I am going to go racing this weekend and I want to fill up on some 101 octaine at this gas station down the street form the strip. I have a mild 355ci with a slightly lopey cam around 9-9.5 to 1 with a pretty much stock bottom end. It makes aroun 275hp and 350lbs of tourque. I was just wondering if it would hurt anything to get a full tank of the 101. Some aditional info for you. It has a preformer rpm intak and a edelbrock 600 cmf, 1 5/8 hooker headers, 2 1/5 in pipe with cross over and 2 flowmasters. It also has an open 10 bolt with 2.73(soon to be replaced by a 12 bolt with a posi and 3.73) Any info u can give will help out.. Thanks

no it will not hurt you at all.

the higher the octain the better it resit's knock and ping. you will not get any more power just run with out and detonation.

by the way the weight, specific gravity, is how you tell how much power is in gas. race gas is a very consistant blend. pump gas varrie's quiet a bit.

You shouldn't need that much octane for than combo. Are you having problems with pinging? It wont hurt anything, but higher octane usually burns a bit slower and causes a slight drop in power, so too much octane can hurt power.

In my opinion octane is over rated, it is nothing more than a rating of how a fuel resists ignition. The higher the octane the harder it is to ignite. If it's harder to ignite, it will not preignite as easy. If you can get optimum timing on pump gas, more octane will do nothing for you.

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www.grapeaperacing.com (http://www.grapeaperacing.com)

Grape Ape I used to think like you do about race gas until I read a two volume book by Reher Morrison { they know about race gas} the say that there is the same amount of energy per volume of pump gas as race gas. I know it sounds crazy but the only difference is the rate of burn.

oger, I agree that the engergy is the same, the rate of burn is where the power loss is. When you look at similar race fuel, the higher octane one will usually burn slower. A slower burn rate will make less power, because you will need more advance. More ignition advance means there is more resistance from the point of igntion to TDC. If you use a faster burning fuel that will require 5* less advance. There will be 5* less resistance while the piston is moving toward TDC. I'm not talking a huge difference here, but my dyno experience has shown that any more octane than what is needed does not help power, and if the octane rating is too high power starts to fall. A change in ignition advance does recover some, but not all of the lost power. The led me to believe the the race gas burned slower, because the optimum timing was always more advanced with it.

It's been a while since I looked into this and modern tech may have found a way to make a faster burning gas with higher octane, so I could be wrong.

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www.grapeaperacing.com (http://www.grapeaperacing.com)

[This message has been edited by Grape Ape (edited 05-03-2001).]

When I read the book I couldn't believe it either. But those are 2 people I don't argue with.

Given your relatively low compression, my opinion is you would be wasting your money with the racing gas. You should have no problems with normal pump gas. I use 5 gallons of racing gas and then fill my tank w/93 pump gas, but I'm running 11.25:1 and 11:1 in my engines and they ping w/93 pump gas only. Save some money for that new rear end and good luck at the track.

I found this interesting. http://www.pontiacpower.com/faqs3.htm



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Sean James
67 camaro convertible
454 - 700r4
4:10 12 bolt
69 Firebird