43inches

There is a broard sweeping statement in all of this. One first of all has to assume that the injectors are well balanced. I flew an IO540 recently, straight out of the box, genuine Lycoming, and bugger me if the peak egt from 1-6 all happened in under 0.2GPH, it went LOP no trouble at all sorts of power settings.

On the other hand.....mine was a PIG, I could not get LOP without it being rough. We had to do no end of tuning to get it right and the fuel flows per injector vary a lot.

So if you had my engine out of the box and followed the Lycoming suggestion.....where exactly do you think you would be? :ooh: Yep.....

The more we discuss this the more there is a lack of education out there. And it is no wonder when you read these articles and they say"giving pilots too much information is not always a good thing" well not giving enough has been the whole problem from the start. :ugh:

Walls of China,

Seems you have had a quick lesson in this stuff, but the comments here
....tells me you have many many more hours of research to go.

Really now.......again I suggest keep doing the homework, you have only just scratched the surface.

Really..... I knew EXACTLY what I was doing. The reason there is not much support for it is its pretty damned hard to get a carby engine LOP....this is true, but armed with the CORRECT knowledge and instrumentation and if you are lucky enough to have an engine that will comply, it can be done. You just can not expect average Joe out there to do it. Unfortunately.

Ohhh really, well I am very capable of showing myself that too. detonation is rather easy to induce at takeoff power, due to a mixture cable pulling back due to thrust, we had the mixture arm cracking back a bit on takeoff, if we did not have an EMS we would have flown like this for the last 500 hours, because a random single CHT probe would have shown nothing. We would have problems any time now.

So for everyones sake what engine and airframe and under what conditions did you melt those pistons? Would make for interesting reading. :ok:

I think you are misguided in the belief fuel inside a cylinder is doing any such cooling of any signifigance. Maybe a bit more study at the GAMI engine test cell would help here.

From all the readings linked here, and few extra's I have found on my own, i came to the conclusion, that if you have enough fuel coming in to affect any sort of cooling, you are going to have so much fuel coming in, you are going to foul spark plugs.....if the engine will run at all.

For an injected engine, even tho the the run into the combustion chamber is a short one, the fuel temp won't be too far behind the air temperature. It has already absorbed the latent heat coming through the FCU, Lines and injectors.

Cheers
Jas

You may be doing a disservice to your argument by discounting the effect of unburnt fuel.
I googled "unburnt fuel effect on cylinder temperature" and found some of the hits to be interesting, (This thread returned the #1 hit :ok:) certainly enough info to provoke thought.
The University of Wisconsin, Engine Research Center paper entitled
International Multidimensional Engine ModelingUser’s Group Meeting 2004, Detroit, MI says in part
Anything that passes through the ignition sequence inside the cylinder, that has a lower temperature of the burnt fuel (approx 1400 deg C) will absorb some of that heat and transport it through the exhaust cycle.

ps. This is not a reply to Clinton, because I can't see what he wrote. still :E

Jabba, I'm not enthusiastic about studying more on this subject because I'm only a little Cherokee driver who was taught to warn passengers not to touch the red knob.

I was more interested in trying to explain base engine technology.

Source: Wikipedia, Top Fuellers

The block is machined from a piece of forged aluminium. It has press-fitted, ductile iron liners. There are no water passages in the block, which adds considerable strength and stiffness. The engine is cooled by the incoming air/fuel mixture. Like the original Hemi, the racing cylinder block has a long skirt (to reduce piston "rocking" at the lower limit of piston travel). There are five main bearing caps, which are fastened with aircraft-standard-rated steel studs, with additional reinforcing main studs and side bolts. There are three approved suppliers of these custom blocks.
The cylinder heads are machined from aluminum billets. As such, they, too, lack water jackets and rely entirely on the incoming air/fuel mixture for their cooling. The original Chrysler design of two large valves per cylinder is used.


Jas, on petrol engines fuel doesn't squirt out the exhaust pipe or flood the apron, but it's coming out as a rapidly expanding rapidly evaporating gas.

If yo want to discuss the thread subject, staying on the exhaust temperature is good - by that stage the gas has expanded, and it has evaporated so you don't have to get all excited or teary about cooling/not cooling. Its a different set of numbers in the exhaust.

Fine, then keep out of the productive discussion then. :ugh:

Strange how you do not answer questions real well. I'll assume those pistons were in a drag engine, and while I have little to none first hand experience with them I have enough to know they are way different to what we are playing with here.

