Turbo leaning question - not LOP

[Henning]

Can anyone else confirm there is no max EGT? What concerns me most is that I think I was running near only 35% power and the EGTs went off the chart. Maybe I have a misperception here, but I had assumed that with all else the same, and increase in MP would result in an increase in EGT. But, if that were true, where would those temps be if I increased MP to 20 or even up to 28"?

Could it have been rough simply because, when leaning, the power was so low, or maybe the rpms were at minimum?

Max EGT will be around 1750*f, that's where you start into weakening of the metal of the exhaust tubing and risk burning through. Pretty mush same for TIT as for metallurgic problems, however you also have oil heat/ coking in the bearing and thermal expansion issues to consider with a turbo.

EGTs only go 'off the chart' if you have an engine issue. You basically need a hung valve or bad injector nozzle or something that is pouring raw fuel and air into the exhaust pipe basically turning it into the "burner can" of a jet engine if you have a turbo.

 

[dennyleeb]

Why the f- should someone bother to demonstrate to your lame mind how to save yourself money? If you can't work it out, and you can't understand when it's explained to you, what makes you think you deserve more effort than that? Waste your money down the toilet for all anyone else cares, you aren't costing me money and stressing my plane.

I hope this post was a joke.

 

[Henning]

I hope this post was a joke.

Dead serious.

 

[Ted]

Why the f- should someone bother to demonstrate to your lame mind how to save yourself money? If you can't work it out, and you can't understand when it's explained to you, what makes you think you deserve more effort than that? Waste your money down the toilet for all anyone else cares, you aren't costing me money and stressing my plane.

So I'm guessing that nobody taught you how to fly or do anything - you just woke up one day and did it?

He's being smart enough to realize that he doesn't fully understand what's going on, and would benefit from having someone who understands it better than him showing him. Same thing with any other skill.

Max EGT will be around 1750*f, that's where you start into weakening of the metal of the exhaust tubing and risk burning through. Pretty mush same for TIT as for metallurgic problems, however you also have oil heat/ coking in the bearing and thermal expansion issues to consider with a turbo.

The TIT limit on the 182 should be 1650F. If you are leaning to 1750F in the process of getting to your operating point, whatever it is, then you are exceeding the limits of your engine, which is exceedingly stupid. The TIO-540-AE2A (Malibu engine) is the only Lycoming that I can think of off the top of my head that has a 1750F TIT limit, and it is easy to exceed that, too, if you do so at the right operating point.

So, why not run at TIT limit? Because the effects of high temperatures over long term are one of those "Maybe not today, maybe not tomorrow..." things. You won't have a catastrophic failure (typically). But you may find yourself having shortened cylinder life, turbo life, etc.

EGTs only go 'off the chart' if you have an engine issue. You basically need a hung valve or bad injector nozzle or something that is pouring raw fuel and air into the exhaust pipe basically turning it into the "burner can" of a jet engine if you have a turbo.

Not sure what you consider "Off the charts", but overall that is not true. It is very easy to go past the manufacturer's prescribed limits on TIT (and the same values for EGT) with a turbocharged engine. On a T182T, you have the advantage of having something that's lower power and thus more forgiving. However, if you pick the wrong power setting to do your leaning, it is very easy to go above limits.

Been there, done that enough times in the process of testing.

Your posts that imply one must be born with a gifted knowledge are neither helpful nor accurate. Furthermore, I'm noticing an increasing number of your statements that are just outright wrong.

 

[skidoo]

EGTs only go 'off the chart' if you have an engine issue. You basically need a hung valve or bad injector nozzle or something that is pouring raw fuel and air into the exhaust pipe basically turning it into the "burner can" of a jet engine if you have a turbo.

My engine does not have an issue, so if you would, please explain why cylinders 1 through 5 are off the chart and 6 is one bar to being there in the photo on post 25.

 

[Alexb2000]

Just to add specifics to the conversation the TIT operating limit for a T182T is 1685. Red part of the gauge is 1685-1700. POH page 4-38.

Everyone can operate their $60K engine any way they like, my personal limit is 1600.

 

[dennyleeb]

Dead serious.

Yeah your dead serious on the price of your plane as well. LMFAO
Somebody did not teach you anything about economics. For example when you can by 10 like it for 30k and you want 90k. In person on the phone you seemed like a decent guy. But you need to get a life and a clue..... While your at a decent plane.

 

[skidoo]

Just to add specifics to the conversation the TIT operating limit for a T182T is 1685. Red part of the gauge is 1685-1700. POH page 4-38.

Everyone can operate their $60K engine any way they like, my personal limit is 1600.

Thank you, and I concur.

Just to reemphasize, as the OP, the purpose of this thread was to discuss leaning the turbo to operate AT PEAK. I did not desire this to turn into a LOP vs ROP discussion. At power levels at 75% or more, maybe even 65%, it is easy to reach that 1685 limit before even reaching peak. So, at those power levels, I just run near 1585 TIT.

And, again, my question relates to slowly leaning to peak at the lower power levels and maybe end up being 25 ROP. Say this occured at 55% power, TIT at 1585 or less, EGT at 1525 or less, and CHT at 375 or less, what is the risk if it happens to inadvertently be at 25 ROP TIT instead of actually at peak TIT. And, by leaning slowly, it obviously would have to pass through that 25 ROP TIT area.

The POH recommends to operate AT peak TIT for best economy. So, who actually has run theirs AT Peak TIT?

 

[Clark1961]

The POH recommends to operate AT peak TIT for best economy. So, who actually has run theirs AT Peak TIT?

