Ok just finishing up my 383 build...what octane gas should i use?

 

I would run at least what the owners manual states, premium. Unless you built up a high compression, monster stroker motor, but you haven't given us too many details.

 

Are you serious?

 

Yes...y would i have posted the thread...it is a high comp. motor..n/a..

 

at least premium. its hard to say what you should run if we have no specifics to go off of.

 

383 bout 11:8:1 compression.tfs heads fully ported...fully ported lt4 intake mani,pacesetter lt's,custom cam,42lb injectors need to no anything else?

 

Since you bumped up your compression ratio, you're not going to be running a fuel with a lower octane rating than you did stock. A stock LT1 is supposed to run 91 octane for optimum performance.

If you can buy 93 octane locally, I'd go with that, otherwise 91 octane will be fine. Whatever you tune the car with, use as fuel. In otherwords, if you tune it on 93 octane, I wouldn't put 91 octane in it on the next tank if I was looking for optimum performance

 

upping the compression means you should up the octane. Don't use octane boosters they are a waste of money.

 

if i tune it for 93+ can i use higher octane in the futture?

 

Tune it using the fuel you plan to run every day. There is no way someone looking at a computer screen, and knowing absolutely nothing about your engine could tell you what fuel to run. If you want to run higher octane fuel in the future, put it back on the dyno and optimize the fuel and timing for the new octane level.

 

Octane does one thing, and one thing only, stops ping, or detonation, what ever you want to call it. Said anomaly is when the A/F mixture starts burning opposite of the wave of burning A/F caused by the plug's spark. When you have a high comp motor, the A/F is more unstable, making it more likely to predetonate, increasing the needed amount of octane. If your motor requires 91OCT stock, and you bump the compression up, you would only expect to have to AT LEAST maintain stock octane needs, and if anything, up it. If the motors not pinging, then your oct rating suffices.

If you didn't know that trivial bit of info that I just recited totally intoxicated, you have no need owning said car..

 

Generally, "ping" is used to describe pre-ignition... auto-ignition of the fuel before the plug fires; "detonation" is used to describe the 2nd flame front igniting after the plug fires and starting the first flame front. Two different phenomena, two differents solutions. Not sure exactly what "predetonate" means... perhaps you could explain that in a non-inebriated condition

There's a good article on "octane" and fuel selection in the current issue of Chevy High Performance magazine.... worth a read.