hey all, i have searched but can't find solid values for a compression test on an 89 crx si, stock, d16a6 motor. i'm consistantly getting 130,146,150,150.... ANY IDEAS where this should be?!

 

Those sound ok, the cylinder with 130 seems like its slowly drifting away from the others. When doing a compression test besides having high numbers, you want all the numbers to be close to each other.

 

right, about 75% between the lowest and the highest.... according to my manuals. But i was also intrigued by the slope. the number one cylinder? (farthest from distributor) is the 130, then 146, then the left two are 150. but i don't think its low enough to merit pulling the head to check head gaskets, etc... i dunno. I'm checking the motor out becuase i want to run it in G-stock autocross, and its got to be solid. it won't be modified, it just needs to be solid... any other ideas, anybody else? (thanks 90blackcrx!)

 

you removed ALL the spark plugs before you tested, right? cause leakage between cylinders via a bad head gasket will give a false test.

and that 130 is a little low, add a small amount of oil to that cylinder and retest the compression, if it raises up to 150ish your rings are starting to go.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by KUjonathan &raquo;</TD></TR><TR><TD CLASS="quote">right, about 75% between the lowest and the highest.... according to my manuals. But i was also intrigued by the slope. the number one cylinder? (farthest from distributor) is the 130, then 146, then the left two are 150. but i don't think its low enough to merit pulling the head to check head gaskets, etc... i dunno. I'm checking the motor out becuase i want to run it in G-stock autocross, and its got to be solid. it won't be modified, it just needs to be solid... any other ideas, anybody else? (thanks 90blackcrx!)</TD></TR></TABLE>

Did you let the engine get warmed up before doing the test ? That can effect the results a little. Also make sure you hold the throttle wide open when doing the test to. (Your welcome )

 

well, yeah, i did let the engine warm up. but get this. after testing the first time, i let the car idle for about 20 minutes (partly becuase i forgot i left it running), to charge up the battery from all the cranking. well then i turned it off, came inside, had a beer, then went back out like 45 minutes later and redid the test (was going to add a bit of oil to the suspect cylinder), but when i ran it, all cylinders were from 150-160 psi. so could it be these? :

good situation: somehow letting the motor run (mostly sits right now) blew out some nasties, maybe helped clean up the valve seats? or maybe just messed up the first test.

bad situation: says something i don't understand.

haha :

any ideas?
thanks again