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Author Topic:   whatcha think
Dirt Freak

Total posts: 429
posted May 12, 2004 12:22 PM  
I have 350 bored 30 over, 70 cc heads and cast iron intake, manifolds, q jet , flat tops. Would I be wasting my money running racing fuel. I been on 93 octane would it help to swap. what yall think

Dirt Forum Champ
Total posts: 2007
posted May 12, 2004 12:41 PM  
yes i think it would be a waste of money. With flattops and 70cc heads i would guess you are close to 9:1 or just under. 93 octane should be more than enough.

Dirt Forum Champ
Total posts: 569
posted May 12, 2004 12:51 PM  
I second that.

Hi-octane fuel won't help you if you don't need it.

Dirt Freak

Total posts: 429
posted May 12, 2004 03:12 PM  
Thats what I was thinking but its always good to make sure someone agrees with you. We are on such a strict engine rule I was just looking for advantages, Guess I should look else where.

Ego Racing
Dirt Forum Champ
Total posts: 724
posted May 12, 2004 07:30 PM  
The Higher the octane number the harder it is to ignite the fuel. I was helping an offshore powerboat team once and was there when they could not get VP racing fuel they used 93 octane (What there engine builder said they sould run) and they picked up about 10 mph on the top end. They went back to VP on the next run and were down 10 MPH from the 93.

Dirt Freak

Total posts: 474
posted May 12, 2004 08:36 PM  
while I agree with these guys I would strongly recommend checking those plugs often to monitor for detonation signs,

Light it up, Baby!

Dirt Full Roller

Total posts: 46
posted May 13, 2004 09:16 PM  
I agree with checking the plugs and also keep a close eye on how much advance your distributor is giving you. On cast pistons even with that low of compression detonation is likely depending on atmospherics.

Dirt Roller

Total posts: 20
posted May 15, 2004 05:08 PM  
I agree with everyone. We saw a 6 hp increase on the dyno going from 110 to 93. 9:1, with 36 deg. timing. The 93 seems to burn slower.

Dirt Forum Champ
Total posts: 1363
posted May 15, 2004 07:41 PM  
lower octane fuel burns faster than higher octane.

....and lower octane fuel is easier to ignite.

[This message has been edited by outlawstock17 (edited May 15, 2004).]


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