I'm sure this has been asked before, I think I even asked a bit about it last year or so, but....
What exactly affects oil pressure?

Background - 1985, 12a, 74k miles, no modifications
Recent changes - OMP was replaced. Doesn't appear to be leaking.

At 1,000 RPM, I'm guessing I'm below 40PSI, if the factory gauge is to be believed.
At 3,000RPM, I'm between 40PSI & 60PSI.
At 4,000RPM, it looks like the oil pressure hasn't moved from where I was at 3,000RPM. And, this is slowly revving from 3k to 4k.

My concern is that previously, as in several months ago, my oil pressure appeared higher under acceleration.

I don't think the OMP has much of an impact on oil pressure since it's only "metering" the oil that travels up the oil injection lines.

Thoughts? Should I be concerned? If I have an issue, what exactly should I be looking for?
thanks!

 

from your description: no concern

minimum oil pressure would be below 15psi at idle

 

Take it easy and enjoy your 7, should be plenty of miles left!

 

I hope y'all are right. I should have added in my original question - it seemed to have a higher oil pressure earlier. I don't drive it every day (shameful! I should drive it more!) But I seem to recall the oil pressure being above 60PSI when I was pulling 4K+ RPM's. So...still not to worry?

 

oil pressure will be higher in colder ambient temperatures, oil pressure will also be higher with thicker viscosity oils.

the stock gauge isn't something you should be comparing on a daily basis, it isn't the most accurate of systems and reliability of the readings decays with the age of the vehicle.

 

Like he said, The oil pressures you're describing are totally normal. Unless it's a very cold day I rarely see anything higher than 60psi, and that's on an Autometer gauge (FWIW the stock gauge matches the Autometer very closely). I have the same gauge setup on both FB's, and I've had basically the same results regardless of what engine I've run (12a or T2).

You should be just fine

 

My gauge reads 0 at idle after warmed up. After being a mechanic, many ,many, mmmmany used cars do not have accurate gauges. Ill never know why .

 

if the gauge was reading 0 i would recommend checking the accuracy with a mechanical aftermarket gauge. a bypassing front cover o-ring will give low oil pressure readings at all RPMs and you could have an issue that you're putting off as normal.

inaccuracy is one thing, ignoring a potential problem is another.

if it is a problem and let you let it go on long enough then you could be slowly frying the engine to death. these engines generally do not give indicators like hydraulic lifters ticking, it will simply lock up one day. if you know the engine is producing over 15psi at idle then there isn't much to worry about.

 

This motor has 15,000 miles from a profrssional rebuild. It came out of my other rx7 which showed oil pressure was fine. This is how i know its not accurate. If it were really 0 my motor would have went kapoof long ago. The oil pressure sending unit is bad, i can see the bubbles out of the end. Im just to lazy to change it. Sold my 84 rx7 with 5000 miles, guy gave it to kid, kid wrecked it, 10000 miles, guy put it in wife's convertible, she got bored with it. 15000 miles, guy bought other rx7 great condition blown motor. Put motor in, sat and his other son didnt want it he wanted a second gen, i bought and the circle goes round and round. Lol

 

i don't really feel like arguing about it but since it passed several hands you can't really be sure of anything.