Author Topic: Help on design of dry sump oil system  (Read 6851 times)

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Offline metermatch

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Help on design of dry sump oil system
« on: December 07, 2012, 04:49:58 PM »
I have a 1500cc Honda B series motor that I would like to put a dry sump system on.  I

don't really want to spend $2000 on a ready made dry oil setup, for a motor that is going

to see very little use.  I'm trying to reduce parasitic losses, and save a few bucks.


     I have a Barnes cam drive dry sump system on one of my 500 inch BB Mopar engines for an 8

second dragster.  I was wondering if I could use the pump and oil tank on my Honda?  All I

would need to buy would be a Honda dry sump pan, a couple of pulleys, belt,  and some AN

hose.


     To avoid the clutter in the engine compartment, and eliminate the problem of mounting pump

to engine, I was thinking of remote mounting the pump (and oil tank) in the passenger

compartment, and drive oil pump by an electric motor.  I was thinking of using a golf cart

-size motor, powered by 1-2 deep cell battries already needed in car, and use a speed

control tapped into the throttle pedal to control pump speed relative to throttle (and

likely engine RPM).


(1)    Is there any obvious problem with pump being about 4 hose feet from oil pan, for the    

 pump and scavenge sections?  Pump would be about same elevation as an engine mounted pump,

so very little head difference.


(2)    Is there any problem with the pump sizing, being too big or too small for the engine?  

   Is it possible for the pump to be too big, if there is a pressure regulator for oil    

   pressure?  Other than being inefficient from taking more power to drive the pump.


(3)    If I maintain 70 psi oil pressure, the same as the engine builder designed the engine  

     with, any unknown problems?  Motor turns 9500 rpm, 10,200 redline.


(4)    Anybody done this before, or is this just a rediculous idea?


(5)    How much power does it take to drive a dry sump oil pump?  I was guessing 1-2 hp.


(6)    Is it possible to draw too much vacuum, and damage the motor?


(7)    Saving 1-2 hp with an electric motor might not seem to be worth it, but remember I am dealing
 
        with  only a 225hp motor, and I would like to use parts I already have.  In addition, moving

        some  clutter from  the engine compartment may make a turbo installation a bit easier in the future.


(8)    Any problems that I haven't thought of?

(9)     Car will first run in the Production class, H/PRO


Thanks for any ideas.


Jeff
« Last Edit: December 07, 2012, 06:12:45 PM by metermatch »

Offline Glen

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Re: Help on design of dry sump oil system
« Reply #1 on: December 07, 2012, 07:36:46 PM »
First is to call Barnes and talk with him, he will steer you the right direction.
Glen
Crew on Turbinator II

South West, Utah

Offline jauguston

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Re: Help on design of dry sump oil system
« Reply #2 on: December 07, 2012, 10:11:57 PM »
Jeff,

Golf cart motors are 36v. If you get serious about that idea I have a stock motor from a 1994  EZ-GO cart and the speed control for it. I think I have the 36v charger also. I upgraded to a more powerful motor on 42v. Pay the shipping and you can have them. They are gathering dust in my shop. The motor is heavy.

Jim

Offline metermatch

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Re: Help on design of dry sump oil system
« Reply #3 on: December 10, 2012, 05:19:01 AM »
Jim,  I sent you a PM.

Thanks,

Jeff

Offline Rex Schimmer

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Re: Help on design of dry sump oil system
« Reply #4 on: December 10, 2012, 02:56:36 PM »
Jeff,
The formula for oil pump horse power is: GPM x Pressure/1714 x (pump efficiency) using your pressure of 70 psi and guessing that the pressure pump is probably around 10 gpm with an efficiency of 65% the hp to drive the pressure pump would be only .63 hp BUT what is not included in that number is the parasitic  internal friction of the gears against the case sides and also shaft seal friction. The power to turn the scavenger sections is probably mostly the parasitic drag of the gears as they normally don't generate pressure unless you happen to run a return filter from the scavenger sections to the tank. Going with a 2 hp motor is probably a good start, what is the rpm that the motor is rated at? I would not recommend going with some sort of variable speed drive for the pump as it will just add extra parts and complexity that is not needed. Set the pump speed and then set the pressure pump relief valve at around 70 psi and then re adjust once you have it connected to a running engine.
Four feet is certainly not to long for the hoses from the oil pan to the pumps just make sure that you use at least -10 or -12 hose and I would suggest going with internal wire re-enforced hydraulic hose that is specific for suction which is specified as 100 R4 hose. I like the idea of going with an external drive for the oil pump you may also consider extending the dry sump pump shaft and run the water pump also from this motor. As you said every HP counts.

