How To Plumb In A Dry Sump Oil Pump?

[38flattie]

Ok, gentlemen, I'd like to hear your opinion/experience on how to plumb a dry sump!
 
We have 2 diverse opinions on how we should do it. Obviously, one person is me, but to be fair to the team, we often fuss and discuss issues like this.
 
One person wants to put the filter on the pressure side, between the sump pump, and the block, which might be considered the 'traditional' way.

The argument:
 
The main issue is that if you restrict the scavenging of the pan, then you've defeated the purpose of the dry sump and you risk backing up the oil in the pan, the sump going dry and then losing the oil supply to the pressure stage of the pump and ultimately the engine.  


The other person, wants to put the filter on the return side, after the pump, but before the oil tank reservoir, on the scavenger return line.

The argument:

With the filter on the scavenger return line, the reservoir does not become contaminated-you have clean oil in the reservoir, and clean oil going through the pressure side of the pump. with the filter on the pressure side,you are contaminating the reservoir, running it through the pump,then filtering that oil, before it goes to the engine.

How do you guys plumb them, and why?
 
 
 

[Queeziryder]

I'm with the filter in the scavenge side, aircraft SOP 
beaten into me by the old man 

[Bob Drury]

  On my Dart BBC, I run a six stage Barnes dry sump.
  I have four scavenge lines coming off of the pan, all with Moroso in line screen filters.
  The fifth scavenge line comes from a manifold that I built in the lifter valley.  This manifold comes up through the existing distributor hole in the tunnel ram manifold (I use a front mount offset drive magneto)  and runs to the pump with no screen filter but I plan to add one.
  The scavenge lines (2 AN-16) come out of the pump and run to my seven gallon dry sump tank.
From the tank I run a single AN-16 line back to the pump pressure section and then it goes to a System One screen canister.  From that filter the oil goes through a two quart Nascar style Wix spin on (car type) filter and then splits up to feed the main block galleys, the valve spring spray bars, and two three quart oil accumulators which are tied into the block feed with a one way valve in the main feed line just prior to where the Accumulatos tie in, to hopefully save the motor if I lose the dry sump belt.
  We check the System One after every run and if we find any debris at all we change the Wix filter.
  If the Wix shows any metal, the pan comes off the motor for a "bearing drill".
  Last but not least I run a oil pressure tattle tell hooked to a large red shift light aimed at my face that lights up any time the oil pressure drops to 50 psi.
  Overkill? Not if you realize that every last cent of equity in my house is in this motor, and if I hurt it, it may be a few years before I can afford to fix it.
  I am 65 and a few more years may be more than I have on this Earth.         Bob
  

[38flattie]

So, two replies, two different views!

Thanks guys!

Queeziryder, I'm well aware of what you are saying about aircraft SOP. My dad was an aircraft mechanic for over 30 years, for one of the major airlines. He also dod all the work on my single engine planes!

[Dynoroom]

I do both! I run a corse (~80 micron) inspection type scavange filter and an automotive type paper element filter to the engine.
IMO you should always run a synthetic or paper element filter to the engine as the fine sediment type debris can not be filtered correctly with only a screen type filter. You know, that fine stuff you see in the bottom of the oil pan when you tear the engine down. 

[SPARKY]

I run both one I can check between runs between the return pump and the tank then the race filter before it goes in the block

[BoredAndStroked]

I'm the guy that likes to debate how to "boil the ocean" with Buddy!  It is all good stuff - as we constantly are learning.

Here is where I am coming from:

a) The oil pan has large screen filters in the scavenge pickups - helps protect the pump.

b) I'l totally okay with large micron screen filters on the scavenge return lines to the sump (we have dual #12 lines) - as this style of filter won't restrict the volume of oil and will ensure that we don't backup oil in the pan.

c) Bonus:  Having two filters on the output/pressure side makes sense to me.   One could be a System One or a Oberg (with a nice screen to inspect stuff) and then another a cartridge type (WIX, etc.. ) to capture the finer stuff.

To me this gives us the best of both worlds.

My main contention is that we don't want to run a restrictive cartridge style filter on the scavenge pump lines that feed the sump -- too restrictive in my mind.

Keep the opinions coming . . .  especially for things that might save the life of a very expensive motor!   We have neither time nor money to start over (at least we hope not.   

B&S

[olepaw]

my tank has srcreen type filter built in on return line (oberg). then a paper filter inline  to supply engine. seems work for me . easy to check oberg wash out and use over and over.

[38flattie]

Haha!

Coming from a background filled with planes, and A&P mechanics, I much prefer their way of doing things.

I don't like to run dirty oil through the high pressure side of a pump-I also don't like to have all of my reserve oil contaminated.

My contention is that regardless of where the filter is, if you plug it, you're screwed! The higher the pressure going through the filter, the higher the differential pressure-therefore the higher the restriction. I seriously don't believe that the filter on the scavenger side is going to hurt us flow wise.

Having 80 micron screens on the scavenger side, only takes out very big particulates. In my experience, if you have anything that big in the screen, the damage is done! The systems I work with daily, use either a 6 or 10 micron filter, and it's always before the reservoir.

