fuel octane
Thread Starter
Racer
Joined: Oct 2007
Posts: 431
Likes: 22
From: Chester Illinois
fuel octane
all you guys with these hopped up engines. where are you getting high octane fuel? around where I live, all you can get is 87 or 89 octane. will they run ok on that? nv
Melting Slicks
Joined: Mar 2008
Posts: 2,666
Likes: 289
From: Spring Park MN
I'd say a more accurate answer would be; it depends. My engine is on the edge with 93, 89 and it would have some serious detonation issues. A lot of the hopped up engines on the forum are low enough compression to get by on 89. There are more than a few with way too much compression for 89.
Drifting
Joined: Nov 2007
Posts: 1,716
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From: New York
Not sure what you are asking. Are you building a motor? You can have a 500 HP motor with Compression Ratio of 10.5:1 which will Required Fuel 91+Octane Pump Gasoline. My old motor was over 11 to 1 and had damage to the forged pistons due to detonation when I took it apart.
Race Director
Joined: Jul 2001
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If the highest octane the OP can get is 89, I'll hurtle to the conclusion that he lives in a relatively high altitude area like Denver or similar. If so, 89 is probably sufficient for just about any street motor.
Race Director
Joined: May 2006
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Intermediate
Joined: Apr 2012
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I typically will only use non-ethanol gas in mind unless in a bind. What you need to consider in your case is how often will the car be driven vs sitting for long periods of time. Obviosly if it's a monster motor you will probably drive it less so you may want an additive if all you can get is ethanol gas.
Melting Slicks
Joined: Mar 2008
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From: Meriden CT
namvet, I have about 9.5 to 1 CR with iron heads and run 89 with no issues.
Last edited by SH-60B; Jul 31, 2013 at 05:48 PM.
Race Director
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Intermediate
Joined: Dec 2012
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87, 89 who cares . . . that's why they make Octane boost additives. I have a 350, 10:1 Aluminum Heads, 400 HP and run 93 Octane plus Octane Boost from the local Auto Store. Easy start . . no pinging on acceleration and no dieseling on shutdown.
Life is good!
Life is good!
Burning Brakes
Joined: Apr 2013
Posts: 926
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From: Castle Rock CO
I live in Colorado and we have 85 87 and 91 Octane all fuels have 10% Ethanol in all the fuel so I like to use Sta-Bil Gas Treatment and Marvel Mystery Snake Oil when it sits over the winter. Helps to lubricate the fuel system and stabilize the gas so that the alcohol does not eat up anything. Running thru the summer is not a problem but sitting in the winter bad.
I run the 85 octane in my low compression L48 engine without any problems on my 1977. If I had the L82 high compression engine I would run the 87 or 91 octane.
I run the 85 octane in my low compression L48 engine without any problems on my 1977. If I had the L82 high compression engine I would run the 87 or 91 octane.
Safety Car
Joined: Jan 2009
Posts: 3,736
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From: anchorage ak
I've researched this and all that I can come up with supports Mike's insight completely. I've got a buddy that runs eleven to one on 90 octane as that's bought as high as you can get up here unless you run av gas which is common but not on every corner. If you keep the dcr at the right point for either iron or aluminum heads you can get away with a lot on 89 octane. There's also a common theory that to much octane for a giving motor will hurt performance more than it will help.
Last edited by bluedawg; Jul 31, 2013 at 10:52 PM.
Melting Slicks
Joined: Mar 2008
Posts: 2,666
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From: Spring Park MN
When a octane booster says it will increase octane up to 3 points, they mean 0.3. If you start out with 89 and add booster at the high end you now have 89.3 octane. Most use either zylene or toluene, which will raise octane, but it takes at least 10 times as much as you get in the little bottle of booster. Some use methanol alcohol, which is not good for your fuel system.I have a friend in the oil business that makes an octane booster that has MMT (methyl cyclopentandienyl manganese tricarbonyl). It does work, but it will eventually foul the plugs with a red deposit of manganese. How much can be used in an octane booster is regulated by the EPA to prevent damage to catalytic converters. He used to have a race version with a much higher content of MMT that worked quite well. I've used it in pinches, but it makes that red deposit pretty quickly.
Melting Slicks
Joined: Mar 2008
Posts: 2,666
Likes: 289
From: Spring Park MN
I've researched this and all that I can come up with supports Mike's insight completely. I've got a buddy that runs eleven to one on 90 octane as that's bought as high as you can get up here unless you run av gas which is common but not on every corner. If you keep the dcr at the right point for either iron or aluminum heads you can get away with a lot on 89 octane. There's also a common theory that to much octane for a giving motor will hurt performance more than it will help.
Intermediate
Joined: Dec 2012
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Octane Boost - Maybe it's a mental thing, but when I don't use it she diesels slightly on shutdown. With it, she stops with no fuss at all. It may be a lot like your car always seeming to run better right after you've washed and waxed her. I guess that's why they call it a treatment. We all like being catered to, so why shouldn't a Vette?
Melting Slicks
Joined: Dec 2008
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From: N.Richland Hills Texas