Milwaukee Midget

[wisdonm]

Stand alone, in-line electric pumps are starting to look pretty sweet by now.

[Milwaukee Midget]

IO -

Okay, here's how I've interpreted your schematic -



Where is the fault in my thought process?  If I'm taking egg on the face, it wouldn't be the first time - I'll make omelets and move on.

 

[Interested Observer]

MM:
Ok, bearing in mind that in practice the path A-C-B would be very short and wide open, with the relief valve probably housed in the pump frame:
1) What is the pressure difference between C and B, and if there is one, why?  (If there is no resistance to flow, there can be no pressure difference.  Consider the electrical analogy--if there is 12V at A, what is the voltage at B and C?)
2) What is the pressure difference between C and A, and if there is one, why?

Now, you apparently accept that there is a depressed pressure level at A due to the pump demand drawing from the pan and overcoming the attending gravitational and frictional losses.   Therefore, the pressure at B is the same as A and there is no pressure benefit from the bypass flow.  There is not enough flow coming from B to raise the pressure to the degree necessary to shut off the draw from the pan, or indeed, reverse that flow.  If there was a lot of flow from B reversing that pan flow would be possible and the manifold pressure would go up, but we know from the nature of the circuit that the B flow is a fraction of A.

The major benefit for the arrangement is that there is no need to provide a return path to the pan for the bypass flow.  The guy at PRI was just giving you a load of sales malarkey.

[Rex Schimmer]

Chris,
Everything that IO has stated is true! The pressure at points A,B,C,D, and E are all the same and they are set by the pump inlet conditions. The pressures are in absolute psi i.e. above zero pressure (perfect vacuum). Again going to the basic equation for horse power to run a hydraulic pump: HP=GPM x PSI/1714 x (pump efficiency), note that I have added pump efficiency into the equation because typical gear pumps used for engines are very in efficient, some times below 50%. So if you take your pump at 10 GPM (which is really pretty large for your little motor) and 75 PSI with a pump efficiency of say 70% the HP to drive it is =.625 Horse Power. This is less than the resolution on the dyno that you run on and is this even worth discussing? You can find 5/8s of a horse power by just providing better air to the engine inlet.

IO's comment that a pressure compensated pump would be a better pump is correct in theory but it is very difficult to get a pressure compensated pump to run well below about 100 psi and as most of them are piston pumps anything over 2000 rpm would require a positive inlet pressure to avoid cavitation so probably not worth even looking into.

I was a hydraulic pump application engineer for the Denison Pump division of the Parker Hannifin Corp for 15 years and have applied gear pump, vane pump, fixed displacement and pressure compensated piston pumps to every thing from steering gear for aircraft carriers to blast hole drill and farm equipment so I ain't no "Johnny come lately" to the discussion of hydraulics and pumps. Believe IO and me it ain't worth the effort for .625 hp and yes, as IO said, the guy at PIR was blowing smoke up your heine because he doesn't know what he is talking about.

Rex

[Milwaukee Midget]

Alright - let me wrap my thick head around this -

The manifold on the intake side . . .  point A . . . actually let's call it "-A" because it is a depression relative to atmospheric pressure and pressure on the outlet side of the pump, and allowing that -A pressure equals B, C, D or E . . . cannot be made to exceed atmospheric pressure in this model, and because fluid being diverted through the relief contains no additional power to be harnessed, no potential for power reductions can be gained by plumbing it into the intake manifold.

[Interested Observer]

Hooray, Rex!!
(And my pressure compensated comment was half in jest)

Chris--now you've got it!   We may have saved you a certain amount of time, effort, and money and provided a degree of enlightenment and/or confusion.

[Milwaukee Midget]

Hooray, Rex!!
(And my pressure compensated comment was half in jest)

Chris--now you've got it!   We may have saved you a certain amount of time, effort, and money and provided a degree of enlightenment and/or confusion.

Or an opportunity to have a little fun? 

Actually, what's happened is that I've been driven to the point of distraction  -



I broke one of the "T"s testing the pump, but I plan on stopping at the tropical fish store after work tomorrow.

It's my hope that the gauge on the charger is sensitive enough to detect changes in current flow - otherwise, I'm looking for a manometer.

And I promise I will post the results.

