High Volume Oil Pump

The main reasons I know for not running a high volume oil pump on any motor involve ending up with too much of the oil in the heads/valley instead of the pan. Under extended high RPM use, you could suck the pan low and have the pump pushing air. That much oil in the top end can allow extra oil past the valve stems and guides, causing smoke.

If the oil drains back fast enough and leaks out the rods and mains fast enough to not cause these problems, you might need one. Otherwise, high volume and pressure pumps are a waste of horsepower.

7991LXnSHO said:

The main reasons I know for not running a high volume oil pump on any motor involve ending up with too much of the oil in the heads/valley instead of the pan. Under extended high RPM use, you could suck the pan low and have the pump pushing air. That much oil in the top end can allow extra oil past the valve stems and guides, causing smoke.

If the oil drains back fast enough and leaks out the rods and mains fast enough to not cause these problems, you might need one. Otherwise, high volume and pressure pumps are a waste of horsepower.

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Wrong answer...

Thanks to Stangnet member bubba-dough for helping to educate all of us by finding this article...

http://www.mellingengine.com/Portals/5/pdf/pdf_catalog/high-volume-pumps.pdf You will need the Adobe Acrobat viewer which is also a free download – http://www.adobe.com/products/acrobat/readstep2.html

From the Melling site, for those who didn't follow the link & read the tech note...



High Volume Pumps: Advantages, Myths & Fables

Most of the stock automobile engines are designed to operate from idle to 4500 RPM. The original volume and pressure oil pump will work fine in this type of application. As the demands on the engine increase so does the demands on the oiling system and pump.

The oil pump's most difficult task is to supply oil to the connecting rod bearing that is the farthest from the pump. To reach this bearing, the oil travels from three to four feet, turns numerous square corners thru small holes in the crankshaft to the rod bearing. The rod bearing doesn't help matters. It is traveling in a circle which means centrifugal force is pulling the oil out of the bearing.

A 350 Chevy has a 3.4811 stroke and a 2.111 rod journal. The outer edge of the journal travels 17.5311 every revolution. At 1000 RPM, the outer edge is traveling at 16.6 MPH and 74.7 MPH at 4500 RPM. If we take this engine to 6500 the outer edge is up to 107.9 and at 8500 it is 141.1 MPH. Now imagine driving a car around a curve at those speeds and you can feel the centrifugal force. Now imagine doing it around a circle with a 5.581, diameter.

The size of the gears or rotors determines the amount of oil a pump can move at any given RPM. Resistance to this movement creates the pressure. If a pump is not large enough to meet the demands of the engine, there will not be any pressure. Or if the demands of the engine are increased beyond the pumps capabilities there will be a loss of oil pressure. This is where high volume pumps come in; they take care of any increased demands of the engine.

Increases in the engine's oil requirements come from higher RPM, being able to rev faster, increased bearing clearances, remote oil cooler and/or filter and any combination of these. Most high volume pumps also have a increase in pressure to help get the oil out to the bearings faster.

That is what a high volume pump will do. Now let Is consider what it will not do.


It will not replace a rebuild in a worn-out engine. It may increase pressure but the engine is still worn-out.

It will not pump the oil pan dry. Both solid and hydraulic lifters have metering valves to limit flow of the oil to the top of the engine. If a pan is pumped dry, it is because the holes that drain oil back to the pan are plugged. If the high volume pump is also higher pressure, there will be a slight increase in flow to the top.

It will not wear out distributor gears. The load on the gear is directly related to the resistance to flow. Oil pressure is the measure of resistance to flow. The Ford 427 FE "side oiler" used a pump with relief valve set at 125 psi and it used a standard distributor gear. Distributor gear failures are usually caused by a worn gear on a new cam gear and/or worn bearings allowing misalignment.

It will not cause foaming of the oil. With any oil pump, the excess oil not needed by the engine is recirculated within the pump. Any additional foaming is usually created by revving the engine higher. The oil thrown from the rod bearings is going faster and causes the foaming. This is why high performance engines use a windage tray.

