View Single Post
Old 10-24-2001, 01:15 AM
yhliem yhliem is offline
Senior Canadian Member
Join Date: Jul 2000
Location: British Columbia, Canada
Posts: 827
well, i'm not an expert, but i don't really see how higher octane would cause an engine to run cooler. a higher octane rating means that the flashpoint (ignition temperature) of the fuel is higher.

by raising the flashpoint, the fuel mixture detonates a little later. without a sufficient octane rating, the fuel could detonate before the piston reached tdc (aka pre-detonation) causing the common problem of knocking.

another common effect of using too low an octane rated fuel is dieseling of the engine when the ignition is shut off.

that all having been said, i can't really see how raising the ignition temp of the fuel would contrbute to cooler water temps. unless it is because the fuel is more completely burned in the combustion chamber and there is less residual fuel making it out into the exhaust before it's completely burned away?

like i said, i'm not an expert
'94 W124.036 249/040 leder; 8.25x17 EvoIIs
'93 W124.036 199/040 leder; 8.25x17 EvoIIs, up in flames...LITERALLY!
'93 W124.036 481/040 leder; euro delivery; 8.25x17 EvoIIs
'88 R107.048 441/409 leder; Euro lights
'87 W201.034 199/040 leder; Euro lights; EvoII brakes; 8x16 EvoIs - soon: 500E rear brakes
'70 R113.044 050/526; factory alloys; Euro lights
Reply With Quote