A little background:

I have been running this engine for over a year now (last August) and oil pressure has always been more than I would expect so I have been running a lighter (10-30W) oil. This resulted in 45lbs idle, 80lbs WOT, 70-75lbs cruise. Or at least that is what I thought.

Just recently (after 40+ drag passes and x000 miles) the oil pressure guage was pegging above 4000rpm, something that would be like 100lbs. I thought it may be an issue with the bypass, but before I did anything I decided to check the pressure with a mechanical gauge. The results left me a bit uneasy.

Cold idle was more like 45lbs, and it would go up to 80 cold. The thing was, once it got hot (180F) oil pressure was down. Crusing oil pressure was 45lbs (2000-2800rpm), higher rpm cruising rpm was 55-60lbs. However, IDLE oil pressure was 20lbs at 900rpm, and 15-17lbs in gear at 800-900rpm. The motor has a noticeable shake at that low of an idle (on the verge of stalling). Could the surging/shake cause that?
I changed the oil and filter before double checking with a mechanical guage. Went from a K&N filter to NAPA Gold (I have always used Napa Gold). Oil pressure jumps right back up to 25-30lbs with the SLIGHTEST bit of gas, 1000-1200rpm, there is no hesitation.

That just sounds a little low to me. The thing is, I have no way of telling how long the pressure has been like this, and in all likely hood it has always been that low (bad guage). I hooked up the windshield wipers (grounded motor) and now the electric gauge (with the old sender) is readin about the same as the mech. gauge.

Question is, should I look for a more serious problem?
When racing, I usually shift at 6800-7200rpm, is 55lbs enough for that kind of abuse?..

The pump is a Moroso blue-printed HV pump. My bearing clearances are on the wide side: Main .0032, Rod .0026. I should be moving plenty of oil, there are no restrictors in the system.

Oil is Mobil 1 10-30. I was thinking of just going with 15-50 and forgetting about it.

I wanted to go racing one more time this year, but dont' want to oil the track!

Thoughts?

Thanks, your insight is appreciated.

 

Rule that I have always heard is 10psi per 1000 rpm min. Sounds like you are good to me.

 

SteveG75 The thing is, with 55-60lbs am I still fine to run it at 7000rpm like I do??? Oil flow is what is important, and I feel i'm getting plenty. The parts actually ride on a wedge of oil that has to be replenished with cool oil. A lot of the heat generated comes from the viscosity of the oil, and the oil systems purpose is to cool the bearings (replenish friction surface)....

I was just a little concerned to see so little idle oil pressure. I guess I can bump the idle up a couple hundred rpm.

Thanks!

 

If you worry about it enough, you'll create a problem. *I* think, you are over thinking it. Don't fix it...It aint broke.

RACE ON!!!

 

CFI-EFI As always, thanks for summing it up!

Caught me just in time to not cause problems

Thanks!

 

wisdom

 

 

If you think you have a problem....you will....

But if you are concerned start a log and record the oil pressure readings and compare from time to time to see if the pressure has deteriored. If by chance there is a change you can make the call on what to do.
best of luck
Mark