Catch Can run to Exhaust

[wileymotorsports]

I was searching different ways to route the catch can and came across some guys running one line to their exhaust instead of the intake tube. I would rather route the catch can into the exhaust then back into the intake. So I made a super advanced drawing of what I would like to do. Will this work? The "T" fitting on the left side is replace with a 90 Degree elbow then routed to the catch can, the PCV will tee into that line and the crank breather line will tee into the line from the catch can to the exhaust.

Sr20det catch can.png

[PoorMans180SX]

Yeah, you can do that, but it's not very effective. You'll pull better vacuum and make more power with it in the intake before the turbo and after the maf.

[Josh]

or you can just reroute it to the oil pan...

[wileymotorsports]

I know a ton of guys run the catch can to the intake, but wont that eventually coat the inside of the intercooler with a film of oil or does the catch can prevent any oil going back into the turbo? Wouldnt you loose power if you send oil soaked air back into the engine upposed to fresh air? Sorry for all the questions, my car has no vacuum now it just has a small filter on the front of the T coming from the vavle cover and I would like to get that fixed.

[wileymotorsports]

Originally Posted by Josh

or you can just reroute it to the oil pan...

Dont you need vacuum, for the catch can to work properly?

[EsChassisLove]

If you have a HIGH QUALITY catch can with HIGH QUALITY baffling inside, along with a healthy engine, you won't ever need to worry about oil on the turbo, pipes, intercooler ect.

I make it a habit to check mine weekly.

Edit-But to answer your question, Yes. If you dont have a proper setup and a good catch can, you will get oil in there most likely. My T25 and Throttle body had a good coat of oil caked on the fins and butterfly valve with the OEM set up. Didn't help i had blow by on some pistons though.

[KAT-PWR]

you can vent pcv and valve cover through a catch can to atmosphere. It moves enough air. But yes to intake pre Turbo post maf is best as you are actively pulling air out. A high quality can with internal baffling is best. EBay cans are shit even if remote mounted somewhere cool.

[wileymotorsports]

Any suggestions on a catch can??? What about running steel whole in the can? If I run it to the intake do I still need a check valve?

[jr_ss]

Steel wool, will effectively trap airborn oil vapor... The only problem with routing back to the intake side of the turbo, is the chance of lowering your actual octane rating with the oil in the air. A sealed catch can with a vacuum on it and the crankcase will net high power numbers than a vented to atmosphere can will.

You can get a check valve and Venturi for the exhaust setup through summitracing. I'm actually going that route on my VVL conversion. The venturi will pull the vacuum you need once the turbo is spooled. Spooled is a relative term, but anything over 2k rpms would create a negative vac on the can.

[Josh]

Originally Posted by wileymotorsports

Dont you need vacuum, for the catch can to work properly?

there is vacuum inside of your crank case........

[jr_ss]

Originally Posted by Josh

there is vacuum inside of your crank case........

Wrong. You have positive pressure in your crankcase, hence the factory catch cans... Pull your oil fill cap and tell me your hand gets sucked in and I'll call you a liar. Healthy engines have minimal to no air coming out, as engines age it increases over time.
Pulling a vacuum in your crankcase helps seal rings to the cyl walls and remove oily air from it. There are so many ways to argue this though. However YOU want to run it will be fine if YOU'RE happy.

[EsChassisLove]

Originally Posted by jr_ss

Wrong. You have positive pressure in your crankcase, hence the factory catch cans... Pull your oil fill cap and tell me your hand gets sucked in and I'll call you a liar. Healthy engines have minimal to no air coming out, as engines age it increases over time.
Pulling a vacuum in your crankcase helps seal rings to the cyl walls and remove oily air from it. There are so many ways to argue this though. However YOU want to run it will be fine if YOU'RE happy.

This.

I found my SR running so much smoother with the vacuum completed and hooked up correctly.

It comes from the factory like that for a reason. I run 2 catch cans, the oem and an aftermarket can. No problems, or oil at all.

