compression test numbers?

[UDM Motorsport]

hi
just curious what's the normal compression numbers for the 325is?
is 150psi across all cylinders good?
thanks

[KenC]

I just had mine check too. The numbers were 160, 160, 155, 150. I've got an M10. Does any one know if those numbers are any good?

[rs4pro3]

The haynes Manual lists 142psi-156psi as normal for all engines, Ussualy in general just so long as two cylinders are not past 15-20 psi of each other your good.

[UDM Motorsport]

thanks

[KeithV]

my m20b25 is 170-180 on all 6 ;)

[KenC]

my m20b25 is 170-180 on all 6 ;)

Is higher pressure better?

[KeithV]

my m20b25 is 170-180 on all 6 ;)

Is higher pressure better?

to a point..

I believe thats how much pressure it holds.. so higher means the seals and valves are in better condition.

[NCm42]

compression ratio is really just a way to express the amount of air in the cylinder when the piston is at bottom dead center to the amount of air in the cylinder with the piston at top dead center. When air leaks out for whatever reason (i.e. bad piston ring or whatever), that ratio decreases. However, tight fitting seals and rings yield the highest compression available with whatever pistons and head you have on there