Hey guys just wondering if i remove the emissions stuff but keep the BAC do i need the hose that comes off the charge pipe to bac i want to install an aftermarket Blow off valve and adapter pipe where the charge pipe would be

 

I have an aftermarket BOV and BAC. They use different openings on the pipe. Instead of using an aftermarket pipe get the BOV flange welded onto the stock pipe where the recirculating valve thing was.

 

does the BAC need the air from the charge pipe?

 

AFAIK it needs air from somewhere pre-TB. From what I understand thats how it controls the idle changes, by blocking or letting additional air into the engine. You could probably route it to somewhere else before the throttle body besides that pipe but then you'd have another hose running around the bay and you'd have to make something for it to attach to in any case.

 

The BAC just uses a metered air source (between AFM & TB), so you could route a hose from somewhere like the intercooler if you wanted to. Actually, I think arghx told me he actually has his BAC inlet open to the air instead. Engine vacuum would still pull air in, but a little filter would be a good idea.

Also, if you haven't done so, remove the coolant passage from the BAC and re-route the hoses between the water pump housing, TB & rear iron. The BAC's coolant passage is overkill for the most part, and it functions fine without it. Plus, it helps clean up the bay.

 

rotaryrocket you got some pics of re routing the coolant ??

 

Not at work I don't. Basically the normal path is this:

water pump housing -> BAC -> thermowax -> rear iron

And the new path can either be:

water pump housing -> thermowax -> rear iron

Or:

water pump housing -> rear iron

I just ran a new coolant hose under the UIM in the open space next to the primary fuel rail, then up to my thermowax, and then the normal hose from the thermowax to the rear iron can be used from there.

 

I rerouted the coolant on mine too, I just went to checkers and looked through their lines for one the right length that had a 90* bend in it and went from water pump housing to rear iron. If you use a straight line it will bind when it bends. That stupid hose was like 18 bucks though.

 

My BAC valve is opened to atmosphere... but I do not have the stock AFM (using a Power FC), so metered air is not required. For those on stock ECU or Rtek, the BAC just needs a 5/8" hose supplied from anywhere after the AFM. The FD BAC valve is actually bolted to the back of the dynamic chamber on the UIM and is fed from a passageway cast into the primary bore of the TB. It doesn't use a hose at all.

I agree that you can eliminate the coolant hose on the BAC. Its primary purpose is to prevent the valve from freezing up (see the s4 training manual, fuel and emissions section), but if you aren't in a really cold climate it's not needed. I have no coolant hose on mine.