Does Higher Octane assist for FI vehicles?

[YeeFit]

I was curious to know whether or not running a higher than suggested octane level for forced induction cars makes any difference, and whether those differences are positive one or negative.

Currently my T1R turbo kit manual suggests 92 octane. Is there any ill effect if I were to run 94 octane or even higher?

I am at the moment running rich, but I will soon be tuned to my elevation which should keep my in the middle for A/F ratios...

[Fa1]

Go for the highest octane you can get. Of course you would need to retune for it. With turbo you're shoving a lot more air and fuel into the same amount of space, and with higher octane, the fueled chemical reaction is slower. Another benefit is that with higher octane you're more resistant to detonation. The only downside I see is the cost for higher octane.

[underdog]

fuel octane is the designation of the fuel's volitility.(the ability to ignite) the higher the octane (less volitile)the harder it is to ignite the fuel. this helps protect the engine from detonation and pre-ignition. in theory you want to run the lowest octane fuel without detonation for maximum power. however in reality where fuels arent perfect from batch to batch and the ambient temps can greatly change the probability of detonation. I like to run the highest octane available from the pump on a FI car.

another good feature of high octane fuels is you can typically run higher timing to gain more power safely. take race fuels for example if you just dumped in 104 octane fuel into your car most likely it would run slower. now if you leaned it out a little more and threw more timing at it, you would make more power safely. in a street car running 94 instead of 92 would probably only cost you a $1.00 a tank more(figure 10 cents a gallon more) and to me thats worth the added safety.

this also brings up another thing thats often overlooked. if you ever re-tune your car, you should always use the fuel you buy most often. from the gas station you'll be visiting most. that way you'll know how far you can push the fuel you use. but never tune to the ragged edge. all it takes is one bad batch of fuel and bye bye engine.

[Sugarphreak]

Originally Posted by YeeFit

I was curious to know whether or not running a higher than suggested octane level for forced induction cars makes any difference, and whether those differences are positive one or negative.

Currently my T1R turbo kit manual suggests 92 octane. Is there any ill effect if I were to run 94 octane or even higher?

I am at the moment running rich, but I will soon be tuned to my elevation which should keep my in the middle for A/F ratios...

Depends on your tune as well; you can tune your car to run on 94, but dropping back down isn't an option later on.

[Mr_ET]

Originally Posted by Sugarphreak

Depends on your tune as well; you can tune your car to run on 94, but dropping back down isn't an option later on.

Adam I would recommend 94 when you drive the car hard on very warm days of if you take it down the 1/4 mile.

Under normal driving conditions 91-92 octane from a reputable provider is fine.