High Volume Oil Pumps - I hear many things..

chepsk8 · Sep 13, 2005

I have a high mileage 5.0, probably close to 200,000 miles, but still runs strong. It just had the oil pump seize, and I replaced it with the high-volume pump, as I figured the motor is loose enough to handle the extra flow without high pressure issues.

PSI Numbers:

30 - 35 cold
50-55 at speed cold
45-50 at speed warm
25-30 idle warm

I hear from many about staying away from the high volume pumps. Is it more of an issue for new tight motors that cannot handle the increased flow?

BTW, as soon as the pressure dropped, I turned off the motor. No new noises since replacing the pump & shaft.

EMW150 · Sep 13, 2005

Correct, it really depends on the clearances,etc. If the engine had lower oil pressure when the mishap occurred, you were smart to install the HV pump to buy some time with the engine. On a fresh engine with tight clearances, I don't like HV pumps for most street type builds. I had one in my 331 for a while and the thing had 80 psi driving when hot. It would get close to 100 cold. I took it out because it pumped oil to the top end like crazy and gave me issues at the breathers, etc. I run a standard volume Sealed Power pump and it sees 50 psi hot idle and about 60 or so at higher rpms which is right where I want it.

chepsk8 · Sep 13, 2005

That was my thinking, so hopefully all will be OK, and I will buy some time with the motor until I can build a good motor!

Also put in 20-50 oil, since the motor is in a FFR Cobra, and it gets out often....

bluevenom867 · Sep 13, 2005

EMW150 said:
Correct, it really depends on the clearances,etc. If the engine had lower oil pressure when the mishap occurred, you were smart to install the HV pump to buy some time with the engine. On a fresh engine with tight clearances, I don't like HV pumps for most street type builds. I had one in my 331 for a while and the thing had 80 psi driving when hot. It would get close to 100 cold. I took it out because it pumped oil to the top end like crazy and gave me issues at the breathers, etc. I run a standard volume Sealed Power pump and it sees 50 psi hot idle and about 60 or so at higher rpms which is right where I want it.

What kinda motor and oil was that?Thats alot of oil pressure.

I got a Mellings HV pump in the 408 with 20W-50 it is more like the second example you posted .

EMW150 · Sep 13, 2005

bluevenom867 said:
What kinda motor and oil was that?Thats alot of oil pressure.

I got a Mellings HV pump in the 408 with 20W-50 it is more like the second example you posted .

My 331. 10w40. It all depends on the bearing clearances. 351 based engines are a different story. Larger journals, etc.

bluevenom867 · Sep 13, 2005

EMW150 said:
My 331. 10w40. It all depends on the bearing clearances. 351 based engines are a different story. Larger journals, etc.

Yea I can see that.

Even with the same bearing clearances,the 351W crank (or in my case,Cleveland journals 2.749"),will still have more surface area to cover.There by using more oil.

Btw,whats the differance between 351 oil pumps and 302 oil pumps?

EMW150 · Sep 13, 2005

bluevenom867 said:
Yea I can see that.

Even with the same bearing clearances,the 351W crank (or in my case,Cleveland journals 2.749"),will still have more surface area to cover.There by using more oil.

Btw,whats the differance between 351 oil pumps and 302 oil pumps?

I think you're right, the biggest difference is just simply larger bearing surfaces. I'm not sure about the volume differences between the two pumps. That's a good question.

bluevenom867 · Sep 13, 2005

EMW150 said:
I think you're right, the biggest difference is just simply larger bearing surfaces. I'm not sure about the volume differences between the two pumps. That's a good question.

Also the longer pushrods.Takes the oil longer to get to the top end.

EMW150 · Sep 13, 2005

bluevenom867 said:
Also the longer pushrods.Takes the oil longer to get to the top end.

True.

TheUser · Sep 13, 2005

I've read not to use a high volume oil pump with a stock oil pan because it can suck the pan dry. I'm no motor expert, nor do I have any information to back this up, just what I've read. Any truth to this?

bluevenom867 · Sep 13, 2005

TheUser said:
I've read not to use a high volume oil pump with a stock oil pan because it can suck the pan dry. I'm no motor expert, nor do I have any information to back this up, just what I've read. Any truth to this?

Thats really only plausable for high rpm use,IMO.

At low rpm,the stock pan should have enouf volume.

EMW150 · Sep 13, 2005

TheUser said:
I've read not to use a high volume oil pump with a stock oil pan because it can suck the pan dry. I'm no motor expert, nor do I have any information to back this up, just what I've read. Any truth to this?

I've talked to different guys who have had pump failures with a stock pan and a HV pump and that's what they attributed it to. I believe it could easily happen, and wouldn't recommend anyone using a stock pan with a hv pump.

EMW150 · Sep 13, 2005

bluevenom867 said:
Thats really only plausable for high rpm use,IMO.

