I was reading where you should not use a high volume oil pump unless you are using a larger capacity oil pan (7 quarts) supposedly at high rpms and hard accel you can drain the stock pan. small block. anyone ever heard of this?

 

To answer your question, yes. I was concerned when i had my L-48 rebuilt, the shop said they use Melling high volume oil pumps all the time and assured me that there would be no problem, 5 yrs and about 8k later, no problems.

 

Straight from Mellings website....

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.


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

2>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.

3>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.

4>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.

5>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 replaced mine with a Melling 55A (stock volume, high pressure) in my stock L82...

 

I always run high volumn pumps. I like to see the hot idle pressure around 50 and running down the road hot at 60-70. If you really lean on it the gage pegs.
I have never had a problem with pumping th pan dry or distributor gears.

 

I put an HV in my BB and it probably was a waste.
These things are for loose engines. The oil sprays out of the large clearances so need a lot of oil to make up for it.
I doubt any engine dumping oil from the crank is going to run out of oil.

I think only 68 or so were built with large clearances, they must have done other things to make them spin with normal clearances.

I agree with norvalwilhelms comments . I don't think it will hurt anything but also don't think it helps anything either. The gauge is always high with normal weight oil. My engine had 70 lbs spun with starter with plugs out. Same as when running.

As a side note. with engine idling check your oil level. Shut it down and check right away, then 10 or seconds later....this blows away the myth that oil for some reason doesn't flow back to the pan with gravity. glyptol in the valley and all that other stupid stuff.

 

I read a good article from Lunati on bearings. They claim that bearings are designed to run at .0025 clearance. At this clearance they carry their maximum load, use 1 gallon of oil per minute and run their coolest.
If you increase to .0035 they loose some of their wieght carry capacity and oil consumption above the 1 gallon per minute goes up really fast.
I actually build my motors around .002, break them in slowly and let them open up a little of their own clearnce.
I also drill a hole in the block behind the cam gear and into the high pressure oil gallery to pressure lube the back of the cam gear and maybe throw a little more oil on the chain.
I also drill a 1/8th hole in the distrubutor where it passes through the high pressure oil gallery to lube the bottom distributor bushing.
I also file a 1/16 by 1/8 wide groove in the side of the distrubutor housing that seals the high pressure oil gallery so it sprays a small amount of oil on the distrubutor/cam gear.
All this takes oil away from the motor and the high volumn pump guarantees hot idle and running pressures.

 

I'm running a hi-volume Melling in my 355. Although I'm using a 5QT oil pan, I radiused the oil passages of the block, moved the oil filter housing 180*, etc. Oil pressure is 40lbs at idle and 60+ crusing down the interstate at 70MPH. I run Mobil 1 10W30.

 

Wouldn't moving the oil filter housing 180* mean that the housing is pointing straight up?

 

I meant rotating the portion that the filter spins onto.

 

Not to be a PIA, but I don't understand what you are saying. The filter spins on to a, for better word, stud, that is part of the block.

How can you rotate that stud and still have a seal?

Very confused!!

 

The explanation on Points 3 and 4 are not quite right.

Point 3: The load on the gears is porportional to the pressure TIMES the flow - that is if you have X cubic inches/rev oil pump operating at 30 psi compared to a 2X cubic inches/rev oil pump operating at 30 psi the latter will consume twice the power at any given speed loading the gears twice as heavily(double the torque). Doubling the pressure at the same volume for rev also doubles the load(torque) on the gears.

That said, the gears can usually take the load without damage for MANY miles.

Point 4
Most oil pumps relief valves dump to sump NOT internally to inlet so I think if you went REALLY wild on volume you might tend to foam your oil although once again, in the range of typical pumps I doubt this would be much of a problem.

 

actually it spins on to an adapter that is attached to the block. not sure what rotating that adapter 180* does but i will have to take a look.

 

Melling oil pumps recirc into the pump - std. OEM GM pumps do as well at least for SBC

See the diagram below, this is a melling pump modified by Moroso for racing purposes... those modifications being the ball milled grooves and the ENLARGED bypass opening...

That bypass opening is where oil is recirced back into the pump..



You can also read Chevy High Performance's article on how oil pumps work where they also say....

 

If i had to guess.. rotating the adapter 180 degrees might block off the bypass valve on the adapter.

 

hi, I have an ls2 2007 c6
I know that picking out a 355 Melling hi pressure pump was not the best pump as these were used for v6-to V8 gmc trucks
Im running with 55 lbs in 5th gear.
my question is, do you think I should replace this pump or will it be okay?
info is scarce on my situation
ty!

 

My engine builder put a high capacity oil pump in my small block. Using 10-30 oil, the OP gauge would stay pegged for many miles until the oil reached operating temperature. That seemed excessive to me, so I put a melding normal capacity pump. I have plenty of oil pressure, but the gauge doesn’t stay pegged nearly as long. Just my two cents.

 

Seems yours is a 2007 with an LS2 motor ?
If so, those have an entirely different design oil pump than those in any-all motors in a C3 (this is C3 forum).

 

I do believe as you move up to higher planned rpm usage, it is advisable to employ more tricks.

The Chevrolet Engineers did not design or feel a need to make **** as a gimmick for marketing!

You basically have stock oil pump
then a High Volume Oil Pump
then High Pressure
and High Volume, High Pressure!

You has 4 quart pans
You had 5 quart with some trap doors
then you had 6 quart pans with all of the tricks.

You have no special mods for oil control in stock and then the sky is the limit!
Windage Trays, oil restricting lifters, chamfering oils, drilling more holes, valve cover dippers, splash shields, drain back tricks, etc etc etc all the way to oversized pans, swinging pickups, to dry dumping, etc etc.

The lower viscosity oils are the newer trick. I think bearing clearance should be more carefully thought out. I have always like 10psi or every 1000 rpms.

 

This thread is over 14 years old.