It will not cause spark scatter. Because of the pump pressure there is a load on the distributor gear. The number of teeth on the oil pump gears determine the number of impulses per revolution of the pump. In a SB Chevy there are seven teeth on each gear giving 14 impulses per revolution. At 6000 RPM the oil pump is turning 3000 RPM or 50 revolutions per second. To have an effect on the distributor, these impulses would have to vibrate the distributor gear through an intermediate shaft that has loose connections at both ends. Spark scatter is usually caused by weak springs in the points or dust inside the distributor cap.

High volume pumps can be a big advantage if used where needed. If installed in an engine that does not need the additional volume, they will not create a problem. The additional flow will be recirculated within the pump.

I used to think most of that was true until I had a LONG talk with a professional builder and OEM consultant, Dr. Olds himself.

A blueprinted, stock pump with restrictors for the top end is what he recommended for my first Olds build and a similar pump for my first 302 hop up too. Mondello (Olds) insisted on the combo for even street/strip builds, even with Hydraulic lifters, and there was more upper oil restriction available for the Olds that may not be applicable here. Although he has passed away, the first post is close to a direct quote as I can make from a conversation we had while I was hopping up my first Olds and Mustang. I will read and consider J's post, but there is a lot of R&D and racing behind my answer. They would have made more money re-selling the high volume pumps than the little restrictors, so I put some weight in his opinion.

I also received a similar opinion on high volume or pressure pumps being a waste of horsepower from a machine shop owner. He specializes in 427 motors for kit Cobras, but will do special projects for other brands or keep his guys busy with a race Chevy. He did not reccomend putting s high volume pump in a Ford small block, especially without maximizing flow back.

I do run a high pressure pump on one engine. It is one that runs low oil pressure at idle, especially when warm, even in factory new specs. But that has not been the case with my 5.0's

7991LXnSHO said:

I also received a similar opinion on high volume or pressure pumps being a waste of horsepower from a machine shop owner. He specializes in 427 motors for kit Cobras, but will do special projects for other brands or keep his guys busy with a race Chevy. He did not reccomend putting s high volume pump in a Ford small block, especially without maximizing flow back.

I do run a high pressure pump on one engine. It is one that runs low oil pressure at idle, especially when warm, even in factory new specs. But that has not been the case with my 5.0's

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I would put advice received from a company that makes oil pumps for the entire automotive industry above the advice from a mechanic with no liability for the accuracy of his answers.

I will evaluate the contents of each place's snake oil claims by what is at stake. Two professional racing builders' reputations and their entire businesses are no minor dogs in the fight, snakes in the oil or whatever metaphor. They could make a few more bucks by drinking the Kool Aid and selling the more expensive pumps if it would help their engines. But they say it will not. That is good enough for me. These are not fly by night, parts house, or mass engine rebuilders.

I am not saying the oil pump company is entirely wrong (even real snake oil had Capsasin in it) but like all the cold air intakes, they may have more to make from selling their parts than caring if you really need it.

A heavy duty oil pump shaft, a better oil pan with a windage tray, kick outs, and the one way flow baffles all increase reliability or oil flow control. They might be a better use of the OP's money. The HD pump shaft should be required on all builds.

If you do use the high volume pump, please check out cleaning up the oil return paths and consider Gyptal red to increase flow back.

I've ran hv pumps on two engines and currently on the one I am building. At idle I always had over 40 psi at idle from a mechanical gauge and no problems what so ever. I'm convinced

high volume and high pressure oil pumps have their place in the overall scheme of things. OP if you are planning on turning more than 6000 rpm regularly, and have issues with oil pressure dropping, then go to a high volume pump. if you are planning on building a healthy race motor, then definitely go with a high volume pump. but for a street engine that wont see the high side of 5500, except out at the track, then keep the stock oil pump as it will do the job nicely thank you. do however upgrade the oil pump drive shaft.