Tech Article Title Author Date
APR 2.7t BiPipe (Cure for the Troublesome TBB) Don Pavlik 2001

If you have a car equipped with the 2.7t engine you've no doubt heard about the dreaded throttle body boot. 2000 and early 2001 model year cars were prone to ruptured boots (more info here). Then, Audi released a revised throttle body boot (TBB) and a revised clamp to solve the problem.

I had two TBB failures on my car, one at 6,300 miles and another 9,400 miles later. The second replacement was the revised "T" boot and I used the revised clamp. After two failures I didn't trust the revised solution and have always carried a spare boot and the tools needed to do the repair in the trunk. The 3rd boot, thus far, had survived about 14,000 miles without an (apparent) failure (more on "apparent" later). 

Now, Audi Performance and Racing (APR) offers a solution for the TBB issue which eliminates the boot all together. Their solution, called the BiPipe ($349), is a one-piece assembly that replaces the two plastic pipes that run from the intercoolers to the TBB and the TBB itself. 

The BiPipe is cast aluminum and includes all required hardware along with what appear to be silicone hoses for the bypass valves. Overall, a very nice piece.

To join the BiPipe with the throttle body you attach a part to the bottom of the throttle body then the BiPipe simply bolts up using longer bolts in place of those that normally secure the throttle body to the intake manifold--no modifications are required. Supplied o-rings fit into the existing groove on the throttle body to seal the connection between the BiPipe and the throttle body. 

Installation was rather painless except for when I sliced my thumb open on a razor sharp edge under the right (passenger) headlight. Be wary of this edge--it is very sharp!

Extremely sharp!

The installation instructions are outstanding (all 59 pages of them!). Each step is clearly outlined including pictures of the task at hand, the tools and parts needed for each step. See for yourself! Say it with me... outstanding. My only addition to the install instructions would be to make a note of where your headlight is aimed (on a wall somewhere) before removing it. Although I was careful putting it back in I had to loosen the headlight assembly and move it slightly after getting hi-beamed 4 times during my first night-time drive. 

Installation took about an hour and forty five minutes to complete. Fitment was excellent, no alignment problems. After the front plastic "Biturbo" engine cover is installed the car looks totally stock. The skill level to do the install is pretty modest--maybe a 3 or 4 on a 1-10 scale. Some specialty tools are need, namely a torx bit and allen socket but otherwise just basic hand tools. 

A discovery

While taking my car apart to install the BiPipe I inspected the TBB which had been in service for about 14,000 miles. Inspection revealed early stages of a tear in the same location as the previous two boots that failed on my car even though I had used the revised parts! It did last longer than the previous two but it appears it too was destined to fail. I have a road trip planned to Dallas... my guess, based on my usual good luck, is that this third boot would have failed somewhere along the way. Evil TBB... begone!


Early stages of a tear!
(click to enlarge)

What I find annoying is that the European RS4 already has similar aluminum intake plumbing. It has a three piece system and it too is lacking the evil TBB. The RS4 gets the good stuff from the factory... the S4 needs just a little help from APR.

The European RS4 factory pipes

So, with the installation of APR's BiPipe I'm happy to report I can finally remove the TBB from my trunk and put it where it really belongs...




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