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Thread: Fuel and compression ratio's ???

  1. #1
    Junior Member SHOW GUEST
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    Fuel and compression ratio's ???

    I have a 383 stroker that has 11:5.1 Compression with a 64cc head... id like to run 94 Octane gas without USING race fuel, is this possible ? I was thinking of buying titanium gaskets and that would bring the compression ratio down wouldnt it ?

  2. #2
    Senior Member RACING JUNKIE
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    Titaium gaskets, what the?????
    I wouldn't reccomend using pump gas with your compression, you can run that new E85 with it though.
    I had a simlar set up and I ran a mix of 110 race fuel and high test pump gas.
    Goodluck, Charles
    ***IN GOD WE TRUST***

  3. #3
    Senior Member RACING JUNKIE
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    I ran an 11.1 406 with 94 octane but kept the timing backed up a bit...I also would dump in a few gallons of cam 2 mixed in with it...boy that was awhile ago..lol. Do they still sell that stuff?

  4. #4
    Using aluminum heads would be a good option to allow you to run pump gas, you can keep your timing up there and the aluminum will get rid of the heat better.

    Lifeinbemidji

  5. #5
    Senior Member RACING JUNKIE
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    How big is your cam?A cam with alot of overlap will bleed off cylider pressure at lower rpms and help with the situation.A short duration cam,with less overlap will probably cause problems.What is it were you trying to figure out about head gaskets??Different materials won't change comp ratio,but a thicker or thinner one will.My 496 is 11:2 and I only run 32 degrees timing,I know a small block will want more,I tried straight 93 and it worked OK,but I mix a little CAM2 in just to be safe.
    "The problem with quotes on the Internet is that you cannot confirm their validity"- Abraham Lincoln

  6. #6
    Senior Member RACING JUNKIE
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    Quote Originally Posted by olds48
    How big is your cam?A cam with alot of overlap will bleed off cylider pressure at lower rpms and help with the situation.A short duration cam,with less overlap will probably cause problems.What is it were you trying to figure out about head gaskets??Different materials won't change comp ratio,but a thicker or thinner one will.My 496 is 11:2 and I only run 32 degrees timing,I know a small block will want more,I tried straight 93 and it worked OK,but I mix a little CAM2 in just to be safe.
    Why only 32 deg? is that where it runs best or is it so you don't have to run race gas straight?

  7. #7
    Senior Member RACING JUNKIE
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    Tried 36 and lost 2mph on two runs in a row.Dropped it back to 32 and saw 101 again :? Figured it was happier there,ET never changed,maybe in the thousandths but nothing major.That was with a pretty crappy exhaust system,though.Now that I got my exhaust right,might play with it a little more.Any advice on timing is welcome,though I do fine without straight race gas and zing to 7000+ pretty regular,if that means anything at all.I mean,my shift point is 6600 but......you know ops:
    "The problem with quotes on the Internet is that you cannot confirm their validity"- Abraham Lincoln

  8. #8
    Junior Member JOURNEYMAN
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    hey all I am new to this fourm but this thread here is why I join mostly.

    I have a amc 401 with about 10.5:1 to 11.0:1 comp ratio( the reason I don't know excatly is because I bought the engine as a "whole") but the highest octane I can get around my parts is 94. Do you think I could get away with this? I also have stock cast iron heads but there ported right out.

    any info would be great thanks justin

  9. #9
    Senior Member RACING JUNKIE
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    Really would just have to try it.With an aluminum head,probablt.Iron gives you less of a chance of it working.Cam profile really dictates alot of it.I have a 350 SBC that only has 9.5:1 compression and aluminum heads and I HAVE to run 93.But the cam is a real short duration HYD roller,like 205 and 215,I think it is.Traps alot of cylinder pressure compared to a big lumpy mutha.Alot of places where I live only have 91 octane and it makes it rattle on a real hard pull.Car is 4300 lbs with me in it,2.73 gears and a 4-speed,so it really works hard on some hill side take offs.So,it's really hard to tell.Try some 94 and if it rattles mix in some good stuff til it passes.JMO.
    "The problem with quotes on the Internet is that you cannot confirm their validity"- Abraham Lincoln


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