hunterdan
Senior Member
- Joined
- May 7, 2018
- Posts
- 846
- Reaction score
- 785
- 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.
Just because you have high oil pressure, doesn't mean you have adequate oil flow.
Melling Oil Pumps Flow vs. Pressure
Melling Oil Pumps Flow vs. Pressure. For more information and to order Melling Oil Pumps call 800.722.2678. www.motorstate.com
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