I have a 2008 Civic Si k20z3, 11:1 is stock compression

well just got done with the compression test again with a brand new gauge. the readings were 150, 160, 155, 160. i was at WOT and cranked the engine about 12 revolutions. when i didnt hold WOT, i got the same results which was weird. I looked down the cylinder with a flashlight and cant really tell much. all i can see is burnt spots on top of the piston. kind of looks like cow spots.

Does this seem normal for a motor with 11:1 compression? guys on the 8th gen forums say they were up at the 180-190 mark. i know some gauges read different then others, but that much off? Where would i be able to get the OFFICIAL honda specs?

here are pics of all 4 spark plugs. they are not TOTALLY covered in this stuff. but very lightly dusted...

cylinder 1 (drivers side)


cylinder 2


cylinder 3


cylinder 4

 

That's ash that can come from burning oil or fuel additives.

 

thats what im hoping it is? does 150-160 psi seem low for a 11:1 compression motor?

 

Yeah a little. That ash is probably coating your valves and seats, causing them to not seal properly.

 

any way to clean that stuff without removing the motor. im going to turbo this car and dont want to experience any problems

 

Well not the whole motor, just the head. Deposits on the valves get hammered over and over by the hot valves closing and become imbedded in the metal. Sometimes intake valves can be cleaned somewhat by adding fuel system cleaner to the tank but if the ash is the problem, it would be on the exhaust valves and you'd need a valve job to fix it. Sometimes if you fix whatever is causing the deposits, after lots of use the motor can slowly clear away some of the crap. When the head is off, you can hold a flashlight to the bottom of the head in a dark room with the valves closed and look for light coming from inside the ports. If light gets through, air gets through.

 

did you do the comp test with the engine warm?

 

Why are you doing a compression test? Is there something wrong with the way the engine runs?

 

yes i did the test when it was warm.

reason for the test is because i am about to install my turbo kit next week, never did one, and learned to always check the compression before you put a nice amount of boost into the engine (learned from my srt4). bad compression motor + boost = no good