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Sealed, vacuumed Dry Sump Systems

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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.