Sealed, vacuumed Dry Sump Systems

Not tuning really tuning related although thought id try my luck,

Anyone here with experience with a sealed engine, vacuumed dry sump setups?

Currently plumbing up a dry sump system and using a Peterson Vacuum regulator to control crankcase vacuum for a better ring seal. The plumbing of the pump, cooler and in/out of the tank etc is sorted. Question is related to the breather side. How are you plumbing your breather, if you're running one?

Obviously you can't run a breather straight from the engine, or no vacuum will be created. However, I have seen some systems where the engine has no breather line to the tank, although the tank goes to a breather, creating vacuum in the engine but not the tank. Or other setups where the engine has a breather to the tank and the tank has none, effectively creating a vacuum in the tank and making it equal with the engine.

First time I have tried running a vacuumed system so hoping someone out there has some tips or advice.

Thanks in advance

My experience with dry sump setups has been that with an N/A engine the dry sump can pull a vacuum in the sump which is beneficial in reducing windage and can show a modest improvement in power - So we definitely want that vacuum in the crank case. To achieve this, the engine must be sealed - ie no rocker cover breathers. Even an N/A engine will create positive crankcase pressure under high load/rpm but the dry sump pump should be able to over come this (provided you are using enough scavenge stages). The vacuum regulator is necessary to prevent the dry sump pump creating excessive crankcase vacuum if you jump off the throttle at very high rpm - Theoretically without the vac reg you could end up with all sorts of nasty stuff happening like crank seals being sucked in etc.

The tank on the other hand needs to be vented as this is where the evacuated blow by gasses end up. Also a side effect of the dry sump system is that it removes aeration from the engine oil and this needs to vent somewhere.

On a turbocharged engine this system won't work as (depending on boost level) the blow by past the rings will still create positive crank case pressure. In turbocharged dry sump systems you still need a breather from the rocker cover. Your option is to run this back to the dry sump tank and vent from there or some people prefer to run a separate breather and catch can system in the engine bay from the rocker covers. You should find that with a dry sump system even a high boost turbo engine doesn't put much oil into the catch can - Breathing should be greatly reduced.

I can't see that running the tank sealed would work very well. As stated, the blow by gas needs to be evacuated somehow.

On my old drag car I ran a 4 stage peterson dry sump pump. I ran rocker cover breathers but used one way valves in them so the dry sump pump could still pull a vacuum at idle and low boost. With 54 psi I still saw positive pressure in the crank case but in this condition the one way valves would open in the breathers allowing them to vent. The one way valves were probably unnecessary but it did allow me to monitor vacuum and gave me some idea bout the ring seal.

Thanks for the reply.

So im thinking I will run a line from the tank to a breather to vent the tank, also ill run a line from the engine to the tank with a one way valve.

This should allow the crankcase to hold vacuum although allowing any pressure which may form to vent to the tank.

so a breather and a oil catch can are the same ? or are they two different things?

A breather vents to atmosphere while a catch can is, usually, a sealed unit that catches oil from PCV or other emission systems stopping it from entering the intake air stream while allowing the crankcase pressure to be evacuated by the engine's vacuum.

http://rehermorrison.com/tech-talk-84-dry-sumps-dave-lives/ “In a wet-sump engine, the rotating assembly whips the oil like a milkshake in a blender.”

http://nutterracingengines.com/racing_oil_pumps/crankcase_vacuum_facts.html “Reducing down to dash-10 scavenge lines will help achieve a higher level of vacuum.” Interesting because virtually all pans and pumps use AN-12 lines. Do any -10 scavenge filters even exist?

The biggest Barnes pumps have 2 -16 return lines...unless there is a piston sealing problem can engine blow more than that into the crankcase? Wet sump Supras typically run 2 AN-12 lines to a catch can. http://barnessystems.com/the-barnes-difference/2730101

The old Peterson pumps were georotor on all stages...not ideal for scavenging air. The current Peterson pumps have 4-lobe twisted rotors.

On the 2JZ, Dailey specs a stage just for scavenging the turbo. Many just continue to drain the turbo to the pan. Lots of discussions about this online.

Update: an on-point article specifically about creating crankcase vacuum on forced induction engines: https://www.dragzine.com/tech-stories/engine/tech-boost-vacuum-finding-hidden-horsepower/

A bit late but possibly of interest -

On my 240BHP 10,000RPM 4AGE I has a mid sized 3 scavenge/1 pressure dry sump pump.

It pulled a partial vacuum once above 2500RPM (it ticked over at 200RPM).

