Race Fuel?

[DiSmO]

Okay guys I was wondering...I have the stock turbo running 17psi (high via profec-b) I got exhaust,intake,icpiping-bov, fuelpump and safc. If I threw in like 2-3gal. of 100 unleaded race fuel would I have to richen or lean out my a/f? thanks..

 

[Awdboost]

You should beable to lean out your AFC. I don't think that you run richer per say. But higher octane fuel has more of a tolarace towards knock, so that you can run leaner. Thus running leaner and keeping your timing advace you can make more power. Also you will see that if you have a EGT. Witch I know you don't, you will see low temps. I don't really know excactly why that happens but I think it got something to do with less knock count.

 

[Silent2g]

you don't have to lean anything out what so ever for race gas
well saying your running 100 octane is not going to cause the car to run funky
116 might do that and might have to take some fuel out of the system.
i have run 110 through mine without and afc and never had a problem

 

[candela]

Silent is right. If your going to be going to the track then 100 octane is fine and you shouldnt have to change anything. As long as its unleaded (i think the highest unleaded is like 104) you wont really notice much difference, maybe a little more timing and power but nothing crazy.

When I go to the track i use c16 (117 leaded) and crank the boost, and it feels like a completely different car. I can run 20+ psi with no knock...its wonderful stuff!

 

[Silent2g]

Originally posted by candela
Silent is right. If your going to be going to the track then 100 octane is fine and you shouldnt have to change anything. As long as its unleaded (i think the highest unleaded is like 104) you wont really notice much difference, maybe a little more timing and power but nothing crazy.

When I go to the track i use c16 (117 leaded) and crank the boost, and it feels like a completely different car. I can run 20+ psi with no knock...its wonderful stuff!

i run 110 and 17 psi
as you said, totally different feeling

with 100-104 octane it will feel
how you say "peppier" then usual and you run a pound or two higher, just be careful

 

[NDgsx]

The different specific gravity of racing fuels allows you to run a shorter injector pulsewidth than you could with pump gas, all else being equal. Upping the boost in esence brings in more air, so you can at times run the same injecor pulsewidth that you did on pump gas/low boost.

As with anything YMMV and you need to just try tuning it youself.

 

[TRBOTSI]

So basically, you don't have to lean the car out while on race gas. The thing is, if your car is tuned, (no knock) on pump gas, then race gas will do little for you. The real power comes from leaning it out...remember leaner is meaner

 

[90GSX]

The real power gained by using race gas is the capacity to increase the boost without detonating. The spontaneous combustion temprature of race gas is higher than lower octane pump fuel. This means that the temprature of the intake charge in the combustion chamber durring the compression stroke can be higher without detonating prior to spark. The benift of this knock resistance allows the boost to be increased without adding more fuel. Thus if you're running 15psi on a 16G on 93 octane, you can run 20psi on C16 at (basically) the same fuel enrichment.

For example, I run 18 psi on pump gas and 26psi on race gas with very little knock in either case, on the same VPC fuel settings. Some people tune their cars specifically for pump gas, some for race gas. I like to be able to easily switch between the two, so I use a fuel setting optimized for 26 psi on race gas, then set my pump gas boost level to agree with the C16 (race gas) fuel trims. Switching from street trim to track trim on my car is a simple as pouring in the C16 and reconnecting the boost controller.