Re: oil pumps?
[Re: DusterKid]
#220647
02/10/09 08:17 PM
02/10/09 08:17 PM
|
Joined: Jan 2003
Posts: 31,027 Oregon
AndyF
I Win
|
I Win
Joined: Jan 2003
Posts: 31,027
Oregon
|
The oil pump is directly connected to the camshaft so pumped volume is a direct function of engine speed, not pressure.
A high volume pump has larger rotors so for each revolution it pushes a larger volume of oil into the engine.
A high pressure pump is a pump that has been equipped with a higher load relief valve spring. You can put the high load spring in either a standard volume pump or a high volume pump.
People are always getting confused on this topic, most likely because they forget about how the relief spring works.
If the relief spring is closed then a higher volume pump will pump more volume into the engine (and raise pressure). If the relief spring is open then the high volume pump basically does nothing but recirculate more oil inside the pump.
The big difference between a high volume pump and a high pressure pump will occur at low engine speeds. The high volume pump will produce higher pressure at idle since it is forcing more oil into the engine. At anything greater than about 3000 rpm the high volume and standard volume pumps start to act the same since the relief spring is blowing off all of the excess volume.
Sometimes the high volume pump will overwhelm the relief port and pressure will continue to increase past the relief point. Put a Milodon pump on an engine with tight bearing clearances and you'll see that happen. At 6000+ rpm the Milodon pump is putting out so much volume that the relief port can't keep up and the oil pressure will go thru the roof. That combination is a good way to blow the oil filter apart. Bad thing is it will happen when you're going 140 mph thru the lights.
From what I've seen over the years, there is very rarely a need for a high volume pump on a big block Mopar. Maybe if clearances are on the high side and full groove mains are used but otherwise it is just a waste of energy.
Last edited by AndyF; 02/10/09 08:36 PM.
|
|
|
Re: oil pumps?
[Re: AndyF]
#220656
02/10/09 09:04 PM
02/10/09 09:04 PM
|
Joined: Jan 2003
Posts: 16,925 NC
440Jim
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 16,925
NC
|
Quote:
The big difference between a high volume pump and a high pressure pump will occur at low engine speeds. The high volume pump will produce higher pressure at idle since it is forcing more oil into the engine. At anything greater than about 3000 rpm the high volume and standard volume pumps start to act the same since the relief spring is blowing off all of the excess volume.
This has been my experience as well. My race motor doesn't need the high volume, it idles at 1200 rpm, the oil doesn't get hot, and both pumps made the same pressure going down the track (using the same spring in each test).
My street motor needs the high volume pump at idle (IMO). It idles at 900 rpm (or less) and when the oil is hot, it is 25 psi. I don't want to see the idle pressure with a standard volume pump in that. Lots of bearing clearance, hemi wide groove 360 bearings (mistake), hot oil, low idle rpm, it all adds up.
|
|
|
Re: oil pumps?
[Re: 440Jim]
#220657
02/10/09 09:08 PM
02/10/09 09:08 PM
|
Joined: Jul 2004
Posts: 19,317 State of confusion
Thumperdart
I Live Here
|
I Live Here
Joined: Jul 2004
Posts: 19,317
State of confusion
|
So then, Are we back to the hi volume pump robs power due to more drag?
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
|
|
|
Re: oil pumps?
[Re: AndyF]
#220661
02/13/09 01:31 AM
02/13/09 01:31 AM
|
Joined: Dec 2003
Posts: 5,314 Carstairs, Alberta, Canada
dave571
master
|
master
Joined: Dec 2003
Posts: 5,314
Carstairs, Alberta, Canada
|
Quote:
I wouldn't put a high volume pump on a 440 that has tight bearing cleances. You'll just end up with too much oil pressure. If you put a soft relief valve spring in it then you just recirculate a bunch of oil inside the pump.
I almost always recommend a standard volume pump. If the std volume pump can't make 60 psi at 6000 rpm then put the high volume pump on there. I don't think I've ever seen an engine where the std volume pump couldn't hit 60 psi though.
I'm glad this thinking is starting to get around.
MANY think a HV pump provides Better oiling, when it does nothing of the sort.
|
|
|
|
|