There were two "breathers" -

One was a -6 line with an inline restrictor to control the vacuum level (by drilling out the restrictor hole size).

The other was an unrestricted -6 line but with a one way flap fitted. If there was positive pressure (so above atmospheric) then the engine could still vent...rather than blow oil out of every seal and really annoy the rest of the competitors.

Both the vents went to the dry sump tank. The dry sump tank had a rather pointless oil catch tank attached to it to meet regs (and a breather for the axle and gearbox...another long story).

Apart from the rear main seal constantly collapsing under the partial vacuum (big wobbly thing, eventually resolved by some welding/machining and a much smaller OD seal) we never had a single issue with the setup.

Bit late, and i hope you got it sorted your satisfaction, but some thoughts on it (and I may be wrong... ;-) ).

1/ Scavenge pumps need some means of getting the oil to the pumps - or, rather, having a pressure differential between the pump gears and crankcase to blow/suck the oil/air mix from the crankcase (and head/valley if used) to the pump mechanism - with too high a crankcase vacuum scavenging properly can be a problem. For best results, sufficent airflow to carry the oil as a mist or droplets is much better than trying to pump oil alone - th8ink of it like a vacuum cleaner - it uses the airflow to carry the dust, it cannot just suck dust alone. You can see what i mean if you have a container of, say, dry sand - if you hold the tip a little above the surface the air being sucked into the vacuum carries the sand with it, but if you stick the tip deep into the sand it will cease working*.

2/ To allow enough air into the crankcase (and disregarding blowby as it 'should' be minimised) some form of breather should be used - there are commercially available filtered breathers that can be set to a desired vacuum level.

3/ The receiver tank/reservoir must be vented, to void the air sucked from the crankcase and prevent pressurisation and in order for the air/oil separator to work properly.

4/ As has been mentioned, with higher levels seals may not function properly as the pressure gradient is the opposite of what they are designed for. I have known some instances where folks have tried fitting them backwards - lip outwards - but is not generally recommended. There are specialist seal companies that can offer seals specifically for these applications.

*Slightly different results, in detail, as one is a centrifugal and one a positive displacement pump, but similar principle.

Hi, sorry for a late reply but this topic seems to be hard to find on the internet.

I have the Honda K20 turbo dry sump setup build ongoing in my 1994 Eunos Roadster and in the near future I have to start making the turbo oil feed and the return lines. I have had this setup working on the NA K24 engine before for 10000kms without issues. My concern is now the turbo oil return line, how to route oil back? In the naturally aspirated versions the oil is returned to the timing cover from the customized chain tensioner lid. However, this way the oil is basically going almost straight to the crankcase where the vacuum is sucking. Is this a bad idea to implement the oil return from the ball bearing turbo to the timing chain cover or does it need some sort of tray in the middle where to drop the oil and then suck it to the circulation?

I can't see it being an issue, the primary reasons for the dry sump are to minimise the windage/oil in the air around the crank' and rods, and to ensure a reliable oil supply to the engine, and you seem to be returning the oil from the turbo' to an area clear of the crank' where it has easy access to being drawn out by the scavenge pumps - but if you could post the make/details of the front cover?

The Turbo is on the left side of the pic on the level of black VTEC solenoid (about) and the oil drain will go to the black lid of the timing chain tensioner cover. Is that a good place to route the turbo oil return considering the scavenge plate is on the bottom of the block a quite distance away?

Have you considered just returning the oil to the dry sump tank?

Returning the oil back to the oil tank is out of consideration since the tank is located at the back of the car.

I have considered to make the return to the timing cover (where wet sump guys put it) or to one of the scavenge stages with a tee.

Front cover or drilled and tapped block or the dry sump should work well - just make sure the material is thick enough.

What's behind the black plate at the front? Might be viable to braze/weld a fitting onto it, if you can keep it flat, or maybe machine an alloy cover with a inlet ready for a fitting?

What you need to bear in mind is the drain is reliant on gravity, so needs to be below the turbo' outlet with a continuous drop to the engine's return point, the greater the drop the better, and it needs to be a large enough internal diameter as practical to ensure it has an easy return. Get it wrong and the oil can gather in the bearing housing to the point where it overcomes the seals and leaks into the turbine and/or impellor housing.

Behind the black cover/lid is the timing chain tensioner. Yes, I have an aluminum one existing already (10mm thick) to weld a fitting there and most probably I will but the oil return there as the drop will be sufficient for it.

