I've been seeing quite a few cars with oil catch cans even though they don't have turbos or anything, whats the purpose, is there any actual benefit?

 

As the oil churns in the crankcase it creates vapors which need to evacuate and are therefore routed through the PCV to the intake. Oil catch cans are designed to separate and collect the oil only returning the air to the intake.

I have been looking into installing one and I read some people don't think it is necessary for a naturally aspirated engine but IMO I would say that there is a benefit.

 

Ran 1 on my srt8...still have it, but this car you need 2 of them as the line is split in 2 locations. Too much trouble find cans that fits plus 2 of them plus the lines & finding room.

 

For most of the VQ35DE guys it is a very common mod - it helps remove oil from intake air (increasing power, albeit minimal) as well as helps to alleviate oil consumption. Beneficial, and there are 2 different styles you can use. Beneficial on these cars, even for NA. Even more requisite for the FI guys.

 

Catch cans don't add anything power wise, it's not a power mod. What they do it prevent oil sludge buildup in the intake. Which if there's enough of the ECU will sense the restriction of air & pull timing which then may reduce your response......
Guys that race or track use their cars benefit far more then your normal DD driving to work & back.
I put catch cans up there with K&N replacement stock filters......Principles based on real facts that have little real world impact.

 

VQ37's are known for sludge and BS build up at the throttle bodies. I think this would reduce it.

 

These motors spit a lot of oil vapor. Most motors do actually as I've installed a CC on almost every car I've owned and every oil change its a good amount. Its best to keep the vapor out of the intake system so it doesn't build up. Over time it will rob power, decrease mpg, and from what I've seen the oil saturates gaskets like the lower manifold to head gasket allowing a little to leak by.


Actually the bottom end builds pressure because the pistons are going up and down and some compression leaks by. This is why it's called "blow by" and why your oil turns black. You're leaking burnt up gases past the piston rings as no rings are 100% air tight. If you didn't have a release point for the blow by you'd explode the bottom end. When the built up compression is pushed out, oil and used gases escape out. Or in a stock form are sucked out by the PCV system attached to the intake manifold acting as a huge vacuum cleaner. Leaving the system as is with a CC actually does add power since the pistons have a draw on them on the bottom vs just taking everything off and letting the PCV vent to atmos.

No you don't need two. Just run two lines to one CC and run two lines back to the manifold.

It doesn't alleviate oil consumption unless you run the CC back to the oil pan. If you have a gallon sized CC and it's not run back and you blow out a gallon out of the motor, the motor will be dry. If you leave it stock and blow out a gallon the motor will just burn it up and spit it out the exhaust pipe. Either way the motors dry. Luckily for us we don't need a return hose to the oil pan unlike Subarus that sit sideways and puke all their oil out of the valve vents during high G turns. If your motors healthy you'll only blow out a little of one quart every 3000 miles.

In a way yes it is. A motor doesn't like air/fuel/oil. Hense the term air/fuel ratio. Every time you lay off the throttle after a WOT run the PCV system starts sucking huge amounts of blow by you just built up since in WOT the PCV system closes. When you return to WOT around the next corner you don't want all that blow by gas and oil vapor sitting in your manifold robbing power. This is why you need a CC or AOS (air oil separator). And the ecu actually can't tell about a restriction since the sensor sensing flow is the MAF sensor which is well before the TB's, and manifolds. You won't pull timing unless you have enough blow by causing knock since the motor is having its AFR messed with. The O2 sensor however will adjust things (lower your power) by what you're spitting out the tail pipe. This is why you lose MPG. The Ecu will add fuel to make up for the robbing of power and poor condition of the motors health.



To sum it up get a CC. Your motor will thank you...PS in winter you produce chocolate milk from condensation plus oil. Summers normal though.

 

That's a lot!

 

Of oil? That's only 1000 miles. That's when I do mine. Every oil change I lose maybe 1/8th inch of the dipstick. I'd guess that's <1/4 of a quart?

 

Meh..I'm not a big believer in these things. Yeah I see your points but I also know that this isn't some race car. 99% of people will never notice anything different.
The 1 I had came with the car so it was just there.

 

What's not to believe? Car blows by oil...period.

Every 1000 miles...



Here's a VQ at 58k. Oil sludge! Period.