[wileymotorsports]

Originally Posted by jr_ss

Steel wool, will effectively trap airborn oil vapor... The only problem with routing back to the intake side of the turbo, is the chance of lowering your actual octane rating with the oil in the air. A sealed catch can with a vacuum on it and the crankcase will net high power numbers than a vented to atmosphere can will.

You can get a check valve and Venturi for the exhaust setup through summitracing. I'm actually going that route on my VVL conversion. The venturi will pull the vacuum you need once the turbo is spooled. Spooled is a relative term, but anything over 2k rpms would create a negative vac on the can.

Thats exactly what I want do to with my car do you have the link from summit racing so I get the right parts. I feel more comfortable running the line to the exhaust, especially if Im gonna put steel whole in the catch can. That way no risk of turbo damage or oil soaked air getting back into the engine.

[codyace]

Originally Posted by EsChassisLove

It comes from the factory like tha for a reason. I run 2 catch cans, the oem and an aftermarket can. No problems, or oil at all.

100% agree, and that's how I run my car as well. Not a drop of oil anywhere.

[lazysk8er2]

Originally Posted by EsChassisLove

This.

I found my SR running so much smoother with the vacuum completed and hooked up correctly.

It comes from the factory like that for a reason. I run 2 catch cans, the oem and an aftermarket can. No problems, or oil at all.

got any pics?

[wileymotorsports]

Pictures of that setup would be great!

[jr_ss]

Wiley, here are the links to the items needed to route it to the exhaust...

Venturi nipple
Moroso 97810 - Moroso Replacement Weld-In Nipple Fittings - Overview - SummitRacing.com

Check valve
Moroso 97800 - Moroso Replacement Check Valves - Overview - SummitRacing.com

[codyace]

Originally Posted by lazysk8er2

got any pics?

Rear block vent, to the OEM Oil Air Sperator in the back behind the wastegate, to the VC T, from the VC T to the Greddy catch can, from the catch can to the intake. PCV hooked up on far side like OEM too. Don't mind the two different catch can hoses they are now the same (man that is an old pic haha)

[wileymotorsports]

Originally Posted by jr_ss

Wiley, here are the links to the items needed to route it to the exhaust...

Venturi nipple
Moroso 97810 - Moroso Replacement Weld-In Nipple Fittings - Overview - SummitRacing.com

Check valve
Moroso 97800 - Moroso Replacement Check Valves - Overview - SummitRacing.com

Thanks!!! Im going to order the parts right now. What AN size fittings and hoses are you guys using to replace the T and PCV?

[EsChassisLove]

Mine basically looks like Codyace' you just can't see the can from that angle.

[jr_ss]

Originally Posted by wileymotorsports

Thanks!!! Im going to order the parts right now. What AN size fittings and hoses are you guys using to replace the T and PCV?

I used -10AN fittings and lines...

[wileymotorsports]

Originally Posted by jr_ss

I used -10AN fittings and lines...

Ok great thanks for your help!

[4x4le]

Im going to be running something very similar to this on my new engine, except its the vibrant performance one. I wont be running a can either.

I do however have the blu 808 modified valve cover. I have found there to be no need for a can anyways with this valve cover when routed normally.

[Kingtal0n]

Originally Posted by jr_ss

You have positive pressure in your crankcase, hence the factory catch cans... Pull your oil fill cap and tell me your hand gets sucked in and I'll call you a liar. Healthy engines have minimal to no air coming out, as engines age it increases over time.
Pulling a vacuum in your crankcase helps seal rings to the cyl walls and remove oily air from it. There are so many ways to argue this though.

good info here, I would like to add:

anything that leaks past the piston rings, into the crank case, is a potential combustion byproduct that should not be allowed to become part of the engine oil, which it may dilute and render less effective. Simply providing a way out (PCV) will keep the oil cleaner, longer. That is the first major benefit of PCV.

