Hello All. I'm using one of Ben's aluminum dry sump tanks and am having some issues with the motor "wet-sumping" and flooding out my turbo.

I have a cracking valve in the oil return hose and I'm pretty sure the oil isn't coming in that way, but I'm wondering if it can come in through the scavenge side instead. I don't have a check valve in there because I assumed (yeah I know what happens when you assume) that the outlet was above the oil level and there would be no way for it to return that way.

Is all I need a check valve on the scavenge line? Does Porsche have one there on it's stock dry-sump setup? I'm not running a Porsche engine but it is a dry sump.

Thanks.

What filter are you using? Check valves internal to the filters can be an issue. I dumped the Mahle filters in favor of Mann and much better. The filter is the only way it can back feed into scavenge side

Oh and what engine you running and what height in relationship to the tank is the engine running oil level. If the tank is the highest point a check valve of some sort will be required. The pump in the 911 engine acts as the check valve and with worn gears it leak into the sump over time. A turbo typically gets feed from the pressure side like from the pressure switch port. The drain will typically benefit from a scavenge pump that leads back to the tank and empties near the top of the tank. That’s also how 930s work

First off. The depth of knowledge here is really amazing. Thanks.

I'm running a turbo Suzuki Hayabusa with a dry sump. The turbo is lower than I would like, but it's still higher than the flat pan by about 4 inches. No smoke or problems when it's running, just after a few days parked.

So when I looked up the oil filters that fit on my tank, they don't specify anti drainback valve. I'm not sure that Porsche ever thought it needed one. Do you have a part number for one that does have an ADBV?

Last question, the filter stud is 1"-16 I seem to remember. Is that right?

Oh dude, you can’t just say “I'm running a turbo Suzuki Hayabusa” and not give us a few pictures. Like of the drive train.

Oc54 is the Mahle filter but they no longer function properly in my opinion. Buy the MANN equivalent

Rothsport does have a check valve or something like this will help. https://www.improvedracing.com/high-flow-fl...e-4an-male.html

Thanks for the tip. There are a few options that have the anti-drain back valve. On it.

I have a low cracking pressure valve already in the oil feed line and it does stop the drainback on that hose. But I now realize that the filter had no valve so the oil was just coming in through the out door.

Thanks for the ideas.

I will post some pics and videos of the car too. It's a bit mental with an 11k RPM 300 WHP motor in there. Separate thread!

@mb911 sorry for the hijack, but with my factory tank over the last 40 years once in a blue moon I would hear gurgling sounds coming from my tank/filter.. I put about 400 miles on my 3.6 install and thought something came loose in the filter / tank. It was pretty noisy, but the motor and oil pressure was fine. I just replaced the filter with another mahle filter and changed the oil. It made the noise a little bit, but the noise went away. The oil lines are the same as before. Can you change the filter without draining the oil or will it make a mess? When it makes that gurgling noise can it hurt the motor? I might just live with it until the next oil change.

I would think it could be noisy when the scavenge pump spits foamy oil into the tank. Betting it's normal.

Gurgling was pretty normal in 911s not very often I hear it in a 914-6 because the engine etc being right there. If you pull the filter it will leak oil everywhere unless the car has been sitting for a while and all the oil has drained down.

Interesting valve from Improved, I've used their products before and I like them. Here's the 12AN I would need:

https://www.improvedracing.com/high-flow-lo...heck-valve.html

Anyone know the math on how much pressure is needed to keep an oil tank from draining back? Their specs show .05psi, which seems low (but "Higher cracking pressures are also possible by replacing the torsion spring"). The bottom of my tank, where supply is pulled, is about a foot higher than the oil pump on my /4.

I'm trying to avoid being stoopit again...

BTW, my return does not drain back because it's dumped back into the airspace in the top pf the tank, so no way for the oil to get there.

GA

The important number is the height of the top of the oil in relationship to your cracking valve. I asked CHAT GPT to do the math and, for a stock height tank, it's between 1 and 2 psi to hold the pressure.

Learning this, I installed 2psi cracking valve on the hose going into the engine. This seems to hold the oil on that line. What I didn't think of was the other hose because I thought it dumped out in the air space like yours. I think on Ben's tanks the oil level might be above that, so there can be leak down. Plus the content of the filter dumps back in too. None of the filters for a 911/914-6 have a drain-back valve.

After some searching I found a modern oil filter with a silicon anti drain-back valve that should fit. It's off a 2009 Range Rover.

https://www.rockauto.com/en/moreinfo.php?pk...5340&jsn=23

I'll report back once I see what happens. My setup is a unique science project, but hopefully what I learn will help others.

So the scavenge goes into the filter then up to a vent that empties on the topside of the tank to drain through mesh to remove air bubbles. So your tank would have to over filled a lot to make that happen

Fair point, I'm using a Canton 8.5qt vertical tank. I'd say my total column height is around 1.5 feet max.

What was your height for those calcs?

Any idea what the suction psi is for a typical scavenge stage? I'm using a modified CB Performance 2-stage pump. Overcoming 2-3 psi should be pretty easy, yeah?

That's what I thought but I am still getting some kind of backfilling. I might be barking up the wrong tree of course.

At that height CHAT came up with around a 1psi cracking pressure needed. I doubt that any pump would be affected as long as the valve cross section is large enough.

Problem solved!

So, it was a two pronged issue. One problem was the sump filling up and making the turbo drain poorly.

Then, the second issue was that when cold, the Hayabusa engine has over 100 psi of oil pressure, so it was overwhelming the turbo even with a restrictor in the line.

The good news is that Turbosmart makes an adorable little turbo oil line pressure regulator. Simple to install and now I'm living smoke free.

Turbo Smart

This probably isn't going to help most of you, but I'm glad I beat this for sure. Ball bearing turbos aren't really supposed to see more than 60psi of oil pressure so this might be a good item for builds using them.