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oil pressure too high ?

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zray:
are the following oil pressures too high ?

@ 75 degrees F. with a 180 degree thermostat

cold engine:

pressure @ idle: 82 psi

hot engine:

idle (800 rpm) .... 35 psi
1500 rpm ..............70 psi
2000 rpm ..............72 psi
2500 rpm ..............75 psi
3000 rpm ............. 80 psi
3500 rpm ............. 82 psi
4000 rpm ............ 85 psi


Basically a stock 289 Hi-Po engine w/ vintage Paxton, 10: 1 compression, 0.020 over pistons, a high volume oil pump was installed 24,000 miles ago during a complete engine overhaul.

 Aside from the break-in period, I've been using Mobil 1 15w-50 for the entire 7 year/ 24,000 miles.

Z. Ray

Soaring:
Yeah, that's a little high.  When cold, it should be 40-50 and when hot it should be 30-40.  If you basically have a stock engine, why do you have a high pressure pump on there?  And why are you running 50 wt. oil when you should be running 10-30? 

zray:

--- Quote from: Soaring on May 07, 2009, 03:33:43 PM ---Yeah, that's a little high.  When cold, it should be 40-50 and when hot it should be 30-40.  If you basically have a stock engine, why do you have a high pressure pump on there?  And why are you running 50 wt. oil when you should be running 10-30?

--- End quote ---

engine sees extreme use, so I went with a high volume pump. Using 15w-50 as it is the only Mobil 1 oil containing all the zinc (zddp) I feel necessary: 1200 ppm.

The only reason I'm reluctant to go to a lighter oil is mainly due to the history of seven year/ 24,000 miles without any problems. But I will do some more investigation before deciding.

Z. Ray

Soaring:
O.K, well, it's your engine, but those two things are the reason why your pressure is that high.  If you haven't had any problems, just keep doing what you are doing.  Just understand that you will have erosion damage to the bearings due to excessively high oil pressure.  But, if you are hammering that engine that much, you understand the wear and tear  of racing. 

exxodus:
Just, for the next oil change to put some 15w-40 in. Pressure will down when hot.

- - - -

More the 1st figure is close to "0", the more fluid the oil is (cold) (that help to quickly protects the engine at startup (70% of wear occurs in the first few minutes of operation)).
 
The 2nd figure is high, the more viscous oil is in hot condition.

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