Plugging the lower intake

01yellercobra

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I'm thinking about plugging the hole on the bottom of the lower intake, but keeping the upper PCV hose connected with a check valve and catch can. I want to keep the PCV in place as I don't want to deal with possible oil smell and, well, California. Has anyone ran a set up like that? My main reason is getting rid of that lower hose is one less thing to possibly break and cause vacuum issues. Thoughts? Opinions?
 

94slowbra1

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Not the same as you but I just deleted the whole pcv system in mine, including plugging that return line. No more oil residue for me
 

01yellercobra

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Not the same as you but I just deleted the whole pcv system in mine, including plugging that return line. No more oil residue for me

I'm trying to stay somewhat legal currently. Down the road when I live somewhere with more relaxed smog laws I might get rid of the system altogether.
 

bigmoose

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I'd go all or none. The concern with plugging the lower intake but still allowing vapors into the intake could result in a good pool of oil in the lower manifold. However, I'm not sure constantly recirculating oil past the intercooler is a good idea either. The system as a whole is flawed and no catch can is perfect. I have mine plugged and I run breathers. I don't have any smell or oil coming out of them. I do run amsoil signature series if it matters.
 

94slowbra1

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^^^, no matter what type of filter, catch can ect... you run some will get by and if you plug the port on the intake it has no where to go
 

01yellercobra

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I've had good luck with the catch can I'm going to be running. I agree that the best way to be sure is to run breathers, but the can I'm running kept my intake dry even after the engine blew. I poured a lot of milkshake out of it. But the intake was bone dry when I pulled it.
 

Roots-type

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if you plug the port on the intake it has no where to go
That was my line of thinking also, but then I took a look at my stock Mach lower intake manifold and it has a floor that is comparable in depth to that of the cobra lower manifold and it was never given a return line like the cobra lower. I don't recall ever seeing another pcv system that had a return line like the cobra's. If it's truly necessary I don't see how the other cars are getting by without one.
 

cj428mach

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That was my line of thinking also, but then I took a look at my stock Mach lower intake manifold and it has a floor that is comparable in depth to that of the cobra lower manifold and it was never given a return line like the cobra lower. I don't recall ever seeing another pcv system that had a return line like the cobra's. If it's truly necessary I don't see how the other cars are getting by without one.

They arent under boost
 

Roots-type

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They arent under boost
What about Procharged and Vortech blown Mach 1s and new edge Cobras? What about turbocharged terms that use the Mach 1 lower?

If anything, I see boost as a way to get these supposed 'pools of oil' off the floor of the intake.
 

vdubn

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In the Dept of Boost setup that runs in the Coyote engines, using the GT500 SC, etc., the lower intake is sealed. In the end, if you are running higher boost, and run a drivers side and pass side catch can. I will be running a drivers side can that comes from the back of the SC, to the catch can, then the other side of the can to the PCV valve at the back of the drivers side valve cover. The pass side catch can will come from the intake tube, to one side of the catch can, and the other side will go into the valve cover, thereby keeping the system sealed, and eliminating oil vapors from the intake track. The other win, is getting rid of about 5 junctions/reducers/fittings that can leak causing vacuum leaks and inconsistencies that can affect performance negatively.

You can run this same setup regardless of boost levels, but according to JLT its especially helpful in the higher boost applications (higher than 15psi).
 

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