fuel type-fanning the flames

[vtwinsport]

Ever wonder what kind of fuel to run in your engine? Here is a quote from an engineer below on the subject- Fuel for the discussion fire ')

***Just so you are aware, "octane" is not "power". In fact, "premium" gas (the stuff with the higher octane number) has fewer BTUs per gallon than "regular" gas.

The extra power that is 'found' with "premium" gas is not a result of the gas. It is a result of higher compression in the cylinder, due to different pistons or cams. Increasing the compression ratio also increases the heat generated by compression. If the compression is raised enough, the mixture can get hot enough to ignite itself. This is called "pinging" or "knocking". Gas with a higher octane number will resist this heat better and will wait for the spark to ignite it. "Premium" gas also burns slower, so you have to light the fire a bit sooner by advancing the spark. How many of us have "advanced the spark" to get some more power?

"Premium" gas and spark advance are both Band-Aids to cover the heat from the increased compression. In your stock engine, neither one is necessary. In fact, just by switching to "premium" gas, you usually lose some power and mileage because there are fewer BTUs and the fire is still burning as the piston goes down, lowering the BMEP (Brake Mean Effective Pressure).***

Sounds reasonable don't it.

[eightyfive]

Woe, i never knew that, And i Work at a Gas Station! Thanks

[redneckchevy]

I have stock compression in my 350 but i still run "premium" gas (91 octane) , just to get rid of the ethanol.

[baclay9]

That is exactly right. The only reason for anything higher than 87 is if you are experiencing "pinging" or pre-detonation due to high compression. Otherwise you are wasting your money.

[Goldfinger]

I had a 10% jet fuel 90% 89 octane. 40 gallon lasted me a week. The engine was getting hotter than usual and i think i got rid of the carbon in my engine(as well as my seals).