Rex
Rex

Not much matters and the rest doesn't matter at all.

Offline metermatch

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Re: Help on design of dry sump oil system
« Reply #5 on: December 11, 2012, 04:57:35 PM »
Thank you for the electric motor calculation.  I'm glad my gut feel is about right.

My reason for running a variable drive was because, well, I just didn't know any better, and normally, the dry sump pump is driven off the engine crank, and of course would change in RPM with the engine.  I kind of figured that this was intentional, and that the engine oil requirements varied with engine rpm.  I was concerned with the pump turning too fast at engine idle speeds, and causing some sort of problem (too much suction or something else unknown).  I believe I was also thinking of saving a bit of battery power at idle.

Ballpark rpm for the pump I was guessing was about 4000 rpm, as it seems like the pump pulley ratios are about 2:1 reduction, and many motors will rev to about 8000 rpm, so the pump would be turning about 4000 rpm.  This still seems a bit fast to me.  Is a driven speed closer to 2000-3000 better for the dry sump pump?  Is there an optimum speed for these pumps, whereby higher rpm is just churning the oil and using excessive hp to turn? (something like an OEM Mopar water pump turning too fast and cavitating, not pumping and robbing HP).

A previous poster has generously offered to send me the old motor and speed control from his golf cart.  I can use these to try different RPM's on the pump, and also check the current draw and calculate the HP needed to see if his motor will be too big or too small.

As far as the oil suction hose material goes, I had not thought about anything other than AN 10 or 12 braided SS lines.  Is the hydraulic hose you mentioned better, lighter, or cheaper?

I was also planning to put a low pressure switch in the ignition circuit to kill the motor if the oil system fails.

I also thought that it is pretty cool that I can pre-lube the motor before startup by just starting the electric motor!

Thank you for the ideas,

Jeff

Offline JustaRacer

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Re: Help on design of dry sump oil system
« Reply #6 on: December 11, 2012, 05:15:13 PM »
DOH!!  Reading error.



« Last Edit: December 11, 2012, 06:03:38 PM by JustaRacer »
My doctor told me to go out and kill people.
Well, sort of.  He told me to reduce the stress in my life.

Offline Rex Schimmer

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Re: Help on design of dry sump oil system
« Reply #7 on: December 12, 2012, 02:48:31 PM »
Jeff,
A pump speed of around 3000 would probably be optimal as the pump speed is increased the chance of cavitation  is increased. Your point about being able to "pre-oil" is a great idea and certainly something that is a plus for this approach. Most people use the SST braided -10 or -12 hose for the pump inlet and do not have problems but it is possible to pull the interior of the hose lose from the braid and collapse the inlet. The 100 R4 hose is probably less expensive than SST braided hose, almost anything is!, and it is typically hose clamped to a hose barb fitting but it is specifically designed for suction as it does have an internal wire molded into it to keep the hose from collapsing from suction. You could use the variable speed motor to find the optimum speed of the pump for your engines requirements and then set your speed 10-15% higher for some cushion. You can also monitor the voltage and amperage and then calculate the required hp to run the system and make sure that your battery pack is sufficient to run the system.

Rex
Rex

Not much matters and the rest doesn't matter at all.

Offline POPS

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Re: Help on design of dry sump oil system
« Reply #8 on: December 16, 2012, 10:50:31 AM »
Jeff,
Check out XRP.com they sell a flat spring for suction lines.  A must in my experience for the long runs on the salt.  Or consider using aluminum tube for the suction lines.  Keep the gap less than 1/2 inch and join the sections of tube with hose and hose clamps.
POPS