miatauser123

iTrader: (7)

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-****-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!

rharris19

iTrader: (41)

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

18psi

iTrader: (76)

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.

miatauser123

iTrader: (7)

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

jbrown7815

iTrader: (1)

Very nice!

hustler

iTrader: (6)

Now leak it.

muoto

how much leakage % is acceptable?

Savington

iTrader: (31)

On a brand new motor, 3-5%.

miatauser123

iTrader: (7)

hustler

iTrader: (6)

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

That looks good, now leak it.

muoto

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