Quote:
Originally Posted by cody
Which system is more important to use a catch can on? I've always read it's bad to use one can for both.
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It's not terribly "bad" as long as the hose diameters are all proper... after all, both systems return to the intake right next to each other. As long as the line from the can back to the intake doesn't cause restriction that allows crank ventilation to circulate into the heads (or vise versa I guess) then one can should be fine.
Though ideally, you'd have two cans, one for the valve breathers, one for the crank/pcv, you can definitely get away with one well designed can. Look at the Grimmspeed AOS... it's basically a single can for both systems, it's just that the can is the driver's side valve cover.
But if you're going to install on just one system, I'd guess the crank case/pcv is the better system for you to catch. Simply because you're not seeing long sustained G's at the track, plus with some mileage on your motor, you're more likely to have piston blow-by that's pressurizing the case more than a fresher motor might. But it's really probably a toss up... the right answer is "which ever system is blowing more oil".