Originally Posted by Max Headflow

I not sure how adding an oil cooler on a bigger motor would cause the motor to sump. Seems to me that the cooler would slow flow unless it was installed on the scavenge side of the pump. On TC's, the cooler typically goes on the feed side.

TC pumps don't cavitate. It's a misused term here. The oil pump fails to scavenge for different reasons and the flywheels aerate the oil. Aerated oil (foamy) is harder to scavenge as it's volume is larger. Once sumping occurs oil temps will spike due to flywheels dragging in the oil. That drag (loss of HP) heats the oil directly which is why the temps spike.

In your case, since the motor seemed to sump after the build, I'd be more inclined to think that the reason for sumping was increased windage due to increased displacement or possibly greater cylinder leakage but there are many other factors that can cause sumping. SnS pump will definitely help tho.