wideopen85

what fuel do you use at the drag strip? Any different than on the street? Just wondering if there's any performance to be had by running a higher octane or not really. Are boosters worth it? Do you use leaded or unleaded? Car is around 11:1 comp.

383vett

110 leaded.

ddahlgren

How bout the one it was tuned on? 103 unleaded is more than enough for 11/1 compression.

bjankuski

If you have an o2 sensor use unleaded. Since you are 11 to 1 compression use as high octane unleaded that you can get. 93 would be the min I would run.

Kevova

Most street driven cars 93 octane. If you change fuel system for E85 is a lower cost alternative to race gas. E85 is more emission friendly if it matters. It also burns at 1/3 higher rate than gasoline. Race gas can require tuning for brand and grade. The different brands and grades can have characteristics that require may some tweaking to get maximum performance.
There is no benefit to running higher octane than you need. If you have a scanner you could watch the knock counts and adjust from there. If engine is properly tuned and you have excessive knock counts higher octane would be required. 11 to 1 is somewhat borderline depending on engine. Reverse cooling is more tolerant than conventional with iron heads.

antfarmer2

What ever you tuned it for.

RustyCFI

11:1 Static compression doesn't tell us much of anything in relation to what fuel should be used. Dynamic or effective compression is what will tell you what fuels you can use and should use. Dynamic compression will be affected by the cam, specifically when the intake valve closes. You could have a 11:1 static compression and a cam with a late intake valve close and give you a dynamic compression ratio of 7:1, which means that using 93 octane will give you no more benefit than using 87 octane. Meanwhile you can have a 9:1 static compression ratio and a cam with an early intake valve close (like my 84) and have an 8.2 dynamic compression ratio, which means I will have severe knocking using 87 octane and will need to use 93 octane. Other stuff gets included into it too, check out the calculators online. Lots of heat in the heads and in the air also push up octane requirements. Using 110 octane when your car is "tuned" for 87 octane will give no benefit, and can give some disadvantages. A higher dynamic compression will give you a ton of benefits (mainly more power and VE) but comes at a price of having to use higher octane fuel to prevent knocking and detonation.