Cylinder Compression Range

[ISONSX]

Before I purchased my '92 48K mile about 3 months ago. I had the Acura dealer do a pre-purchase inspection. I think they were a little overwhelmed by the amount of stuff I asked them to check. I downloaded the checklist from Prime and also asked them to do a compression test (leakdown test) to make sure the results were OK. I had no specific reason to suspect anything, but what the heck, I figured I'd spend an additional $120 for some additional piece of mind. For the record, I'm not extremely knowledgable about this type of stuff. All 6 of the cylinders had a reading of 195 psi. According to the dealer, this was good. I've searched the FAQ section to see what range to expect, but either I missed this info or its not something that is in the FAQ. Can anyone help educated me about 1) what the compression test tells you 2) what the factory setting was, 3) what range is "good" (and if that depends on mileage) and 4) what does it mean if one or more cylinders have a lower reading than the others (mine are all the same). Thanks in advance for the help.

 

[Lud]

1) A compression test tells you the compression in each cylinder when the engine is turned over by the starter. A leakdown test is different, but related. It tells you how much (and, even more importantly, WHERE) you are leaking compression from a cylinder.

2) & 3) See section 3-2 of the service manual under standards and service limits.. http://www.nsxprime.com/FAQ/Reference/1991_svcman/1991_svcman.htm -- nominal is 199, minimum is 142, so 195 is fine.

4) Some variation within spec is OK and in fact pretty normal, but they should all be close. You want to see a MAX of 10% difference between the highest and lowest. If there is a 20% or greater difference between min and max, you have a serious problem.

Also see this thread http://www.nsxprime.com/forums/showthread.php?s=&threadid=6195