Project SR E30: Part 8 – Fabricating a Custom Stainless Steel Oval Exhaust
Back purging and entire exhaust
Now comes the greatest purge of all. We’re going to weld both sections together as well as the round tip section at the same time so that we only have to purge once. We left this one for 15 minutes to let it purge completely.
Welding a custom stainless steel exhaust
Welding it obviously requires you to rotate the entire pipe. To achieve this we had two people holding the other end of the pipe and rotating it slowly as I was welding. At a certain point, the downpipe rotates to a position where it’s hanging below the purge line. When this happens we were forced to stack another two tires under the exhaust to raise up the ventilation hole.
Custom exhaust hanger
All that was left now was to add an exhaust hanger.
BMW E30 SR20DET O2 sensors.
We also added bungs for both the wideband O2 sensor and the factory narrowband O2. To add heat protection we heat wrapped the first half of the exhaust.
Custom BMW E30 SR20DET stainless steel oval exhaust.
And here is the final product!’

We are really happy with the end result. It took a lot of work, but the ground clearance we achieved definitely made it worth it. Nothing is perfect, however, and our exhaust has a couple of drawbacks.

First, we simply didn’t have any room to fit a flex pipe anywhere. Thankfully we are currently using the stock cast iron exhaust manifold and the engine is mounted with fairly rigid polyurethane bushings. These factors should mitigate the risk of cracking stuff so we don’t expect to have any issues. If we ever switch exhaust manifolds we will go for a top mount manifold which will give us more room to add a flex pipe.

The second drawback is the proximity of the exhaust to the fuel and brake lines. There is nothing we could have really done about this, there was only one spot for the exhaust to go. We heat wrapped the exhaust to mitigate any problems this can cause, but we will also be adding additional heat shielding to the fuel lines later on.

Look for the next article where we will be upgrading the suspension to finally make this car handle. Meanwhile, check out the rest of Project SR E30.



    1. At the time, we couldn’t find any decent oval exhaust flanges that wouldn’t have taken away from the ground clearance.

      That being said, the exhaust is actually pretty easy to remove.

  1. Nice work, I was gonna see if you can check out the treehouse racing lollypops. they are smaller in physical size and gain more clearance. Your build reminds me of one of my friends who went KA-t in an e30 and it ran pretty gnar.

    Tip: might want to 2-piece the exhaust for when you need to change out the guibo, subframe bushings, and other rear maintenance.

    1. Yeah we’re definitely going to switch to a heim-style lolipop bushing down the line. I’ve gotten that burning polyurethane smell a couple of times already.

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