Crazy dry sump idea

[steved0x]

Dry sumps - I had a crazy idea.

What if we replaced the current oil filter cartridge with one of those remote oil filter adapter that has 2 ports, an outlet and inlet.

We could take the outlet of this adapter and feed it to a big dry sump oil tank with air separators and whatever goes into that.

Then, we "somehow" drive a pump, that feeds the oil from the bottom of this dry sump tank, and feed it into the inlet port of the remote oil filter adapter, and send this new pressurized source of oil back into the engine.

The oil filter would be added somewhere in this chain, and it would be easy to add in an oil cooler as well.

The stock oil pump in the car would serve as the scavenge pump, and would pull the oil out of the current oil pan and send it to the dry sump oil tank via the remote oil filter adapter, with the defoaming etc... that occurs there.

I am sure I am missing a lot as there has to be more to it than that, but:

Pros:

• Reuse the existing oil pump as a scavenge pump
• The addition of the dry sump-ness would resolve the oil pressure drops during hi-G cornering

Cons:

• Extra weight from adding the new dry sump components
• All that extra pumping seems like it could change the vacuum inside the crankcase?
• All of this would probably have to go in the trunk, but at least you could still store stuff in the front trunk

Sanity check:
If it was this easy, it seems like there would be a kit out there already. Why isn't there?

• Room?
• Weight?
• Cost?
• Other?
• I have no idea what I am talking about and this post has so many issues it is impossible to respond to it...

All of the dry sump kits I have looked at for other cars seem to have all sorts of elaborate replacement oil pans, multiple scavenge pumps and deletion of stock oil pumps, many external lines to carry the oil along its journey.

The idea I propose above would eliminate many of these complexities. I wouldn't mind carry some extra weight if it would definitively resolve my oil pressure issues.

What is/are the fundamental things I am missing

[The Radium King]

so, here is an image of the oil circulation in an m96:



typically a dry sump system would intercept the oil pickup (#2 in the image) so that it is direct-fed from an external oil pump which draws from an external reservoir. the external reservoir is filled with oil that collects in the sump and is pumped back to the reservoir (which has a large enough volume to allow time for defoaming, etc.). the same pump is used for both pumping applications. these pumps tend to be very expensive.

you are suggesting injecting the oil at the oil filter instead (#5). another place to inject it might be at the cooler (#7). looking at early aftermarket supercharger kits might give some ideas as to where to mount the pump. intent is to also collect the oil at the oil filter - ie, use the existing oil pickup. the oil pickup is a weak spot in the system, but offset by a large reservoir. would you use the internal pump to supply the reservoir,? regardless, opportunity to oversupply the engine with oil - external pump is sending a steady stream of oil, while internal oil pickup is cavitating and not removing the same amount of oil? i have read that people have purposely overfilled the m96 with 5 litres of oil to no ill effect, so perhaps not an issue? strikes me as very similar to an accusump, yet engines w accusumps still fail due to oiling issues?

thinking (typing) out loud, would it be possible to not use an external pump? the oil pump on the engine might be strong enough if you don't introduce much head or friction loss (long pipe runs). you would have to run a hose from the pickup (#2) to an external reservoir. mount the reservoir low and have it gravity fed from another hose from the bottom of the sump? EDIT. gravity feed from sump would never work. however, there is a long tradition in turbo applications of using small electric pumps to provide oil for turbos, so something like that might be sufficient to scavenge the sump to refill the reservoir? https://www.rbracing-rsr.com/oilsystems.htm. system might just consist of an after market sump pan with a pass-through to access the oil pickup, and a bit of baffling to direct oil to the scavenge. some AN fittings and hose, an adaptor to attach to the end of the oil pickup, an electric scavenge pump and a reservoir tank?

[steved0x]

I was wondering what would happen if the two pumps weren't evenly matched? Would the oil accumulate on one side or the other? I guess it is pretty complex...



In the picture above, pretend that #5 (the oil filter) is actually a big oil tank with defoamers built in, and another oil pump built in that then sends the oil along to the engine via the same path it already follows in the current configuration.

If the existing oil pickup (#2) momentarily sucks air during a hard corner, then so what since this pickup now feeds the oil tank. The new oil tank/pump that replaces #5 would be the one responsible for defoaming this oil, and then sending the foam/air free pressurized oil on to the engine.

The OEM oil pump would now be serving the role of a scavenge pump, collecting return oil from the engine and sending it to the new external tank, which would then be used to supply pressurize oil to the engine via a "new" pump from somewhere. Checking to see how the supercharger guys do it might give some ideas.

