Especially on a low mileage car... I'm just curious as to how many people are using them and why? I figure that it's something that Subaru would have thought of. What are the benefits and are there any problems or risks? I understand the idea, but is blow-by really that big of a problem on these cars?

 

No risks or problems with running one, provided it's routed and hooked up correctly. Frnakly, I'm surprised catch cans aren't OEM on turbo cars, since dumping the can into your dirty oil after an oil change is better for the environment than burning the vapors anyway. I'd run one personally.. if I had a turbocharged car that is.

 

hippie alert!!!!!!

 

Yes. Catch tanks are very much so worth it. Mainly for 2 reasons. Both have to do with oil getting into the intake system and eventually into the combustion chamber. First, the oil mixed into the air/fuel mixture will lower the knock threshhold making your car more prone to detonate. You want to keep the oil out of the combustion chamber at all all costs. Second of all, oil in the intake system will foul the sensors. You have a number of sensors in the intake manifold. Also, oil will screw up your idle control system and throttle body. generally speaking oil will coat the insides of your intercooler too making it less efficient as well. So yeah, keep the oil in the catch tank.

However, simply hooking up the tank is not good enough. It must be routed right in order to catch all the oil it needs to catch, leave the oil it shouldn't catch alone and provide enough vaccum for both more efficient oil "catching" as well as insuring that the crank case pressure is at the very minimum EQUAL to that of the cylinder heads. In best case scenario, lowering pressure of the crankcase below the cylinder heads will increase your overall compression and insure that the maximum potential combustion occurs.

Properly setup oil catch tank, crankcase/cylinder head ventilation system is somewhat of a black magic. Those who archive maximum results usually don't talk about it. Personally I have been playinig with hose routing and sizing for a very long time on a number of my cars (WRX, Legacy and shop EVO). I think that I am very near archiving my goals with proper oil catch tank setup.

You must remember that hose size, routing setup, t's or no t's, fitting sizing all very much affect how your oil catch tank crankcase/cylinder head ventilation system performs.

In case all this got you crosseyed, with a basic catch tank you want to maintain the hose size from the vent point to the tank without t'ing it and having same # and size of OUT fittings are there are IN fittings. You DO want to vent the other (out) side of the catch tank into the intake system PRE-TURBO insuring that proper vaccum is there. In other words, your crankcase/cylinder head vent system MUST remain the same BUT you just add the catch tank between BOTH cylinder heads and ONE of the crankcase ventilation system outlets.

 

That's what I call a good answer! ^^

 

HMMMM.....interesting. I had also heard that you need to run 2 of them on an STi...something about PCV systems off both cylinder heads. I'm not sure if I'm using the correct terms. I was looking at the Perrin catch can. I assume that the instructions from any manufacturer are detailed.

 

Damn.. that was a fricking great answer!

Anyway - I now know why I have an oil catch can. I have the Perrin and like it. I have had it installed for about 3 months and the oil which is collected might be 1 cc but hey... its 1cc that didn't go into my FMIC!

Question to those running a catch can... how much do you usually collect and what turbo are you running.

I run an FP Red and catch 1cc (approx) per 4 months.

 

I run two of them simply to keep the PCV and crankcase ventilation separate. They both dump back into the intake, with or without catch cans, but there is some conjecture as to when each of them dumps and what state and or cycle the engine is in. To be safe, I just separated them as they are in stock form.

I think I have some pictures at home - I'll check.

 

Thanks guys! Everyone is helpful as always. It's a little bit off an adjustment for me... when it comes to Mustangs, Lightnings, and the blue oval I'm usually the one in the know, not the one relying on everybody else for good info. Thanks again!

 

Hyperflow makes an awesome catch can.

 

Speaking of the American muscle. They have kits for those cars. It is basically a PVC system that is routed into your exhaust system and the back pressure created vaccum sucks the crankcase pressure out of the crankcase, actually creating vaccum in the crankcase, thus improving the pistom ring seal and increasing overall combustion pressures and create more power. The only downside is, your car will smoke a lot.

 

damn Alex nice answer........so when will you have a diagram out for us idiots?

 

I second that.

 

bump for the diagram!!!

 

catch cans work I dump mine every oil change

Please excuse the different hose diameters, I was in a bind at 3am in the morning and I've been lazy to change it for the correct size.