I've got my FLT level 5 transmission ordered with the Vacuum Mod Kit. I've read when using the Vacuum mod in Boosted applications i'll need to install a "blower bypass check valve" to prevent boost from entering the vacuum circuit.

How did you guys install this and what vacuum lines did you tap into? Talking to Chuck he said I don't need a bypass check valve if i tap into a line that never sees boost, only vacuum. That just confused me even more. Does anyone have any experience with the vacuum mod kit and FI? If so, how did you run your lines? Thanks!

 

You'll have to run a vacuum line from somewhere on your engine to the vacuum modulator on the tranny. I used a T fitting off the brake booster line. Then you just put the bypass check valve somewhere in the line that runs to the tranny. You'll want to make sure that the check ball faces upward or it won't work right.

The only line I can think of that should never see boost is the crank case line in the PCV system.

 

Ask him how he knows this...

 

The vaccum line just has to be pre boost. I hooked mine up to the j-tube. There is a place for it to go just behind the TB.

 

Just to clarify, by doing so you're NOT using the blower bypass check valve, correct? So the vacuum line your connected behind the TB goes straight into the transmission to the vacuum mod? Did you use a T-fitting at the TB?

 

Very well said, I guess I didn't get my message across clear enough in my conversation about the j-tube connection.

 

Is this right?

 

That should do it, or put a "T" in the line to that brake booster hose. The "T" FLT sent me fit right in there. Anything ON the J-Tube should work.

 

So using one of those ports after the TB i don't need the check valve or a T-fitting, right? It just goes straight into the Vacuum Mod on the trans?

 

Correct. With the Radix boost is built below the rotors. If you were running a stock manifold that was pressurized externally like I am, you would need the check valve because all of the vacuum lines end up pressurized when you get into boost. The only ones that you should stay away from are the ones below the J tube on the back of the blower manifold. Those are pressurized because they are below the rotors.