i have a 2003 evolution with a toga hv oil pump on a built motor, new mitsu block with wiseco pistons, crower rods and full ferrea valve train and hks 280 cams. i replaced my stock oil pump due to it only being 30 psi at idle and drops to about 5-10 psi at 5000 rpm. when i replaced it i check all of my rod bearings and they were all fine. however when i got finished withe the repair, my idle oil pressure was almost 60 psi so i thought it was fixed. until i gave it some throttle while it was on the lift it dropped to 30 psi at 4500 rpm.
the only reason i thought the original oil pump was going bad was that i could hear the lifters at high rpms, it seems to have enough pressure now to keep it quiet but i need to figure out how in the world it drops in pressure at higher rpm.. in case it helps it drops in steps. for example if at idle it is 60 then at 2000 it is 47 and at 3000 it is about 35 and at 4000 to 5000 it drops to 25 and then i quit pushing it, this is all while on a lift and no driving. any suggestions would be greatly appreciated.
thanks[/B]

 

where is your oil pressure gauge sender installed?

 

i am using a mechanical oil pressure gauge installed where the oil pressure sensor goes. it is a hand held gauge.

 

Oil pressure is caused by restriction not flow, flow is distributed by the oil pump. If your pressure drops, its highly unlikely that the oil galleys are opening up under throttle so best bet is to check the oil pump.

 

how do i check the pump, it is brand new and i never opened it or anything.

 

you know, I might try another gauge if you can before tearing back into the engine... you're on pump #2 already

 

yeah i was going to do that on monday but since the idle pressures have changed from one pump to the next i would guess it is a bearing problem somewhere in the engine but i will be trying a new gauge on monday.