7quart panCan be to much If the bearings are not clearanced for it . It tries to cram oil into a space it can’t get into and the pressure goes sky high .
Also what pan is on it ? They are known to suck a stock pan dry .
Wrong answer...Can be to much If the bearings are not clearanced for it . It tries to cram oil into a space it can’t get into and the pressure goes sky high .
Also what pan is on it ? They are known to suck a stock pan dry .
Sorry that I am off on it sucking the pan dry , according to many builders that is the case .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.
Mine too.My engine builder specifically instructed me to use the standard volume Melling oil pump on my 331.
Sorry that I am off on it sucking the pan dry , according to many builders that is the case .
As far as being clearanced and having larger mains for the HV pump To do it’s job this seems to be law by just about every person you speak to and is even mentioned in your quote . I have been to 7400 rpm with a stock melling with no issue and made over 720 Rwhp with it . With no indications of any pressure issues in my data logs .
Again personally If the engine doesn’t have large enough tolerances for that extra amount of oil it’s moving with the pressure sky high - my concern would be the oil almost becoming a brick wall at that pressure and not dispersing evenly and getting around the bearings the way it should because it can’t physically get into the space .
@srtthis what ya think ?
My engine builder specifically instructed me to use the standard volume Melling oil pump on my 331.
The point is that Melling builds oil pumps for Ford and GM, that is their business. I believe that they know what they are talking about since they work closely with the engineers who design the engines we are all so vocal about.
When Ford builds engines that make 430+ HP and no N02 or pressurized induction power adders from about 281cubic inches and wind up to a 7000 RPM redline and still offer a standard warranty, that says that they know what the are doing. There isn't an engine builder around that can do all those things and offer the kind of warranty that comes with one of the new Coyote engines.
ARP Shaft alwaysNo matter what pump you use, please use a HD pump shaft. The stock ones can end up looking like a broken Twizzler, even with a stock type pump. It happened twice on my 79, once with the stock, high mileage 302, and then on the first highway run with the E-7 5.0 crate rebuilt motor from Marshall/Blueprint motors.
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