cruising egt temps vs a/f ratio

[norbs]

I have been doing some egt vs a/f ratio testing and it appears that egts peak while cruising at stoich 14.7, and any leaner they begin to drop. ANyone else have any findings to prove this wrong? Someone was telling me on this board that this is not true is it?

 

[bruce]

I have been doing some egt vs a/f ratio testing and it appears that egts peak while cruising at stoich 14.7, and any leaner they begin to drop. ANyone else have any findings to prove this wrong? Someone was telling me on this board that this is not true is it?

Highest EGTs, should be at stoich.
14.7, thou, isn't always stoich.
Tweaking the timing, can induce a slight AFR error.

For determining true stoich you need to use a 4 gas analyser.
Then as you reach peak torque, it's also a very sweet spot in the VE.
I've had nice cruise modes, that have ranged from 850dF, to 1,200dF.

While stoich, is chemically the sweet spot, it doesn't mean the engine is happiest there.

 

[RickWI]

I have been doing some egt vs a/f ratio testing and it appears that egts peak while cruising at stoich 14.7, and any leaner they begin to drop. ANyone else have any findings to prove this wrong? Someone was telling me on this board that this is not true is it?

The trend you see is true Norbs, that's why on the dyno only using EGT's can be very expensive. If you don't know what side of the curve your on you can easily burn something up. Past a certain point as you further lean out the mixture your EGT's will drop off.

 

[norbs]

This might help out .

 

[ijames]

Norbs, Bruce posted this link some time ago. Has good discussion of egt, cyl head temps, afrs, etc. http://www.avweb.com/news/columns/182084-1.html