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Discussion Starter · #1 · (Edited)
The Rabbit TDI project
Part9: Ins and Outs: the intake, downpipe and exhaust.

Or: You can't get there from here.

My engine came with the MAF, but not the airbox.
I didn't like the look of the intake pipe, all twisted and bent,
with numerous changes in diameter, plus it looked like the stock
intake would hit the frame rail. I chose to create my own.

I started with a 2.5" mandrel bent J-pipe.
A nip here, a tuck there, extend a little, trim a little, and viola:
one custom fit intake pipe, complete with mounting boss for the MAF

The intake starts just behind the passenger headlight with a K&N filter.
It runs along the frame rail and squeezes between the shock tower and
the timing belt cover. It continues on then turns down as it loops back
to a reducer. A 90degree rad hose connects the pipe to the turbo inlet.

The section taken out of the pipe is so the pipe fits between the shock tower
and the timing cover.

Shots of the pipe:

This is a photo looking down over the passenger fender.
At the top is the timing belt cover, to the left is the shock tower (and the
dangling lens cap of the camera). To the right is the fuel filter.
The pipe at the top is the has the bung for the IAT/MAP sensor.
Immediately below, hidden in the mass of wiring is the MAF and the intake pipe
kindof running diagonal across the photo.

These two shots show the air filter. It's a K&N, special ordered locally,
but it's a stock K&N item. The yellow wires over the air filter are for the
MFA air temperature sensor which I currently have placed to tell me the
approximate air temperature at the K&N.

The downpipe was fabbed using the original A4 downpipe, which thankfully came with
my engine. Basically, it comes straight off the turbo, turns down, turns again,
and mates up to the exhaust. Nothing too special. I figure I can fit a 2.5"
downpipe if I choose to at a later date. The bung is for the EGT probe. Yes, it's
after the turbo. Yes, I wish I had pre-turbo, but the manifold is an expensive item,
and I didn't want to mess it up.

As for the rest of the exhaust system, I took it to a local muffler shop, and when
I picked up the truck later, it had a 2.5" exhaust with a superturbo muffler and
dual outlets. Nothing too fancy...

summary: air in, exhaust out.

stay tuned...


Part 1: Introduction
Part 2: Installing the Engine
Part 3: Transmission
Part 4: Wiring 1
Part 5: Speedometer and Cluster
Part 6: ImmobilizerIII
Part 7: Drive By Wire
Part 8: Intercooler
Part 9: Intake and Exhaust
part 10: MFA and Cruise Control
Part 11: The Dash
Part 12: The Little Things
Part 13: The End (for now)
Part 14: 6spd transmission and brake upgrades
One Year Later
Dyno results
Who Needs a VR6
TDI Rabbit
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