ejbta

I have a 2000 ta mods are in signature thinking of using good fuel , don't under stand timimg need more or less or leave it alone ? 91 pump to VP 101

01ssreda4

iTrader: (96)

Adding more octane does nothing if the tune is not setup for it. You could actually lose performance.

Mmicheletty

Increase timing. The higher the octane the more "aggressive" the tune can be.

redtan

iTrader: (5)

True, but continuing to increase timing doesn't necessarily make more power. Sure he could put some 114 octane on there and run 36* of timing at WOT, but that's probably not going to make anymore power than say 28* on 101 octane.

Best bet would be to get on a dyno and see what kind of timing your car likes, not just blindly throw timing at it with some racing fuel and that's it.

Mmicheletty

^correct

ejbta

I am running 91 and was woundering if I put 101 in would I have detonation problems.

YellowToy/A

iTrader: (1)

No, but don't waste your money. No gain. If you are boosted then it will help.

MontecarloDrag

iTrader: (3)

91 octane with stock timing is more than enough for a stock CR engine.
101 octane is overkill, unless you are spraying nitrous or going forced induction, you'll only waste your money with 101 or higher gas.

redtan

iTrader: (5)

Higher octane means less chance of detonation, so no you're not going to have more detonation with 101 octane than with 91...if anything you will have much less.

bigboykilroy

iTrader: (48)

Higher octane fuel won't do you anything unless you can burn it. The higher the octane of the fuel, the slower it burns. Basically, you want to run the lowest octane fuel you can get away with. If your cars timing is optimized for premium unleaded, it can compensate somewhat for lower octane gas (a little less performance). Now if you had high compression, advanced timing, lots of boost or nitrous you may benefit from running higher octane fuel. In the end don't waste your money if you don't have to. Your system needs to be setup to work with each other, timing, compression, etc.

ejbta

I was told by a vp dealer at the track I could get a couple tenths to going to his 101 or 109 but my car runs good for no more than I have done to it , being a bolt on car

joecar

Only if you advance timing... but see the comments above.

Optimum timing is when maximum cylinder pressure coincides with a particular piston/crank position... higher octane fuel burns a little slower so you can advance the ignition event... the problem comes (as was alluded to above) when you movethe maximum pressure position away from optimum (i.e. you lose "leverage").