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Old 04-17-2012, 02:15 PM   #1
The Twin
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Join Date: Feb 2011
Location: ontario
Posts: 578
M20b25 compression test result prior to boost install

cross-posted from the F/I sections...figured get more exposure here.
if Mods feel it's clutter, please nuke the appropriate one.

My 1990 325ic will be undergoing some updgrades shortly.

in preperation for it to accomodate the boost setup that will be installed, I went ahead and performed another compression test...with results that kind of surprised me.

Please note, I overheated my engine last summer during the heatwave while stuck on Decaré in MTL...I suspect HG damage, which will be replaced prior to boost.

regardless, I wanted to get a feel for the health of the block.


145, 150, 120, 125, 150, 150


WARM ENGINE RESULTS...WITH oil added to cylinder, AND open throttle.

160, 180, 180, 180, 200, 180


I'm being told a few things, such as "complete rebuild" to a new ring job+hone+HG.

Would it be wiser to scrap this engine, and just get a new(used) one or even with the "better" results of a warm compression test, still reveals it has issues?

I'll be running 8psi with a .60AR turbo...

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