ehall

As a topic.

If two identical cars are running 15 psi, but one is running race gas, will the higher octane alone create more power, or will it jusy allow the a/f ratio too be better in the higher ocatane car?

badcoupe

dunno for sure depends on the race gas My dad is a VP dealer and we sell the oxygenated fuel and it really kicks a$$ The higher octane allows you to run more timing and or boost with less worry of detonation. Alsso race gas is more (pure?) as it doesn't have a lot of emissions additives etc that pump fuel contains

adrial

Far as I understand it, there will be zero/negligible difference unless you change timing/boost to take advantage of the increased octane rating.

streckfu's

The race gas allows you to run higher boost which is wat gives you the power. All things equal, race gas offers to advantage other than a lighter wallet.

mark944turbo

Race gas can make LESS power. Flame speed decreases, and instantaneous cylinder pressure integrated w crank angle's mechanical advantage decreases. I dont know by how much though.

Tb311

Is that only with n/a engines? Cause I know I heard that before with people putting high octane (91 here in CA) in their V8's which only require 87.

Tom M'Guinn

It depends. If the car is pinging on regular gas, then race gas may allow the DME to run more timing and make more power. If the car is not pinging on the regular street gas, then street-legal race gas should no no impact on HP at the same boost level. As mentioned, some non street-legal race gases have special ingredients that create more power (kind of like NOS-laced gas), and these blends can make more power even at the same boost level and even if street gas is not pinging. The magic of race gas is that it lets you run more boost. In any event, changing to race gas will not alter your a/f ratio unless you retune for the different gas.

Dark Lightning

Race gas + pump gas timing + pump gas boost = pump gas power.

Adding more timing or boost = more power.

KuHL 951

They are wasting their money and it will actually increase emissions for smog testing. Some people feel that higher octane gas than necessary makes there car run better...it must be a guilt complex; if it says 87 use 87 unless you have tweaked timing through chips or something

ukporker

As a matter of interest, in the UK, we can only easily get 95 octane unleaded and 98/99 octane super unleaded - does anyone know if we measure it differently or do we have higher octane petrol available in the UK. It was interesting to see that 91 octane was considered to be high octane (in CA).

Richard
87 951 - Marine Blue - Stock (at the moment)

toddk911

The higher the octane (race gas) the LESS power. Think of it as the motor has to work that much harder.

Higher octane only fixes pinging and/or allows higher boost/timing to be run.

To get more power from fuel alone, it would have to have a higher kilocalorie potential.

Chris White

But the race gas does have that nice track car smell....about the only plus if you put it in a car that runs well on street gas!

Chris White

RKD in OKC

It has been my esperience that, to a point, higher ocatane at the same boost level does increase the performance. Even if your car isn't pinging there is some timing retardation done by the KLR (that's why you don't notice any pinging). The higher ocatane fuel will reduce the timing retardation and provide some increase in performance. That being said, the difference you will notice would be about the same as running 87 octane then moving up to 91. It will feel a little more responsive and that's about it. My butt dyno would rate it at about 3hp.

aeronautica86

octane does not equal hp

RKD in OKC

I agree that octane does not equal horsepower, but decreasing anti-knock ingnition retard does. A 944 Turbo running 15 psi of boost is running higher than stock boost therefore creates more cylinder pressure than the stock controls were designed for. This means even with 91 octane the stock timing maps will be retarded as the boost pressure goes past stock and the anti-knock sensor starts sensing knocks. If your octane level is high enough to prevent pre-ignition at the higher boost levels your car will create more horsepower.