namvet6869

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

Mike Ward

Yes.

v2racing

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.

cottoneg

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.

Mike Ward

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.

namvet6869

just doing some planning. no use building something big if I can't get fuel.

cottoneg

OK, so you are building a motor. The point I was trying to make is I would not build a 12.5 to 1 compression ratio motor and expect it to run on 87 octane.

MelWff

you could look here

http://www.racegas.com/fuelfinder

Hop's 78

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.

FKING1

Both Sunoco & BP sell race gas in the Detroit area. 110 octane.
I mix 1-1/2 gal of 110 with 93 each tank in my mod 383.

SH-60B

Poor job hurtling, he's from Illinois.

namvet, I have about 9.5 to 1 CR with iron heads and run 89 with no issues.

Mike Ward

Wonder why he can't get 91 or 93 like the rest of the continent then.

Bel

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!

MakoJoe

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.

Mike Ward

99% of octanes boosters are useless snake oil.

bluedawg

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.

v2racing

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.

v2racing

DCR will only get you so far. It is only figuring the adjusted compression at the intake valve closing. An engine with high VE can still make too much cylinder pressure around the torque peak for low octane fuel.

Bel

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?

U17

This might help ... http://pure-gas.org/