I am thinking about running a higher octane fuel in the 383. I can get 110 from the gas stations near the track or I can get some 114+ from a small air field. Will i see any change at the race track? will it be worth the extra $.


Give me + and -'s

 

depends on your comp. ratio if you are 12.5:1 or higher you may see a gain,we use c-12=112 octane on the TTA w/21lbs of boost and changed to c-16 and we noticed less knock retard on the scanmaster.
i think that you should try it if your compression is hi as i stated but it may cause you to slow down your E.T.s if you have less compression....
it would be more helpful if we knew the important details like what parts you have,piston type,rpm you are shifting,the altitude etc.

 

As mentioned if running radical compression or power adder which would otherwise cause knock then it might help. Another thing to consider is a lot of really high octane stuff like that is leaded, lead kills O2s and cats, you may not care about cats but the pcm wants to see the O2s and while you could tune it to work without it would be major work.

 

Going to a higher octane fuel won't do anything for you, unless you are getting knock retard with the lower octane fuel. If you don't have any knock retard on your current pump gas, you would have to try retuning, probably adding a little more timing to see any benefit from the higher octane. Without that, you are just wasting your money.

I did extensive engine dyno tuning on my 381, 10.8:1, mild 230/242 114LSA cam, and we got max HP with 94 octane fuel. Running 100 octane showed no gains, even when we tried playing with the timing and A/F ratio. With the 300-shot of juice it was a different story.... .

The highest unleaded fuel you will find will be in the range of 104-octane (R+M/2). Anything above that is leaded. Fuels for aircraft are almost always leaded, and use a different basis for measuring octane, and have a blended vapor pressure that is specific to high altitude operation. Your O2 sensors will not like the lead.

 

I will have to say that if you're not knocking the extra octane will actually hurt you....

BUT!!... it does seem that racing fuel does have more to offer than just knock resistance. Formulation comes into play.

A blend of "racing fuel" and pump gas can get you a few ponies. But unless you are putting dollars on the line then it's really not worth it. Spend the dough on getting your combination running the way it's supposed to run.

 

Am running 13.5 to one on 110 why do you want to go more.DCR is 9.96.
If you have 10-11x1 it will slow you down with 110.A tune will help but your DCR with 11.0x1 is probably 8-8.5x1 and no need for more than 92 octane.