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Discussion Starter #1
OK a while ago when I did a compression test, I got pretty good results which was....


cylinder #1- 140psi
cylinder #2- 140psi's
cylinder #3- 140psi
cylinder #4- 140psi's

They wern't all excatly 140psi's but were pretty close..like some may have been 139psi's ect, so I just went with 140psi's.
My question is...I have seen a few compression results from 1st gen MX-6 GT's and the compression ws usually around 120 but no higher than 130psi's. Now my engine has been rebuilt in 1996 is it possible that they used slightly higher compression pistons when they did the rebuild? because 140 is pretty high. Don't get me wrong I love the fact that my compression is 140psi's and all of my pistons/rings are wearing excatly evenly in every cylinder. But my compression seems high and I was wondering if mabey I should be carful on how much boost I run until I find out if my pistons are stock compression ratio or not.
Could a compression reading as high as 140psi's on the GT mx-6 indacate that the compression is possibly higher than stock?

Methman
 
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Factory manual says that 140psi is in spec. Your still running 7.8:1 compression :)

Your lucky about getting that good of a reading, when I first got my six it was 125-135.
 

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I got 75 psi on cylinder #1 at the moment, I cracked a piston again. lol

consider yourself lucky. I believe mazdameister also got in the 140's on his 165k motor..
 

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Mine all between 115 and 120 after 230,000 km.
 

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Mine was 150 on all cyl's, tested a few months ago. I assume some carbon buildup on the pistons increased the compression a little. I'm not complaining. :)
 

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Discussion Starter #6
Thanks Guys...and Flyswat especially, that answered my question 100%. Yeah I like to think that I am lucky too, 140psi's in every cylinder indicates good stock compression (according to you guys) and an 100% even wear in all cylinders! My mechanic also told me that all of the seals and gaskets looked brand new when he had the head off...so I guess its safe to say that my rebuild isn't that old. I assumed it was done in 1996 because the plug wires said 1996 on them, thats is, of course, before I changed them to accell 8.8mm wires. but it could of been done sometime after 1996, but deffintally not before 1996 since every thing that was done during the rebuild looks brand new. I guess whoever it was that rebuilt it knew what he was doing.

Methman
 
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