I have a dry sumped N/A BMW motor and I am trying to work out how best to achieve vacuum and pressure relief from the rocker cover. My initial thoughts were to run the line from the rocker cover to a catch can that has a morosso vacuum relief valve at the top with a filter fitted which would allow the vacuum to be adjusted but if there is positive pressure it has a relief valve integrated into it which would vent if there was positive pressure. My thoughts were to mount the catch can above the rocker cover with the line connecting it routed to the bottom of the catch can thinking that if there is positive pressure oil or air can enter the can and when there is vacuum the oil collected will then get sucked back into the rocker cover. What i am worried about however is that air entering the catch can whilst it is partially fill with oil that the bubbles will cause oli to exit the can via the breather..How have others achieved this. Also the dry sump tank in the boot and are trying to avoid another return line through the cabin if that were another option...

Any help would be appreciated

Thanks

Any real reason you can't run a drain from the bottom of the catch tank to the sump, or some other point, the scavenge pumps will be applying a partial vacuum to pull the oil out and the tank's breather would be a good place to have additional, controlled air available to balance the scavenging's air removal?

It might be a good idea to also re-visit the oil separator(s) in the cam' cover, as they 'should' just be letting oil mist through.

Hi all - first post! having a few issues myself with a breather tank / dry sump setup on an RX-8 (REW swapped - new build with only 300miles done). I'm running 13B REW swap, with a 7.6 litre dry sump tank mounted in the boot (oil pressure is good). Along with this, a small catch can attached to the dry sump tank - running Peterson R4 pump.

Essentially the little breather tank had its own filter/breather which was on top, and filling the car with fumes (no back seat). So I added a pipe for the breather to go out of the fuel lid - 2 problems, 1. the catch can is filling up and 2. the breather pipe/filter is sending oil out the fuel lid!

Any ideas? I run the dry sump tank around half full (as recommended). :-) Pics attached also. [thanks in advance!!!]

Just checking the obvious...how are checking the oil level? This should be done with the engine running, somewhere near operating temperature and on level ground.

The entire engine is now venting out that single tiny hose and filter, which is not adequate, causing high pressure which will fire oil out of the main tank.

Personally I would add 2 -20 bungs to the dry sump tank, and cap one of the new ports for now. You don't want to have to weld an oiled tank twice.

Then run an unkinked loop of -20 hose up as high as you can go, looping back down to a -20 bung you add to your catch tank. I'd change the top fitting on the catch tank to a 1.5" nipple and run 1.5" hose to where you want to vent, with a filter on the end.

Big ports and hose reduce pressure, which slows air/oil/fuel mix velocity.

The loop allows the heavier fluid (oil) to go up a bit and come back down into the main tank instead of getting fired into the catch tank.

When you have sufficient breathing, you won't get ANY oil in the catch tank, just some fuel and moisture. If one -20 isn't enough, get a second breather tank and use the second -20 port on the dry sump tank to feed it, vent the second catch tank the same way, with another 1.5" hose.

If your installation doesn't have room for the loop between the dry sump tank and breather can to go up much vertically, it's worth making the hose long so you can run it up to a point a few feet higher somewhere in the car, then back down to the breather can. Running the hose over top of a cage tube is often the easiest way.

Make sure the path from the dry sump tank to the high point has no low spots where anything can collect. It must be increasing all the way from main tank to high point. The same goes for the way back down. Make sure there are no low points in the hose routing from high point to catch tank.

It's possible one or both of your tanks doesn't have good baffling, which would certainly compound the problem, but every install I've encountered with this issue has been either 100% or mostly resolved sufficiently when the venting is done as I suggest.

Good points, Mike, but I don't think the chap mentioned what the engine side breathers/vents are, as they are also critical parts of the system?

Thanks Denis - checking the oil level visually in the tank a few minutes after running (warm temps). The tank is 7.6litres apparently and is meant to run half full.

Thanks Mike for the detailed reply / suggestions - I’m trying to visualise what you have suggested - think I get it - but are you also saying to run initially a -20 line to the catch tank? - sorry if i misunderstood (It is very small). Just wondering though - should I look to running a larger diameter main tank? (I have had this suggestion also). For doing the large bungs - assuming it would be important that I put these in the right place on the main tank?

One thing that I can do pretty easily is run the longer lines to and from the breather tank - can go through the back seat area to top of rear window area.

