So I need a new oil catch can for the boosted set up.
I saw the Motion Raceworks can that uses no pull of vacuum from the intake, which is what I want.....ZERO OIL MIST GOING INTO THE INTAKE. For like 10+ years, I ran a N/A big LS stroker engine with absolutely no crankcase evacuation of any kid. All vacuum ports on the intake capped off. I put little fuel filter breathers on the valve covers and one on the valley cover port. Oil was always pretty clean at 3,000 mile oil changes.

But about 5 years into owning that big stroker I installed an small electric vacuum pump the size of a pack of cigarettes that constantly pulled a fixed amount of vacuum no matter what rpm, from idle to full throttle. It just always ran. Not sure I ever saw any oil dripping from the line coming out of the vacuum pump. So I'm thinking it just pulled air out of the crankcase. Still, always pretty clean oil at every oil change for the next 5+ years.

So is this Motion Raceworks can the best choice for a boosted set up, with the crankcase pressure itself being the only force that "pushes" that pressure out of the crankcase through the large hoses and into the can? Seems like having zero oil pressure going through the intake is a HUGE plus, and having a catch can also. Instead of just having 3 vents, 1 on each valve cover (2) and 1 on the valley cover port.

This one:
Motion Raceworks Top Loader Billet Catch Can KIT 32-100K

 

Motion makes solid products that they test on their in-house racecars so I wouldn't have any problems using it.
My current catch can is similar, just a bigger can but still uses dual -10AN lines from each valve cover.
I've been making street pulls all summer and still haven't had to empty it so the Motion unit would be fine.
The big thing with cans that vent the pressure is having large enough lines so the pressure can exit easily, the more power you make, the more venting you'll need.

 

ok, so you’re set up has no oil entering the intake? This is my main question, I’ll be around 15-18psi realistically. Brand new motor. I can simply cap off my vacuum ports and have no crankcase vacuum taking place.

No problem?

I ask because all I’ve heard for 20 years is that you MUST pull vacuum to get rid of the toxic gasses. As I said I got away with having no vacuum pull but……..that was an N/A Steiner engine that had 3,00 mile oil changes.

Now it’ll be boosted pretty good.

 

Nope, there is no attachment to the intake, it's a vent to atmosphere only setup.
My car runs around 14 lbs. currently but will see 20+ in the future and I'm very confident I'll have more than enough to vent that.
You can do a PCV catch can that works off engine vacuum, the Mighty Mouse PCV can works very well in that regard.
I ran one for years and never got any oil in my intake, keeps the oil smell out of the engine bay and the cab as well.
Even with the open can I run now I still don't get any oil smell in the car, probably depends on where you mount it.
If you mount it on the firewall close to the cabin intake, you'll probably get the smell, mine is mounted up front by the radiator.

 

Ok cool, so any can with 10an or larger coming off each valve cover should be fine.......thanks.

 

Not forced induction yet but that's how I did mine.

 

I just used -12 lines off each valve cover to a single catch can with a breather on top. No issues at all for me I'm running at 16 psi

 

Thats exactly what I want to do. And the can doesn't need to be any kind of expensive can with special NASA baffling, right? Because there's nothing returning to the intake....correct?

So vacuum pulling from the crank case just isn;t needed....???? Just let the crank case pressure push itself out....yes...?

Why are cars made with vacuum if its not needed?

 

OH....I'll be running around N/A for a few months at most. So do I need some kind of vacuum pull on it????

I have a 12v electric vacuum pump that pulls pretty good. I could hook that up to pull crankcase gases full time at a steady rate.

 

I bought a cheap can with dual -12an fittings welded on each side with a breather on top off eBay. And I'm using a set of motion race works bolt on valve cover breathers to go -12 off each cover. Crankcase pressure vents out naturally.

If you want to go spend a few hundo go right ahead it's still gonna do the same thing.

Picture of the can I got except the fittings are welded on the sides not straight on

 

No, I want to spend as little as possible because for sure there's no expensive can out there thats going to do anything more than the cheapest can. I'm gonna get a $40.00 can with the two -12an fittings side by side near the top of the can like the Motin Raceworks can is.

 

Vacuum is not NEEDED and vented is not evacuation.

It just becomes a question of if you want it.

It can be done. One side with be a breather OR a line to a catch can and the outlet is a breather. Should be big lines like -10 or bigger. This will allow clean air IN and blowby out.

Other side is check valve allowing manifold vacuum to pull on a catch can and stopping boost in the intake from going further. After the check valve is outlet of catch can, the inlet goes to other valve cover.

Most cars do not care for evacuation, especially trailed drag cars but there is no doubt evacuation is a cleaner crank case.on a street car.

 

Yea, I ran a big striker LS for 13 years without any vacuum being pulled on the crankcase by an intake vacuum port. I simply thought having oil mist going into an AIR intake was the most ridiculous design ever. But I was told by everyone from top LS builders to car dealership techs to speed shops, YOU MUST have vacuum pulling crankcase gases out of it.

pretty obvious we don’t. It was a 500 RWHP daily driver for 13 years. Oil was always quite good at oil changes.

im just doing the twin -12 line breather can with an air filter on top.

 

Spending as little as possible is vent everything. I vent both valve covers and the valley cover if possible and no issues ever.

 

Even better. Do you have any oil soaking the filters on the breathers ?

 

I do not. Typically the valve cover locations are the PCV port in the back on the DS and then I change the oil fill cap to a breather.

 

there is a difference between a car that is expected to run well for 100k+ miles and our moded cars. i never bothered to do a vaccum evacuation either, be it boosted or not.

tip: in case of nocicable blow by use better oil. makes a hell of a lot of difference.

 

Highly debated topic.

My take is for a street driven car, I want to last and not smell, or leak oil from blowing out seals, I want a full functioning PVC system. It’s not that difficult.

 

If you're gonna do a vent to atmosphere setup on a streetcar then big, free flowing lines are needed for anything making decent power.

 

I run 2 -12 an lines off my valve covers into a can and I've got no smell, leaking oil or blown out seals. It's not that difficult