Topic for discussion: Oil Pump - Standard Volume vs. High Vol.

[Ranman69SE]

The machinist that is putting together my 493 short block wants me to run a standard volume oil pump, instead of a high volume.  I believe his thinking is that a h.v. pump can send too much oil up into the engine during an extended high rpm blast, and starve the pan.  I remember reading an article in Hot Rod about a high performance Chevy engine builder who also did not go with a h.v. pump as he thought it was not necessary, and felt the h.v. pump took more power to turn, thus taking away power from the engine. 

I personally don't think an engine can have too much oil circulating, both for lubrication and for cooling.  But I trust my machinist implicitly, he is an older guy who's been around the business for years, and regularly builds 440's and Hemis.  I plan on running a low profile Milodon pan (7 qts + filter) which should help with the oil supply.

I would like to throw this out to get members opinions.

Randy

p.s. Ron, I just received my custom-ground Comp Cams solid lifter cam per your recommended specs.  I'm going to wrap it up and put it under the tree for myself!  Thank you , Santa!

[Chryco Psycho]

I use HP std volume pumps in al;l but extreme engines with large oil pans

[firefighter3931]

Randy, i'm a firm believer in lots of oil pressure and lots of oil capacity. With the Milidon 7qt pan and a windage tray you will never suck the pan dry. I would use the HV pump and a new hardened oil pump drive. 

Congrats on the cam purchase ! I don't remember the specs off hand but maybe you can refresh my memory 


Ron

[Dartbloke]

High volume pump, 7 quart pan, bypass spring cut to give 70 psi @6500, I'm happy with that.

[John_Kunkel]

The old "starve the pan" myth reappears. The only time a HV pump can pump the pan dry is if the pan is dinky or the clearances are super loose.

At normal BB rpm's the extra volume the HV pump supplies will be turned into excessive pressure, not excess volume.

[john108]

The old "starve the pan" myth reappears. The only time a HV pump can pump the pan dry is if the pan is dinky or the clearances are super loose.

At normal BB rpm's the extra volume the HV pump supplies will be turned into excessive pressure, not excess volume.

Is excessive pressure a BAD thing? or a GOOD thing?

[GreenMachine]

The old "starve the pan" myth reappears. The only time a HV pump can pump the pan dry is if the pan is dinky or the clearances are super loose.

At normal BB rpm's the extra volume the HV pump supplies will be turned into excessive pressure, not excess volume.

Is excessive pressure a BAD thing? or a GOOD thing?

  I am by no means an expert, but I think what he means by excessive pressure is the bypass is dumping oil back to the pan due to the extra volume the pump is putting out that the engine can't use. Where a std. pump is supplying less oil and might not be able to supply enough for the bypass to dump except for maybe when it's cold. When the bypass is dumping, that's wasted power.

[GreenMachine]

  Oh, and one more thing, excessive pressure IS bad when you're using cheap oil filters.

[John_Kunkel]

If you take a look at the pressure relief valve in the pump you'll see that it has limited opening size, even if the valve is fully open it can only bypass a certain amount of volume and when the volume exceeds what the valve can pass the excess volume turns into pressure.

IOW, if the pump supplies five gallons per minute at 5000 rpm (imaginary figures) and the engine can only use three gallons per minute, the excess volume must be bypassed but if the bypass valve can only bypass one gallon per minute the extra gallon per minute of volume will raise the pressure because there's nowhere else for it to go.

Excessive pressure puts strain on the pump drive, wastes power and heats the oil.

[Challenger340]

This is an interesting topic for sure !

So many variables once again given, given many different applications. I don't wanna start any arguments, rather, just some "food for thought".

IMHO
"one pump" doesn't "fit all" applications. 

IMO,  "Std. Volume" or "High Volume", is determined by Targeted Engine Bearing Clearances, as per the given application, Bearing eccentricities, and Oil being used.

Think of the engine Oiling system in terms of supply, (Pump & Pickup), and demand, (leaks in the system), being Bearings, Shafts, etc., etc. and Pressures (Valve Springs / Rate)

A "Garden Hose" with a bunch of holes down the length to the end. If you've got bigger holes close to the source, less travels to the end, and vice-versa, if smaller holes close to the source, "more" makes it to the end of the hose.

All depends how "Big" your holes are in your engine, that you are trying to supply with Oil on a "given" application.

The BIGGEST misconception, and MOST OVERLOOKED factor, to the Volume Size of Oil Pump selected in a given application, IMO, is the "cooling role", the Circulating Oil plays, on engine bearings, especially in BB Mopars/Strokers in general, and Valvesprings for "real" Cams.

The 4 "ESS's"
"SET" your bearing Clrc.
"SET" your Bearing Eccentricity.
"SET" your Side Clearances(leak-off).  You can have adequate Vertical Bearing Clrc., and no Oil leaking out(cooling the Brg), because of not enough Rod side clearance.
"SET" your Valvetrain Oiling.

Talk it over with your builder, as per your application, driving style, Oil being used, Valvetrain & rpm expected.

If he says "it's all the same",

IMO,
WALK AWAY !

Bob out.

Just my Opinion.

[firefighter3931]

Randy, quick question if i may :

Has the builder talked about bearing clearances ? I ask because Bob brings up some excellent points. 

Fwiw, i like them a little on the loose side....especially in high rpm/high hp applications. With a .0025 main & rod clearance the HV pump is what you need and want. 

Personally i wouldn't run the clearances any tighter than that allthough some here will probably disagree.....


Ron

[Challenger340]

Randy, quick question if i may :

Has the builder talked about bearing clearances ? I ask because Bob brings up some excellent points. 

Fwiw, i like them a little on the loose side....especially in high rpm/high hp applications. With a .0025 main & rod clearance the HV pump is what you need and want. 

Personally i wouldn't run the clearances any tighter than that allthough some here will probably disagree.....


Ron

IMO

THAT'S THE SHIT ! 

Use the HV Pump.

.003-.0032", don't scare me at all on the mains either ! Such a big main.
Especially if theres ANY Crank runout (up to .0005")

Far more forgiving, and it'll love 10W40 all day with EOS, and Oil the top end just "puss" at Idle.