Front Exhaust Section / Downpipes

On a naturally aspirated car, the downpipe is the second component of the exhaust system. First you have the manifold coming straight off the engine and then the exhaust downpipe.

On Turbo charged/forced induction setup vehicles, you have the manifold, a turbo and then the downpipe, making it the third component of the exhaust system.

The front section of the exhaust consists of the downpipe, which usually hosts the primary catalytic converter with the primary o2 lambda sensor, and an exhaust flexi pipe. Some vehicles have the primary and secondary cats, both, on the front section of the exhaust. In most cases this section of the exhaust has flanges on at each end which separates it from the manifold and the rest of the exhaust system. A down pipe isn’t just a bent piece of pipe to build a path for the rest of the exhaust. Rather, we implement catalytic converters, pre and post lambda sensors for lambda sensor functionality, flexi units, mandrel bends and even flanges on the downpipe.

The downpipe gets a lot hotter than the rest of the exhaust that follows. This is because it is the closest component to the engine after the manifold. As you can expect, the manifold gets very hot and on some race applications the manifold can even be glowing red. Naturally, the downpipe has a lot of extreme heat traveling through it. Temperatures can be going up to 700/800 degrees! This is important to mention, because if someone is looking to upgrade their down pipe, it is highly advised by MIJ Exhaust to go for a mandrel bent pipework, as this setup allows for the exhaust gasses to expel freely. We do not want any sort of restriction in this area particularly.

Talking about heat, the exhaust fittings in that area go through extreme pressure. They heat up and cool down again and again, and eventually they deteriorate. This part of the exhaust system may seem like just 20% of the exhaust, but it isn’t a simple task and to replace this part of the exhaust can take the same amount of time and longer to replace than the rest of the exhaust.This isn’t just the case with the flanges, the nuts,and bolts, rather it can also be the o2 sensors and lambda bosses. At times, their condition isnt the best. They need to be heat treated to take them off. Once the lambda sensors are removed they can be stripped of its own thread, so it may not be a simple case of taking the existing sensors off and replacing them on the new section. There is a lot of little details that need to be taken in to account when replacing the downpipe and these make it a crucial and intricate part of the exhaust and the work carried out must be done by a professional. Just a quick heads up, we replace the bosses here but not the sensors. We advise that the lambda sensors should be bought from the dealerships, we wouldn’t trust the aftermarket sensors, especially for such an important part of the exhaust system.

This may be a tricky task but the team at MIJ Exhaust are trained and highly skilled for the job, which is why we offer this service.