Up to 4,000 RPM oil pressure remains steady. The further above 4,000 RPM the lower the pressure goes. If I reduce down to 4,000 RPM the pressure will stay around 40 psi. Oil temp remain steady around 200. Changed oil cooler and all external oil lines to no positive affect. Looked at the original dyno pull data and it was even happening then in the short pull time period (of course I was focused on torque/hp at the time!). It dyno'd without any external lines or cooler - oil temp increased only a few degrees during pull. It's a 515 Gen IV with a Titan billet oil pump (idles at 80 psi when started) and 12 qt oil pan. Using Kendall conventional 50W and it's not losing any oil. So the issue is internal plumbing and or bearings issue.

Any ideas what's going on? Oil getting aerated at pick up? Windage? Bearings installation?

Thanks Fella's.

40 psi @ 4k revs is low, should be in the 65-70 range.......did the builder recommend running a straight W50 oil ?....what does the builder have to say, been seeing this way to much on new engines, where were the bearing clearances set, what size oil lines and fittings are you plumbed with.

I'm not a mechanic, but a few guesses;

Windage/oil pan issue. Too much oil is as bad as too little.

The new bearing clearances are too tight for the hv oil pump and the pressure relief valve is opening.

Bad sender or guage

What pan are you using ?

I was using a straight sump 11 qt and my engine was doing about the same thing except my oil pressure would come right back up when I dropped the RPM back down....

http://www.offshoreonly.com/forums/g...e-issue-2.html

I've since switched out the pan to a 12 quart marine "T" style pan but haven't gotten to run it again yet....

any screens in the lifter gallery openings?

Did you try 9-10 quarts in the pan ?

How close is the pickup to the pan ? You measured it right ?

A couple good/new/clean vents in the valve covers ?

I agree, sucks you didn't look at this data on the dyno.

Did you use a mechanical guage on the dyno pulls???
If so, I would lean toward either too much oil and its getting aerated OR too little oil or pickup too high and sucking air.

How close is the pump pickup to the bottom of the pan?

And what is the optimal distance between pick up and pan? I have heard as close as a quarter inch.

Is there a pressure bypass in that oil pump? What is the pressure at hot idle and does it fluctuate at idle?