I was wondering how much of a difference does the octane in pump gas make a difference of how a vehicle runs. I usually use 87 octane in my 94 flare. There's also 89 n 92. Does the.age of a vehicle make a difference also with the type of gas used. I have several complete unused cans of VP 110 race gas to use n wanted to mix with the 92 pump gas. I jus didn't know the ratio. Although I have a front tank n was thinking of using 5 gals in it. Jus hit the selector switch to run it on race gas only but really wanted to find a ratio mix to use with pump gas. It has a different smell n looks purple in color. Open to all comments n opinions. P.s. my motor is all stock. Except for headers n exhaust no cats.

 

Higher octane is wasted on these trucks, the EFI system isn't smart enough to take advantage of it.

 

X2

 

Nothing will change in stock form but higher octane would allow you to advance your ignition timing. Power and mileage would go up but gains will be small if even noticeable. It's unlikely the difference will be worth the extra fuel cost. That said, I'd be happy for you to try it and report your findings.

 

High octane fuel isn't what most people think it is. You don't get more power with it. You actually want to run as little octane as you can get away with (without detonation or preignition). Low octane fuel has, on average, shorter hydrocarbon molecules, and will burn faster--packing more of a punch during the power stroke for a lower compression motor (the timing of the pressure front from the combustion meets the piston top at a more ideal time). High octane burns more slowly, and is suited for high compression motors (not a 8.8:1 old truck motor, think 10.5:1 hot rod or better). The pressure front from race gas combustion meets the piston top after the piston has moved down the cylinder further, bc the race gas burns more slowly, so you actually lose performance! Yes you could advance ignition timing but it would still be a waste of good fuel, that probably costs around $6.50/gallon. In the mountains, our lowest octane offered is 85 because at altitude there is less cylinder pressure due to the lower ambient air pressure; it's an attempt to regain some performance that is lost at high altitude.
I didn't even run race fuel in my old 13.5:1 snowmobile, it was on the ragged edge but ran like red headed stepchild.

 

As I read down the thread I was starting to write (in my head) what my response was going to be, and then I read GoinBoardings post. That exactly what I was going to try to say.

Summary: only use the high octane stuff if you already have it and otherwise will be throwing it away. Never buy higher octane than you need to keep it from knocking at the "normal" spark advance.

 

Thanks guys for that octane lesson .......

 

I accidentally put 92 Octane in my truck one day... The only difference was a lighter wallet... And I honestly felt a sight power loss...

 

Some times some refineries will put better detergents into "premium" fuel, which can be an advantage to buying high octane gas that has nothing to do with octane. But I think now that most regular octane fuels have good detergent additives too, so even that slight advantage probably doesn't exist anymore.

 

Unless I have plans on doing allot of heavy hauling or hard driving for a good period of time I will use the lowest octane I can in my truck.