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Discussion Starter · #1 ·
I am just curious about oil pressure @ idle. I have noticed lately that my oil pressure usually falls between 25 and 27 psi while stopped, but under load or steady speeds it goes up from slow speeds @ low rpms it is around 35 psi or so, harder acceleration or higher speeds in 4th, etc results in approx. 45 to 50 psi of pressure.


sooooo after all of that, what is your idle oil pressure? I'm just wondering if I should change my oil pump or something.

thanks,
danny
 

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Chirodan said:
I am just curious about oil pressure @ idle. I have noticed lately that my oil pressure usually falls between 25 and 27 psi while stopped, but under load or steady speeds it goes up from slow speeds @ low rpms it is around 35 psi or so, harder acceleration or higher speeds in 4th, etc results in approx. 45 to 50 psi of pressure.


sooooo after all of that, what is your idle oil pressure? I'm just wondering if I should change my oil pump or something.

thanks,
danny
My pressure runs around 20 psi at idle with 10 psi per every 1k rpm after that. However, oil pressure at idle depends on number of variables including ambient temperature. Let's assme the engine has been running 20 minutes or so and has achieved operating temperature of around 200-210 degrees F. The following variables come into play:

-Ambient temperature
-Oil temperature (200-210)
-Oil viscosity - 15w50 vs 5W30 vs 0w40. I run 15W40 in my 427 cid because its a race motor with different bearing tolerances since its designed and built to run at high rpms for long periods of time.
-Engine build tolerances - a race engine will tend to have looser tolerances to allow for expansion and so will tend to have lower oil pressure since the oil is encountering less resistance to flow.
-Presence or absence of oil cooler
-Total volume of oil in circulation.

All of these factors impact the average oil pressure. As I recall, GM has an oil bypass valve that open above 50 psi so 50 psi is the max you should ever see on your car.
 

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Discussion Starter · #3 ·
ok, thanks....
I was just worried it was too low @ idle. Just to clarify a little bit more, after the car has warmed up to normal operating temp.(approx. 220 deg.), in 95 + El Paso, Tx. temperatures, with stock motor/stock mobil 1.
 

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I saw many different oil pressure numbers during the break-in period than I do now. It seems to have stabilized to the same as yours.
 

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Sounds okay to me, although perhaps a little on the "low" side. But like the other reply you received, there are a number of factors that can influence oil pressure. The hotter the operating temp of an engine the lower the pressure at a given viscosity grade of the oil in the crankcase. Are you running Mobil 1 5W-30 as recommended by the factory?
 

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ScDFACHE said:
All of these factors impact the average oil pressure. As I recall, GM has an oil bypass valve that open above 50 psi so 50 psi is the max you should ever see on your car.

I see WAY more than that when i run it hard.
 

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The pressures you are experiencing are normal, for street driving.

However, if you track the car at all you might consider using a higher viscosity oil.

An even better solution might be having your OEM oil pump ported, polished and reshimmed to output higher flows and pressures. Ported, polished and reshimmed racing oil pumps are available on an exchange basis for around $175.

There is now a larger racing Gearotor type pump available for the LS1/LS6 that has a much higher output but requires a special billet split front cover.
 

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Discussion Starter · #9 ·
thanks for all the replies.

I use factory spec. mobil 1 in the car. If that is normal that thats fine, I just wanted to make sure and ask.

I do drag race about once a week or so. Would it be better to use thicker oil??
 
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