Re: [DML] Fuel Octane

["B Benson" <delornut@xxxx>]

This has been brought up before but to avoid confusion about octane ratings
you should understand that octane ratings ARE directly related to the
combustibility of the fuel. Higher compression in the combustion chamber
means higher temperatures which require a fuel that ignites and burns at a
slower more controlable rate. This would be a high octane fuel. When you
hear the engine ping or knock it's not the valves rattling, it's the piston
and rod bearings reacting to a pre-ignition occurring because the high temp
in the combustion chamber has ignited the fuel before the spark plug fired
and the piston is still on the up stroke, way too far ahead of the 13
degrees before top dead center than the DeLorean requires. If you continue
to use a high octane slower burning fuel in a car that doesn't require it
the slow burn will eventually create carbon deposits in the combustion
chamber. These deposits take up space and result in raising the compression
ratio. In other words your car can, over a period of time, become dependent
on high octane fuel.

Bruce Benson
vin 6870

> Much confusion about octane. Measures ability to compress fuel mixture
> without premature detonation. Does NOT measure "burnability" or any
> other characteristic.
I shoot
> my spark a little closer to TDC than factory spec (high energy
> ignition), so burn 89 octane to avoid ocassional valve clatter.
>
> Bill Robertson
> #5939