EGTs on O-360-A1D

[phxcobraz]

Beating a dead horse here probably but want some clarity, as most info you find on leaning is focused around injected and LOP/ROP discussion.

You can also just tell me to not pay any attention to EGT and that is pretty much what I have been told by a few people.

What are you all seeing for peak EGTs on your carbureted engines? Where do you normally operate at?

My M20C(O-360-A1D), carbureted, has no issues with warm CHTs, in fact I usually climb about 400deg in the AZ summer and cruise at 325 hottest around 7-10k ft. Engine runs pretty flawless. Full rich on full power climb I am about 1475-1500 EGT on the hottest cyl.

My EGTs are hard to pin down,, usually cyl 1 peaks first, at cruise(7-10k) if I lean to a stumble and then enrichen just enough for smooth operation my highest EGTs on Cyl 1 & 4 is around 1580. I have found it loves to run right around 1500-1520 very smooth with fuel flow right at 9.5gph, but the POH has no guidance as to acceptable range(the POH doesn't even reference EGT ranges, even though it had a single probe). The spread is quite a lot, but from reading that is normal on carbureted engines.

 

I guess my question is should I be fine running based on engine feel or pay any attention to specific EGT ranges?

[ShuRugal]

Don't get hung up on EGT. The number will change based on ambient conditions.

CHT is the critical number. If you're seeing no higher than 400 during a full power climb, you're doing it right.

The EGT numbers will vary as much as a couple hundred degrees between aircraft, even running the exact same engine, mixture, and power. This is because there is no fixed/measured position for the EGT probe in the exhaust tube, and each probe has its own thermal properties. The EGT for my plane at a given power will not be the same as the EGT for yours.

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[phxcobraz]

12 minutes ago, ShuRugal said:

Don't get hung up on EGT. The number will change based on ambient conditions.

CHT is the critical number. If you're seeing no higher than 400 during a full power climb, you're doing it right.

The EGT numbers will vary as much as a couple hundred degrees between aircraft, even running the exact same engine, mixture, and power. This is because there is no fixed/measured position for the EGT probe in the exhaust tube, and each probe has its own thermal properties. The EGT for my plane at a given power will not be the same as the EGT for yours.

Sent from my Pixel 5a using Tapatalk
 

Thank You. That goes with what my understanding has been, but recently had a conversation with someone that made me doubt it. 

[Hank]

What counts with EGT is how far you are from peak, and Mt C doesn't do LOP very well.

FYI, I often peak around 1475-1500, so I cruise 1425-1450. But the number does drift around during the year, sometimes over just a few days.

[47U]

2 hours ago, phxcobraz said:

The spread is quite a lot, but from reading that is normal on carbureted engines.

How far down from the exhaust flange are the EGT probes?  I think the preferred is between 2” and 4”.  Obviously, they should all be at the same distance, but if yours are at the close end of the range, then the temps will be hotter.  

As far as the spread, once you’re at cruise altitude, and the air is clean (above the haze, dust, smoke) try pulling a little carb heat.  Not nearly enough to drop RPMs, but it induces some turbulence in the carb throat that helps the fuel mix with the air.  So I’m told that is the theory.  It evened out my EGTs quite a bit.

[jcolgan]

I also fly a 0-360-A1D and will use a little carb heat to even EGT temps, also pulling the throttle off of full a bit helps get a more even mixture, with the throttle plate causing eddies in the air flow (or thats how I think it works anyway) Often I am able to slowly push the carb heat back in after the temp spreads have decreased and they will stay that way.

[phxcobraz]

1 hour ago, jcolgan said:

I also fly a 0-360-A1D and will use a little carb heat to even EGT temps, also pulling the throttle off of full a bit helps get a more even mixture, with the throttle plate causing eddies in the air flow (or thats how I think it works anyway) Often I am able to slowly push the carb heat back in after the temp spreads have decreased and they will stay that way.

I too pull the throttle out a bit as I read that helps with leaning. 
I’ll have to try a touch of carb heat and see how that evens out. I would imagine it helps smooth out the vibrations. 

[Hank]

9 hours ago, jcolgan said:

I also fly a 0-360-A1D and will use a little carb heat to even EGT temps, also pulling the throttle off of full a bit helps get a more even mixture, with the throttle plate causing eddies in the air flow (or thats how I think it works anyway) Often I am able to slowly push the carb heat back in after the temp spreads have decreased and they will stay that way.

When cruising nice and high, I pull the throttle until the MP needle wiggles; that is sometimes a surprising amount of travel. I call this WOT-, because it's a little less than WOT. Adding in some carb heat will sometimes let me run smoothly LOP, maybe 20-25°. But honestly, it's simpler to just run closer to peak, I've done so around 8 gph with normal indicated airspeed.