I’ve got a few hours in research on how to plumb my drysump system, but there are many different approaches from different manufacturers, cars and engines. I have an idea of what I want now, and want to confirm that this is correct.

i have an Aviad 2.5 gal 3 stage system. Both scavenge lines are in the pan. (-12 with internal spring). The tank has a “vent in” and a “vent out”.
My engine is sealed, OTHER THAN a -12 going to the “vent in”. The “vent out” is supposed to go to a catch can/breather to atmosphere. the vent in/out are both in the top of the tank and are not baffled differently from each other. The top of the tank is essentially a pass through for the valve cover to the breather.
my concern is that this will not allow the scavenge section to pull a vacuum. (This is plumbed as per Aviaid’s instruction) So now I’d like to put a vacuum regulator in between the valve cover and tank “vent in”. Is this correct? Anyone see any issues with this? Would it be better to have the tank under vacuum as well by putting the vacuum regulator in between the “vent out” and breather tank to atmosphere?
what about a pop off valve in case of positive crankcase pressure? Are there vacuum regulators that will open (essentially opening my system to atmosphere) in a positive pressure situation?



Unfortunately this is the best photo I have of the plumbing, the tank is in the lower left of the picture. Breather and “vent out” are under the fender and not visible

 

Hey Chris-

From my understanding- to really take advantage of the dry sump vacuum would require a 4 stage pump set up- and drop the size of the scavenge lines to -10.

Here's a good article- I spoke with this guy when I set up mine- I was mostly concerned with getting the drive ratio correct.

http://nutterracingengines.com/racin...uum_facts.html

BTW - the engine compartment looks bada$$!!!

Richard

 

Richard- Thanks! And thats a good read, I had not read about the -10 lines before (most suggest at least -12. the reasoning behind the -10 makes sense though)
I know a 427 with only a 3 stage wont pull an ideal vacuum (or maybe even any at high RPM), but Id like to take advantage of whatever I can get from this pump. I dont have room in the chassis to add a 4th stage unfortunately. It is only a street car, after all
When you google "dry sump vent plumbing" the results are mostly people talking about how they are puking oil out of their breather/catch can after one or two sessions. That is the LAST thing I want with the sidepipes running underneath most of my oil system.

 

HAHAHA- that's like saying- "no, she's not a prostitute!!!"

Couple of thoughts-
Are you running an oil temp sensor in the tank? Since it's a 'street car'- I'd wanna make sure it's up to temperature.

Have you looked at running one of these between the valve cover and tank?

https://www.moroso.com/catalog/produ...all-body85682/

 

I use a -10 from each rocker cover and a -12, and if it fits, a -16 into a Peterson 08-0400 breather can.

 

It’s whatever I need to tell myself to justify my spending

as far as a catch can In between the valve cover and tank, I think the top of my oil tank is working like that already... if oil comes through that hose, it will drop into the tank before the vapors go back out the tank to my catch can. The valve cover is not baffled, maybe I’ll put a baffle on that and on the “vent out” of the tank.
I don’t monitor tank temp, but I do monitor oil temp as it enters the block from the pump. I’ll also be using a strap on tank heater for the colder months.

Does your rocker cover go to the dry sump tank? Or just straight to the Peterson breather?

 

Each cover vents to the can. Same for the tank. This is how i do it on LS3, 6, 7 C5's and 6's with either production or a.r.e. or Daily dry sump engines. A small block should be no different.

 

So on these cars are they not generating a crankcase vacuum?

 

Yes, like all engines. We want crankcase pressure out of the engine as much as possible. With the stock production hose sizes with stock production routing, the engines tend to have too much crankcase pressure causing 1- forcing oil into the intake manifold and 2- tending to cause either the front seal or rear main seal to leak oil. I also add a drain hose with a one way check valve and plumb it to the dry sump tank or to the oil pan on a wet sump application so whatever oil the can catches, drains back..

 

You can't have your cake and eat it too here.......if you have a breather can, it will not pull vacuum in the crankcase........
A sealed four stage 358 ci small block with no vacuum pump might pull 10-11 inches at 10,000 rpm......so you can see that using a dry sump pump to create vacuum is not a hot plan.....BUT.....why don't you add a vacuum pump? It sucks everything out into a catch can and will make 20 inches hg if done right......vacuum pumps improve ring seal too.....
I don't like more than 18 inches on the street as it starts to pull oil away from the cylinder walls.......but yes, there is small 1/4" NPT regulators for that.
But if no vac pump then just plumb the can to atmosphere and run it......the Dry Sumps main job is to provide a constant oil supply from the reservoir under adverse conditions.....
Your 2 stage is not going to pull enough to worry about vacuum......

Jebby

 

I try to eat my cake whenever possible! Looks like this is an either/or situation. This is my first dealings with a dry sump (can you tell??)... you can read for hours and get 10 different explanations on how to plumb these and what to expect. I guess I’ll forget about the vacuum and run it into the catch can. This motor is not built to really take advantage of a high vacuum from a dedicated pump. No piston/wrist pin/auxiliary oiling provisions or low tension rings. I’m just trying to maximize what I already have.
thanks everyone for the input!

 

I couldn't have said it better myself.. especially when you are talking about a street car. And as you know doing a dry sump ain't cheap!!!

Richard