Summits online catalog has different part numbers for the two so what is the difference. I mean I know the difference betwen the two but which is the one you want and why?

 

High volume, for high HP engines so you don't oil starve when rev'ing high.

~M~

 

for anyone reading that doesn't know the difference.

high volume
volume is how much mass you actually move so a high volume moves more quarts of oil per minute.

high pressure
pressure is how fast its being pushed in. so whats really being done is its compressed more in the oil passages.

a high pressure mechanical pump will rob you of horsepower. if you are making the horsepower that needs high pressure then ok but most street engines will do fine on stock oil pump. if i'm correce in quoting David Vizard from his book a stock chevy oil pump will be good up to and sometimes over 450 hp. now the way it robs you of power is that your cam has to turn it to make it pump oil. if you have ever messed with any kind of pumps you know to get higher pressure you have to have a smaller exit hole or else pump the stroke faster so your engine is having to work harder to pump the oil at a harder pressure. its like underdrive pulleys can free up hp by making your accessories turn less and therefore easier to try and turn.

someone correct me if i stated it wrong because it is late when i posted :tired:

Andrew

 

On the head.

~M~

 

I dont think you really answered my question. ::could be wrong tired also:: I was wondering why the difference between the two and what are the benefits if any between them. I'm pushing pushing over 450 HP and 600 ftlbs and am still using the stock oil pump (for break in only) and I'm wondering the specifics on the differences between them per application.

Thanks

 

You want high volume, when your engine revs up to 5k you want lots of oil there for it because things like your crank are going to be slinging the oil off as fast as you can pump it to it.

~M~

P.S. Only ever seen a high pressure pump in Pontiacs (real Ponchos, not the chevy powered ones) myself, and I think they used them there because of the distance the oil has to travel in those huge block of theirs.

 

You can put a stiffer spring into a STOCK oil pump and you will have a "Hi Presssure" pump. And it will also flow more due to the higher pressure.

A "Hi Volume" oil pump is a different housing, bigger rotors, bigger inlet. The mechanical design is changed to allow more flow.

Me personally I'd rather be 10 psi high than 10 psi low.

 

Great explanation! GM makes the industry standard high pressure relief spring, part# 3848911 also known as the "white" spring because of it's white stripe.

You can buy a plain-jane Melling M55 $19 pump, add this spring, and have a high pressure pump.

The case for high volume pumps is spelled out by Morley above...at high revs you have a good deal of centrifugal force at the rod journals pulling oil out of the crank.

For my most recent engine I split the difference between high vol and std vol, went with the Melling 10552 pump which is only 10% more volume than std:

http://www.melling.com/10552.htm

I used the high pressure relief spring, and have 30psi idle and 60psi above 2000rpm. Yes, it chews up a few HP turning it but in my opinion it's a good investment.