Tapping Intake Manifold for Larger Vacuum Line (N54 – TiAL BOV)
2020 Update: BMS now sells a plug and play kit that requires no drilling or the removal of the intake manifold.
Since I had to remove my intake manifold while walnut blasting my intake valves, I decided it was the perfect time to tap the manifold for a larger vacuum line. TiAL recommends that their blow off valves be connected to 1/4″ vacuum line, not the small factory 1/8″ vacuum line. This is crucial on modified BMW 135i or 335i.
You will need the following parts:
- 1/4″ Barb x 1/4″ NPT Male Fitting
- 1/4″ NPT Taper Tap
- Drill Bit Set
- 1/4″ Vacuum Hose
- Vacuum Nipple Kit
- Teflon Tape
- Epoxy
Once you have all of the parts, it’s a pretty straightforward procedure. First, cap off the existing port with a vacuum nipple and a zip tie. I like to leave this nipple untouched in case I were to ever go back to stock, then I can just plug the larger port we’re about to create.
Next you’ll want to find the flat surface next to the old nipple. Then you’ll start drilling a hole with a small drill bit and eventually work your way up to a 1/4″ bit or until the tap can thread into the hole.
Now you’ll use the tap tool to thread the plastic to accept the fitting. Run this tap into the hole until you can thread the fitting in.
Grab the fitting and wrap some teflon tape around the threads. Then carefully thread it in until it is nice and tight.
Lastly, you’ll bust out the epoxy and coat the outside so it won’t leak.
Vacuum or blow out any plastic shavings that are left in the intake manifold and reinstall. Now you’ll grab your new 1/4″ vacuum hose and connect it from the blow off valve to your larger port for ideal operation.
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