down pipe question
 

I hear you mention the exhaust down pipe being crappy. What is the down pipe? I'm new to this so please be gentle.

Th only downpipe I know of is on a turbo charged car. NA cars have a manifold or header.

on a turbo car the down pipe comes off the manifold to the exhaust. on a N/A 2.0L the downpipe is the pipe that conects the first cat to the second.

maybe he means a flex pipe
:eek:

isn;t the flexpipe that connects the second cat to the rest of the exhaust.

The downpipe is located between the primary catalytic converter and the first section of the exhaust system (which may or may not include another cat, depending on the year and model of your car). The primary cat is located right after the exhaust manifold, behind the radiator; it's a can-shaped part roughly 6" long and 4" in diameter. The downpipe goes from the exit of this cat to a point underneath the engine next to the oilpan, where the remainder of the exhaust system connects to it. It is about 12" long, has an elbow in it, has a metal heat shield around it, and includes a fitting for the secondary o2 sensor. FWIW the FSM calls it the "connecting pipe" but most folks on this list prefer the more common "downpipe" terminology. :)

The reason that folks on this list will sometimes talk about replacing the downpipe is that it's only about 1.7" in diameter on the inside. Just like a chain is only as strong as its weakest link, an exhaust system only flows as well as its narrowest point, and in the case of the Protege's stock exhaust, that point is the downpipe. :( None of the common "cat-back" exhaust systems available for our cars replace this part. Some people have replaced it with a larger-diameter custom piece for a gain of a few horsepower.

Hope this explains it. :D

Proteges don't have a flexpipe, they use a flex joint between the downpipe and the first section of the exhaust system. Most modern FWD cars use flex joints because they're less expensive and don't wear out like a flexpipe. :bt: