Quote:
Originally Posted by HeadlesNorseman
for what its worth, some of the energy contained in the gasoline is needed to generate heat for combustion... so preheating from another source theroetically saves some energy for the combustion process... thats rocket science stuff lol
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In this case I don't think that is correct, what we need the heat for is to boil the gas all into vapor, vapor is what powers the car...
Even the fine droplets of fuel ONLY what has converted to vapor really burns and powers the car. Problem is in the nanoseconds of burn time only so much is really vaporized in time for the burn power stroke cycle, the rest is slower and burns after the power stroke...
From:
http://www.rockettbrand.com/download...20Gasoline.pdf
A gallon of gasoline will usually contain from 115,000 to 125,000 BTUs. Most enthusiasts want the gasoline with the most BTUs, and that can be misleading. The BTU content is of little value if some of the gasoline is still burning when the exhaust valve opens and all of that energy escapes out the exhaust as heat and unburned hydrocarbons.
Most engines that exceed 7,000 RPM can benefit more from a 115,000 BTU per gallon gasoline than a heavier gasoline that may contain 125,000 BTUs per gallon, but does not have time to completely burn in the combustion chamber.
Think about this: One gasoline has 115,000 BTUs and is 95% burned before the exhaust valve opens; the other contains 125,000 BTUs but is only 85% burned before the exhaust valve opens.
Simple math tells us that the first gasoline gave up 109,250 BTUs. The other gave up 106,250 BTUs. Which would you prefer? I would take the 109,250 BTUs from the 115,000 BTU per gallon gasoline.
Does this actually happen? The answer is “Yes”. Although some heat energy does go out the exhaust, some goes to the cooling system, some goes to pumping losses, etc. some of it goes into making horsepower at the
rear wheels. The bottom line is that the greater the percentage of the gasoline that is burned in the combustion chamber, the better off you are since those BTUs contribute to more horsepower.
A slow burning fuel that is still burning when the exhaust valve opens will put a flame out the pipe that can scare the bejesus out of the guy next to you. In roundy-round racing or road course racing this may gain you a position by making the other guy stay at “flame length, but you could get better results by using a gasoline that burns faster, providing a higher level of thermal efficiency and therefore, more horsepower.
It may look spectacular with three feet of flame coming out of your race car pipes that singes the paint on the car next to you, but those flames are energy being released in the exhaust rather than in your combution chamber.
The same thing can happen to a good gasoline if the spark is retarded. Gives high exhaust temperatures also and contributes to overheating the engine.