Optimium clone head temp

All these different ideas on the ideal CHT temperature! Oh my!
Never had any those problems with the EGT.
Al not everyone knows that the amount of work done in an internal combustion engine is dependent on Delta T. The higher it is the more work done.
It is Usually taught in college level Thermal Dynamics. Usually around the 3rd. year engineering classes.
So it is not something that everyone understands or is even exposed to.The same way that I don't have a clue on how to electrically wire a house or paint a car. I never studied it.
On some of the engine that are being raced in the stock classes, I don't think you can even change the jet size? If that is the case then It would be very hard to change the EGT ? If I am wrong in this assumption. Then I am sure that someone will correct me. Believe it or not. I have been wrong in the past. My wife reminds of this often!
But I cannot think of running a racing engine without knowing the EGT. Once you do, It makes a difference.in how you tune the engine.
 

alvin l nunley

Premium User
Al not everyone knows that the amount of work done in an internal combustion engine is dependent on Delta T. The higher it is the more work done.
It is Usually taught in college level Thermal Dynamics. Usually around the 3rd. year engineering classes.
So it is not something that everyone understands or is even exposed to.The same way that I don't have a clue on how to electrically wire a house or paint a car. I never studied it.
On some of the engine that are being raced in the stock classes, I don't think you can even change the jet size? If that is the case then It would be very hard to change the EGT ? If I am wrong in this assumption. Then I am sure that someone will correct me. Believe it or not. I have been wrong in the past. My wife reminds of this often!
But I cannot think of running a racing engine without knowing the EGT. Once you do, It makes a difference.in how you tune the engine.
As popular as they are, I'm thankful that everybody doesn't run in the box stock classes. "Fixed jet" is not what I read in the Briggs & Stratton rulebook. There is some leeway. Even after that, people adjust the float level. Same as a different jet. But I'm glad to hear you like EGT, at least I think that's what you said.

By the way, .0002" change in jet size would be necessary for a 1% change in air density. There is room to tune the carburetor even with a fixed jet rule. It might be interesting to know exactly how precise Briggs & Stratton jets are in size and flow. The company where I once worked had a need for rocket engine jets, very similar to Briggs & Stratton jets. They were CAD/CAM designed and machined on a Swiss CNC lathe. Of the 200 jets we had manufactured, then flow tested, we found about 14 different flow rates. With more precise testing methods, we might have found more. It would be interesting to perform that same test on say, 100 Briggs jets. There is a carburetor manufacturer in Europe (forgot the name) that marks their jets with flow numbers rather than sizes. Makes me wonder, if they think it's that important, why don't we do the same thing?
 
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