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Old 06-21-2010, 01:47 PM
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Compression Check

Can someone tell me what Compression I would be at with this combo please?

http://www.summitracing.com/parts/TFS-K314-445-405/
http://www.summitracing.com/parts/ESP-B13455L030/

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Old 06-21-2010, 02:22 PM
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11.3:1 with a 0.041" gasket and a zero deck.
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Old 06-22-2010, 03:03 AM
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What's the highest compression allowable while using premium pump gas?
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Old 06-22-2010, 05:00 AM
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Quote:
Originally Posted by Nova21
What's the highest compression allowable while using premium pump gas?
Depends on intake valve closing point, efficiency of cylinder heads, squish dimension.

I don't understand the fascination with high static compression ratio in a street motor anyway. From 9:1 to 10:1, for instance, will allow an additional 4% power. That's 16 horsepower on a 400 horse motor. Big deal! You could generate more power than that with most any change and you wouldn't risk detonating the motor. Plus the fact that you may be able to put all the ignition timing into the motor at 9:1, but may have to pull some of the timing out with more CR to prevent detonation. So you make another 16 hp with the additional CR, but you give back 16 hp when you pull the timing out of the motor.

Also, with the 10:1 CR, you need more cam. More cam makes power higher up in the RPM range. Great for a race motor. Not so great for a street motor. You need shorter gears, looser converter, more expense.

I hope I'm making sense here. In my opinion, 9:1 to 9.5:1 is all you need for a street motor.
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Old 06-22-2010, 02:00 PM
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Ya that makes sense. I just didn't know what kind of compression I should be building for. I found a setup that puts me at 9.48:1 and I think that's where I'm going. I do have a question though, my cam says 9.5:1 minimum, am I ok with 9.48?
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Old 06-22-2010, 02:29 PM
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Quote:
Originally Posted by Nova21
Ya that makes sense. I just didn't know what kind of compression I should be building for. I found a setup that puts me at 9.48:1 and I think that's where I'm going. I do have a question though, my cam says 9.5:1 minimum, am I ok with 9.48?
Yes, it will be just fine, not enough difference to change anything.
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Old 06-22-2010, 02:29 PM
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Quote:
Originally Posted by Nova21
Ya that makes sense. I just didn't know what kind of compression I should be building for. I found a setup that puts me at 9.48:1 and I think that's where I'm going. I do have a question though, my cam says 9.5:1 minimum, am I ok with 9.48?
Yes. Or just use a slightly thinner head gasket and get the CR up that tiny bit- but I wouldn't be worrying about it as long as the quench was correct.
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