MM Catch Can Question
MM Catch Can Question Dumb question ahead. 
Ordered a MM can to setup as a draft can, nothing fancy. But I was curious on the inner setup of the can, since there is a filter on the top of the can, how can you pull a vacuum through it?
Its still early so cut me some slack.
Ordered a MM can to setup as a draft can, nothing fancy. But I was curious on the inner setup of the can, since there is a filter on the top of the can, how can you pull a vacuum through it?
Its still early so cut me some slack.
from what I understand there is a 1-way pcv valve on the top of the can (check valve) that only allows pressure to escape. So if you plumb the rest of the can to a vacuum source, that check valve should remain closed allowed pressure to drop inside the can.
However I am not a fan of any extra pcv valves in a pcv system (besides the one you already should have on the intake manifold side) so if you do not need the extra valve for whatever reason I would find a way to disable it.
However I am not a fan of any extra pcv valves in a pcv system (besides the one you already should have on the intake manifold side) so if you do not need the extra valve for whatever reason I would find a way to disable it.
from what I understand there is a 1-way pcv valve on the top of the can (check valve) that only allows pressure to escape. So if you plumb the rest of the can to a vacuum source, that check valve should remain closed allowed pressure to drop inside the can.
However I am not a fan of any extra pcv valves in a pcv system (besides the one you already should have on the intake manifold side) so if you do not need the extra valve for whatever reason I would find a way to disable it.
However I am not a fan of any extra pcv valves in a pcv system (besides the one you already should have on the intake manifold side) so if you do not need the extra valve for whatever reason I would find a way to disable it.
I do not have a PCV source as I run a single plane so draft style is all I can realistically run.
TECH Apprentice
Joined: Feb 2008
Posts: 315
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From: IOWA
I have his can and a single plain too. Get his oil cap with -8 male.Assuming you got -8 fittings on the can. Its a nice piece. Plug all the other ports in the valve covers ect. that came with the catch can. Connect oil fill to one side of can. Connect the other to the inlet of the turbo. He has the instructions on his site. Dont worry. I badgered Dave with the same questions. Really nice guy. In the end, I just had to follow the instructions that it came with. lmao
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Verdad Gallardo I drilled a hole in one of the pipes, installed a grommet and stuck a nipple to 6an fitting in it. Than 6an line up to catch can.
As far as how well it works, IDK yet. MM can seemed to be smoking a little at idle which has me concerned but did not really get the car hot or drive it.
As far as how well it works, IDK yet. MM can seemed to be smoking a little at idle which has me concerned but did not really get the car hot or drive it.
Note: the PVC & one way filter are separate components
The MM website instructions for FI show:
Intake manifold ( behind TB) to can ( for suction), this is where the PVC is located.
Then valve cover to can. Lastly, valley connects to pre compressor. In my case it's on the intake just under my air filter.
The concept is that under normal conditions ( out of boost) the intake behind the throttle body is sucking gasses from the VC. As soon as the intake see's boost the valve in the can closes ( this is so you don't send pressure into your crank). At that point, under boost the vacuum created by the supercharger ( at the air filter) is then sucking gasses via the valley outlet. What always seemed strange to me is that there is no catch can on this last valley connection. Nothing to catch oils if they make it through. It seems to work fine. When I asked Dave about this he said, this system avoids any pressure build ip in the crankcase and that is why you won't find oil mess being pulled from valley. ( also the valley has a better baffling compared to VC.
The little airfilter on the can has a one way outlet. This helps if some boost does bleed through and gets caught in the system. It at least finds its way out before it hits the crankcase.
This is my understanding hope it helps. Like many of us .... I had a hard time wrapping my head around catch can routing. Use the MM website instructions for your setup.
The MM website instructions for FI show:
Intake manifold ( behind TB) to can ( for suction), this is where the PVC is located.
Then valve cover to can. Lastly, valley connects to pre compressor. In my case it's on the intake just under my air filter.
The concept is that under normal conditions ( out of boost) the intake behind the throttle body is sucking gasses from the VC. As soon as the intake see's boost the valve in the can closes ( this is so you don't send pressure into your crank). At that point, under boost the vacuum created by the supercharger ( at the air filter) is then sucking gasses via the valley outlet. What always seemed strange to me is that there is no catch can on this last valley connection. Nothing to catch oils if they make it through. It seems to work fine. When I asked Dave about this he said, this system avoids any pressure build ip in the crankcase and that is why you won't find oil mess being pulled from valley. ( also the valley has a better baffling compared to VC.
The little airfilter on the can has a one way outlet. This helps if some boost does bleed through and gets caught in the system. It at least finds its way out before it hits the crankcase.
This is my understanding hope it helps. Like many of us .... I had a hard time wrapping my head around catch can routing. Use the MM website instructions for your setup.
On The Tree
Joined: Jan 2015
Posts: 123
Likes: 0
Haha I remember when I was confusing myself when I first purchased a mm catch can. So i just started thinking about the can in two different modes. the first mode I think of is pcv mode, the can is essentially your new pcv setup while under vaccuume. plain and simple. then the other mode is boost mode, which the one way check valve stops intake boost, but the dirty line going to the can that coming from the valve covers is venting any blow by you may have through the can. and that's it, it's that simple. no reason to complicate it any further. i was just like chub stated, in the end I thought in my head whst u just told you and I read the instructions for pcv mode and It made sense!
I have an lt1 gen 2, so that's that lol
I have a single plane so no pcv source either. I run a draft can from Dave, so it's only working under engine vacuum. I use vac source prior to the turbo and use a valve cover to pull from dirty side wise.
I drove it to a car show this weekend and other than my heat soaked dead starter, no fumes at idle! #sucess
I have a single plane so no pcv source either. I run a draft can from Dave, so it's only working under engine vacuum. I use vac source prior to the turbo and use a valve cover to pull from dirty side wise.
I drove it to a car show this weekend and other than my heat soaked dead starter, no fumes at idle! #sucess