Compression

[2.2LturboI]

Hey Guys I just picked up a 86 crysler laser xt

Im going to run a compression test and I was just wondering if anyone knows what the compression should be around.

Thx

[Screamin4banger]

I think you should be happy with 135 - 150 with less than 20% deviation.
just make sure to do the test with the engine warmed up, HEP disconnected, and throttle blocked all the way open.

[detobias]

and all 4 spark plugs out

if one seems low then add 1 tablespoon motor oil; if the psi jumps up it suggest a ring sealing problem

[2.2LturboI]

Alright thats for the #s I just needed something to compair against.

[detobias]

its more important that all 4 are close to each other, say within 10 psi

the turbos have a lower compression than NA cars

my TI pushes 125-135 psi

altitude will affect it too but I see U R in FL ; were U in denver U would expect a bit lower psi readings

let us know what U find !

[pobort]

cam profile also greatly effects compression pressures as does cam timing.

also make sure to disable the primary ignition ciruit so you don't have stray spark (could induce a voltage into the wire harness and fry a computer)

and hold the throttle Wide Open

and install a battery charger so you have the same cranking voltage on all cylinders

[cawcislo]

I agree that absolute number doesn't matter that much. If the car runs good it's more important that they are all close to each other. 120 or so range. Plus each guage will give you different numbers. So the absolute number isn't that important. Make sure to do it engine warm and with the throttle wide open.

[pobort]

Quote:

Originally Posted by cawcislo I agree that absolute number doesn't matter that much. If the car runs good it's more important that they are all close to each other. 120 or so range. Plus each guage will give you different numbers. So the absolute number isn't that important. Make sure to do it engine warm and with the throttle wide open.

i disagree with that "absolute number isn't that important"

if all the cylinders are equal but low, cam to crank timing may be off a tooth or two.