hi guys, i got very unusual compression readings from my last compression test.

#1 205
#2 175
#3 155
#4 135 !!!!

strange thing is i'm still making power, at the last dyno day i posted 199 WHP on a very hot vegas day 108 degrees. i made more than most N/A S2000's that day. but the problem is i'm not making the power that i should be making.

power mods: spoon n1 single, spoon test pipe, comptech intake, AP1 intake cam transplant

based on the readings it looks like a constant decline from 1 through 4 we did the compression tests back to back with another AP2, his was 250 on all 4 cylinders. and we did the compressoin test 4 times all with the same results. i should have put some oil in cylinders to test rings but wasn't able to.

some history
car was bought used 55k miles, it came with an upgraded clutch (ACT I believe)
no i did't do a compression test when i got it
honestly i did a couple of over revs before (who hasn't?) but not too serious (instant clutch in)
AP1 intake cam transplant and valve adjustment recently performed

What do you guys think? Are we throwing away the motor or rebuild? Other people said everything from worn rings, head not torqued in right, bad gasket. It's killing me!!!!

T.I.A.

 

well since you admitted to over revving i would say thats the problem. obviously you wouldnt know unless you did a leak down test, so i think next step is to do a leakdown test and find out if your leaking through your valves. if you overrevved then your valves are going to have the problem. even though you say "instant clutch in" the moment it overrevs, because its a mechanical overrev, the rpms will jump IMMEDIATELY, im talking less than a half second and your response isnt fast enough to save it. so do a leakdown to see where its leaking.

cylinder 4 compression is usually a problem in earlier ap1's but not in ap2's because of the earlier lot of oil jets, i think its really going to be a valve problem in this situation.

 

^^^ yeah i did over rev a couple of times. thanks for your advice!

 

K-Lo,

perform a leakdown test. That way you will be sure of where the leak is ... whether its the valves or rings. If the valves are the culprit, before you change the seals I would check the clearances just in case ...

Joaquin

 

i'll definitely schedule a leakdown with my mechanic. thanks r1

 

Yep, do a leakdown test at a garage with an experienced technician and figure out where the loss of compression is occurring. My money would be on valves, and if that's the problem, you'll save yourself from severe bottom end damage by fixing it now. A head rebuild is much less expensive than replacing pistons and the head.