How much oil pressure is too much?

We run a small motor with an R & R external oil pump that has 90lbs. oil pressure at the finish line which is 6800 rpm. Cold start up is 110lbs at about 1500 rpm. 10W30 full synthetic oil. Seems like we could be wasting horsepower pumping oil but we have never had a pump or drive belt issue.
Didn't the old rule use to be 10 lbs. per 1000 rpm.

You are correct that your wasting power.. even the
10# per 1000 rpm is a bit high.. but I like to see
about 20# at idle with hot oil.. 110 cold your
asking to blow a filter

Try a lighter weight oil? I would be pretty happy with it where it's at. My RB runs around 80 to 85 at the stripe at 7,200rpm.

I shoot for the 10 lbs. per 1000 RPM with HOT oil
My last pump gas stroker had 65lbs at 5000 RPM and up with 180+F degree oil temps, I should have shimmed the bypass spring to get 10 lbs. per 1000 RPM but I left it that way and ended up needing to shift that old rascal at 7000 to 7300 RPM to get it to go as fast as it could I never had a bearing or oiling failure issue that I know of

Oil pressure is doing nothing more than costing you a nominal amount of HP, nothing more. Do you need that much pressure, no not at all. Is it hurting anything not much

I would switch to a 5-20 oil and use a mobile one filter to reduce the chance of blowing up the filter. I had one running pressure like that and it would swell up or just plain blow up any other filter I tried.

Well in this video you can see the oil pressure gauge pretty well. It is the second to last gauge on the right. In the burnout and at the top end it is over 100psi. On the racepak generally we would see 110 or a bit more. Engine went 1000+passes this way with no ill affects and many while playing the game up top...

https://www.youtube.com/watch?v=bXBb9Jtatpk

You are probably wasting a small amount of power but I wouldn't think it is much of an issue. Try a lighter weight oil to see what that does. I use 5w-30 Royal Purple in my engines and it seems to work pretty well. Depends on what the bearing clearances were set at so double check on that before going to light with the oil.

Put in thinner oil.. you are wasting power and even
you know it, otherwise you wouldnt have asked... like
I said before that 10# per 1000 is a decent number..
and at the rate you are running its WELL above what
you want

Last engine we ran started out at 90 psi - lowered it to 65 (at 7000) and it picked up 13 hp. How much would you expect to spend to pickup 13?

He can lower the pressure pretty easy to pick
up power

Mark, doesn't that pump have an external adjuster?

The pump does have an external adjustment, I just don't want to go too low on pressure. We run an Oberg on top of the oil tank and never have had any problems.
We will start with a lighter oil and if that doesn't drop it much we will adjust the pump.
I don't want to get greedy. All we need is to pickup a tenth. We put some weight on the clutch and added air to the slicks and picked up a tenth and a half. We have been in a rut doing the same old thing.
Thanks for all the help!

Mark

Had that issue years ago on Pettis's dyno and I foot-balled the filter but didn't burst. I run low pressures street/strip w/zero issues running 5w3-10w30 and larger than some bearing clearances past 7000 and just peek in a Pro-Stock car on the line...........15-20 lbs at idle is what I personally saw when I freeze framed Erica's car last year but who knows up top...........

What was the idle RPM at that 15-20psi.. myself
I like to see that 15-20.. I dont trust a gauge
thats less than that

10 psi per 1,000 RPM is not a magic figure, and the actual requirement is slightly different among engines. Luckily, the range is narrow - and in antiques it may not be safe.
The gauge gives only the pressure at the point where its sender enters that part of the pressurized system – not everywhere, not an average, nor a generalized picture of the systemic pressure. Don’t trust it to guarantee bearing condition.
Local pressure (at the crankshaft journals and bearings) is far higher than the 50, 60 psi &c. at the pump’s relief valve and on a pressure gauge, and will actually reach over 100 psi.
This higher pressure is developed by the relative speeds of the crankshaft journal itself rotating against the bearing in feet per second (not RPM or journal size directly), the bearing width (to the closest pressure leak), oil viscosity, and temperature, balanced against the bearing clearance (the leakage rate).
All engines are open-ended hydraulic systems, because the oil returns to the pan by a series of controlled leaks. The bearings farthest from the pump always have the lowest pressure because of the number of leaks between the pump and that bearing. Excess bearing clearance increases the pressure lost between the first and last bearing in a series. Depending on its condition, an engine may have acceptable gauge pressure, and still only have 5 psi pressure at one connecting rod, which will fail under high load.

I want to say around 2000 r's idling...............

FWIW the clearances on my deal were .0030-.0035 and the oil we used was 10w30 Brad Penn. New engine uses the same oil and on the dyno saw 66psi, once warmed up it idles at 15ish psi. This is for a Top Sportsman deal and we did not want to leave "free" power on the table. Time will tell how well it works. Even on the heads up piece we see right at 70 at 9800rpm.