So enough of the distracting antics, and if Trent wants to push the little bit of unburnt fuel cools theory, fine, but let mea sk this question. If you move from beyond 50ROP the CHT will drop, so between 50 and 125ROP the CHT is dropping but how much fuel is unburnt, and how much heat is that tiny amount taking with it?

Seriously its two tenths of three sixteenths of farkhall. The only way it could really make a big difference is if it was so rich it was about to quit, and then the CHT would be down due to lack of power. If it made 1 degree F that would be a surprise.

So regardless of the micro arguments, its seems that the bulk of piston operations are done with lack of knowledge and instruments. :ooh:

Exactly!

That's why in my opinion the "don't LOP with a carb or without an engine monitor" idea is false. If you lean till rough, then richen a little, you're already running a cylinder(s) lean of peak. If you enrichen a little bit more, you've now moved the LOP cylinder(s) closer to ROP, and so hotter. Of course, the cylinder(s) that were already at peak or just ROP will now be even more ROP, so slightly cooler.

So, if you have a carb and/or no monitor, you don't know where your engine is running. So my advice to students is lean as far as possible for fuel economy and a cleaner engine, and fly at a sensible power setting for your density altitude, so that the engine stays cool. That does mean that some of your engine is at the worst place, ie 50ROP, but what options do you have?

The only other option is to fly with a very conservatively rich mixture, and whatever power setting you feel like.

Jaba, I can't answer that question.
Jaba asks- How much heat is that tiny amount taking with it? 75 degress worth!
I don't know the percentage of fuel not burnt, but if in stable cruise and the only change that is made is to enrichen the mixture enough to decrease the EGT's by 75C degrees (from 50C ROP to 125C ROP(your figures)), then as a consequence the CHT's will slowly decrease, as a function of external cooling and due to less heat being applied from the inside at a rate that would differ for each individual installation and circumstance.
Nothing else has changed therefore the addition of the extra fuel has the ability to drop the EGT by 75 degrees or even more.
Now you tell me that a lower EGT will do anything other than lower the CHT in a constant cruise config.
You stated earlier that fuel cannot pass through the ignition process and remain unburned. Well that's wrong. I'm not a thermodynamist but I know enough to know that.

Aerozep, for the bulk of teh O-320 or O-360 type fleet, once at a suitable power setting around 65-70% lean until you get either the fuel flow or the speed you want. You will not harm anything. By the time you get to peak or just past it you will be fine anyway. Of course doing this at full combat power down low is not such a smart idea :ooh:.

Here is a sample of numbers that work for an O-320 and fixed pitch prop RV6.---Yes a proper plane with the little wheel on the back :p
This is not what I recomend you all try to use....I know this worked in this machine. But you might start to see how the theory works, even with a carby.

Clinton, the sight of your last two postings, picqued my interest enough to have a look, and you offer this unattributed quote, but none the less, I don't disagree.
However, would you like to explain to me what becomes of the fuel/ air mixture that is not reached by the 'slowed down flame front', during the fraction of a second it is present in the cylinder.
I'll give you a hint.
If the flame front does not reach that portion of unburnt fuel, then it does not reach its ignition temperature and is ejected into the exhuast manifold in gaseous form as unburnt hydro carbon. Not as liquid petrol falling from the exhaust pipe, as some wits on here seem to think.
I'll look forward to your next post, as I was quite surprised your last one was a lot better than your previous. We're all learning.

Trent, one of us is not reading the others posts properly, it may be me but lets look at what I said and what you just said. I think we said the same thing, except I must point out I am talking deg F not C as F seems to be the norm.

So what is your point of difference? This??

Yep and it does it by changing the combustion event, not by some latent heat effect.

I think Chimbu Chuckles summed this up just recently....here are his words

And what were you trying to say here, my apologies but I do not follow you here.And thisone maybe needs a better explanation, but again we are aguing over nothing:ugh: it makes no difference whatsoever to the reality of things.NOT FULLY COMBUSTED, is that better? The fuel molecules that are not fully combusted. Just like throw a log on the fire, pull it out after 30 minutes its burned, but it is far from fully combusted. Either way whatevber is left is doing bugger all cooling. Unless someone can show me signifigant cooling from not fully combusted fuel, we can therfore assume that it is irrelevant............does this feel like mythbusters ;)

Degrees F or Degrees C doesn't matter really. I fly Euro Trash and you fly stuff Noah bought over from America with his ark. :EThere is no such thing as a 'not fully combusted fuel molecule'.
A burnt hydro carbon (fuel molecule) has an altered chemical state and presents as CO2 and H2O.
If you disagree, don't tell these people because they spent a lot of money designing and building an instrument to measure it. (Hydro Carbon)
Wouldn't it be dumb if they built a machine to measure something that doesn't exist.
Definition for HC
It's not irrelevant, it's just that you don't believe in it.

