First flights EGT Gauge Discussion/Questions

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Roadburner426
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First flights EGT Gauge Discussion/Questions

Post by Roadburner426 »

Alright. Got about 7 hours in her so far today (first round of flights). Flies awesome! However read the manual front to back, and the one mystery lurking in the cockpit is that EGT gauge. I have dug around on all of the pilot sites and there seems to be a lot of opinion on this. So in an effort to try and gain some clarity as I am sure I cannot be the only one with this question figured I'd lay it out here.

To my understanding using the gauge requires you to lean the aircraft until the need peaks out, and this is your peak EGT. This is what you set the adjustable bug/needle to. Now from this point if you lean the mixture you are leaning from peak, and if you richen the mixture you are running rich from peak (what I have been doing all day). So in laymans terms is this how that is supposed to work? Other than that really good job on this. Learned really fast with the STEC beeping at me to keep it in trim. So far it is a happy Cherokee. Just trying not to detonate the motor by over leaning/misusing the EGT gauge. The whole leaning by ear thing is not my cup of tea as I am terrible at it.
S. Jordan
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taildraggin68
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Re: First flights EGT Gauge Discussion/Questions

Post by taildraggin68 »

Hey roadburner, In this cherokee, I have been leaning aggressively. I lean until it starts to sputter, then about 5 turns back to rich and mark the bug there. That in conjunction with the fine wire plugs, I have not had any temperature, power, nor fouling issues. Depending on altitude, throttle setting, etc, that keeps me in the 6.8 to 7gph fuel burn cruise. So far no issues

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maubrenta
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Re: First flights EGT Gauge Discussion/Questions

Post by maubrenta »

I've been leaning 50ºF ROP (Rich of peak). Lean until EGT peak, put the marker, then enrich until 50º above the marker. Same procedure on the 172.
I know some real pilots lean LOP but I'm just a virtual pilot who always trust the manual. :lol:

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Great Ozzie
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Re: First flights EGT Gauge Discussion/Questions

Post by Great Ozzie »

Roadburner426 wrote: To my understanding using the gauge requires you to lean the aircraft until the need peaks out, and this is your peak EGT. This is what you set the adjustable bug/needle to. Now from this point if you lean the mixture you are leaning from peak, and if you richen the mixture you are running rich from peak (what I have been doing all day). So in laymans terms is this how that is supposed to work?
Yes.
Roadburner426 wrote:The whole leaning by ear thing is not my cup of tea as I am terrible at it.
Then this recommendation from Lycoming Engines Key Operations (worth googling) could be useful:

LEANING THE NORMALLY ASPIRATED ENGINES

For cruise powers where best power mixture is allowed, slowly lean the mixture from full rich to maximum power. Best power mixture operation provides the most miles per hour for a given power setting. For engines equipped with fixed-pitch propellers, gradually lean the mixture until either the tachometer or the airspeed indicator reading peaks.


Also worth googling the "Lycoming Operators Manual O-360 Series Operating Instructions"
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L.A.
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Re: First flights EGT Gauge Discussion/Questions

Post by L.A. »

What we did in the Pipers. Lean until rough. Then put a finger at that position, and push halfway back to rich. Does this Piper have the throttle quadrant? I haven't even looked. I'm also assuming that this Piper is just running a EGT gauge from one cylinder. Usually the one they considered the hottest. In the case of my Lycoming, it was from cylinder #3. Usually the hottest, but you can't say for sure. For me, seeing 1325 degrees F........was a good judging point for leaning. I would be rich of peak. But you can't even say that for sure. Without EGT readings for all cylinders, you might not fully be rich of peak on all cylinders. I leaned my Lyc until rough, and then twisted the Cessna type knob, three turns rich. The engine ran well, with this setting, and plugs wouldn't fowl. The 1325 F on the EGT, won't apply everywhere. It depends where the probe in the exhaust is located. Mine WAS in a rather standard location. Point is, I didn't use the EGT to make exact settings. But just looking at it, I knew if I was in the ballpark or not. If it was around 1150 F., I could count on fowled plugs. I'd also re-adjust mixture quite often, on a cross country.

