Hybrid Dry / Wet Sump System - Would this work?

I've been thinking about dry sump systems for my stock car project that will allow me to use as much of what I have as possible. My main concern is oil capacity and starvation, not so much performance - I just want to keep this thing from eating itself in high-G corners.

The pan appears to be baffled and has a side resivoir with the oil pickup tube going over there, as you can see in this picture:

My thinking is this: could I use the built in oil pump as a sort of scavenge pump, sending the oil from the sump to the actual scavenge pump via an oil filter relocation kit, which then goes to the filter, the tank, the oil cooler, and the pressure side of the dry sump pump, then back into the engine at the same oil filter relocation fitting? The pan also has two more scavenge outlets, so I could run 3 scavenge stages. I've drawn up a diagram:

Would this work? It makes sense to me, I suppose it's possible that the scavenge ports would steal too much oil and starve the in-block pump, but then I could just block those off and just use the standard oil scavenging system. Thoughts?

I'm on my tablet and I don't have that patients to type out a long answer but my initial thought is that you'd be adding complexity without any real benefit.   If you want to suck oil out of that part of the pan just put a fitting over there and hook the dry sump pump directly up to it. 

I agree, from a mechanical standpoint there's no benefit and it's a little extra complex, but from a "I can save myself a bunch of work and time and money and not really lose anything" standpoint it seems to make sense to me. If I went with this I wouldn't have to remove the headers to take the pan all the way off, find a solution for the existing oil pump, block off half the oil filter relocation plate, or tap the pan. I already have almost all the external stuff I need  - the filter relocation plate, oil cooler, and oil pump mount and pulley came with the car and are already installed. I already have a tank. If I could just plumb this up without messing around in the engine it would be very helpful.

The "typical" way hybrids like this are done is: scavenge pump does all the work clearing the pan and sending the oil to the tank/deaeration/filter/etc, and the engine pump does the job of actually supplying the engine with the inlet/supply at the bottom of the tank. That would require some rerouting of the pickup to mate to the tank and make use of the pan scavenge fittings already installed in the pan. Plus adding the scavenge pump and drive to the outside.

AMiataCalledSteve said:

I agree, from a mechanical standpoint there's no benefit and it's a little extra complex, but from a "I can save myself a bunch of work and time and money and not really lose anything" standpoint it seems to make sense to me. If I went with this I wouldn't have to remove the headers to take the pan all the way off, find a solution for the existing oil pump, block off half the oil filter relocation plate, or tap the pan. I already have almost all the external stuff I need  - the filter relocation plate, oil cooler, and oil pump mount and pulley came with the car and are already installed. I already have a tank. If I could just plumb this up without messing around in the engine it would be very helpful.

The chances of you being able to get the pan to seal without pulling it the rest of the way off so you can really clean the surfaces are extreamly low.  There's also the challenge of cleaning the surfaces without having crap fall into the bottom of the pan.

You should also make sure that there are screens on inside the pan on the scavenge port fittings.

Removing the existing pump and dealing with the drive is not a big deal.  I'm going from memory hear but I think it's pull the pump, pull the distributor, push the drive gear up from the bottom and pull it out the top, cut the drive shaft for the pump off the bottom of the drive gear and reinstall the drive gear and distributor.

Blocking the pump port is as simple as threading a plug into the filter adapter plate.

We ran a system similar to what you're describing on an RX7 for a number of years. We just used the stock pump to scavenge and send oil through the filter to the tank. We cut the external pump down to just the pressure section.

APEowner said:

...I don't have th[e] patients to type out a long answer ...

Well, doctor, most of us don't either :)

jgrewe said:

We ran a system similar to what you're describing on an RX7 for a number of years. We just used the stock pump to scavenge and send oil through the filter to the tank. We cut the external pump down to just the pressure section.

That's encouraging to hear, most of these pumps are modular so that sounds easy to replicate

I'll add that we were worried about the stock pump losing prime when we first came up with the idea. It wasn't a problem. We set up a test where we could spin the pump without the engine running.  The pump would empty the oil out as fast as we would pour it in. Wait a few seconds, pour another quart in and it would be sent to the tank in a few seconds.

It wasn't my car and I kind of thought it was more complicated than it needed to be, but it never had an oil related failure. If you are going to make this car turn both directions now a well baffled/trap door pan would probably be just as good. If you really want to run an external pump and tank you are on the right track but a simple dry sump pan would be the easy button.

Are there any rules against dry sump system's in the group you are going to run?

In reply to jgrewe :

Not that I know of. My main goal with switching to the dry-ish sump system is to increase oil capacity. The pan that's in the car is very shallow and has a side reservoir off to the side like in my diagram, and that's where the pickup tube is. This is probably ok for left turn stuff, but I'm concerned that on long rights the oil would pool away from the intake and starve the engine. Having several gallons in reserve would help my mind greatly.

After doing some research, it looks like a dry sump pan for the 5.9 Mopar in the car costs about $500, so maybe that's an upgrade path going forward