Wrambler242@xxxxxxxxxxx wrote: > Thinking about it. > Is there not a finite amount o ftime per revolution that the "heat" is useful? > Once that piston has descended past a certain point the push is gone. In principle, if you squeezed the mixture small enough, and let it expand big enough, and metal didn't absorb heat, you could get all the energy out. The trick -- that Yunick could clearly pull off -- was to get as much energy as you can afford, out. I recall some thing, maybe in his CIRCLE TRACK column, where he had exhaust temperature down to 300 degrees C (572F) in some test motor. That's energy extraction! Flames out the open headers is wasted energy, but I assume that for rail type drag cars that's marginal case stuff like start up and a fraction of the total energy extracted at speed. I mean some of it is seat-of-the-pants obvious -- with no other changes to a motor, at WOT, retarding the spark much makes the flame shoot out the exhaust and makes it run hot and lose power. Exhaust temp up, power down. Oh yeah -- the 'paper' physics is easy, putting it to metal is what counts :-) _______________________________________________ Amc-list mailing list Amc-list@xxxxxxxxxxxx http://splatter.wps.com/cgi-bin/mailman/listinfo/amc-list