Thanks Gord, yes there is a breather off the engine / this is from the existing Mazda dipstick to a catch can in the engine bay - this appears fine, no oil on the tank gauge (pic attached)

Thanks again all - great responses 🙂

With the breather on the engine, that should be letting air INTO the engine, to allow the scavenge pumps to work correctly, so any catchment there may be a problem and indicate a LOT of ring leakage.

Can you post the actual reservoir tank model your using, as it may just lack the ability to de-aerate [sp?] the air-oil volume returning to the tank, and so it may be building up on the separator rather than allowing the oil into the lower part. On that, have you noticed ANY drops, or variations, in oil pressure, as if the oil is being prevented from getting to the actual oil reserve... For the potential flow, that tank does seem to be rather small.

It may also help if you gave some info on the scavenge pumps - in particular the rpm you're using them at, as I am wondering if you're running it/them too fast, ~5k max' should help, as per their guideline "D. Pump Speed, Speed of the pump must not exceed 6000 RPM. Please adjust the speed with your drive pulley selection based on what RPM the motor will see. Damage to the pump and motor can result from high pump RPM." Source - https://petersonfluidsys.com/Images/PetersonPumpInstructions_Pump.pdf

-20 is a 5/8ths pipe size, it could be called "small", at just under 14mm bore - https://www.pegasusautoracing.com/document.asp?DocID=TECH00096 - and larger wouldn't hurt and would help oil droplets to 'drop out', as Mike suggests. Something else, come to think on it, are the fittings' bores - there are some "motorsport" specific versions that are significantly larger than others, and they're much less restrictive and should help oil drop-out.

Oh, the tank breather does have a separator built into it, too, doesn't it?

For these engines, the oil plays a BIG part in the cooling, are you monitoring the oil temperature from, and hopefully to, the engine?

Hi Gord, (thanks for your info. it really is appreciated!) understood for the tank in the front - tank doesn't have any oil on the indicator gauge, assumption is this is working fine - I have seen other rotary engines where the catch tank in front of car (with a wet sump) does actually accumulate oil. .ps This is a 13B rotary REW single turbo engine.

I'm pretty confident the 2 x catch cans are these ones here - which say they are baffled (difficult to actually see in the tank itself)... https://www.obpltd.com/product-page/1-litre-bulkhead-mount-baffled-oil-catch-tank-round/

I believe the oil pressure is good also - but I'm only running the engine in - so RPM's max around 4500rpm so far - see some log info attached (max. around 82-84psi at just over 4000rpm - which I think is right).

As for the main tank size - I am tempted to go for a larger diameter one, but I still feel that I'll need to do some work on the plumbing as Mike has suggested.

So it is the Peterson R4, I believe I was supplied with the correct pulley on the from (from PPRE many years ago). However, might not be a bad idea to confirm exactly which pulley is on it (assuming I could try and measure it?) - engine will certainly be revving more than 6000rpm (as per their guide) - but hoping the pulling is the right ratio, thanks for link.

I'm confused about the -20 bung/pipe size - this is 1 1/4inches (32.4mm) inside diameter right? Dash 8 I think is more 1/2 inch 13.1mm (what am I missing sorry?)

I don't think the breather has a 'separator' as such? do you have an example of a separator?

100% agree on the engine cooling from the oil (especially being rotary), I'm running two larger oil coolers mounted at the front - (annoyingly!!! I don't have an oil temp sensor), which is on my list of things to do.

I attached some more pics (with some notes on) - hopefully the set-up is making more sense?

Thanks again Gord.

Just trying to help you find that "Eureka" moment - there are much smarter guys who can help more, and catch the silly mistakes.

Could well be, keep forgetting if the -xx is in 16ths or 32nds - the former seems more logical, as you say - I blame old age, and posting late into the night... like now, as up (almost) all night with the motor racing on the TV..

I had in mind the breather in the top of the oil tank, sometimes they have a baffle in them to catch the oil in the tank's breather before it gets out, but if it was sold with the external catch tank, maybe not.

Can't comment on the oil pressure, per se, but the guide may be useful for when you're using the full rpm range, as it looks like just under 20psi/1000rpm and I don't know how high you will be using it - the concern is the oil will be trapped in the engine and top of the reservoir, allowing the pump to suck in air at high rpm as the level drops.

There are different versions of the R4, as I understand their options, but I don't see any point messing around with them unless you actually need to.

That rpm limit was for the pump, easiest way to check is to take the peak engine rpm expected, multiply by the teeth on the engine pulley and divide by the pump pulley - right now it won't be an issue, I was forgetting you were still at relatively low rpms, but may need to be looked at - see above.