[Ben.R33]

Hi all, my RB25DET has the following compression:
Cylinder 1 - 135 psi
Cylinder 2 - 130 psi
Cylinder 3 - 129 psi
Cylinder 4 - 125 psi
Cylinder 5 - 130 psi
Cylinder 6 - 119 psi
These results were taken whilst the engine was at operating temp and throttle was wide open.
I plan on running 400-450 bhp, would this cause any problems/ be a restriction?
Many thanks in advance,
Ben

 

[Tricky-Ricky]

It's not the lower figures that are a problem it's the 16psi difference between the lowest and highest reading the maximum you really want is 10% so 13.5psi a leak down test will tell you if it's the valve seal or rings that are the reason.

 

[Ben.R33]

It's not the lower figures that are a problem it's the 16psi difference between the lowest and highest reading the maximum you really want is 10% so 13.5psi a leak down test will tell you if it's the valve seal or rings that are the reason.

yes i think ill do a leak down test, thanks for your help!

 

[niz406]

FSM states minimum compression 125psi - so yes this is a problem, the 16% difference is also 6% over the allowable difference in the factory specifications. time for a refresh, do your leak down test and it might just be a set of rings and bearings providing the bores are all in good condition, if not it might be a trip to the machine shop.