5.7 oil pump options

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

hunterdan

Senior Member
Joined
May 7, 2018
Posts
836
Reaction score
777
Location
SE PA
Ram Year
2019 classic
Engine
5.7 Hemi
So, after reading a post on Facebook where a guy installed a high pressure melling oil pump in his 4th gen 5.7 after doing the cam and lifter swap/mds delete, I figured I'd post this thread trying to clear up the differences between high pressure and high volume pumps. High pressure pumps, are just standard pumps, with a higher pressure relief spring. It moves the same amount of oil, you will have the same pressure as oem, except at higher rpm where the spring allows the pump to build up more pressure before opening. Oil pressure isn't created by the pump. It's created by the clearances in the bearings. Tighter tolerances will create higher pressures, looser tolerances will create lower pressures. By contrast, a high volume oil pump will move (flow) more oil than oem and a high pressure pump. A typical high volume pump will include a heavier and oem spring so that you can run high volume with an oem pressure relief, or high volume with higher pressure relief. Now, a high volume oil pump, due to the higher flow of oil, will create higher pressures since its now trying to force MORE oil through the same size passages. A standard volume, high pressure may see higher oil pressures after rebuild, but it's because of new oils (typically heavier break in oils) and tighter tolerances. At higher rpm, it'll reach higher peak pressures, but its still only moving the oem amount of oil. A higher volume pump will produce even higher idle pressures (moving more oil at idle) and higher, high rpm pressure (more oil flow, higher pressure relief).
Just because you have high oil pressure, doesn't mean you have adequate oil flow.
Screenshot_20220429-005740_Drive.jpg
 

James OBrien

Senior Member
Supporting Member
Military
Joined
Mar 17, 2019
Posts
440
Reaction score
684
Location
St. Louis
Ram Year
2018
Engine
5.7 Hermi
You're absolutely correct, the only minor adjustment to your post is that the MMX Hellcat oil pump is a high pressure/high volume pump due to the slightly larger/deeper rotors.
 

crash68

ACME product engineer
Staff member
Administrator
Supporting Member
Joined
Mar 20, 2016
Posts
10,704
Reaction score
16,709
Ram Year
2015
Engine
3.0 EcoDiesel
Just because you have high oil pressure, doesn't mean you have adequate oil flow.

Now, a high volume oil pump, due to the higher flow of oil, will create higher pressures since its now trying to force MORE oil through the same size passages.
Your statements are contradictive. If flow raises the pressure, then how is it high pressure doesn't mean you have adequate flow?
A pumps design dictates how much flow a pump is capable of at a given rpm @ a given psi. If you don't have enough volume, your pressure will drop.
High flow pumps will have larger/deeper rotors, for higher pressure pumps the ratio of compression is higher within the rotors.
 
Top