After 15 hours I started losing oil pressure when I would get on the throttles hard (from cruising to wide open). Pressure would go from 75 down to 45, when I back out of the throttles pressure would pop back up to 75. Just pulled the main and rod caps and everything looks brand new, looks like ill be digging deeper. The pick up is verified at 3/8 from the bottom of the pan and no metal in the pan, I did find real fine metal in the filter when I cut it open. I have Canton 9 quart pan with wind age trays. My other motor is set up exactly the same with no problem.

the pump could be scavaging for oil what type of power and oil are you running, more info so the guys can help..............

Most typically a pick-up problem. Either air getting to screen or the pick-up has a crack or pin hole or not fully sealed to pump.

Does your pump have enough volume for your engine's clearances ?

During assembly did you fill pan, install dipstick, and then mark dipstick ? This is important with these pans.

750 hp blower motor running Valvoline 50 racing and also tried rotella 15/40 no change.

Yes

Cat,
Any pressure drop at steady state RPM...4500/5000/5500? Does it only fall off under hard acceleration?
Bob

Cat,
Just for clarification, did the pressure situation happen prior to, or after wiping the bearing?
http://www.offshoreonly.com/forums/s...d.php?t=140256
Bob

Change your oil filters. If you are using mercury filters, I have had two collapse in the past two seasons causing low oil pressure.

All bearings are like new, that is what I originally though. The drop happens under hard acceleration, cruising is 70 psi.

I have seen the same thing happen. You might want to try the HP series from Fram. I have used those with excellent results.