Road Rage

Over in the TL forums, there was the usual "premium vs regular" thread, and it got to the point of absolute stupidity - such as "I used regular and mt MPG went down by 25%". That kind of thing.

Then, some Einstein "mathematically proved" that regular was unjustified, based on a 1-2 MPG cariation.

I go fed up with the whole thing, did some research, and found something you all might find interesting.

Short version? The max difference in fuel economy between regular and premium is 3%.


3%!!!!

http://tl.acurazine.com/forums/showthread....d=1#post1027351

JDM Baller

Do they not realize that regular vs premium is not about fuel economy but about avoiding pre-detonation in certain vehicles?

Gernby

I am surprised that there would be any difference at all in fuel economy between octane ratings as long as it is high enough to prevent pre-detonation.

mikegarrison

91+ octane costs more and it is called "Premium" so it must be better. Kind of like JDM coilovers or slotted rotors or "performance street pads" or aftermarket exhaust systems or....

mikegarrison

I suppose on lower octane gas the car runs with less optimal timing, so maybe it doesn't quite get all the energy out of the fuel that it does with higher octane. But I'm sure the effect is minimal.

I know I could much more drastically affect my gas milage by keeping my RPMs lower, but where's the fun in that?

Gernby

The way I see it, if the ECU doesn't detect any pre-detonation, then it will run "optimal" timing. I doubt the ECU would notice any difference between 93 and 100 octane fuel on a stock car.

mikegarrison

I've used 100 octane unleaded race gas (it was the only unleaded available at the track) and noticed no difference between that and regular 91 octane pump gas. Except the race gas cost $6/gallon, of course.

Sik -S

Try not noticing a difference between 86 and 91...your car will mock you!

jankemi

Per RR's link in the TL forum:

http://www.chevron.com/prodserv/fuels/bull...ormance/pg4.asp

It is an interesting read. I always blamed ethanol for my poor gas mileage. Maybe it is not the problem?

Interesting quotes from the above source:
In otherwords the octane required for optimal operation of your engine might be as much a 10 from the optimal for my (identical) engine.

And:
So you need enough octane to keep from knocking & that is all. It would be nice the the car's knock sensor would light up something on the dash when it kicks in.

jankemi

If some is good, then more is better, and too much ought to be just right!