Thread: Hi Volume Or High Pressure / Pro's And Cons

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HI GUY'S....I'M BACK, AND I WAS WONDERING IF I COULD GET SOME FEEDBACK ON THIS SUBJECT; PRO'S & CON'S OF RUNNING A 'HIGH PRESSURE' OR 'HIGH VOLUME' OIL PUMP. VIRSES A STOCK ONE. THANKS FOR YOUR INPUT....DENNIS

Hey Dennis
The topic which you have chosen has got to be of concern to everyone that builds an engine. I will try and explain it to the best of my ability, but know this in advance, words used in communications attempts can be interpreted differently in different parts of the country, but allow me to try anyways.

Imagine if you will, a typical .5 inch diameter garden hose. Now, if you have NO nozzle at the end of it, in other words, just a wide open end, and if you were to hold this hose perfectly horizontal four feet from the ground, (depending on the pressure of the water at the other end but for argument’s sake, let’s suppose 60 psi.), let’s say this water stream will shoot out 8 feet when held 4 feet off of the ground.

Now suppose that you place a nozzle on it which is .25 inch in diameter. This will in effect change the distance of the stream to let’s agree on 25 feet before it hits the ground. After this, suppose now that you removed the rubber gasket which seals the hose to the nozzle and that the stream dropped from 25 feet to 18 feet.

What do you suppose you would have to do to achieve the greater distance of water stream? You would have to either seal off the leak, or increase the supply hose, the delivery system. If you replaced the .5 inch hose with a .75 inch hose and even with the same scenario as above, you would again have a 25 foot stream. You see, the escaping water can be compensated for by increasing supply.

With the supply being consistent in any given situation, one can never make up the pressure loss with a high pressure spring, whereas one can compensated for pressure loss with a greater supply.

What I am trying to communicate is this. That no matter how high a volume pump or how high a pressure spring you install into an engine oil pump, the net pressure has more to do with the clearances of your bearings than with the spring in the pump. A higher pressure spring will do nothing in the above situation but a higher volume pump will.

Keep in mind that the spring in most oil pumps does not open until it hits pressures which are off of the typical engine oil pressure gauge. When an engine is cold, the pressure might hit 80 plus psi and even then the spring is not open but once the engine is hot, the pressure gauge usually never sees those numbers again. Thus, a higher pressure spring is not the answer, however tighter clearances or a higher volume pump, or a higher viscosity oil,....is, for it will cause higher pressure numbers. Why?? Because the supply is keeping up with the demand.

In the garden hose illustration, when the hose is capped, the pressure would read 60 psi, but as the water escapes, the pressure would drop, unless you can increase the supply.

Now obviously if you installed a 200 psi oil pump, the increased pressure would overcome the losses, however this type of increased oil pressure delivery system would cost more horsepower that if you installed a high volume oil pump.

Hopefully this helps somewhat.

Dennis,

You might take a minute to read this old thread from CHR where my friend Uncle Bob shares some of his knowledge on the subject of oil pressure and engine lubrication.

http://www.clubhotrod.com/forums/sho...=&threadid=425

There are also other threads on CHR that discuss oil pressure and related subjects that you can find by doing a search.

Dan J

HI TY, YUP...THAT ANSWERED MY QUESTION PERFECTLY. JUST AS I 'KINDA' FIGURED. I'M GOING WITH THE HIGH 'VOLUME' PUMP. I WAS ALSO WONDERING IF THIS IS TRUE OR NOT. CAN A HIGH PRESSURE PUMP PUT MORE AIR BUBBLES IN THE OIL AND MAKE IT KINDA FOAM UP AND BREAK DOWN THE OIL FASTER. THANKS AGAIN AND TAKE CARE........DENNIS

THANK YOU DAN J. I WENT TO THE ARTICLE YOU RECOMENDED. MAN WHAT A MESS!!!. IT ALSO GAVE ME MORE KNOWLEDGE. THANKS AGAIN...DENNIS

If you have some loose clearances then it would be good to use the high volume pump, but also keep this in mind...if you keep a stock sump oil pan you might suck the pan nearly dry in a high rpm application. Some say it happens at higher rpm, and you will notice a fairly rapid loss in pressure until you get off the throttle and lower the rpm. So, either get a larger sump or don't go with the high volume pump...I would always choose the former of those two considering that the benefits of high volume oiling are gonna outweigh the larger pan...on a performance level anyway.