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| voxace |
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Hey,
Does anyone here know how to work out the compression ratio roughly of a motor, without going to the trouble of measuring a heap of things. I was just curious as to what mine would be. I am using a stock AU bottom end, stock EB head with only 5 thou taken off, and a 1.6mm head gasket. I'm guessing that it won't be all that high, as AU's supposedly had 9.6:1 with a 1mm gasket. How much would the extra 0.6mm drop compression you reckon? Cheers. |
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| madmax |
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Only way I know is to cc the head and measure bore & stroke. Don't see any other way it could be done, you'd be just guessing.
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| MARK.TANIA |
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get a compresson tester and see what is the differnce to factoury spec
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| stockstandard |
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MARK.TANIA wrote: get a compresson tester and see what is the differnce to factoury spec
doesnt work if you have an aftermarket cam though
_________________ Stoke me a clipper, I'll be back for Christmas |
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| tickford_6 |
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Posts: 6449 Joined: 11th Nov 2004 |
voxace wrote: Hey,
Does anyone here know how to work out the compression ratio roughly of a motor, without going to the trouble of measuring a heap of things. I was just curious as to what mine would be. I am using a stock AU bottom end, stock EB head with only 5 thou taken off, and a 1.6mm head gasket. I'm guessing that it won't be all that high, as AU's supposedly had 9.6:1 with a 1mm gasket. How much would the extra 0.6mm drop compression you reckon? Cheers. the i messured the au gasket i used on my engine, it's .47mm the old (compressed) acl gasket was 1mm from some basic in my head yours is around 9.2 to 9.4 |
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| voxace |
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Hrmmm, I should have bloody used a thinner gasket then. Ah well, probably better taking the safe option. We just saw how much less dish the AU pistons had on them and was left wondering if it would be ok with the cam.
Will figure out my clearances, and might chuck on a genuine AU one soon. |
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| tickford_6 |
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Posts: 6449 Joined: 11th Nov 2004 |
you will push 10:1 + with an au gasket..........not a bad thing. you have a dissy to pull a little timming out if needed
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| Slick |
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This compression calculator might help, you just gotta convert mm to inches.
http://www.rosspistons.com/calculator.php
_________________ Mind f**k!!! it works on feeble minded ignorant sheeples... there's plenty of em on this site... some are very intelligent but by god they are so thick!!! Pakrat wrote: You can buy them seppertly
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| altedxr6 |
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when i put the tester inyour car, it was over 200 so thats pretty good, (and you have a alted/rpd cam) Yeah, we could of gone for a 1mm ACL gasket, But yeah, Maybe next holidays?
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| voxace |
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Hehe, I'll wait til the head comes off for porting.
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| opto |
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Do what madmax said in post and as a clue your total head cc (standard) no milling/shaving should be approximately 68 cc.
_________________ I post here cos the russian tank driver doesn't |
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| voxace |
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OK, sweet as. Put in all the details, and it looks like my comp ratio would be about 9:1, 9.4:1 with the 1mm gasket, and about 9.7:1 with the AU gasket.
A bit pissweak 
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| voxace |
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Turns out I got a 1mm gasket anyway, so it's all good.
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