Can someone explain oil pressure?

CptanPanic2 · Post by **CptanPanic2** » Fri Jul 28, 2000 9:40 am

I am kind of confused about oil pressure. First off, what exacty is oil pressure. Is it the pressure of the oil flowing through the oil passages? So does more flow pump, equal more pressure? How much pressure is enough for a engine, and when would you need to get a better pump?
Thanks.
Brian

[email protected] · Post by **[email protected]** » Fri Jul 28, 2000 10:17 am

The Gene Berg catalog and technical articles explain this very well. I suggest you buy them, it is worth the money.
Steve Arndt

Post by **Tom Notch** » Fri Jul 28, 2000 10:43 am

Just got the latest RACER magazine in the mail. go out and get it for the VERY GOOD tech article on oil pressure. It covers briefly some really good points on dry sumps and oil sump systems. I considered putting it on my web page but the copyright laws are a bit imposing.

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Tom Notch
[email protected]

beetle_freak_53 · Post by **beetle_freak_53** » Fri Jul 28, 2000 10:43 am

Oil pressure is in relationship to volume...
same amount of oil(2 3/4 qt's), stock volume (1600cc)= approx. 20psi. Larger displacement, same amount of oil = less pressure. I agree w/ vw... get the Gene Berg catalog it should have a chart of some sort stating at which displacement requires a boost over the stock pump. I don't have that particular catalog, but I'd like to know where I can buy it.

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it's not a car...
it's a cult!!!

JeffH · Post by **JeffH** » Fri Jul 28, 2000 3:56 pm

I must disagree,oil pressure has very little to do with displacement of the engine.
An oil pump or any pump running at a given speed has the ability to pump at a certain flow rate depending on the pressure it must pump against.
Lower resistance(pressure) gives higher flow and higher resistance gives lower flow
Also a "high volume" pump will be able to maintain higher pressures because it is pushing through more flow against the same resistance.
Generally oil pressures are measured immediately after the pump and filter.
Besides the capabilities of the pump the main governing factors in pressure are the viscosity of the oil and the clearances in the items fed with pressurized oil(eg main,rod and cam bearings and lifters)
higher temperatures decrease oil viscosity allowing increased flow and therefore reduced pressure.
Wear or temerature induced increased clearances also allow increased flow and hence reduced oil pressures.
So the oil pressure you achieve is a function of the clearances achieved in your engine on bearing surfaces, the temperature and viscosity of your oil,and the flow capacity of your pump.
Jeff

[This message has been edited by JeffH (edited 07-28-2000).]

GDRBO · Post by **GDRBO** » Fri Jul 28, 2000 4:32 pm

As a very general rule of thumb you want about 10 psi for every 1000 rpm. I believe someone posted on another site that the VW spec for a type one motor is 28psi at 2500 rpm.

CptanPanic2 · Post by **CptanPanic2** » Fri Jul 28, 2000 7:33 pm

So in building an engine, you would only need a non-stock pump would be if you are going to run high rpms. I plan to set the rev limiter at 6000 at least at first. Without using a type 1 pump, what would you recommend.