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Octane and Compression

This is a discussion on Octane and Compression within the General Help forums, part of the LSx Technical Help Section category; I have reviewed most of the information on this site and some from a few others about octane booster. As ...

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    Senior Member Z28_Driver's Avatar
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    Octane and Compression

    I have reviewed most of the information on this site and some from a few others about octane booster. As this is not the way to go. How do you raise the octane of fuel safely?
    It is for an old car that has 11 to 1 compression.
    Race fuel is not an option as a trip to the nearest seller is over 50 miles.
    The engine has a carb and flat tappet cam if that helps.

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    Senior Member bills98ta's Avatar
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    Basically, if you run lower octane, just retard the timing. If you hear valve ping, take more out. Higher octane allows more timing advance. I'd still run 92 and higher if I were you.

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    None Shall Pass Knight's Avatar
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    Quote Originally Posted by bills98ta View Post
    Basically, if you run lower octane, just retard the timing. If you hear valve ping, take more out. Higher octane allows more timing advance. I'd still run 92 and higher if I were you.
    Agreed. You could always fill up drums with the racing gas to have on hand when you need it - I used to fill three 55 gallon drums when I ran my 72 Roadrunner. Expensive, but I knew I was running the right gas then.

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    Senior Member bills98ta's Avatar
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    I have a Sunoco right up the street with 100 & 112 octane !!!

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    None Shall Pass Knight's Avatar
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    Quote Originally Posted by bills98ta View Post
    I have a Sunoco right up the street with 100 & 112 octane !!!
    I've got one about 10 minutes from me. The only thing I use it for now is the boat though.

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    Senior Member bills98ta's Avatar
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    I hear that boat motors don't like ethanol...

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    None Shall Pass Knight's Avatar
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    Mine's not a typical boat motor. It's a built chevy 350.

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    Quote Originally Posted by Z28_Driver View Post
    I have reviewed most of the information on this site and some from a few others about octane booster. As this is not the way to go. How do you raise the octane of fuel safely?
    It is for an old car that has 11 to 1 compression.
    Race fuel is not an option as a trip to the nearest seller is over 50 miles.
    The engine has a carb and flat tappet cam if that helps.
    At 11:1 CR, I dont see why you cant run a good 92+ octane fuel. My motor was close to 11.5:1 and ran great on 93 octane.
    Quote Originally Posted by bills98ta View Post
    I hear that boat motors don't like ethanol...
    They HATE it.

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    Member 408WS6's Avatar
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    Since it's for an old car, I'm assuming that you have iron heds rather than aluminum. That changes things up some. In the old days, 10.5:1 is as much as you could run. So your a little over the limit. You kinda screwed maybe..

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    Senior Member Z28_Driver's Avatar
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    It has iron heads. I usually put 93 octane from shell in my 2002 z28. One response so far that this will be okay for 11 to 1.
    Anyone know of a formula to estimate the required octane?

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    Senior Member Z28_Driver's Avatar
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    Quote Originally Posted by Knight View Post
    Agreed. You could always fill up drums with the racing gas to have on hand when you need it - I used to fill three 55 gallon drums when I ran my 72 Roadrunner. Expensive, but I knew I was running the right gas then.
    The only problem with that idea is I don't have a truck to use to haul it in. And its more money than I can afford.
    Maybe double the heaad gasket to reduce the compression?
    Either that or I guess I'll run 93.

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    Senior Member bills98ta's Avatar
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    What motor is it ? SBC, BBC, Hemi ???

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