At low rpm,the stock pan should have enouf volume.

Good point, I'd say 6k and up you might have problems.

Stormwalker · Sep 13, 2005

One thing that I see totally overlooked in this thread is the fact that a HV oil pump significantly increases the temperature of the oil, sometimes to the point where you have viscosity issues depending on the type and weight used.

Stock and even most modified 5.0L engines do not need a HV oil pump, and if for some reason a HV oil pump is needed, then an oil cooler is pretty much required.

Most track cars use a blueprinted oil pump, which is tedious, but necessary if you want a trustworthy pump, and this should be done even if the pump is brand new.

Daggar · Sep 13, 2005

Stormwalker said:
One thing that I see totally overlooked in this thread is the fact that a HV oil pump significantly increases the temperature of the oil, sometimes to the point where you have viscosity issues depending on the type and weight used.

Stock and even most modified 5.0L engines do not need a HV oil pump, and if for some reason a HV oil pump is needed, then an oil cooler is pretty much required.

Most track cars use a blueprinted oil pump, which is tedious, but necessary if you want a trustworthy pump, and this should be done even if the pump is brand new.

Consider for a minute the kind of heat that oil picks up when lubricating a centrifugal supercharger. No HV oil pump could even come close! If modern oil is able to stand up to those kinds of applications without thermal breakdown during normal oil changes then why would a HV pump be a consideration? I don't consider heat transfered to oil in a HV oil pump to be a factor.

EMW150 · Sep 13, 2005

Daggar said:
Consider for a minute the kind of heat that oil picks up when lubricating a centrifugal supercharger. No HV oil pump could even come close! If modern oil is able to stand up to those kinds of applications without thermal breakdown during normal oil changes then why would a HV pump be a consideration? I don't consider heat transfered to oil in a HV oil pump to be a factor.

I agree, the difference may be 1/2- 1 degree or so. Definately not to the extent of viscosity breakdown.

Stormwalker · Sep 13, 2005

Daggar said:
Consider for a minute the kind of heat that oil picks up when lubricating a centrifugal supercharger. No HV oil pump could even come close! If modern oil is able to stand up to those kinds of applications without thermal breakdown during normal oil changes then why would a HV pump be a consideration? I don't consider heat transfered to oil in a HV oil pump to be a factor.

I guess all I have to say to that is what you can get by with on the street is one thing. There is a right and wrong way to do everything. Keep in mind that heat and pressure work in different ways, yet are similar.

I have not run a HV oil pump, and I have been told NOT to by several racers far more experienced than I. Also, William Mathis describes why a HV oil pump would rarely be the correct choice in the books he has written.

Obviously this is an issue if you are competing in a time trial or PDE event, probably even autocross, but like I said, if it just sees street/strip use, it might not be an issue without an oil cooler.

Daggar · Sep 13, 2005

Stormwalker said:
I guess all I have to say to that is what you can get by with on the street is one thing. There is a right and wrong way to do everything. Keep in mind that heat and pressure work in different ways, yet are similar.

I have not run a HV oil pump, and I have been told NOT to by several racers far more experienced than I. Also, William Mathis describes why a HV oil pump would rarely be the correct choice in the books he has written.

Obviously this is an issue if you are competing in a time trial or PDE event, probably even autocross, but like I said, if it just sees street/strip use, it might not be an issue without an oil cooler.

I agree that there are more reasons to NOT use a HV pump on the street than there are reasons TO use one. I just don't think that heat transfer from the pump is one of those.

chepsk8 · Sep 13, 2005

Good thread!

In my case, I open track the Cobra, so lots of RPM's, and lateral movement. I also have a 6 QT. Baffled road-race pan, so lots of oil in the pan.

Stormwalker · Sep 13, 2005

Well, I do remember hearing and reading about a temperature issue relating to the use of a high volume oil pump, but perhaps what I have heard is wrong (I am not being facetious here, I want to learn something out of this!). I looked up a couple of things and found a couple of interesting tidbits of knowledge. First, I found this:

Article said:
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.

Also, I found this tidbit of info too, which correlates with what I had presumed earlier:

Article said:
A high-volume or high-pressure oil pump may be recommended in engines where bearing clearances are looser than normal, in engines where an auxiliary external oil cooler has been added to improve oil cooling and in racing engines where an oil accumulator has been installed.

So on one hand, I hear about wear and tear on the distributor/cam gears, and then I hear that it is not true, and I am also getting mixed messages about the temperature issue (which Daggar is adamant about not being an issue - and I see his points). Now I am starting to get confused.

Article sources:

http://www.melling.com/support/bulletins/bulletin-3rd.htm

http://www.aa1car.com/library/2004/ic110446.htm

High Volume Oil Pumps - I hear many things..

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