Octane question
Thread Starter
Instructor
Joined: Jan 2006
Posts: 160
Likes: 1
Octane question
I have a question about adding 100 octane to my 91 octane fuel,will my car run ok even though it was dyno tunned using 91 octane.
My car is a 99 vert that has the aps twin turbos and cam and heads.
Thanks; Donnie Brooks
My car is a 99 vert that has the aps twin turbos and cam and heads.
Thanks; Donnie Brooks
Racer
Joined: Dec 2006
Posts: 322
Likes: 0
From: Alexandria Louisiana
St. Jude Donor '08
Safety Margin
Donnie - Although using 100 octane on a tune built around 91 octane won't, as MissZ06 says, help U make anymore power & will be more expensive than straight 91, it WILL give U a better safety margin against detonation ( in case U get a load of bad or non-spec gas ). 
. That's something that I keep arguing w/my tuner over. 
He wants to tune my F1-R'ed 383 to run on 91/92 although 93 is at every gas station here in Louisiana. 
I keep telling him that I'll only run 93 + Torco & I also have methanol injection so even if I do get a bad tank of gas 
, I should be OK. 
Slightly OT but I'd like some opinions around the benefits of more timing vs more boost. If there's a legitimate concern over head lift if I run more boost ( 17# vs the present 14# ) then does anyone have any experience or guesses
to how much more power is to be found by running more timing instead? Granted, I can't make nearly as much power through additional timing as opposed to more timing but head lift then becomes less of an issue & I can always step up to 100 octane myself. 
Just trying to see if it's worth it.
Gene
. That's something that I keep arguing w/my tuner over. He wants to tune my F1-R'ed 383 to run on 91/92 although 93 is at every gas station here in Louisiana. I keep telling him that I'll only run 93 + Torco & I also have methanol injection so even if I do get a bad tank of gas , I should be OK. Slightly OT but I'd like some opinions around the benefits of more timing vs more boost. If there's a legitimate concern over head lift if I run more boost ( 17# vs the present 14# ) then does anyone have any experience or guesses
to how much more power is to be found by running more timing instead? Granted, I can't make nearly as much power through additional timing as opposed to more timing but head lift then becomes less of an issue & I can always step up to 100 octane myself. Just trying to see if it's worth it.Gene
Melting Slicks
Joined: Sep 2005
Posts: 3,082
Likes: 0
From: eagle mountain utah
I've seen a stock LS1 run 23* of timing on 9 psi and 91 octane without meth. When it hit 23.5*, it dropped to 13.5* when the knock sensors registered a knock that couldnt be heard by anyone. 10* of knock retard is two five degree increments so teh computer thought the knock was big. But, each degree of timing advance above the initial 15* netted about 15hp. I dont like running that close to knock, you dont get a second chance.
