View Full Version : So I've been reading about Z06 Catch Can
XfireZ51
09-14-2015, 09:43 AM
I installed an oil/air separator last year on the ZR. One thing I have noticed was how much cleaner my exhaust tip are now. They don't have a sooty film over them, and they clean sooo much easier now. However, I have been reading about the C7Z06 and the catch can being used there. It utilizes 3 inputs/outputs.
They also utilize a check valve flowing away from the catch can to the vacuum source. Of course, the Z06 is boosted and so I don't know how that changes things relative to our NA motor.
There's a post here that discusses the install of the Z06 can.
http://www.corvetteforum.com/forums/c7-z06-discussion/3703677-oil-catch-can-and-clean-side-oil-airseparator-tech-discussion-2.html#post1590396406
Wondering if the check valve is something I should consider. I am assuming th chck valve shuts off flow from the can to the plenum when going WOT.
Anybody lend any clarity to all of this?
Looks similar to this for the C7 Stingray.
https://www.youtube.com/watch?v=Mk4e5XFe47A
The check valve closes when the intake pressure (source of vacuum for PCV system) goes from negative(vacuum) to positive to prevent boost pressure from going into the crankcase.
XfireZ51
09-20-2015, 12:31 PM
So Jerry, although we are nowhere near boost pressures, at WOT, atmosphere and manifold pressure is nearly identical so does that mean we are not getting much in the way crankcase pressure relief? I'm asking because I seem to be getting a bit more blue smoke under hard decel after hard accel.
XfireZ51
09-20-2015, 12:35 PM
Karl,
So it looks as if they are using a check valve on the LT1 despite it not having a SC. HMMM
Then they still get vacuum at WOT by using a third port and tapping in upstream of the throttle body.
So Jerry, although we are nowhere near boost pressures, at WOT, atmosphere and manifold pressure is nearly identical so does that mean we are not getting much in the way crankcase pressure relief? I'm asking because I seem to be getting a bit more blue smoke under hard decel after hard accel.
You are correct. The PCV system is essentially non-functional under WOT conditions.
Under hard deceleration, intake vacuum is at its greatest, resulting in higher than normal PCV velocity to the intake, which lessens the effectiveness of the catch can system.
Karl,
So it looks as if they are using a check valve on the LT1 despite it not having a SC. HMMM
Then they still get vacuum at WOT by using a third port and tapping in upstream of the throttle body.
My "guess" is, it would serve the same purpose the LT5 cam cover vent tubes do, which is two-fold, (1) as a filtered air purge of the crankcase for the PCV system under normal operating conditions, and (2) as a vent for high crankcase pressure at WOT.
I don't believe there would be any appreciable/measurable vacuum upstream of the throttle body.
XfireZ51
09-20-2015, 04:50 PM
Jerry,
You're correct in that the cam cover vents into the airhorn.
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