Maximum advance

[Greg Hermann]

At 9:30 AM 7/13/01, Bernd Felsche wrote:
>Greg Hermann tapped away at the keyboard with:

>
>Let's keep the computation fluid thermodynamics out of this. Heat
>transfer to the walls is a small factor; as is heat transfer to
>end-gas. The compression of the end-gas, and hence its increase in
>energy, should be taken into account.
>
I agree that I was being a bit of a smart *ss, sometimes that's fun to do!

BUT--heat transfer to the piston crown and chamber walls, both convective
and radiative, is, in fact, _quite_ significant, especially while near TDC.
I would hazard a guess that it can account for somewhere between 10 and 20%
of the total heat input value of the fuel. Which is precisely why piston
and chamber polishing and thermal barrier coatings make a significant
difference in performance--both in terms of torque/power output and BSFC
(fuel efficiency).

Greg


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