The next benefit is piston ring seal. A long time favorite for blown V8 engines is the vacuum pump- Drawing as much vacuum as possible from the crankcase may yield between 50 and 100 horsepower on a roots-blower style 700 horsepower V8 engine. The additional horsepower speaks for itself, having a vacuum in the crankcase is a benefit to power production, regardless of the arguable reasoning for it, It works.

So we have additional power, and cleaner oil. Now lets talk placement and functioning.

On an OEM SR20DET engine, if you notice, there is always a slight vacuum during idle coming from the T-shape valve on the valvecover. Thats because there is a direct connection from the crankcase to the intake manifold, that, during engine vacuum situations, pulls a vacuum from the crankcase.

But during a boost situation- that is, when power production is expected, that valve shuts off tight. Why? because if it remained open, the boost pressure in the intake manifold would ADD pressure to the crankcase, instead of pull a vacuum (we want a vacuum, not additional pressure). So where does PCV come from during boost situations? How can the engine have a vacuum in the crankcase during boost, if there is boost pressure in the intake manifold?

The only source inlet vacuum on the SR20 engine during a boost situation is: The pre-turbocharger inlet pipe. That is where and why the OEM PCV valve connects to the valvecover from the turbocharger inlet- During boost, the turbocharger is sucking air from the inlet pipe, and some of that suction is applied to the crank case!

The negative of this situation, is of course, oil vapor from the valve cover may enter the turbocharger. And indeed, some of it does. The factory has a decent baffle and catchcan designed to somewhat deal with this situation, but it may be improved upon with an additional catch can of proper design, placed between the valvecover and turbocharger inlet. This is perhaps the safest design, however, some catch cans do not provide an adequate vacuum source to be applied through them, and there is very little testing and development done this way, so choose carefully and route carefully when adding a catch can between the valvecover and turbocharger inlet.

The only "safest possible way" of keeping a PCV system during boost functioning without utilizing the turbocharger as a vacuum source is: an external vacuum pump. If you have an external pump (say, belt driven) Pulling air from the crankcase- you no longer need to worry about oil getting into the turbocharger inlet and fouling your precious plumbing.

[EsChassisLove]

Next question is who makes the BEST catch can.

I know theres a catch can thread, but that thread seems like mainly pics of set ups.

[wileymotorsports]

I have one more question, do you guys replace the PCV with the AN fittings if I'm going to T everything or do I keep the PCV and add the AN fittings to that??

[4x4le]

There really is no reason to replace the pcv valve with an AN fitting. Also routing it to your exhaust properly will pull a vacuum on the crank case still. In all actuality running it in the exhaust is pretty much the same thing as putting it in the turbo inlet if not better. There isnt much of a vac AT ALL between your filter and turbo and if there is your filter is too restrictive. There is a small lack of pressure but it really isnt drawing as hard on your crank case as you might think.

The shape of the venturi does cause a pull on the crank case (if positioned properly). The velosity of your exhaust will create a lack of pressure in the system and pull on the crank case. Just as in your turbo inlet, there really isnt a vacuume to be measured, there really isnt positive pressure to be measured in your exhaust.

[wileymotorsports]

The Venturi holes face towards the rear of the car, correct??

[kevmeistah21]

Originally Posted by codyace

Rear block vent, to the OEM Oil Air Sperator in the back behind the wastegate, to the VC T, from the VC T to the Greddy catch can, from the catch can to the intake. PCV hooked up on far side like OEM too.

I never thought about that, I just bypassed the oem seperator. I'm gonna put it back tomorrow
Lol! Thankss!

[cotbu]

Most people that ditch the oem oil/air separator remove the hose with it. In that hose is a brass fitting that slows down the air and oil before it reaches the T. I kept my separator for a while until experimenting with megan and ebay manifolds. That's when I noticed oil in my intake pipes all the way to the intercooler. After cleaning and putting everything back to stock, I notice I split the old ass hose, so I peeled it apart. That's when I found the fitting. Put that fitting in the new hose, removed the separator, and took it for a spin all good. So I left it like that for a month or so. Checked my pipes clean, no film. I eventually swapped the megan crap back on. Yeah it cracked! This Is R&D!