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Noah930 Noah930 is offline
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Join Date: May 2005
Location: Los Angeles
Posts: 13,851
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I've never done it myself, but you need a compression tester (looks like a gauge you hook up to a sparkplug hole). Engine is supposed to be warm when doing the test. Leakdown is not just whatever numbers you calculate, but also it makes a difference from where you hear the leaking.

When I had my PPI, they obtained both numbers. I have no idea what the "factory specs" are supposed to be. I've never seen them printed anywhere. Has anyone else? So I just went with the fact that the numbers were all clustered together. (Maybe that just means the engine is entirely worn out in all 6 cylinders?) On Pelican, I've seen people post numbers in the 110-120 range, and others in the 160 range for turbo motors.

For leakdown, the lower the better. Again, clustering of the values together is a good thing. Some guys have posted values of 3 or 4%. I think mine were closer to 10-12%; I realize those figures seem very high, but that was 20K miles ago and the car still scoots, so who knows...
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1987 Venetian Blue (really looks like grey) 930 Coupe
Old 06-18-2010, 08:56 PM
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