Hi flow oil pump with stock 402 pan

[FrnkNsteen]

Hi Guys,

I've read that people have had issues running a hi flow oil pump with the stock oil pan, causing it to drain the pan quicker than it can run back down into it. I believe my engine builder said he put in a hi flow oil pump, and I know we put a stock #402 B-Body oil pan with baffles and windage tray on the motor.

Wondering if I am going to have issues? Would issues only arise at high RPM? If so, I think I may be ok, as I don't see taking it over 5K rpm very often. I'd hate to pull that new motor apart to change out the oil pan and pickup (and add skid plate to K-member). Guess the other option is changing the oil pump out for a standard flow oil pump.

Opinions?

 

[67Charger]

From a technical standpoint, NO. Your pump will only supply what the engine can use. The regulator will bleed off all excess flow. A standard volume pump will reach max system flow at a particular rpm and then bypass the rest as the RPM's continue to rise. A high-flow will reach that bypass point at a lower RPM since it moves more volume per revolution. As the engine gets hotter and the oil gets thinner, a standard pump may not be able to keep up with the increased flow demands of the engine even with more RPM, possibly never reaching the bypass. A high volume will hold out longer.

As far as drain back is concerned, that is only going to be a NEW problem if the old pump could not supply sufficient volume at high rpm (indicated by pressure dropping off) and thus never exceeded the fixed drainback rate. A high volume pump will move more oil, hold full pressure earlier, longer, and ultimately may be able to flow more than your engine can drain back.

All that being said, My 440 with a HV pump would suck the 402 dry during a 1/4 mile pass in 11 seconds. Not enough pan volume. Volume allows each drop of oil to spend more time in the pan defoaming so you don't get down to sucking oil foam as easily. If I had an extra quart over the 402, the first bit of oil to leave the pan at the start of the pass may have made it back to create a continuous flow.

 

[FrnkNsteen]

From a technical standpoint, NO. Your pump will only supply what the engine can use. The regulator will bleed off all excess flow. A standard volume pump will reach max system flow at a particular rpm and then bypass the rest as the RPM's continue to rise. A high-flow will reach that bypass point at a lower RPM since it moves more volume per revolution. As the engine gets hotter and the oil gets thinner, a standard pump may not be able to keep up with the increased flow demands of the engine even with more RPM, possibly never reaching the bypass. A high volume will hold out longer.

As far as drain back is concerned, that is only going to be a NEW problem if the old pump could not supply sufficient volume at high rpm (indicated by pressure dropping off) and thus never exceeded the fixed drainback rate. A high volume pump will move more oil, hold full pressure earlier, longer, and ultimately may be able to flow more than your engine can drain back.

All that being said, My 440 with a HV pump would suck the 402 dry during a 1/4 mile pass in 11 seconds. Not enough pan volume. Volume allows each drop of oil to spend more time in the pan defoaming so you don't get down to sucking oil foam as easily. If I had an extra quart over the 402, the first bit of oil to leave the pan at the start of the pass may have made it back to create a continuous flow.

So is that a yes, or a no??

 

[67Charger]

Sorry, sometimes the full answer is not so clear. The pump will not CAUSE any problems. It will protect your engine better right up to the point you run the pan dry. The only way you will run the pan dry is excessive rpm for excessive time. Hot oil will drain faster. Cold oil will require and use less volume. Both of those are in your favor. If you blast high rpm the pump will do its job better than a standard one. If this causes problems, your old pump was not up to the task of keeping up with demand.

Your pan volume is the limiting factor, as it was with mine. I run large bearing clearances (more volume demand) and a HV pump. I cant drag race and use my small 402 pan, and it's why drag racers use deep, high capacity pans. You could almost never drain a 402 on the street even under spirited driving. 6500 RPM for 11 seconds is different. 4000 rpm forever is fine.

 

[66Satellite47]

I agree with 67Charger, the pump will deliver what engine can take. Larger bearing clearances, looser cam bearings, looser rocker clearances increase oil demand. For high RPM (5500+) the 402 pan could get empty before the drainback. In most of my drag race motors we used a 2" deeper 402 pan/HV pump & with the higher RPM motors (7000+) we restricted the oil to the lifter gallys. Also have used dual external Milodon pump with 10 Qt dragster/side kickout style pan. Ductile & roller style rockers (& roller lifters) tend to not need so much volume. All depends on the engine build & how you use the motor.

 

[mopar 3 B]

A good mechanical oil pressure gauge will tell you if there is ever a problem. Otherwise for normal street driving I would not worry about it.
The stock pump on the 360 will suck the pan dry over a 5 mile run at 4800 rpm.
So when the oil pressure starts to drop slow the rpms.

