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Author Topic:   why run high octane gas?
posted October 22, 2003 12:08 PM
Ok, factory stock class we have to use stock exhaust, can use center dump style and vortech style too. Running 4412 holley and either 882's or vortech heads. Compression is 9.0 or less. From what I've read, there is no benefit to running VP racing fuel or higher octane because the low compression won't allow the engine to benefit from the higher grade fuel.

Is this wrong? Should I buy at the pump or at the track?

posted October 22, 2003 03:40 PM
With 9:1, I'd run pump premium (Sunoco 94 or Amoco/BP 93 if available). Higher octane fuel actually burns slower than lower octane fuel. So, a 9:1 motor with 115 octane race fuel will make less power than if it had 93 octane fuel. Actually, depending on the cam, a 9:1 motor may foul the spark plugs with 115 octane race fuel.

Anything more than what is required to stop detonation will hurt power. Too much above the required level will spit unburnt fuel out the exhaust.

posted October 22, 2003 06:07 PM
exactly right i run the same fuel in my pickup as my 9-1 motor it's a **** of a lot cheaper too

posted October 23, 2003 09:41 AM
That's what I thought guys, No need to buy that VP racing fuel then! Thanks for your help.

posted October 23, 2003 11:44 AM
Or engine builder told us we had to run 110 in our 9:1 motor. I laughed at him when it ran like dog poop. It ran much better when I siphoned it out and put the 91 octane in.


posted October 23, 2003 09:40 PM
One value when running race gas is that it is always the same. You never know what you are getting at the pump. It changes week to week. Refineries add 4 to 6 % of junk by-products to pump gas. If they didn't they would have to dispose of it as TOXIC WASTE.

Okay, it cost a little more but...Call VP and ask about 9:1 and 2 barrel gas. SLEEPY

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