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IO 360 M1B

Chipper G

Well Known Member
Anyone know what the egt limits are on the M1B. I went off older stuff like max 1650 but I could not fine it in the Lycoming book?
 
I am not an expert but according to the ones that I read, absolute EGT is more or less meaningless as it depends on where the probes are in your exhaust pipes, and is only an average anyway since the actual temps within that exhaust stream change drastically and moment-to-moment.

https://www.avweb.com/ownership/the-savvy-aviator-59-egt-cht-and-leaning/
https://gami.com/articles/egt_myths.pdf

Personally I set the EGT limits on my EFIS to the range that I have determined (operationally) that they normally stay within. So when they go outside that I know to look for an anomaly.
 
EGT temp

You have one engine. My goal is to see the engine as my friend.
- above 75% power, no leaning.
- at 75% power, 100F on the rich side of max readout EGT.
- at 65% or lower power, 100F on the rich side of max readout EGT or on the
lean side of max readout EGT.
The goal here is to stay away from max readout EGT.

To lean/ set fuel flow, pull the red knob until peak EGT shows.
Then adjust to desired EGT according to power setting.
I have a IO-360-B1E 180 hp engine, typical EGT is 1300-1400F.

Good luck
 
The only time I have seen EGT limits was on turbocharged engines. Even then, it was called a "turbine inlet temperature", or TIT and protected the turbo, not the engine.

No EGT limits on any normally aspirated engine that I have seen.
 
I am not an expert but according to the ones that I read, absolute EGT is more or less meaningless as it depends on where the probes are in your exhaust pipes, and is only an average anyway since the actual temps within that exhaust stream change drastically and moment-to-moment.

https://www.avweb.com/ownership/the-savvy-aviator-59-egt-cht-and-leaning/
https://gami.com/articles/egt_myths.pdf

Personally I set the EGT limits on my EFIS to the range that I have determined (operationally) that they normally stay within. So when they go outside that I know to look for an anomaly.

Yep. The relative/expected values tell the story. Adjusting the range of your Man-Machine interface is smart and lessens the related pilot's workload. Assuming here there's a bar type representation probably with associated digital display.

I'm not a race fan but love the tech. Way back before downlinks, composite displays, master alarms, etc. the driver's compartments had steam gages. Very commonly, the engine gages were physically rotated so that normal/expected parameters ='d needles facing vertical. At a quick glance, the driver could tell if everything was within expected; simple and cleaver.

Side note/internal post drift; I'm close enough to Daytona to see some of the related news. The results don't interest me but if anyone is ever caught trying to game the rules, it's an automatic read for me. The ingenious ways these crews go through to gain HP, weight, aerodynamic advantages is quite awesome.
 
There is no hard limit quoted as there is no way of knowing the absolute temperature of the gas as it exits the exhaust valve. The value shown on your gauge depends on the distance the probe is installed down the exhaust pipe. Agree that much leaning above 75% is unwise. Below that it is all about the difference below the recorded maximum temperature - the peak EGT.
 
……. - above 75% power said:
I’ve always heard that at 65% or less that it’s safe to run “at” peak. I personally have 60% as my hard-deck for operating at peak.
 
You have one engine. My goal is to see the engine as my friend.
- above 75% power, no leaning.
- at 75% power, 100F on the rich side of max readout EGT.
- at 65% or lower power, 100F on the rich side of max readout EGT or on the
lean side of max readout EGT.
The goal here is to stay away from max readout EGT.

Gustav, I'm sorry, but there is no reason to think you're doing your friend a favor by staying away from peak EGT, or remaining full rich at WOT.

To the OP's question, Lycoming does not specify a maximum EGT for the normally aspirated engines. And they have long recommended "best economy cruise" as peak EGT, allowable at anything less than 75%.

As for WOT, a Bendix type injection, in theory, meters fuel in proportion to the square root of air density. As such, it does a fair job of leaning itself as air density is reduced in the climb...but it's not perfect. I've measured my FM200, knob full rich, WOT, 200 to 15K feet, and the "auto enrichment" effect is there. The operator must lean in the climb if full power is desired. The constant EGT method works well.

Lycoming's leaning guidelines are ancient. More recently, we've seen interest in reduced valve sticking. The leading theory is condensation of lead oxides, and the suggested preventative is keeping gas and surface temperatures high. I'm not aware of any hard research on the subject, but right now practically everyone in the industry will ask about your leaning methods if you show up with a stuck valve...and the goal isn't low EGT.
 

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Latest AOPA Pilot magazine has a Mike Busch article on this topic.

CHT control is the road to happiness. EGT is largely worthless, and it's all over the thermometer...see Dan above and read Mike. I've never heard of any upper EGT limit.

John Siebold
 
Thanks all. After 2800 hrs flying Navajos lean of peak and never replacing cylinders I love lean of peak operations as the oil was still clean at 50 hrs. Those were turbo charged and one had an inner cooler and TIT and CHT with a glance at the EGT is what we used. I understand that EGT can not mean a whole lot however the gauge must have limits clearly defined per the DAR so I was just asking. And fuel flow lol
 
I understand that EGT can not mean a whole lot however the gauge must have limits clearly defined per the DAR so I was just asking. And fuel flow lol

Have your DAR give you some examples of max EGT :D Unfortunately most planes, certified included, don't have EGT limits because the engine makers don't provide them. TIT is not relevant without a turbo, as the limit is to protect the turbo (or prevent oil coking in turbo bearing), not the engine. If you set low end limits on EGT, you are likely to be getting alarms in your ear on final.

EGTs can provide a lot of great insight data to the trained observer, but is not a limit oriented reading like CHT, OT OP, etc. are.
 
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Valve sticking

Dan, I said above 75% power, no leaning.
The throttle setting (WOT) is not relevant here.
Yes, it's normal to lean when climbing, if you are at or below 75 % power or
if the engine is running rough.
I'm running on Mogas (no lead) and still had problem with valve sticking,
so I think that it might be related to hot oil cocking in the valve guide.
Therefore I'm advocating not running at peak EGT.
Lycoming have an interest to present a low fuel consumption, so I find it understandable that they allow running pek EGT.
Leaning to beyond peak will provide lower fuel flow and lower exhaust valve
temperature.

Good luck
 
Yes, it's normal to lean when climbing, if you are at or below 75 % power or
if the engine is running rough.

Good luck

You should be leaning in a climb even if 100% power? The higher you go the richer the mixture gets if you don't. Otherwise that ever richening mixture just wastes fuel and drops the output power. Ever take off in Denver with full mixture? Makes for a longgg take off roll. This is a big issue with carbs, but less so with FI as it adjusts a bit to air density.

If it ever gets rich enough to be rough, you have reached an insanely rich condition. If I am not mistaken, Lycomings are typically detonation free at best power mixtures (~100 ROP), where they are tested.
 
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