Dry sump using a wet sump pan?

andyf · Post by **andyf** » Sat Dec 06, 2008 12:48 am

This motor probably didn't pick up any power when we changed over to the dry sump but I'm sure some motors would show big gains. I think it has to do with the combination rather than the type of oil pump. For instance, this motor doesn't turn really high rpm and the wet sump pan was already 9 inches deep so we were probably in good shape there.

Also, this is a pretty wimpy dry sump that we put on here so it isn't pulling any pan vacuum. I'd think on a high rpm motor with crankcase vacuum and gas ported pistons a dry sump setup would be worth significant power. The guys over at Reher Morrison claim 50 hp on their big bracket motors by switching to dry sump.

xenginebuilder · Post by **xenginebuilder** » Sat Dec 06, 2008 7:43 am

andyf wrote:Also, this is a pretty wimpy dry sump that we put on here so it isn't pulling any pan vacuum.

You can always add a vacuum pump later. Wimpy or not, I think a dry sump is the way to go for any serious engine. Good job by the way, making brackets that are rigid and durable enough for pump mounting when none are available is some work.
I would make one suggestion now, and that is substitute a 1.5" wide driven pulley for the 1" with the belt guides. You have essentially two belt guides now, and unless the alignment is just perfect, you can get some belt edge wear between the two ends fighting each other. With the wide driven pulley, the belt can move a little and will self center. For a limited use drag engine, you'll probably never see a problem. On endurance engines that spend a lot of time at high speed, you can overheat the edge of the rubber from friction and start a fray.

Mario428 · Post by **Mario428** » Sat Dec 06, 2008 1:01 pm

One of the local go fast guys switched to dry sump last winter and did not find any power on the dyno either.
But he did say "the oil is sitting still on the dyno!!!"

andyf · Post by **andyf** » Mon Feb 09, 2009 2:16 pm

I did recently purchase an actual dry sump pan so I'll swap pans and re-run the dyno tests. This new pan will allow me to step up to a 5 stage pump so once I do that I'll probably be able to start pulling some crankcase vacuum.

Engguy · Post by **Engguy** » Mon Feb 09, 2009 3:44 pm

Along the lines with Joe. I don't see how with all things left equal, other than a dry sump system. That a dry sump system would produce more power, especially since your adding more parasitic losses. The scavenge pumps! And then there is the distance of pumbing etc. all added losses.

andyf · Post by **andyf** » Mon Feb 09, 2009 5:43 pm

If the motor has a windage problem then pulling all of the oil out of the pan will certainly free up some power. Some combinations pick up a lot of power with the dry sump, others not much. I'd think any high speed motor would benefit from a dry sump. Also, anything with a really long stroke and more than moderate crank speed should benefit.

idoxlr8 · Post by **idoxlr8** » Wed Feb 11, 2009 8:53 am

andyf wrote:I talked to Charlie and he said the same pan would work okay. He thought it would work even better if I sent it back to him for some mods to the pickup but I'll try it as is first.

I had to fabricate a bunch of parts to hang the pump on my BB Mopar engien since it doesn't appear to be a popular combination with the vendors. I bought a blank spline drive set up from Peterson and then machined it to fit a Mopar. It all seems to have turned out okay but it was a bunch of custom work.

Hey Andy where did you find those bulkhead fittings you used on this pan? I'm wanting to add some drainback lines to my pan and was wondering if those would work ok.

andyf · Post by **andyf** » Wed Feb 11, 2009 1:25 pm

Standard #12 AN bulkhead fittings from Aeroquip. I turned the nose down on the other ends to fit into the pickup that I was using but you don't have to do that.

I like using the bulkhead fittings when going thru the pan wall since it is a lot easier to seal up. You have space for a thick washer on each side so you have a good chance of getting the RTV to seal. There are also washers available that have an internal o-ring in them but I haven't used that style. I've never had an issue with flat washers and RTV so that is what I go with.

idoxlr8 · Post by **idoxlr8** » Wed Feb 11, 2009 4:38 pm

Thanks Andy - I didn't think about using a bulkhead fitting and RTV.

Strange Magic · Post by **Strange Magic** » Wed Feb 11, 2009 6:26 pm

From the looks of that 2 stage pump, I can't image that it is capable of pulling any vacuum and you might even come to find that you run the risk of pumping the oil tank out faster than it can recover the oil back out of the pan and into the tank. I don't mean to sound crude, but your wasting your time with only two scavange stages.

andyf · Post by **andyf** » Wed Feb 11, 2009 10:46 pm

Actually it worked just fine with two scavenge sections. Worked on this dyno motor and worked fine in the car before I used it on the dyno.

Strange Magic · Post by **Strange Magic** » Wed Feb 11, 2009 11:32 pm

How much oil did the engine take when running with this new style pan? Got a picture of the tank?

This new pan will allow me to step up to a 5 stage pump so once I do that I'll probably be able to start pulling some crankcase vacuum.

That will depend on which 5 stage pump you buy.