Oil tank elevation relative to engine sump

[patkeefe]

I am in the process of building a test stand, so I can run my engines before they go into the cars. I have a rectangular Sennecker oil tank which I am going to mount on the stand. I am assuming the location of a 911 oil tank is related to the amount of oil which can be assumed to be carried in the engine sump. Does anyone know at what capacity the oil tank and sump are at an equal level in the car? I plan on running a remote filter, and would like to minimize the amount of oil I need to carry on board the test stand; I will be strictly relying on the engine mounted oil cooler during test runs on the stand. My turbo SC, for example, holds 14 quarts on an oil change, but I have four oil coolers! (Yes, I am out of control). I would like to get by with maybe eight quarts on the stand, and not run anything dry.

TIA,
Pat

[patkeefe]

How much oil does the engine case hold statically, ie, when the engine is stopped and all of the oil has been allowed to reach height equilibrium? I believe that if you were to open the drain plug on the engine sump, and leave the plug in the tank, most of the oil will come out the sump drain over time.
Thanks!
Pat

[HawgRyder]

For starters, the bottom of the tank should be slightly above the input feed to the pump (case hole).
This will allow the pump to fill before starting the engine (so that you don't get a dry start for the first few seconds).
Next...I hope you have allowed for a support to the back of the engine because the car has one and I believe you might damage the case when a fully assembled engine is on that stand.
Finally...good job on the stand so far.
Have you allowed for controls on the stand or are you going for remote operation? (get far away just in case..LOL).
Bob

[KTL]

Pat,

The S-hose which supplies oil to the engine is basically level. So your tank outlet and engine inlet (pump inlet) should be at the same height if you want to mimic the setup with the engine installed in the car.

As far as the level of oil in the engine at rest, that depends. A hot engine that has just been shut off has little oil in the sump (that's why it's a dry sump....... ) and most of the oil in the tank. As the engine cools, the oil is hydrostatically applying a bit of pressure to the oil pump gerotor/impeller. Oil slowly migrates past the pump gerotor over time and goes out the oil pump scavenge pickup tube, back-flowing into the sump. When you start the engine again, the pump scavenges the oil and spits it out the oil-out fitting on the engine case and sends it back toward the t-stat, then up into the tank to be filtered and dumped to the tank reservoir for discharge thru the S-hose again.

For simple guesswork, I would say 10-11 quarts would be your test stand amount. Think of it this way, when you change the oil in the car, it's no different than changing it on the stand. You dump the sump, dump the tank, add a new filter, run it and top it off to mid-level on the stick. That's usually about 10.5 qts. Even though the engine is running in the car (and the t-stat is assumed to be open, feeding the front cooler), that doesn't matter. The external t-stat doesn't appear to allow that "forward" oil to come out of the lines and the front cooler when you change the oil. The only additional oil that you need to account for in a dry engine is what's needed to fill an empty engine-mounted cooler, oil hoses and filter. The 10.5 qts already includes the filter.

Why not use a factory tank mounted on your stand? It already has the filter plumbed into itself and avoids the need for extra lines. All you need are an S-hose and a scavenge line back to the tank. Factory tank also gives you a place to hook up the case breather, and then a catch can on the oil tank (or plumb it back into the intake- not a big fan of that.....)

[KTL]

BTW, check out JB Racing's test stand for some visual references/ideas how to set yours up?

Gert’s Engine Rebuild & Upgrade (Chasing 300Hp, yes another one sorry)

[boyt911sc]

Pat,

I use about 10 liters of oil for my engine test stand with factory oil tank. No auxiliary cooler and thermostat. I used the oil tank configuration (height/level) to that of an engine installed in car to minimize deviation from original set-up. Less to worry. PM me if you need a factory oil tank for SC/Carrera. Nice welding job.

Tony

[patkeefe]

Guys, thanks!!!
Tony, I just put a 2.0 cheater in my helmet yesterday. The difference is amazing. I can actually see what I'm doing.

Problem with calculating oil volmes is the odd shapes ot the tank and case. My Sennecker tank is rectangular. I'm building it so I can adjust the height of the tank easily. I'm using all the parts I have lying around the garage to build this.

Bob, isn't the threaded case hole the outlet of the scavenge side of the pump, and the through tube on the oil cooler that connects the tank via the "S" hose is the case inlet? So, the case gravity feeds from the tank into the sump, and the scavenge side of the pump pushes the oil back out through the filter. This is where my concern is in sucking the case dry.

I'll post some more pictures. I think this will make a hellofa go-kart!
Pat

[HawgRyder]

Patrick...you are correct...the inlet to pump hole is the one going thru the bottom of the cooler.
If your oil tank is a bottom hole type feeder...then by all means adjust the height to allow for an elbow to the "S" hose.
If your tank feeds out the side...then it mimicks the porshe tank.
I believe the outlet on the porsche tank is slightly above the bottom ..perhaps to catch or reduce the "gunk" going to the engine.
If you are going to run up an engine to do the break-in, you might want to think about cooling and filtering of oil.
As I said before...good job.
And this is the time to ask questions...before you weld....LOL
Bob

[patkeefe]

I am going to post some more photos and brief explanations of the stand here:
Engine test stand??

I'll try and keep the oil questions in this thread. I may indeed want to put one of my oil coolers on the stand, just in case.

[boyt911sc]

Originally Posted by patkeefe

I am going to post some more photos and brief explanations of the stand here:
Engine test stand??

I'll try and keep the oil questions in this thread. I may indeed want to put one of my oil coolers on the stand, just in case.

Pat,

Unless you would be running the motor for an extented time to reach the operating temp. of 180 F or higher, a 10-liter oil tank would be sufficient for start-ups and test runs. Your turbo engine would definitely produce much hotter temp. than my SC's. I could use your design for my second engine stand. Nice work.

Tony

[patkeefe]

I got my engine running on the stand. Interesting to see the oil return to the tank.

https://www.youtube.com/watch?v=SfIcAvIcUSk&feature=player_detailpage