i wanna buy this b20b crx and i went to test the compression and it tested as follows: 130, 125, 125, 125

the car was boosted at one point because the current manifold is a turbo with a block off plate, plus the owner told me he blew the turbo.

he bought it as is tho, my question is, could the motor have low comp pistons to make the comp so low?

btw without the turbo the motor runs great at higher rpm, below 2k the car shakes.

thanks

 

im asking about a car im buying not a motor alone.

and u didn't even get close to answering any of my questions lol

 

i dont believe lower compression pistons would cause such low readings, but i may be wrong. minimum for the b20 is 135 psi and nominal is 220 psi.

 

yea i know but the car runs fine, i was thinking piston rings... but it doesn't burn oil

 

Depends on if the compression test was done right or not. You have to put the gas pedal to the floor and crank it so it goes at least 5 cranks.

 

it was done right

 

anybody else have any opinions?

 

there all in the same area thats good so if the compressions low maybe they did change something to make it boostable

 

was the motor hot or cold when the compression test was done

 

Did you follow up with a wet test

 

Leakdown compression test shows all

 

screw that. my stock b16 reads 195-205 all the way across.. 125 is low imo

 

motor was hot, and i haven't done it wet yet

 

does it have to be hot?

 

yes, the oil has to be flowing fast like it normally would in ur engine to get an accurate reading.

 

the oil has to be flowing fast? *facepalm*

the motor needs to be warm so that the piston rings seal properly. you will get an inaccurate reading if you do the test on a cold engine.

OP: if you retest and the compression numbers jump up significantly then your rings are muffed. if it remains mostly unchanged then it's also possible your timing could be off.