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The compression on my 6 cylinders is around 120 each. I think that normal compression for a TT engine is around 155. I was worried at first but when I saw that all 6 were 120 and they were all holding psi I stopped worrying. Now...

Why would my compression be low in my jspec? Do these engines have a lower ratio? Thicker head gaskets?

OK, considering that I have lower compression, would it be accurate to say that I can run higher boost and still be safe?

Any other jspec brothers do a compresion test?

Thanks
 

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Says here in the mechanical manual on page 11-2 that the lower limit for compression pressure should be 115 psi (standard) for turbo engines.
 

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I guess its good that I am within specs! Now, does this mean that "stock for stock" my car makes less power because of the lower compression?
 

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Hey Matt,

I checked my JSpec's front bank (after cam spring back on the timing belt change) it was 130, 130, and 140 (on #1 - the cylinder I thought the valve might have been bent).

I think all you're seeing is ring loss - the 115 is probably when Mitsu warrants a re-ring.

I could be wrong,
Hope it goes your way, Rick
 

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You're right. With that low of compression you're going to need more boost to make the same power as a car with 155ps on all 6. One reason why my cars so quick at 16psi and knocks at low boost is because it's 155 across the board. You will actually make more power at full throttle with lower compression and more boost...providing your turbos are capable of high boost at a decent air temperature.
 
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