JMHO-I posed this question to learn from the experience, and failures, from you guys replying. Thanks for the answers!

[Dynoroom]

Buddy, the idea you like is great, use it.  

 My way makes more power (less restriction of 3 or 4 -12 bodies) and allows you to inspect the engine between runs, which is why I do it that way. I always try to inspect the scavange filter between runs as it lets me know I have a problem before it's a major issue. My oil tank & lines come apart for cleaning after any type of engine failure anyway. This is what my testing has lead me to believe.  

Besides we're talking race cars here, and we're supose to inspect them regularly. Tough to pull to the side of the road in an airplane and check things.... 

[38flattie]

Haha! Sure ,Mike,  tell me what I want to hear!
 
Seriously, though, I don't doubt that this has worked for you-you have the numbers and records to prove it!
 
I am trying to figure this statement out, however-"My way makes more power (less restriction of 3 or 4 -12 bodies)"
 
Since I have only one scavenge return, between the pump and reservoir, but two pressure lines, how am I going to have less restriction with the filter on the pressure side, as long as the scavenge is of sufficient size?

Add to the fact that B&S proposes to take each pressure line into a 1 to 3 fuel block, to run to each main, and it seams to me ALL the real restriction is being created on the pressure side.

I'm not trying to be argumentative-rather, I'm trying to understand a different way of 'skinning the cat'.

[Dynoroom]

Haha! Sure ,Mike,  tell me what I want to hear!
 
Seriously, though, I don't doubt that this has worked for you-you have the numbers and records to prove it!
 
I am trying to figure this statement out, however-"My way makes more power (less restriction of 3 or 4 -12 bodies)"  
Since I have only one scavenge return, between the pump and reservoir, but two pressure lines, how am I going to have less restriction with the filter on the pressure side, as long as the scavenge is of sufficient size?

Add to the fact that B&S proposes to take each pressure line into a 1 to 3 fuel block, to run to each main, and it seams to me ALL the real restriction is being created on the pressure side.

I'm not trying to be argumentative-rather, I'm trying to understand a different way of 'skinning the cat'.

Simple, my point is you may only have one return line but you have 3 or 4 scavange sections returning oil & AIR to the tank. A filter of the type you propose creates more back pressure in the pump. This is why you see multiple return lines on real race motors....... 

Of course you may have a filter with zero pressure drop.........  J/K

[Rex Schimmer]

Woody,
I agree with almost everyone regarding screen strainers, make them coarse, number 60 minimum, (that is 60 openings per sq inch, pumps don't like to suck) then run a very high flow but efficient (i.e. very fine) filter between the scavenger and the tank, the scavenger sections will have no problem pumping through a good filter. I would then put some sort of filter, I would even agree to one of the screen filters everyone is so infatuated with, but only because you can open them up for inspection. But now think what are you going to find in that filter? If you find metal it can have only gotten there by the pressure pump failing or you poured it into the reservoir so if the filter that is between the scavenger sections and the tank it doing its job then the filter on the pressure pump hasn't got anything to do! EXCEPT that new oil right out of the bottle can be amazingly contaninated. I have personally done microscope inspection of "new" oil that I ran through a 1/2 micron filter pad ( 1/2 micron is .0000020 inches) an you cannot believe the stuff you find, yes some can be to small to be a problem but there are a lot of  10-25 micron size particles also. 

One of the things you need to think about is the quality of the filter. 99% of all automotive filters are cellulose based, paper, and they are easy to plug, inefficient but cheap and they are truly 1940 technology. I have always recommended going with a good industrial filter which uses glass fiber technology for the elements. You will get the finest filtering with the least pressure drop  especially compared to paper automotive filters. Good ones are not cheap, but neither is your engine. It is kind of like buying a motorcycle helmet, if you have a $25 dollar head then buy the $25 helmet same for oilfilters. The names you want to look at are Parker, Pall, Donaldson, Schroeder and there are several more. Pall is the best and the most expensive. I have an element for a Pall filter that is 1-1/4 inch in diameter, by 4 inches long and the pressure drop with 100 SUS oil at 6 gallons/min (approx what a good high pressure section on your pump puts out) is less than 5 psi and it will filter down to 2 microns at 99.99% efficiency. No auto filter can even come close.  I designed high pressure hydraulic systems for 20years, some with flows over 1000 gallons per minute at pressure over 5000 psi and good filtration and clean oil is the life of this type of system

Rex

[38flattie]

Rex,

Parker, Pall, Donaldson, and Schroeder are filters I use everyday- I manage a very Hi-tech drilling rig, with several hydraulic systems, based on a 800 gallon reservoir. All of our filters are on the return side, not pressure side.

Most of the filters I use are 6 micron, with a few being 10 micron. I have differential gauges on most of them, so that I can see by the pressure differential, when they are needing changed out.

It's interesting how different backgrounds, and experiences, lead to such different ways of doing things!

[38flattie]

This is why you see multiple return lines on real race motors.......  

Mike, you REALLY know how to hurt a guy!