Oil Pump Dyno

[pbf777]

A pump design that doesn't recirc bypass oil back into the suction of the pump and instead dumps it back into the sump will be less likely to aerate the oil..............

     ............attempting to being directly ingested by the pump.  Absolutely!   

     Put do keep in mind, that the sum of fluid that is within the capacity of the pumping volume, that proves to be in excess of the volume required, not being returned to the inlet side of the pump, is now a volume that must be drawn from the sump; and this increases the velocity rate and a greater pressure drop within the inlet or pick-up tube hence exasperating the potential for cavitation, again!     

     This probably one reason why the 427's received larger pick-up tubes as there appeared the "remote-bypass" in the rear of the block emptying to oil back into the pan.     

     Scott.

[427John]

While I agree that the larger pickup tube is going to be better,the fact that the pump is bypassing indicates that flow is already excess to requirements.As flow requirement increases the bypass will shut and if requirement continues to increases beyond the capacity of the pump pressure will start to drop.This is why when bearing clearances open up enough oil pressure will start to drop,it is also why when years ago in a misguided attempt to restore oil pressure in a worn out engine I installed a HV oil pump it worked like a charm,but unfortunately the worn main bearings allowed the minor rear main seal leak to turn into a major one.

[427John]

     I wouldn't "dead-head" these units at speed particularly H.V. units as I'm not under the impression that the by-pass circuit has the capacity for 100% of the flow volume of the pump; and something will give!   

     Scott.

   

I can tell you that dead-heading my rig, even at idle, causes drive torque to peg and bad noises to emanate from lots of places.  Scott is right - Very unhappy pump!

Dead heading a pump and causing the bypass or relief valve to recirc is one of the quickest ways short of a heating element to heat up an oil sump...........

     I wouldn't "dead-head" these units at speed particularly H.V. units as I'm not under the impression that the by-pass circuit has the capacity for 100% of the flow volume of the pump; and something will give!   

     Scott.

   

That would indicate that the bypass circuit does not have the capacity to recirc 100% that may be part of the aeration issue during bypass.

[1968galaxie]

That would indicate that the bypass circuit does not have the capacity to recirc 100% that may be part of the aeration issue during bypass.

Why would the bypass circuit need to have 100% capacity of the pump. Surely a engine would use some of the pumps capacity?
Trying to understand.

[Gaugster]

Great work and contribution to the FE world! Thanks you!

[WConley]

Great work and contribution to the FE world! Thanks you!

Thanks guys for the support!  I'm not totally doing this out of the goodness of my heart though.  It's needed to develop a new type of pump I'm working on.  More on that in the near future.

In the meantime, it's great to share results on our current pump technology.  I'm always amazed at what you can learn if you just start measuring stuff!

- Bill

[427John]

That would indicate that the bypass circuit does not have the capacity to recirc 100% that may be part of the aeration issue during bypass.

Why would the bypass circuit need to have 100% capacity of the pump. Surely a engine would use some of the pumps capacity?
Trying to understand.

In an application where you don't have to worry about the pump being deadheaded such as a car oil pump it doesn't.In applications such as a lube oil or hydraulic system for a peice of machinery or a large power unit that has lots of piping and manifolding with its attendant valves that uses a positive displacement pump there is a risk of a valve being closed inadvertantly and deadheading the pump which will cause an immediate pressure spike that could damage the pump or worse split the piping causing an extreme fire hazard.In those cases pump manufacturers will commonly build in a bypass/relief system into the pump that will recirc 100% of the capacity of the pump.

[427John]

This brings up the old argument of using hi volume oil pumps or not,while the car oil pump will never reach deadhead status as its capacity increasingly exceeds the flow requirements of the engine and the fact that the bypass circuit has a limited capacity,if the volume is high enough you can possibly reach the scenario he saw on his test rig where his drive torque spiked up which could eventually spiral or break the pump drive shaft.So if your engines flow requirements are high enough to require a hi volume pump then you have to do what you need to do,but if the flow requirements are well within the capability of a std. pump then use of a hi volume pump is not only a waste of power,but could also possibly be risky.

[KMcCullah]

Neato Mr Bill!  M57HV with 15/40 Rotella please...Lol Edit: I'm pretty sure running Rotella at too low of temp, say 160-175, at 7000k+ is what roasted my distributor gear. It was steel too!

Maybe I missed it but, is this cavitation issue with a 1/2 or 5/8 pickup tube?

Kevin -  I'll have to check on the pickup tube.  It's nothing special - stock replacement.  I am seeing no pressure fluctuations that would indicate starvation though.

Also, running thicker oil will not cause a crazy increase in the load on the oil pump drive (unless you're cold starting it at 30 degrees LOL!)  Thicker oil does knock the flow down, but load is tied to pressure.  You'll be running in the higher end of the normal pressure range for sure.  My tests show that the load torque doesn't move a huge amount in the normal pressure range - maybe 2X.  If it was 5X more load then I could see trouble for the gears.  Your wiped gear is a head-scratcher...

Are you running that steel gear on an iron cam?  That'll cause big problems!  I haven't heard of anybody wiping a steel gear in any reasonable amount of time...