[Jack Gifford]

... a pressure compensated pump would be a better pump is correct in theory but it is very difficult to get a pressure compensated pump to run well below about 100 psi...
... I was a hydraulic pump application engineer for the Denison Pump division of the Parker Hannifin Corp for 15 years

Rex- sounds like you're the person to respond to this: I've always praised the performance of the front pump in old GM Dual Range HydraMatic transmissions. It's a variable-displacement vane pump driven directly at crankshaft speed, and does an admirable job of coping with the flow-rate fluctuations of the hydraulic circuits under widely varied demands. Hundreds of beefed-up examples (called 'HydroStick") survived dragstrip use (in the sixties)- many in 10,000 RPM blown 'gassers'. I've often wondered how well a pump of this design (with appropriate maximum displacement) would work as an engine oil pump? It certainly would attain the efficiency being sought by 'Midget'. And for a wet-sump configuration, the whole pump could be submersed in the oil supply- thus minimizing aeration.

[Crackerman]

Hooray, Rex!!
(And my pressure compensated comment was half in jest)

Chris--now you've got it!   We may have saved you a certain amount of time, effort, and money and provided a degree of enlightenment and/or confusion.

Or an opportunity to have a little fun? 

Actually, what's happened is that I've been driven to the point of distraction  -



I broke one of the "T"s testing the pump, but I plan on stopping at the tropical fish store after work tomorrow.

It's my hope that the gauge on the charger is sensitive enough to detect changes in current flow - otherwise, I'm looking for a manometer.

And I promise I will post the results.

that gauge might not be accurate enough. but a shunt in line (built into amp gauges) read with a quality multimeter down to the .01 scale in MV should be able to definitely detect a difference in load.

[jacksoni]

It doesn't look like massaging the current wet sump system for power is likely to find much. I do think pan vacuum can help as I mentioned before (and higher pan vacuum can reduce oil pressure some so you can back off on the bypass some). If you go the scraper route, talk to Kevin Johnson as I mentioned. He looks a lot at what is going on in the crankcase and may have some suggestions.

Electric water pumps may help a little. I don't remember if I have posted this link before, if so my apologies for duplication. I use this pump:  http://www.stewartcomponents.net/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=ElectPump In my engine, with a radiator and it cools just fine. It is perhaps easier to rig than a belt driven by electric motor pump. My engine is in the 275-300 range and it ran both short course in my G/GC car and long course in G/MS car with a small (8-9gal) water tank. No trouble. Worth look if you decide to go that route.

[Rex Schimmer]

Jack,
Regarding the variable displacement vane pump in the early GM Hydro trannys I think that the displacement was varied by off setting the cam ring that the vanes ran against. If the ring was concentric to the vanes the displacement was zero and as you pushed the cam ring to be off set to the center line of the vanes the displacement increased. This design was later used by the Racine company(Now part of Bosch) on their commercial variable displacement vane pumps. They were very fast in changing displacement so worked well for the Hydro.

Rex

[Jack Gifford]

Rex- yes, that's correct. But I don't know whether this type of pump has ever been used for an engine oil pump.

[Dean Los Angeles]

Pressure is a function of resistance. Just as there is resistance loss in wiring, in tubes it is far more complicated.
But you can make it easy and say there is no pressure in a short tube with no restriction.
Trying to make something out of the relief pressure (it's not overflow) is better spent reducing it in the first place.
Entrained air is a fact of life for engines. Minimize it, yes, eliminate it, no. The flow coming out of the pressure relief valve is not what you want to stick right back in the pump.

Instead, run total loss. Put a ten gallon tank 18 feet above the engine. What! No?

If the rules allow an electric pump, why wouldn't you? Water pump too. Dragging the big battery around probably would be less then the gain from the friction reduction. 

[wisdonm]

If the rules allow an electric pump, why wouldn't you? Water pump too. Dragging the big battery around probably would be less then the gain from the friction reduction. 

Exactly.

[fordboy628]

Midget,

Whilst surfing the boards on the forum came across this nugget:  http://www.hotrod.com/techarticles/body/113_0703_car_aerodynamics/photo_02.html

After reading the article there were several items of aerodynamic note:

A/  Starting and finishing drag co-efficient . . . . . .
2/  Starting and finishing front/rear down force/lift values . . . . . .
d/  And this final nugget:  "We also tested the Moon discs, which reduced drag by two to four counts. The farther the wheels are (in) from the outer edge of the front fender, the less the discs matter."

As I suspected all along, you are going in the correct direction with your aero mods.   Better aero = less need for bhp . . . . . . .

Feel smart today!

Merry Christmas to you & Mrs. Midget from all at the ranch.
 
Fordboy