D they should take a long hard look at their current product. They would discover that for little or no increase in their selling price they could more than halve the effective cost to their long suffering customers.How?

I'll use the IO520 as an example.New it currently sells for near Aust $50,000 and has a TBO of 1800 hours. Increase that to 3600hours and immediately the effective cost is halved. Is this possible? In the fifties and early sixties it was done with the most complex reciprocating engine ever built - the turbo compound R3350. This engine had 6 times the capacity of a 520 but put out 12 times the horse power. In cruise it achieved a specific fuel consumption of 0.4 or better .
They achieved the long life and low fuel consumption by running LOP.
All Continental has to do is sort out it's intake system and then bite the bullet and subcontract the injectors to GAMI.They should then do a deal with suppliers of engine management systems and mandate their installation. Finally they should educate their customers how to run the engine LOP.
I said more than half. The rest is fuel saving over the life of the engine With mine I save 5 litres per hour running LOP . At $2.2 per litre over 3,600 hours the saving would be $39,600 . Worth doing I think.

andrewr
4th Dec 2013, 21:55
There is nothing, and I mean NOTHING that has come out of the auto industry that can compete with the TCM or Lycoming engines at the power settings we consider "normal." According to one engine test engineer in Detroit, if the best engine test facilities in Detroit run their best auto engine at 75-80% power, they can only get about 300 hours out of them. If it were easy, everyone would finish the 24 hours of LeMans. Not all even make it 24 hours at the same powers we ask of our aircraft engines every flight.

I don't think that's really true. Auto engines would be getting well over 1 hp / cubic inch - more than 2 hp in many cases. Aircraft engines get around 0.5 hp? So 80% power on an auto engine might be 200-300% of the power you get from the same capacity aircraft engine. How long could an IO-360 sustain 400hp? I don't know how much power they get out of LeMans engines. I wouldn't be surprised if it was 3x what they get from a production engine, so maybe 10x the power per cubic inch of a Lycoming?

Maybe power/capacity is not a fair comparison - but it's better than a percentage of an arbitrary number that was set in part based on the reliability required.

To be frank, auto manufacturers can't afford to make engines as fragile and finicky as aircraft engines or their reputation would be junk. I have no doubt that if you had a projected market of a few million engines, auto engine designers could easily design and build an engine that was smaller, lighter, cheaper, more powerful and more reliable than current aircraft engines.

The problem is then the aircraft manufacturers would say "What we really need is something about the same size and the same weight as the current engines. And not too much more power either..." (or you run into potential problems with VNE etc) So you need to design new aircraft too. Unfortunately, the market doesn't exist to support it.

rutan around
4th Dec 2013, 22:37
Andy
To be frank, auto manufacturers can't afford to make engines as fragile and finicky as aircraft engines or their reputation would be junk
If this is true why has every attempt to use Auto engines in aircraft ended either in abject failure or major disappointment in the sustainable power reliably produced?

andrewr
5th Dec 2013, 00:13
If this is true why has every attempt to use Auto engines in aircraft ended either in abject failure or major disappointment in the sustainable power reliably produced?

It's typically not problems with the engine itself, but with changes or systems that have to be designed to install it in an aircraft:
- A custom cooling system, to provide enough cooling without excess drag
- A system to turn the propeller at an appropriate speed, without transmitting vibrations to the engine that it is not designed to handle
- Perhaps, you put a different ignition system on to give you redundancy
- Perhaps, the oil system (sump) is not designed to work in the range of attitudes encountered in an aircraft.
- You probably have to fit all this in a space designed for some other type of engine

None of these systems are likely to have the detailed engineering work done that was done on the original engine installation, and they are the typical areas where problems are encountered. It's no different to dropping a Lycoming in a car and discovering you have cooling problems, and have to strip the engine after a sudden stoppage when your foot slipped off the clutch.

I'm not arguing for auto engines in aircraft. Creating a reliable installation is a major undertaking. It's much easier to choose an engine that was designed for the task, where it is well known what is required for a reliable installation. But I don't agree that aircraft engines are superior technology to auto engines.

