1986redbird

just that, is it possible to run too much octane in a factory motor. aside from being expensive what are the negative affects of running 110 octane on a factory motor???

MrDude_1

loss of power.

pat12spe

burning a hole in your pocket

1986redbird

"loss of power", any one care to elaborate on that. a little theory would be nice.

Sitting Bull

Any octane level above what your engine needs is a waste of money. The higher the octane rating, the harder it is to spark. This is to avoid preignition or detonation on higher compression engines. If your engine is 9:1 it won't help to run anything more than 87. So if GM tells you to use 87 octane, then running 93 is throwing money away.

F-BIRD'88

*Some* high octane fuels have a slower burn rate.
The fuel burns slower. thus without the high compression ratio
of a race motor, a stock motor would loose power.

It may need more ignition advance too.

*Some* high octane fuels have a fast burn rate. As fast as 87 octane and a stock motor would not see any power loss.
Depends on the actual fuel blend.

Further , Some high octane fuels have a different specific gravity. This would require a jetting adjustment to equal the air/fuel ratio of 87 octane street gas. A lower specific gravity fuel would need a larger jet.

As said above , you only need enough octane to prevent detonation, any more is a waste of money.

1986redbird

OK, heres the deal. I have a '94 LT-1 motor in my race car which is basically stock with the exception of open headers, the motor has a factory C.R. of 10.5 to 1, I have been running 110 octane race gas in it since I installed and am wondering if that is too high for a stock High compression motor.

Mark A Shields

umm yeah, I wouldn't think GM would produce a vehicle that requires race gas, at least now a days anyways.

since it has aluminum heads usually you get away with running a little more compression with the same octane fuel. least that's what I thought i read on here

kfoley

Yes you can run safely 93 octane in an iron headed motor with ~10:1 compression, and with an aluminum headed motor you can run about a half to a full point higher on the same octane. Of course this is assuming you have good combustion chambers and a tight quench area.