Confusion about catch can

GroundhogSS · 07-31-2016, 03:53 PM

I was watching a recording of "Detroit Muscle" from a few weeks ago where the people are building up a twin turbo hemi to put in a challenger. The said they were going to put on a catch can to keep oil out of the intake, a Moroso, I think. Okay so far. When they installed it, they ran a line from the PCV valve to the intake on the catch can. Then they plugged the outlet with a cap and also capped off the input to the intake manifold. How is this going to do anything, other than build up pressure in the crankcase? Am I missing something here? Those guys must be actors and not real mechanics.

Ian SS · 07-31-2016, 04:14 PM

Some catch can setups are just vented, where they run a line from the PCV to the Catch Can and the can itself vents to atmosphere. This doesn't really work as effectively as a can that routes back to the intake to pull pressure out of the crank case, but it does work. If they just capped off the catch can and it's not venting then that is pretty stupid lol.

Ventmaster · 08-01-2016, 04:47 PM

They plug the inlet to the intake manifold because it will be pressurized when the turbo's provide boost, but I agree they need to provide a vacuum source to the can.

Most systems run a line from the air intake prior to the pressurized turbo output. If the engine is running, on boost or not, there is vacuum there. That line would be the catch can output (pulling from) line.

07-31-2016, 03:53 PM	#1
GroundhogSS Drives: '17 2SS convertible'20 Yukon Denali Join Date: Nov 2011 Location: Cedar Park, Texas Posts: 2,934	Confusion about catch can I was watching a recording of "Detroit Muscle" from a few weeks ago where the people are building up a twin turbo hemi to put in a challenger. The said they were going to put on a catch can to keep oil out of the intake, a Moroso, I think. Okay so far. When they installed it, they ran a line from the PCV valve to the intake on the catch can. Then they plugged the outlet with a cap and also capped off the input to the intake manifold. How is this going to do anything, other than build up pressure in the crankcase? Am I missing something here? Those guys must be actors and not real mechanics. __________________ Richard 2017 2SS SIM convertible, A8, NPP, MRC, 56R wheels, GM CAI, Diode Dynamics Side Markers Delivered: 08/15/2016 #TeamBeckyD

07-31-2016, 04:14 PM	#2
Ian SS Drives: 2016 1SS, 2017 JKU Wrangler Join Date: Mar 2016 Location: San Diego Posts: 876 View My Garage	Some catch can setups are just vented, where they run a line from the PCV to the Catch Can and the can itself vents to atmosphere. This doesn't really work as effectively as a can that routes back to the intake to pull pressure out of the crank case, but it does work. If they just capped off the catch can and it's not venting then that is pretty stupid lol. __________________ SLO 1SS - sold 1SS MRC NPP 6MT 2018 Ram Rebel 4x4 5.7

08-01-2016, 04:47 PM	#3
Ventmaster Drives: 2017 1SS 6spd Join Date: Jan 2011 Location: Utah Posts: 2,869	They plug the inlet to the intake manifold because it will be pressurized when the turbo's provide boost, but I agree they need to provide a vacuum source to the can. Most systems run a line from the air intake prior to the pressurized turbo output. If the engine is running, on boost or not, there is vacuum there. That line would be the catch can output (pulling from) line.

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