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Great Ozzie
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Re: First flights EGT Gauge Discussion/Questions

Post by Great Ozzie »

L.A. wrote:What we did in the Pipers. Lean until rough. Then put a finger at that position, and push halfway back to rich.
Not sure where that 'halfway back to rich' originates from.

Fwiw... something "close" is one way to lean to Best Economy from Lycoming S.I. 1094D:

For a given power setting, best economy mixture provides the most miles per gallon. Slowly lean the mixture until engine operation becomes rough or until engine power rapidly diminishes as noted by an undesirable decrease in airspeed. When either condition occurs, enrich the mixture sufficiently to obtain an evenly firing engine or to regain most of the lost airspeed or engine RPM. Some engine power and airspeed must be sacrificed to gain a best economy mixture setting.

When leaned, engine roughness is caused by misfiring due to a lean fuel-air mixture which will not support combustion. Roughness is eliminated by enriching slightly until the engine is smooth.
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L.A.
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Re: First flights EGT Gauge Discussion/Questions

Post by L.A. »

Great Ozzie wrote:
L.A. wrote:What we did in the Pipers. Lean until rough. Then put a finger at that position, and push halfway back to rich.
Not sure where that 'halfway back to rich' originates from.
It was an excellent "ballpark", rich of peak setting..............for our higher altitude, mountainous takeoffs. If we want perfection these days, we include CHT & EGTs for every cylinder. We use fuel injection, and go to the trouble of matching fuel injectors, to get the most even cylinder temps. And then, for best fuel economy, not power, we go lean of peak. :D

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Great Ozzie
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Re: First flights EGT Gauge Discussion/Questions

Post by Great Ozzie »

L.A. wrote:It was an excellent "ballpark", rich of peak setting..............for our higher altitude, mountainous takeoffs.
Well again... from S.I. 1094, simple to just lean to smooth engine operation:

For 5000 ft. density altitude and above or high ambient temperatures, roughness or reduction of power may occur at full rich mixture. The mixture may be adjusted to obtain smooth engine operation. For fixed pitch propeller, lean to maximum RPM at full throttle prior to take-off where airports are 5000 ft. density altitude or higher. Limit operation at full throttle on the ground to a minimum. For direct drive normally aspirated engine with a prop governor but without fuel flow or EGT, set throttle at full power and lean mixture at maximum RPM with smooth operation of the engine as a deciding factor.

It just seems to me there are so many ways of leaning... I start to get a bit of heartburn if it doesn't come from the POH or Engine Manufacturer.

The one exception being what we have discussed before (regarding the Savvy Aviator) in the C172 forums which we talked about engine monitors and the associated equipment.
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Raptor05121
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Re: First flights EGT Gauge Discussion/Questions

Post by Raptor05121 »

Asking a group of 8 pilots "how to lean properly" and you'll get the same type of answers if you asked them "who makes the best truck". 4 of the 8 will pick either Ford, Dodge or Chevy. Another 2 will ramble about japanse pickups, one will begin to explain the origins of said pickup and the last will think you are talking about picking up women.
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L.A.
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Re: First flights EGT Gauge Discussion/Questions

Post by L.A. »

Great Ozzie wrote:
L.A. wrote:It was an excellent "ballpark", rich of peak setting..............for our higher altitude, mountainous takeoffs.
Well again... from S.I. 1094, simple to just lean to smooth engine operation:

For 5000 ft. density altitude and above or high ambient temperatures, roughness or reduction of power may occur at full rich mixture. The mixture may be adjusted to obtain smooth engine operation. For fixed pitch propeller, lean to maximum RPM at full throttle prior to take-off where airports are 5000 ft. density altitude or higher. Limit operation at full throttle on the ground to a minimum. For direct drive normally aspirated engine with a prop governor but without fuel flow or EGT, set throttle at full power and lean mixture at maximum RPM with smooth operation of the engine as a deciding factor.

