Dry Sump Tank issue

[BlitzA64]

OK, I have a 6 stage pump on my 360" oval engine, 4 from pan and 1 in valley. Two -16 fittings come out of the scavenge and into a manifold to one -16 into the tank. Pulling vacuum obviously with a break to limit it to acceptable levels. My problem is with both tanks I am blowing oil out of the breather. I tried 1 1/2"id hose straight up to try to get the mist to fall but still a mess.

I changed tanks to a different type that I had ran before with a 4 stage pump with no problem but still doing the same. My thought is I am moving so much air that cutting the return into 1 -16 is causing a high velocity sort of like putting a nozzle on a garden hose. To fix I would have a 2nd bung for return into the tank, get rid of the 2 into 1 manifold and run 2 return lines. Not a 5 minute project and not cheap, no problem if it works, what say you?

I am sick and tired of cleaning oil mess, been racing for a few decades with dry sump and never had an issue like this, man I can't afford to pull any more hair out

[billet]

Are you checking oil level with engine running and warmed up and with some RPM?


Brand of tank or any other info might help someone help you out


You might also check the relief valve to make sure it's sealing and not allowing a huge amount of air into system

[1972ho]

What size tank are you running and how far is it from the pump.

[BlitzA64]

The oil level is actually set on the low side for testing in the tank I ran for seasons with a different pump

The bypass has to be continually open, it is set at 10" and the pump will pull 21" with everything plugged up
Yes I could get away with a smaller pump but this is what was spec for what I have. Basically a NASCAR type set up.
The pump is cam driven so 50% and can't be slowed.

There is about 4' of -16 return line back to the tank. It is moving a lot of air and oil back to the tank, I need to find a way to control it. Maybe some sort of breather box but I'd like to find a way to get the mist itself under control rather than pumping it into another can to be drained. NASCAR stuff runs for hours, I'm missing something other than the pump sections are too big for the application.

[MadBill]

You're right; the big difference in 21" max available vacuum vs. 10" regulated means a relatively high volume of air is being entrained. I expect in NASCAR configuration, the bypass in this system would have been set higher than 10", thus reducing the mass of bypass air compared to to yours.

A second line might help and for sure shorter scavenge pumps would, but a more elegant solution would be an air/oil separator such as : https://www.spintric.com/new/index.php/technical-info

Do you run a crankcase vacuum gauge? Besides the occasional glance on-track to see that all is well, the length of time it takes to bleed down after engine shutdown is a good indicator of ring seal and external leaks. A well-sealed engine will take 60 sec. or more.

PS: how about that; the last post in the first 'Similar Topics' index below is by a four years younger me! Here's an addendum to it: If the separator is mounted near the pump, the pressure drop through the oil return from there to the tank will be reduced, by virtue of the large air volume (30-70%, per Spintric) diverted to the dedicated vent line.

[billet]

I'm far from a professional engine builder but:

Just about every Dirt Late model in the country runs a sealed system but may have a one way valve on a breather in case it knocks a hole in a piston and keeps it from building pressure. I would imagine that going from a 4 stage to a 6 stage (2 extra scavenge stages) that with the 10 inch vacuum limit is pulling a ton of air thru the system. When the LM community went to more pump sections a lot of people had tank issues and blowing oil out the breather on the tank. A lot of tank redesign happened and completely sealing off the system has pretty much eliminated all the issues besides when someone over fills the tank.

Is there a reason you want to limit vacuum to such a low level? I know people worry about wrist pin oiling and what not, but I haven't seen/heard much problems with any of that in the LM world. We have taken older motors that used a breather on the valve cover and just capped them with 5 stage pumps and no issue with the high vacuum.

I mean it really boils down to how well the tank can deal with the high amount of air going thru the system if you're bleeding air to limit vacuum. I don't see a ton you can do, really that air has to go into the tank and the tank has to deal with it somehow.

[frnkeore]

Are you running a Oberg 800 filter in your return line?

Another way would be to make a circular (360°), multi, fine screened baffle, on the return, inside the tank or use both, if you aren't using the Oberg return filter.

[BlitzA64]

Thanks all.

No Oberg in the return line
I went with 10" vacuum as there was less than 1% hp gain between 10 and 21+ figured I'd rather be safer with all the "possible" issues
I run a logger which shows vacuum at all times when running so the number is accurate
My back up engine has a 4 stage off the shelf pump and pulls 7-8" sealed on the dyno

I can try the Oberg deal and also build a screen system in the top of the tank. I am going to plumb in a Moroso breather tank 85391 mounted as high as I can get it and also add a second breather line (two -16 lines) to that from the tank, currently there is one -16 line. Hopefully this will fix the issue, otherwise I may just bite the bullet and swap out the pump to a 5 stage and let her rip with that.

Thanks for the thoughts

[BlitzA64]

Hey Bill,
That Spintric sounds pretty slick, I have an Oberg around here so I will try plumbing that in before buying something else, come to think of it the dyno oil tank has one and never saw anything out of that tank at all. Adding a 2nd breather line to the tank should slow the velocity some as well. Thanks for the info, I appreciate it