Mini Racecar Exhaust

Another area of improvement is the exhaust system.  When I installed the turbo initially, we just cut off the muffler & vented the turbo wastegate directly via a short pipe.  This prevented restrictions, but also made things a bit loud.  It also made it difficult to hear the engine for timing issues/knock once the wastegate opens.  I decided to add a racing muffler and to re-merge the wastegate output smoothly back into the exhaust.

The first step was selecting the racing muffler.  I chose a model made by Coast Fabrication.   For something that's going under the car that noone will ever see this thing is a piece of *art*. Because it is repackable, you need to be able to take the muffler on & off. So I had them weld two tabs onto a metal band clamp. I can then bolt this onto braces attached to the car:

I went with the perforated steel mesh option. It's the most resistant to heat:


Next I needed to merge the wastgate output back into the exhaust.  

I TIG welded the merge pipe on myself, and I cut off & welded on a new exhaust was a good excuse to learn how to weld. Next winter I have a goal to build a new downpipe with a better design all myself....but I'll need to practice a *lot* before that!!

The key in this design was re-merging at the bend at the bottom to avoid back-gas.  This necessitated adding a flex joint on the bypass itself.  Complicated but effective:

Posted on January 28, 2014 .