It just seems to me there are so many ways of leaning... I start to get a bit of heartburn if it doesn't come from the POH or Engine Manufacturer.

The one exception being what we have discussed before (regarding the Savvy Aviator) in the C172 forums which we talked about engine monitors and the associated equipment.
Better get some Rolaids.... :D
I'm going to find that Lycoming guide, that recommends "against" carb heat for every landing. In the meantime, Lycoming was dead set against running LOP (lean of peak) for a long time. The attitude has been changing. I can't remember anybody around here.............just leaning to maximum RPM, let alone running to full power for the adjustment. 1800 to 2000 rpm is enough. Some are even happy with 1600 rpms.

edit: actually, even the thumb method for pulling a Cessna red knob was pretty good. Just pull out the knob, about a thickness of your thumb. Might vary with different size hands, I suppose. :)

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Great Ozzie
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Re: First flights EGT Gauge Discussion/Questions

Post by Great Ozzie »

L.A. wrote: I'm going to find that Lycoming guide, that recommends "against" carb heat for every landing.
That is going to be a bit of a chore, as, is not what their Service Instruction on Carb Heat (1148C) recommends.
L.A. wrote: In the meantime, Lycoming was dead set against running LOP (lean of peak) for a long time. The attitude has been changing.
By others in the industry, yes... afaik, *not* Lycoming. See their Experts Are Everywhere To Help You -- The "New" Old Leaning Technique. John Deakin wrote quite the rebuttal to that Lycoming article - and Deakin's article worth a read too.
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ftrusky
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Re: First flights EGT Gauge Discussion/Questions

Post by ftrusky »

Interesting, with the Cherokee I've been using the chart and leaning to a peak RPM setting but not over 2600 to get 140MPH at altitude.

I've never tried that approach in the 172, I'll have to try it out (if I ever get out of this Cherokee :lol: )
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Re: First flights EGT Gauge Discussion/Questions

Post by J van E »

maubrenta wrote:I've been leaning 50ºF ROP (Rich of peak). Lean until EGT peak, put the marker, then enrich until 50º above the marker. Same procedure on the 172.
I know some real pilots lean LOP but I'm just a virtual pilot who always trust the manual. :lol:
Sounds to me you are leaning LEAN of peak...? To lean rich of peak you have to enrich 50 BELOW the marker. You have to push the mixture lever back and not pull it out even further.
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Roadburner426
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Re: First flights EGT Gauge Discussion/Questions

Post by Roadburner426 »

Well I have tried the leaning till rough method. Had her coughing and sputtering then added like 5% of the mixture back but was not at the RPM I set it to before. So then I get to playing with it, and trying it a bunch of different ways. Doing it the run rough way though there is a hard airframe vibration sound (deep groan is the best description) that comes in that makes me think I am doing it wrong. Can tell all I have done is fly the P-51, P-40, and B-17 cause all of those have auto mixture. Will continue playing with it though. Worst thing that can happen is I need a new engine.

As far as the Cherokee goes I haven't seen an EGT chart. I have just been using the power setting table to set a power percentage based on altitude. Downloaded the manual for the C172 and see where they put an explanation about it in there. Thanks for the answers though.
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Great Ozzie
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Re: First flights EGT Gauge Discussion/Questions

Post by Great Ozzie »

Roadburner426 wrote: As far as the Cherokee goes I haven't seen an EGT chart.
Yeah there won't be... just the manf. recommendation with respect to peak EGT.

I like the best power method (peak rpm) since it is easy and I don't have to worry about paying for gas in the sim. I always used it RW too as it was the preferred method at the time where I flew.
Roadburner426 wrote:I have just been using the power setting table to set a power percentage based on altitude.
Just for clarity let me say... "me too".

Pick an altitude, pick a % power to find the appropriate rpm... then lean accordingly.
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