I frequently run the Frankenkota at peak or slightly lean of peak. The manifold pressure gets a little jumpy (tends to fall) so I have to watch it closely. 2400, 30 inches, and peak gets me under 10 gph and around 130 knots TAS. Sometimes I wish there was a manual wastegate STC rather than either the factory solution of fixed or the upper deck pressure controller (Merlin). Anyway, the redline is 1650 and peak is usually 15 to 25 degrees below redline. The previous owner always ran it at or below 1550 and the engine used to have a lot of blow-by and sub-70 compressions on all cylinders. Last annual only had two cylinders below 70. So either I'm burning valves or I'm doing good, or both.

 

[Henning]

So I'm guessing that nobody taught you how to fly or do anything - you just woke up one day and did it?

He's being smart enough to realize that he doesn't fully understand what's going on, and would benefit from having someone who understands it better than him showing him. Same thing with any other skill.



The TIT limit on the 182 should be 1650F. If you are leaning to 1750F in the process of getting to your operating point, whatever it is, then you are exceeding the limits of your engine, which is exceedingly stupid. The TIO-540-AE2A (Malibu engine) is the only Lycoming that I can think of off the top of my head that has a 1750F TIT limit, and it is easy to exceed that, too, if you do so at the right operating point.

So, why not run at TIT limit? Because the effects of high temperatures over long term are one of those "Maybe not today, maybe not tomorrow..." things. You won't have a catastrophic failure (typically). But you may find yourself having shortened cylinder life, turbo life, etc.



Not sure what you consider "Off the charts", but overall that is not true. It is very easy to go past the manufacturer's prescribed limits on TIT (and the same values for EGT) with a turbocharged engine. On a T182T, you have the advantage of having something that's lower power and thus more forgiving. However, if you pick the wrong power setting to do your leaning, it is very easy to go above limits.

Been there, done that enough times in the process of testing.

Your posts that imply one must be born with a gifted knowledge are neither helpful nor accurate. Furthermore, I'm noticing an increasing number of your statements that are just outright wrong.

I learned everything from other people, duh, that's what we do, I DON'T make teaching me a burden though! I make it easy for people to teach me, that's why I get so many good teachers. I've been very fortunate in getting to pick who I worked for coming up in several industries. I don't do the 'Doubting Thomas' thing. Time is the only thing in the universe that has a substantial value. You can burn my stuff and take my money, I don't give a f-. I've been broke and worked myself back up so many times it's not a big issue, just don't waste my damn time.

Read what I wrote with regards to 1750 degrees EGT and TIT again, I did not say it was a safe temp to operate at, I said it was where you start into destructive issues. If I see a 1750 TIT, I have a problem that is not related to my pulling back on that red lever. I should not be able to achieve that in the leaning process, not by a long shot.

 

[RotorAndWing]

Furthermore, I'm noticing an increasing number of your statements that are just outright wrong.

Noticed that too huh?

 

[Alexb2000]

Help! I went out today and set power for the normal POH numbers at 8000 ft, 2000 rpm, and 20" mp. Then, pulled back MP to 14" and putted around a bit. So, I thought I am at very low power, lets see what how it feels if I try to see a peak. So, I slowly dialed back the mixture some more. The TIT temps were fine, but I did not like where the EGT's were going. At normal power levels the EGTs were always lower than TIT. As you can see in the photo, all EGT's were maxed out in the indicator. I could not really find a peak before the engine began running rough. I did not like that either, so mixture just above rough and I snapped a photo, then back to normal mixture setting.

In the Lycoming leaning procedure it states

"(b) Lean slowly in small steps, while monitoring instrumentation, to peak TIT or maximum allowable TIT whichever occurs first."

and then earlier it says

"For best economy cruise, operate at peak EGT. If roughness is encountered, enrich the mixture slightly for smooth engine operation."


What I don't understand is if it reaches peak and becomes rough, and then enrichen slightly, and say the leaves it at 25F ROP, there are those who say that is the worst place to be. I could not find any such warning in the Lycoming leaning procedure nor the POH.

What are your thoughts on this and the settings in the photos.

Also, I see a redline for TIT, but don't see any for EGT. Anyone know why not?

I'll throw out an answer to this and maybe put the conversation back on track.

It is interesting to call Lycoming and discuss their view of leaning and temps. Their first comment is, 'this isn't a Continental". So of course they recommend leaning and running according to the POH and they are happy to discuss it with you. Which as you point out would be 25 ROP. I have run your same engine that way many hours with no problems. One of the things they point out is the location of the probes is different, the metallurgy is different, the cooling is different, and the engine is fully capable of running at the POH limited temps to TBO and beyond. They seem to have a reputation of being able to make TBO when run that way, so something to consider. BTW-If some of you don't agree with the above don't shoot the messenger, that's what they say, if you want a debate about ROP-LOP call Lycoming yourself, I really don't want to discuss leaning.

In a turbo the TIT is the best indicator for leaning. If you look at the POH the TIT gauge is a required item for flight because of this. That's why they don't print a EGT limit because they want you to lean according to TIT and the EGT becomes secondary for leaning and useful for identifying problems with a specific cylinder, etc.

With regard to the pictures. It is easy to confuse the lean assist program if you pause too long, or richen then lean, etc. I prefer to just do it manually, but that's an aside. First picture appears to be well ROP and would be fine to operate at, although you'll burn a lot of extra gas. Second appears to be close to peak and would also be fine to operate at given those temps IMO. Try those techniques at max cruise power and the limitations will show themselves much more clearly. Also, the cooler air temps this time of year let you get away with more than you would in summer.

Also, try looking at the EGT gauge with the lean assist off.