Oil Pump Dyno

[pbf777]

While NPSH(oil above suction of the pump) shouldn't have a major effect on the positive displacement pump performance it will minimize if not eliminate the effect of any air leakage into the suction side of the pump.

This was my point.  If a positive displacement pump is seeing strong output changes from a few inches variation in the input head pressure, there's a problem.  That problem typically involves input side air leakage.

     Though not exactly the same effect, but there seems to apparently be the unconsidered fact that an air leakage in a functioning engine is not required as described as the oil is generally already well aerated at the point of ingestion at the siphon tube entrance, this greatly instilled with not only the pumping and by-passing as witnessed and described previously in this thread with it's negative effect on the pumping efficiency, but also the rest of the path required for the oils' return to the pan, and the sum of aeration varies greatly with operating conditions that the engine subjected to.

     This consideration is probably the greatest value in the increased capacity oil pans' purpose.  Think about it, if your pumping say as much as eight gallons a minute from a less than two gallon reservoir how much time is being allotted for de-aeration?  And have you witnessed the appearance of the oil after its' tortuous route?   

     And this is one of the reasons one doesn't want to draw to hard on the siphon tube as these little air bubbles expand in area as the pressure drops this displacing the wanted liquid volume, and compromises the pumps capabilities and further upsets the bypass function and effect.     

     Scott.

[427John]

While I agree that entrained air can cause flow and pressure fluctuations ,I don't believe it will cause a catastrophic temporary loss of flow like ingestion of free air.If all the entrained air was able to somehow overcome the surface tension of the oil and merge into one big bubble it would have the same effect but fortunately thats not the case.What would be interesting would be to observe the visual appearance of the oil in the sump while monitoring the appearance of the oil under pressure in an extended run to see if when oil in the sump starts to appear aerated at what point does the pressurized oil start to appear aerated,and when and if this happens what does flow and pressure do.

[JC-427Stroker]

Hello,

I joined just so I could post in this thread.   What a great "dyno" test stand.   Mad skills and knowledge to put that together.

I didn't read every post, so sorry if this has been asked and answered:

What viscosity oil did you use in the testing,  and have you heated the oil up to 180*  or so and run it ?

It might be interesting to see what a pump would do with 10-40  vs 20-50  with the oil temp at 180*.  Also a "dino" oil and a synthetic oil of the same viscosity.  Over the years I've run several engines back to back with conventional oil vs Mobil 1.  From  342",  351, 512, 565 (current engine 950 hp single 1,050)  the least I've seen was 8 hp - the most 15.

Anyway ....  GREAT DEAL !!!

Jon


I have a Stroker  (4.25 x 3.98)  project I'm working on with Barry's MR heads. Hopefully it will be together this year.  I'll post up about it later.   I have a lot of reading to catch up to on my FE stuff.   

[WConley]

Jon -  Welcome aboard and thanks for the kind words!

All test runs were done with 10W-30 conventional oil at 200 deg F.  Simply running the rig up to speed for several minutes will heat the oil to that temperature.  That gives you an idea of how much heat is generated by 2+ HP of parasitic load.

Yeah it would be interesting to compare conventional and synthetic oils of different viscosities.  Right now I've got the rig tied up for a couple of more months to develop a new pump design.  (The new pump is the reason I built the rig in the first place, and I'll share that work here in due time!)

A study of different oils will be interesting, but time-consuming.  I have to drain and purge the oil completely with every change.  Being a big fan of Mobil-1 though, it would be cool to see how the viscosity holds up with temperature.

Again, glad to have you here Jon!

- Bill

[JC-427Stroker]

Gerry -  I think it's the time sitting still in the dry sump tank is key to getting air out.  There would be so little time sitting in the filter that I don't think we'll see much of an effect.

Sorry if this re-hashes something you've already covered.  I apologize in advance. And thanks for the info in the above post. 

Is it just the time that matters ?

  If oil has has pass thru something like 12-16 micron filter would that not "squeeze" some of the air out of the oil ?

This is a  Baldwin Cummings filter I adapted for the boat 8 years ago. It flows 24 gpm at 10 psi with a 12 micron element.
It flows 10 gpm at just 3 psi.




 After the rebuild this year I might be switching back to the dual B253's ( 18 micons flow 12 gpm at 5 psi):


The Cummings filter does not have a bypass. Still makes me nervous after 8 years of running it ....  lol
Just because you are paranoid doesn't mean they are not out to get you.

[WConley]

Jon -

From my experience and everything I have read, a filter isn't going to be effective for removing entrained air.  The hydraulics guys use centrifugal separators to force the air out at high velocity.  Some dry sump reservoirs use a tangential (swirling) return to help accomplish the same thing. 

I've never seen a filter used successfully.  The air has nowhere to go if the bubbles get blocked, since there is only oil inside.  I would think the bubbles would get broken up further until they can pass through the media.  The air would have to stay in the oil.  Tanks or separators allow the air bubbles to escape from the oil and stay away.

[JC-427Stroker]

That makes sense.

Thanks.

[pbf777]

Jon -

.............. a filter isn't going to be effective for removing entrained air. 

I've never seen a filter used successfully.  The air has nowhere to go if the bubbles get blocked, since there is only oil inside.  I would think the bubbles would get broken up further until they can pass through the media.  The air would have to stay in the oil.

     Agreed.  Once air is entrained on the high pressure side there isn't going to be any opportunity to remove it until after it's release into the free area of the crankcase.     
   
     But for thought, filter media can be used to aid in the removal of oil from air, as in vane or rotary-screw air compressors' oil-air separators mounted post the compressed-air-ends.     

     Scott.