Some of the things encountered in aircraft engines that would not be acceptable in a car engine:
- manual mixture control. My car engine automatically runs lean cruise (lean of peak) when power settings allow.
- worries about shock cooling
- having to strip an engine or check the crank after any sudden stoppage.
- a manual primer pump, or the incantations required to start a hot fuel injected engine. Chokes on cars disappeared decades ago, if you told people a fuel injected engine could be harder to start than a carby engine they would think you are mad.
- new engines making metal with the frequency that seems to happen with aircraft engines
- worries about corrosion in engines that sit unused for a while
- changing a cylinder etc. way before the projected engine life.

rutan around
5th Dec 2013, 01:11
Andy, An earlier post stated that aircraft engines need to be powerful, efficient and lightweight. I think reliability and (within reason) simplicity should be added to that list. Every new system introduced adds to original cost plus ongoing maintenance costs. Every additional system is another potential point of failure. If it aint on there it can't fail.

One old engineer reckoned water cooling an aircraft engine made as much sense as air cooling a submarine.
Another factor often overlooked is total installed weight. It's all very well producing 4HP per cubic inch or whatever but it's not much use if you then need huge radiators,huge oil coolers and a strong heavy gearbox specially made with appropriate torsion dampeners to make it all work.
All the above doesn't mean that there isn't room for improvement. One of the most promising is the PRISM system being developed by GAMI. If you're not familiar with it Google it up. Many of the problems with air cooled cylinders should disappear once a PRISM system is installed.

BEACH KING
5th Dec 2013, 03:49
It's typically not problems with the engine itself,
Oh yes it is. This new type auto based engine must operate at 85-100% of it's maximum rated power for it's entire life cycle at a very high RPM, which causes accelerated engine wear. Auto engines are not so designed, and hence cannot do this. An example of this is the Bathurst 12 hour race for the "showroom" class. A good many of these cars have engines fail.
but with changes or systems that have to be designed to install it in an aircraft:
- A custom cooling system, to provide enough cooling without excess drag
- A system to turn the propeller at an appropriate speed, without transmitting vibrations to the engine that it is not designed to handle
All this adds weight and service complexity compared to existing aero engines.
- Perhaps, you put a different ignition system on to give you redundancy
- Perhaps, the oil system (sump) is not designed to work in the range of attitudes encountered in an aircraft.
- You probably have to fit all this in a space designed for some other type of engine
All these "perhaps" mean large development costs, and a high sale price to recoup investment over a very small market.

I don't agree that aircraft engines are superior technology to auto engines.
You got that right. Aero engines are Jurassic. However, like it or not...what we have is going to be around with no alternative while fossil fuels are the power source. The reasons for this are weight and cost of any new development. Don't get me wrong... I would love to be able to buy a new technology engine that costs about the same, has the same horsepower, same weight, and less fuel flow. Sadly.. ain't gonna happen

Aussie Bob
5th Dec 2013, 07:51
Some of the things encountered in aircraft engines that would not be acceptable in a car engine:
- manual mixture control. My car engine automatically runs lean cruise (lean of peak) when power settings allow.
Does it? How do you know? When did you last take your car to 10,000 feet or even go through a wide change in atmospheric pressure? You may want the mixture dumbed down, I don't.
- worries about shock cooling
I don't worry too much about this, Jabba will pipe up shortly, shock cooling is mostly an old wives tale, not an issue.
- having to strip an engine or check the crank after any sudden stoppage.
This is safety issue, not an engine issue! and how often does your car engine suddenly and instantaneously stop while developing 75% or more power? Having kicked around the industry for a while, I have seen engines suffer a prop and go straight back into service numerous times. Most engineers will tell you that a prop strike at low power settings is highly unlikely to cause damage.
- a manual primer pump, or the incantations required to start a hot fuel injected engine. Chokes on cars disappeared decades ago, if you told people a fuel injected engine could be harder to start than a carby engine they would think you are mad.
Hard to start engines can be a problem for some pilots, I have always been able to get them started without major problems. Cars aren't impervious from this problem either.
- new engines making metal with the frequency that seems to happen with aircraft engines
How many car filters have you cut open?
- worries about corrosion in engines that sit unused for a while
Made of metal? It will corrode. This problem is in all engines.
- changing a cylinder etc. way before the projected engine life.
Not all that common when the cylinders are correctly prepared before service

Andrew, old technology does not mean bad technology. Current piston aero engines are outstanding devices. If it aint broke there is no need to fix it!

andrewr
5th Dec 2013, 22:50
This new type auto based engine must operate at 85-100% of it's maximum rated power for it's entire life cycle at a very high RPM, which causes accelerated engine wear.

