Just saw another post about what sort of numbers you should get when doing a CR test with lower comp pistons and it got me thinking, this is one subject that is hard to get a decent answer to. At least, it's hard to get an answer that inspires any real degree of confidence anyways.

So what I'd like to propose is that people with CRs other than stock post their results in this thread. After a while, it could be moved to TWSB and there would be a good thread to find out just whether or not those 150s you just got after it was all warmed up were a good thing or a bad.

I guess if you're a super mod, genius type who already knows with certainty where comp test numbers should be at different CRs, then you could just post that info and simplify all of this, couldn't you, Dino?

Maybe someone like myself could take the information in this thread and make a write up for the no0bs on how to do dry/wet compression tests and have a chart or something to show acceptible ranges for popular CRs on 2GNTs. Just some ideas.

Discuss...

I'll be sure to post my CR with my 8:8.1 CP's. My motor should be back together in the following week, given I get my head back this weekend.



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Completely invalid premise.

There are too many things that will cause a lower compression number on a gauge besides actual compression ratio. Cams, for one. a 12:1 motor and an 8.8:1 motor could have the exact same reading on the gauge if the 12:1 motor had enough overlap in the cams.

All a compression test is good for is comparing the numbers in one cylinder to the numbers of the other three. You want them to be even. Given a known set of circumstances (stock compression, stock head, stock cams, stock combustion chamber volume) you can use "perfect" numbers to determine the health of an engine, but once you get into it and start throwing in cams, different compression pistons, bowl work, all that shit goes out the window. Unless you compile a list of brand new motors with your exact mods, you can't really compare your numbers to anyone else's. A leakdown test is the only thing that can really give you an idea of how well the combustion chamber as a whole seals anyway - a compression test is just easier and the equipment cheaper.

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