sawfun
Pinnacle OPE Member
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Goats and turtles aside (no goats or turtles were harmed in the making of this statement, at least I hope), A discussion of static vs dynamic compression seems relevant. Depending on the application, compression readings will not tell the whole story. While it is a 4 stroke, the old L88 Chevys had a 12:1 ratio but would measure around 90 lbs on a gauge. Using the fuel mixture as added material in itself to the combustion chamber decreases the space thereby raising dynamic compression. Cam or port timing are the most relevant things to effect this as they are the control valves that dictate behavior. Some top fuel racers like Dale Armstrong, figured out that more fuel actually aided in cooling the combustion chamber, that's when you began to see larger fuel systems and of course major increases in power. Some saw racers have figured this out, from what I have read, and have lower compression pressure saws that perform better than when they had the higher numbers. Easier starting may result, but having your engine be less of a compressor can't be all bad either. I am not convinced of just how parasitic the losses are. Picture a turbo car vs a directly driven supercharged one. Much less loss with a turbo equates to free power. We now are starting to see tubo cars performance exceed conventionally supercharged ones, generally with less noise and better manners. The less resistance, the more free power, not made, just not lost.
Heat in the combustion chamber does of course good and bad things. Heat can cause damage, but as was mentioned, can aid in burn speed. There was an article in a car magazine in the early 80's where a top builder known as Smokey Yunik built a Pontiac Fiero to heat the fuel mixture to just under the flash point prior to entering the combustion chamber. The results were greatly increased power AND fuel economy. Someone bought the rights to this and the info on it seemed to vanish. That kinda flys in the face of the idea of a cool dense charge providing more fuel thereby releasing more energy. Though it does explain fuel economy/lower emissions. The idea was there was a lot less waste of time/energy if the fuel was just under its flash point. There are several thoughts on what works best, I think that just when we think we have answers, we learn we have very few.
Heat in the combustion chamber does of course good and bad things. Heat can cause damage, but as was mentioned, can aid in burn speed. There was an article in a car magazine in the early 80's where a top builder known as Smokey Yunik built a Pontiac Fiero to heat the fuel mixture to just under the flash point prior to entering the combustion chamber. The results were greatly increased power AND fuel economy. Someone bought the rights to this and the info on it seemed to vanish. That kinda flys in the face of the idea of a cool dense charge providing more fuel thereby releasing more energy. Though it does explain fuel economy/lower emissions. The idea was there was a lot less waste of time/energy if the fuel was just under its flash point. There are several thoughts on what works best, I think that just when we think we have answers, we learn we have very few.