As I said in post #23, rated power is an arbitrary number, based in large part on how long you need the engine to last at that power. Yes, you might have problems if you use the quoted power in an auto application as the rated power for an aircraft application - but again, that might be 4 times the power/capacity you get from a Lycoming. If you were developing an aircraft engine you would be more conservative in setting the power rating.

BEACH KING
6th Dec 2013, 00:15
As I said in post #23, rated power is an arbitrary number, based in large part on how long you need the engine to last at that power. Yes, you might have problems if you use the quoted power in an auto application as the rated power for an aircraft application - but again, that might be 4 times the power/capacity you get from a Lycoming. If you were developing an aircraft engine you would be more conservative in setting the power rating.

I see your point, however your "arbitrary" number will never be achieved at less than 2500 RPM, which is the requirement to eliminate the need for a weight adding reduction system. Auto based engines can never produce the required horsepower at such low rpm, and be of a small physical size and cubic capacity and be of caparable weight. So it's a given that some type of rpm reduction system must be incorporated, which means weight and something else that can potentially fail (Thielert gearboxes anyone?)

By your post quoted above, I think that you mean that an automotive engine capable of producing 500HP can be derated to reliably produce 300hp continuously?
For an example, I have just taken delivery of a new Mercedes Benz A45 AMG. Mercedes claim the engine in this vehicle to be the most powerful production 4 cylinder engine ever made. It produces 385hp from it's 2 litres with a large turobcharger producing 26psi of boost. It will propel the car to 100km/h in 4.6 sec and claimed fuel economy is 6.9l/100km. It is actually capable of producing 300hp at 2500rpm. So we can potentially use this engine without a gearbox.
It weighs 150kg dry compared to 218kg for your average IO550. With a cooling system and other necessary equipment, it could potentialy weigh less than the Continental. Would this Benz engine last 2000 hours? What fuel flow would you get? Would you be able to keep this engine cool at altitude? I'd rather you be the test pilot. ;)

andrewr
6th Dec 2013, 01:14
I'm not arguing for auto conversions. My original statement was:

if you had a projected market of a few million engines, auto engine designers could easily design and build an engine that was smaller, lighter, cheaper, more powerful and more reliable than current aircraft engines.

But, you would likely end up with a different form factor and weight, which would require airframe changes. And that size market doesn't exist, so it is unlikely to happen.

Incidentally, I suspect that if you did design such an engine, it would have liquid cooling and a gearbox. The advantages from smaller components (which are inherently stronger and lighter) and not having to have finned cylinders and head assemblies to allow a few hundred hp worth of cooling from passing air would offset the cooling and gearbox weight.

I'm sure reliable light weight PSRUs could be designed. With enough money, computer analysis, testing and engineering expertise (not to mention existing successful and less successful examples) it could be done. Would it be easier or harder than designing an automatic car gearbox? I don't know, but I suspect many of the problems would be similar.

ForkTailedDrKiller
6th Dec 2013, 01:18
It will propel the car to 100km/h in 4.6 sec and claimed fuel economy is 6.9l/100km.

I bet it doesn't use 6.9 l/100 km while propelling the car to 100 km/h in 4.6 sec! :suspect:

BEACH KING
6th Dec 2013, 02:51
That's for sure :E

Aussie Bob
6th Dec 2013, 05:18
Next time you blokes see an aero engine, look very closely, for its capacity it is very small and quite light. Its fuel burn when expressed in fuel per HP is right up there with a modern auto engine and it is reliable and proven.

Just because the design is old doesn't mean it is not good. Many have tried to improve it over the years, no one has succeeded. Anyone remember Orenda? or Porsch?

Jabawocky
6th Dec 2013, 13:24
BSFC and TBO

EOM

dubbleyew eight
6th Dec 2013, 13:37
my previous neighbour had a race car that did the same speed as my aircraft's cruise speed.
I asked him how much fuel he used. 200 litres for 8 laps of wanneroo.

to do 222km I use about 21.2 litres.

</sarcasm on> aircraft are dreadful arent they </sarcasm off>

Aussie Bob
6th Dec 2013, 19:23
BSFC and TBO EOM

:ooh: Yep that too! Thanks Jabba, correct terminology helps ...

rutan around
6th Dec 2013, 21:00
EOM
You had me there Jabba. I had to look it up on Google. What can I say ? WIBF?