 

[66Satellite47]

A good mechanical oil pressure gauge will tell you if there is ever a problem. Otherwise for normal street driving I would not worry about it.
The stock pump on the 360 will suck the pan dry over a 5 mile run at 4800 rpm.
So when the oil pressure starts to drop slow the rpms.

Interesting observation. Guess that's why we all should be thinking about higher capacity oil systems.

 

[BSB67]

Said more simply, a high volume oil pump at 60 psi will be pumping the exact same amount of oil to the motor as a standard pump at 60 psi, on the same motor, same rpm.

 

[67Charger]

Interesting observation. Guess that's why we all should be thinking about higher capacity oil systems.

For the sake of conversation, I would conjecture that is actually the oil getting hot, thinning out, and exceeding the flow requirements of the stock pump. At that speed, a lot of heat is being produces, the oil is being forced though the engine at high speed, but still only draining back via gravity. It spends less and less time in the pan defoaming and cooling. If it was strictly pan volume requirements at 4800 rpm, it wold have more problems when the oil was less hot and not flowing back to the pan as quickly. Hot oil returns faster, but is also pumped out faster. The telling part here is that it only happened after 5 minutes. The only thing changing over time at that point is the viscosity drop due to rising heat in the oil. More pan volume would still help, though, since the oil would be able to spend more time in the pan cooling.

 

[mopar 3 B]

Slowing down to 65 and dropping 1300 rpm was a way cheaper and more realistic solution. Was in a hurry and destroying a perfectly good engine was not an option.

 

[mopar 3 B]

Said more simply, a high volume oil pump at 60 psi will be pumping the exact same amount of oil to the motor as a standard pump at 60 psi, on the same motor, same rpm.

Right but if 60 psi is max to the stock pump pressure and volume only goes down hill after that. Where the high volume will continue to deliver oil if available.

 

[BSB67]

Right but if 60 psi is max to the stock pump pressure and volume only goes down hill after that. Where the high volume will continue to deliver oil if available.

Correct. If bearing clearances are such that a standard oil pump cannot maintain 60 psi, the high volume pump may. That being said, I have not experienced this, even with loose clearances and full time rocker oiling. If your motor cannot maintain the relief spring pressure rating with a std oil pump, you probably have problem.

In reality, only very extreme applications might need a HV pump.

 

[91r/t]

Sorry, sometimes the full answer is not so clear. The pump will not CAUSE any problems. It will protect your engine better right up to the point you run the pan dry. The only way you will run the pan dry is excessive rpm for excessive time. Hot oil will drain faster. Cold oil will require and use less volume. Both of those are in your favor. If you blast high rpm the pump will do its job better than a standard one. If this causes problems, your old pump was not up to the task of keeping up with demand.

Your pan volume is the limiting factor, as it was with mine. I run large bearing clearances (more volume demand) and a HV pump. I cant drag race and use my small 402 pan, and it's why drag racers use deep, high capacity pans. You could almost never drain a 402 on the street even under spirited driving. 6500 RPM for 11 seconds is different. 4000 rpm forever is fine.

On a side note 67Charger.....What does your motor with the looser bearing clearances run for oil pressure at idle and running cruise speed? I have a motor that's fairly fresh and I run 15psi at idle and it shoots right up to 40 as soon as you hit the throttle. I figured I had clearances that were a bit larger. I run a standard oil pump and not a HV.

 

[mopar 3 B]

I run the HV, HP pump with .003 clearence rods and mains. 60 psi idle warm. BB block, primary fuctions street and top end runs.

 

[91r/t]

I run the standard pump so was curious if that was low. Might take it apart this winter and check bearing clearances.

 

[mopar 3 B]

I run the standard pump so was curious if that was low. Might take it apart this winter and check bearing clearances.

15 at idle would be minimal.

 

[91r/t]

15 at idle would be minimal.

That is what I thought. I have never had one that dropped so much at idle until this 440. Its fresh with only 5000 miles or so on it, so I suspect the bearing clearances to be large which could be causing it to do so.

 

[FrnkNsteen]

Thanks for the information guys. Sounds like for normal street driving (with the occasional throttle drop), I should be ok. I'll leave it as it is and just keep an eye on it.

Thanks again!

 

[BSB67]

..... I run 15psi at idle and it shoots right up to 40 as soon as you hit the throttle.

You're fine. Be happy to know that you are not unnecessary wasting hp driving the oil pump.

 

[91r/t]

You're fine. Be happy to know that you are not unnecessary wasting hp driving the oil pump.

Yea, I am going to check the clearances when I have the pan off for shits and grins, but I won't worry.