Brad,

I spoke with a fellow engine builder I know that has built several 496s. He said the challenge with the procharger 496 system is it builds positive crankcase pressure when under boost. The orifice built into the factory intake manifold needs to be plugged to fix this, but there's no easy way to do that other than removing the manifold to make the modification. This must by why procharger doesn't have that in the instructions.

87Mirage,

I hear that.

I’m not really pleased with the intake location for the ProCharger, either. It’s drawing air from under the engine. Not entirely, but it’s way down there, and tucked right against the port side of the engine, and with cooling plumbing laying right across the breather. I’m planning on adding some ducting and reworking the plumbing a bit to remedy this issue. Would it be feasible to add a bung to this intake ducting, ahead of the ProCharger intake snout, and plumb the filler tube vent to it to mitigate some of this positive crankcase pressure? I’m pretty sure we can generate an RPM relative vacuum this way. Don’t know if it would be ideal, but it’s what I’ve got to work with, short of pulling the intake manifold.

Thanks. Brad.

That's a good question, can you create enough vacuum to overcome the crankcase pressure under boost. Well, one way to find out!

87Mirage,

As long as it’s enough to keep from pushing oil out of the dipstick tube, I’d be happy at this point.

I also noticed there is a line going from just downwind from the throttle body, leading off behind the engine, but goes beyond line of sight and reach. I have to assume it’s a vacuum line of some sort. I wonder where it’s going and what it’s doing at positive manifold pressure condition….?

Thanks. Brad.

You are probably seeing the air bypass line going to the IAC valve.

I had come across Raylar's explanation of the PCV setup on the 496 and was going to add to this conversation, but I figured the folks at ProCharger would have addressed this in their installation. I guess I was wrong! This explains why I've seen some other 496s with ProChargers blowing oil and the dipstick out of the tube.

Building the crankcase ventilation setup is a good idea in concept, but I do not think it will be enough to overcome the pressure produced by the supercharger. Rather than go modifying stuff for an uncertain gain, I would try to live with it for the season, and then pop the manifold off during the "off" season to plug it up.

TomZ,

That shouldn't be a problem, since I've been living with it for three seasons now. That said...

I plan on extending the intake tract to get the breather up into clean, cooler air regardless, and the filler tube vent has to go somewhere. THAT said..........

This is going to end up being a winter project anyway, I think. The plumbing issue is going to be a PITA to deal with, as I have no room to work with, and I ain't as flexible as I used to be. If the original project that kicked this topic off is any indicator, the ducting project will take longer than anticipated, and I don't want to have to keep taking crap apart, then putting it back together, every time we plan on taking the boat out. I took the plumbing apart once, to get a general lay of the land down there, and, after putting it back together blind, I was paranoid as FARQ when we took the boat out last, worried about whether I had everything back together correct, hose clamps tight enough, etc. The last thing I want to do is sink the boat trying to solve a minor oil loss issue. I need to acquire some formed radiator hoses of the appropriate sizes, with various bends in them, so I can Frankenstein the plumbing out of the way for the ducting. There's just no "working with" what's already there.

Thanks. Brad.