114 octane in a 318

[darren509]

Going to Infenion raceway on memorial weekend and want to know if using this race fuel will gain me anything. My set up is a 318 with .030" over, forged pistons, eddy heads and intake, all msd set up, roller rockers, and about 8.5.1 comp. Im currently running about 16* advance and total of 36*. If this octane is ok to run, will I have to make any timing adjustments ? I have never had any detonation problems yet and that was @ 20* of initial at one point in time. Any help is appreciated.

[dwc43]

Yeah it will do something al right it will slow you down. You can run 87 with an 8.5 to 1 engine. Race fuel is for 10 and up with high timming cause it burns slower and wont detonate as quickly. In yours slow burning fuel will just slow it down less hp.

[darren509]

Thanks, good to kmow before I shell that much $ to go slower...

[6 packin]

Mix it about 4:1 it wont slow you down. It will help. The longer the burn the more push/power you can make. I witnessed this with a friends stock mid 80's Chevy truck with a stock 305, he was getting use to the lights. It helped his make noticable more power.

[JVMopar]

I did some dyno testing last fall. I made more HP with 87 pump gas than 114 sunoco race fuel. This was on a 350 chevy spec. race motor. 9.5:1 compression.

I made even more HP when I mixed in 50% ethanol 50% gasoline. 30 more HP and all it required was a jet change and the time to mix the fuel.

[ehostler]

If it isn't pinging, you don't need it.

[92whitedak]

well said, ehostler.

[darren509]

No ping.. This will be my first time on the track and off the street so I think I'll stick with the same set up and try new things at another time. Does the theory stand true for a big block with high comp, about 10-5-1 and iron heads; no pinging on that motor either.

[dwc43]

If your at a real 10.5 to 1 in any engine and on 87 pump gas it will ping unless timming is real low and that reduces hp. You might squeak by with 97 but timming will still be too low. Any thing over 10 is going to need more octane to run more timming. A 100 would work nice on 10.5. We run 110 on 10.7 but we have to run track fuel or I would run a little less and make a little more power. Dont over think this. Power is in the heads,cam, carb, headers, and not what you put in the tank.

[darren509]

Im going to check the timing on my dads 440 tomorrow. By your description his motor must way retarded. Cam is a MP509 heads have some porting done but we dont know how much, holley 750 {4150} 727 391 gears. Approx. where should the timing be on this set up ? Car is 68 satellite

[ehostler]

A total of 38* at no later than 3,000 RPM (preferable by 2,000 RPM).

[dwc43]

I agree !!

[darren509]

How about the initial ?

[ehostler]

The initial will be taken care of, when you setup the max timing.

[amoparguy]

My 440 likes 20º initial with the .509, the mechanical advance is limited to 18º for a total of 38º. The extra initial advance increases manifold vacuum and really helped clean up the idle.

[cuda66273]

We have not found any advantage on any street strip low octane motors after 34* of total timing.

On a all out 12-13:1 compression Al headed motor we will crank them up to 36 total but after that we've found nothing much happens except detonation.

Just my 2 cents worth...based on over 500 Mopar distributors dialed in for specific engine combinations.

Now the Chevy guys will get more out of their stuff at 38-40-even 42 but it's mostly because of the plug location and distance of the flame travel in the Chevy heads.

But, if your happy and your motors happy with 36-38-40 go for it.