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Discussion Starter · #1 ·
What is a good oil pressure for a 350, warm running about 2500 rpm? I've allways heard about 30 psi, is that right or wrong?

Rick

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70 Malibu
350, 350TH
"In the Works"
 

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um.........I don't think so. By that standard at 1000 rpm I will have 10 lbs pressure and at 9000 rpm I will have 90 lbs pressure? That's not how it works sports fans. A normal chev stock oil pump will usually put out around 40 psig at somewhere between 1500 and 2000 RPM. Once it hits its peak pressure it has a relief valve that holds pressure at around 40 lbs and excess oil is ported back to the pan via the relief.Any further RPM will NOT increase pressure. Of course there are many oil pumps that are calibrated to pump at higher pressures or volume but not the stock ones in older cars.
 

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Discussion Starter · #4 ·
So if I'm running about 30 psi @ 2500-3000 rpm, thats a little low? Does that in itself indicate a potential problem?
 

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The 10psi for every 1000rpm is just a rule of thum, and I'm sure there are numerous exceptions.

Most of our engines do not see 9000rpm. 90psi may be out of range for a stock oil pump, but high performance oil pumps are required for engines that will see 9000rpm.

I see 80psi routinely on my engine when it's cold at 3000 rpm. But, 30psi at 2500rpm is plenty.

Too high of an oil pressure may have more damaging effects than too low. Too high of an oil pressure will also rob horsepower.

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Randy Johnson
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Don't certain weight oils add or reduce oil pressure? and if so which would add and which would reduce it? If it's minor adjustment it might help?
 

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I think somebody took the 10lbs/1000rpms literally for everything here. I don't think everyone is saying that the pump should absolutely produce that pressure at a certain RPM's. It is just a rule of thumb that is if you are turning 5,000 rpms you should have about 45-55 lbs of pressure for an engine to last a while. Of course a new engine should be carrying more pressure at idle than a 170,000 mile engine. It is called wear.
 

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I haven't figured out where that 10lbs per 1000rpm came from. On some engines with a bad oiling system it is correct. {I used to play with FE Fords they have a bad oiling system}Unless I am mistaken the Trans Am Zs ran a max of 40lbs because it took more horsepower to make more pressure and 40 was all they needed.
 

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The machine shop that did the machining on my motor said that race motors have a little more clearance than stock on the mains. My motor does. Has .0005 over size mains. This puts the clearance at 2 1/2 to 3 thousands.
He also said to run 80 psi at any rpm over 3000. If you have stock clearances, you only need 30 - 40 psi max.
A sure sign an engine is wearing out is if the oil pressure drops significantly when the engine heats up and your oil pressure at idle is way low or nothing. Way low being 10 -15 lbs or so.
 

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I know that at 180 degrees which is running temp in my car, My pressure is at 60 psi at 3000 rpm which is highway speed doing 70 mph. At idle when warm is around 25 psi. So am I under too much pressure ? I can say it doesn`t squirt out of the breathers.
 

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SS_DAVE and Lucifermoon are on the money. The last time I built a drag engine I set it up for 60 lbs maximum oil pressure based on oil at operating temp. Lucifer you are looking good on oil pressure. My point about the first post was that there are no linear RPM/pressure relations and to look for one would be an error. Thats just not the way an oil system works. Understand I am not finding fault here rather I am trying to help correct thinking that could lead someone down the wrong "expectation" path. Dave I appreciate your kind comments in the other post also.
 
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