Yes he is and in the process I am going round in circles not making sense either. trent is right, a molecule is burnt and that is it, but a whole F:mad: bunch of them swimming along together then, is that better.

Either way it is irrelevant.

Ohh yes it is Trent. Go find me proof there is a signifigant Cooling effect, no not a less heat generated, a signifigant cooling from those random bunches of unburnt hydro carbons, and show me how this really is providing serious CHT cooling and I will believe in it.

I can give you lots of proof the Santa came to visit, the cake was missing bar a few crumbs and the Bundy bottle half empty. Proof indeed! :ok:

Are you asking me or telling me? I didn't say anything about exhaust valves.

Clinton, I provided a link earlier to
Perhaps you can explain to them what they have published has errors of fact.
(That HC's cannot remain unburned on their trip from fuel tank to exhaust pipe exit).What were those fools thinking, anyway.

Jaba, That fat B@stard drinks your rum too?
I don't know how he does the job.

EGT is basically irrelevant unless you have a turbocharged engine when TIT (turbine inlet temperature) limits may apply.
CHT is the killer and for most carburetted engines is variable between cylinders which is a problem.
In my RV-9A fixed pitch prop and IO-360 with multipoint CHT and EGT indicators I normally just select a power setting I am comfortable with (high RPM if I want to go fast or lower for long range cruise ie 2200 RPM) then lean to give a max CHT of 380 degrees on the hottest cylinder (not much spread between cylinders anyway) and for long range cruise this gives a TAS of 140 kts and fuel flow of 26-27 L/hr - don't worry about EGT at all.

Clinton, I'm actually enjoying the discussion. I must be a bit odd.
The NSW RTA (Arseholes) use this Summary of Emission guideline for measuring engine exhaust, and according to them HC (which by earlier supplied definition can only be unburnt fuel), is possible and allowed from a petrol engine exhaust, to the specified amount . (Obviously not applicable to aviation ops. Rather just to prove a point).

Therefore as per your earlier offer, I will assume you are wrong.

Are you wrong about anything else?
---
Not wishing to hog the debate, I'll add my reply to Jaba and Clints following posts, here.

Quote:

---

Talking about some experimental tests on a DIESEL engine using n-heptane as a fuel

---

Not so, it is an international standard (sans spark plug ignition) for data consistancy.Clint, it's all very well to accuse me of being disingenious, but you won't accept proof that petrol can remain unburnt in an engine. BTW I notice you quote the most recent RTA requirements for emission levels. Those would be after the gasses have passed through the catalytic converter, and yet the HC's can still be present even after that. Ho Hum that's all from me folks. Still one of the best threads running ATM IMHO.
ps. I'm not really Santa Claus, I just pay a lot toward his wages.

I don't get it :ugh:

Trent 972 is Santa Claus :eek:

Now I know where all the rum goes :ok:

What are you doing man :ugh:
And what are they doing in this International Multidimensional Engine Modeling User’s Group Meeting ??

Talking about some experimental tests on a DIESEL engine using n-heptane as a fuel.

Come off the grass trent, get back on the straight and narrow. I am over playing games, stick to the real world here please or some Moderator will crack the Sierra Hotel 1 Tango's and lock the thread. Some folk are learning a heap and that would be a shame.

If you want to denate it more, put your money where you keyboard is and go to ADA, next March I think :ok:. I could show you stuff on my airborne dyno rig ;) but I doubt I could convince you there.

Hooroo! :ok:

For those with a mind for education, here are some links I should have put up before.

Discount the fact GAMI sells injectors, these guys know more about the engines we fly behind than anyone on the planet.

General Aviation Modifications, Inc.

General Aviation Modifications, Inc.

General Aviation Modifications, Inc.

General Aviation Modifications, Inc.

Enjoy!

I can't believe the amount of coverage this subject has gotten , makes the QF debacle seem like childs play!:) Entertaining I guess the wild theories/stories that abound in here.



Wmk2