Maybe I shouldn't have described the gear as "roasted". It was more like "worn excessively". The teeth had a good .020 missing from their thickness. Backed my timing off a degree or so. Cam is a Bullet solid roller. I think the gear was a Crane. Went to 10W30 Royal Purple synthetic and things seem happier now. Bearings look better too.

[KMcCullah]

Neato Mr Bill!  M57HV with 15/40 Rotella please...Lol Edit: I'm pretty sure running Rotella at too low of temp, say 160-175, at 7000k+ is what roasted my distributor gear. It was steel too!

Maybe I missed it but, is this cavitation issue with a 1/2 or 5/8 pickup tube?

If it was a steel distributor gear with a steel cam, a high volume pump won't kill it. 

The biggest issue with distributor gears on Fords is the install height.  Under no circumstances should you ever just line the hole up on the new gear and put the pin in.  The holes vary from gear to gear and there's a specific install height that has to be held.

The gear was tight as hell but I pressed it to MSD's spec for the Pro Billet. Set it up in the Bridgeport and punched a completely new pin hole too. Even measured from the distributor pad to the gear pad in the block. Measured the distributor and had .010 clearance. I suspected the gear was soft when I drilled it. Seemed too easy. It was a NOS Crane piece I found on epay. I wish I knew somebody locally with a Rockwell checker. Cam is a Bullet solid roller btw.

[pbf777]

While I agree that the larger pickup tube is going to be better,................

     Well, although the pick-up tube (system) ideally would be of say sufficient diameter so as to be capable of supplying fluid to the inlet of the pump at the pumps' greatest pumping rate without restriction or loss in pressure within, keep in mind that as the diameter and length of this increases, so does the pumping or say drawing effort required particularly if lifting function is required as say in a deep sump pan where one may attempt to have greater distance between the oil pool and the crankshaft and revolving components or rear sump pan where the P.U. tube is lengthen.  This is also one of the reasons why the original O.E.M. engineering has the pump intended to be submerged below the oil pool level, and as we have tested, the pump delivery is affected notably as the oil level drops in the pan at speed.     

     Scott.

[pbf777]

Ironically me and a buddy of mine were having this conversation a  few months back how this type of pump was prone to aerating oil and yet we all still get in line to buy and install them.

     If I recall correctly, this "Gerotor" type pump design came from Caterpillar (tractor) of the 1920's - 30's, and it has proven to be, in my opinion a superior design at moderate speeds, those as intended by the O.E. for transportation vehicles; but as the engine R.P.M.'s have risen, particularly in the automotive racing endeavors, well it starts to become a problem.

     This thread has brought up the issue with the re-injection of an oil volume within the pumps inlet and yes there is the issue of the high-pressure (relative to the pressure on the other side of the relief and in the area of the return) and heated oil being injected at an angle perpendicular to the appreciated flow volumes' intended path as this can depending on the ratios of intervention create significant turbulence.  But this isn't the only issue, as with this oil volume comes vapor, little air bubbles compressed to the high pressure value and then released to the low pressure arena where they literally explode in dimension displacing the fluid volume causing, depending on the sum, perhaps even greater mayhem in causing interruption of homogeneous directional flow, creating an inefficient delivery.  And this vapor expansion can be quite violent also leading to an upset of the by-pass valve causing it to fail to regulate as intended including failure to reacquire seating timely, this further being realized as a loss in delivery volume and resultant pressure.     

     This is particularly where the idea of a remote by-pass can be appreciated.     

     Scott.

[runthatjunk]

First, way cool!

I have to wonder about using the fixed orifice.  It seems to me the faster the engine turns the more oil it's going to be able to flow for a given pressure.  Which makes me think getting into cavitation due to excessive bypass may not happen quite as easily as it appears here.  At least with these oil pumps. 

Also If your really bored  I'm curious how much a stock filter would bypass if any when cold, full RPM, etc.

[winr1]

Thank you Bill

I have a short 352 oil pump and a tall 391 oil pump if ya ever wish to test the differences

Should say, the bodies are shorter an taller than a normal pump for any that have not seen them




Ricky.

[WConley]

First, way cool!

I have to wonder about using the fixed orifice.  It seems to me the faster the engine turns the more oil it's going to be able to flow for a given pressure.  Which makes me think getting into cavitation due to excessive bypass may not happen quite as easily as it appears here.  At least with these oil pumps. 

Also If your really bored  I'm curious how much a stock filter would bypass if any when cold, full RPM, etc.

From what I understand, a fixed orifice is pretty standard for testing oil pumps.  I'm also pretty sure the bearing clearances drive the oil flow a lot more than the surface speed.  These change when the engine heats up.  Sure the journal bearings will pull a bit more oil at higher rpm, but the side clearance leakage is a lot more than this at all speeds.

As for oil filters, that is a whole other thing.  Those bypass mostly when the media gets clogged up.  They also have primitive bypass valves that vary all over the place with pressure.  I'm not really set up to look at those.  It would probably require making clear filter housings and mounting the guts to watch the flow.  Pretty big project...