Built 1.8 Motor - What should my compression results be?
 

Hey guys - So I'm running a 1.8 with CP 9:1 pistons and I'll be running a compression test after about 800 miles of break-in/beating-the-piss-out-of-it.

What should I see for numbers? Clearly it will be lower than factory but is there a way to determine the numbers, or does anyone just know them? What are you getting with your healthy 9:1 built engine?

Thank you!

Gauges will all read a little different, so just try to look for variance and not so much a raw number.

You're looking for consistency, not a set number. If they're within 10% from lowest to highest, you're good.
Obviously the closer together they are the better it is.

Results 150 149 150 150. I'd say that's good. Break in successful!

Very nice!

Now leak it.

how much leakage % is acceptable?

On a brand new motor, 3-5%.

Bro, that 710 cap is tight. Come at me.

That looks good, now leak it.

Quick question for you guru's (especially Savington)
I made metal plate between head and block so I can measure my valve leakage %
Results were:
cyl1 = 2% leakage
cyl2 = 6% leakage
cyl3 = 2% leakage
cyl4 = 2% leakage

should I do something to that cyl2 (slightly leaking exhaust valves)? When my engine was warm I got 190 psi compression from that cylinder

cylinderhead work here is expensive