Thread: Intake tubing lines....

I have a lowport... doing blow through...

I'm in the middle of boosting my car and I need to know if and where to reattach the big vac. line that use to be on the bottom side of the stock plastic intake or do I even need to?

Next, the line that comes off of the valve cover that goes to the stock intake... do I run that before the turbo or the same area as stock? I was thinking before the turbo but I'm not sure...

Thanks,
Truett

The large vacuum line you describe feeds the cold idle control valve. It's important if you ask me, but others remove that system entirely. It needs fresh, filtered air and with a boosted car, I believe it is a potential for a boost leak if you just put a filter on it, so it should be plumbed back into the charge piping. Basically, reproduce what the factory has done.

The other line you mention that comes off of the valve cover, that needs to be run to before the turbo (no boost, just as you thought) or if you have to, you can just vent it to atmosphere.
Again, not mandatory, but if you plumb it into the intake system before the turbo, it's a good idea to put a secondary catch can in-line with it. One that can flow a decent amount of air too. Although technically there is already a catch can for both sources of crank-case ventilation. The lower block has a visible catch can mounted by the exhaust manifold, and the valve cover vent has an elaborate oil separation labyrinth inside the top of it already.

Thanks a bunch Ben... So would need another catch can? I still have the stock separator.

Like I said, you don't need it, but it's nice to have. And how much oil gets by the two stock separators can vary a lot between engines. You might have almost no oil coming past them, while you might have a good bit that a second catch can would catch. You can always put a white rag over the line as a filter and vent it to atmosphere for a week or two to get an idea of how much oil is getting past the stock separators.

you can ditch the catch can if you switch to a rr or ve valve cover. this is what I am going to do.