Stubourne Oil Pressure Isssue

[GD51LA]

i told him to write this him self, but he does not no how to turn the pc on yet (one of them)

so i am writing on his behalf. hope im not breaking forum rules...

anyway he's mechanic he has rebuilt the engine for a 32 gtr (customer/friend) and it's spun the bearing for the fifth time now, yes engine out. engine in. everytime!

the motor is standard, exc cat back, steel wheels, pods. he fit a N1 oil pump after the secound build, note al bearings were spun at low RPM? once while it was idling??

he and other mechanics cant figure it out each rebuild hasn't done more than 2000ks.

so he's asked me to ask YOU,

the last time finaly instaled a A/M oil pess gauge after realising the satndard one was not accurate

he tells me that oil pressure is fine when free reving, but when driving and at low RPM when he puts his foot down the pressure spikes down to 40psi the goes up to 60..i think.

now with the car on the hoist sump out he discovered light swell marks at the front of the crank? apparently where the pump fits could this be the cause? is he missing to tighten sumtn? never run more than 8PSI of boost

any info will be greatly appreciated as every rebuild is coming out of his pocket!

please dont hesitate to ask questions .......

[R34GTFOUR]

oil pressure is rpm related not load related so there should be no difference in free reving and driving. If it reads 60psi at 3000rpm while in neutral it should read that exact same 60psi while driving at 3000rpm.

Its either a oil delivery issue or the crank and rods are machined correctly. Since it spun the bearings at idle i would lean more towards a machining issue. Get the crankshaft and rods/caps professionally inspected.