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Author Topic:   Dumb question of the day
posted May 20, 2004 01:55 PM
Is there a way to tell or figure out what your compression ratio is with the engine put together? And part there a way to tell if you aren't running enough octane before you melt something? And I will stop with part three.....Anyone happen to have the guide for compression to what octane is needed handy?

Ego Racing
posted May 20, 2004 02:10 PM
FIRST You can do a volume messurement for the compression ratio.
SECOND Listen for pre detonation or Knocking.
THIRD There is no TRUE rule for compression to octane referace. It has way to many vairiables to be put into a simple form. We have run 13:1 with 93 octane but you must have the correct components and flame travel across the piston. The Key to the most power is to remember that the octane number is a reference to how hard it is to ignite the fuel, so running a higher octane than needed will slow your car down because you are not getting a complete burn and are waisting fuel. Run just enough octane to keep the engine for knocking.

[This message has been edited by Ego Racing (edited May 20, 2004).]

posted May 20, 2004 04:07 PM
VP Racing fuels has a brochure. 93 octane is good to about 10.5 or so in normal applications. If you know your chamber size bore and stroke you can use the compression calculator in the toolbox on this site.

posted May 20, 2004 08:27 PM
If you run open ex how do you listen for the "knock"?

posted May 20, 2004 10:06 PM
just stick an ear in the header'll hear all the knock you ever wanted....and then some!



[This message has been edited by stockcar5 (edited May 20, 2004).]

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