[JFP in PA]

I really don't think the current oil pump in the M96/97 is up to this task. All pumps are "head limited", meaning that they can only pump a given fluid so high or so far, which is why you cannot put an air to oil cooler in the front of the car, it is simply too far for the oil pump.

True dry sumps use "stacked" pump sections divided into suction and delivery, and there needs to be a proper holding tank with a deaerating section ahead of where the bulk volume of the oil is stored. This is one for a 928 set up for racing:



And here is a simple one for use on LS engines:



The belt driven pumps come in all sizes:



So even if you are not cash constrained, you are space constrained, and it is going to be difficult to find usable places to locate all this expensive hardware. This is a triple pickup system (AN-16 lines) on the bottom of a 944 turbo; you can just imagine what one is going to look like under an M96:

[The Radium King]

your idea ...




my idea ...

[steved0x]

Originally Posted by The Radium King

my idea ...

Adding an electric pump would probably be a lot easier than a belt driven pump...

[The Radium King]

belt pump is rpm sensitive so required if used in a supply situation i think (faster engine needs more oil). for scavenge then electric is fine, as long as it can scavenge faster than the max supply rate. internal oil pump capability is a concern, but keep piping short and put reservoir higher if uses as supply / lower if used as scavenge and no head issues.

[itsnotanova]

I don't have anything to add for designing one but I know it can be done. I have a customer that has a working dry sump for the M96. I haven't seen it in person and haven't had a chance to ask him questions about it yet.

[The Radium King]

from what i've read, the issue is not with the supply pump, but it's ability to scavenge adequate oil in high-g situations (either the oil gets stuck in the heads, or the oil sloshes away from the pickup). so, no need to replace the pump, just improve scavenging by tying it direct to the reservoir.

i think the issue with my soln is to get adequate scavenging in a low-budget dry sump system. at max honk the supply pump moves what, 12 gpm? from the little bit of reading i've done, you want scavenging at 2x the supply amount, which means a 24 gpm max pump. with a belt-driven system the scavenging is rpm-sensitive as much as the supply so you are not moving 24 gpm all the time. also, most belt-driven pumps have two (or more) scavenge stages for each supply stage. with electric you are stuck with one rpm, not to mention that 24 gpm is a lot. on the link i posted previously, a 4 gpm electric pump was $500. perhaps two or three smaller pumps - one on always and the others on an rpm trigger? at that point, however, the cost and complexity make it just as easy to put in a belt driven pump. so, back to a standard dry-sump system.

another thing. reading the rennlist posts, the thinking seems to be that the scavenge issue is not so much with the supply pump not being able to find oil in the sump, but rather that the scavenge pumps in the heads (the two #10's in the diagram) can't find the oil (pushed away in high-g situation) so oil builds up in the heads and doesn't make it to the sump. what i am wondering is: what is the role of the overpressure valve in the supply pump? could the failure of the scavenge pumps in the heads create a false pressure situation such that the overpressure valve is opening and recircing oil directly back to the sump and not moving it through the engine? perhaps a stronger spring here to force the pump to push the oil through and into the scavenge pumps in the heads? EDIT - note that porsche did upgrade the piston in the overpressure valve to a 997 part # ...

[Robert986]

So... Old thread, any new thoughts on the subject? I find the general idea quite reasonable and Worth exploring.

[Gilles]

There are full time electric, heavy duty (full time), oil pumps that used on motorsports that are designed to move gear oil to an external cooler.

But I had been dreaming of a dry sump system as well and I ran into this great article, however is Not a cheap proposition... but good reading none the less

https://rennlist.com/forums/racing-and-drivers-education-forum/981880-boxster-dry-sump-system.html

The down side is the fact that they cost almost as much as a properly built racing engine..
.

[Robert986]

You have all Heard it, some say this or that works, others say it doesnt.. Accusump, deepsump etc. I´m sure I don´t understand enough, but.. Are there any kind of consensus regarding the actual cause of oil starvation in track situations? If we cannot agree on the root cause then all solutions would be a guesswork.

If the oil pickup would always get a good supply of air-free oil, would all starvation issues then be solved? If yes, we know where to start, if no, then what?

I believe that the oil pickup doesn´t get enough air-free oil due to lack of oil return to the sump, so baffles will not help if the oil stays in the heads too long.
Connecting a drysump oil tank to feed the standard oil pickup/pump would feel like a reasonable thing to do, adding scavengepumps to suck the oil from the old sump back to the new oil tank.

Why not?