(yes there’s actually an exhaust is this part)
Before starting on the exhaust itself there were a few more brackets to make for the rockers. The final plans for this area include a rather complex side skirt for aero purposes that will also channel air from the front wheel well down the side of the car to continuously pull the heat of the exhaust away. I’m not making those yet since they aren’t a priority to get the car up and running, but I’ve got them about 90% figured out in my head and now was the time to make the mounting considerations for them:
Finally, on to the actual exhaust!
Materials ordered, not everything used is in this photo – ordered a few more parts later on. R2-D2 approved of the shiny stuff:
Began with the downtube. V8R has the CNC formed downtubes for traditional down-the-tunnel exhausts, and I almost got a set of those to start off from but it seemed a shame to cut those up and only use the top half of them so I decided to do it from scratch. I strongly recommend getting V8R’s downtubes for anything but the most custom needs because forming the round tube to the rectangular shape of the engine flange within the 90° bend of the tube where it needs to be is not easy.
Sacrificing an exhaust flange, I made a jig for the shop press that would press the tube into the shape of the flange, it’s crude but got the shape to 95% and then hammer-formed it the rest of the way:
Exhaust curves down quickly just like normal, but then makes a turn to head out towards the wheel well:
I was in the zone and didn’t get many pics of the build process. Woops! I did snap a pic of cutting the exhaust exit tips:
Fast-forwarding quite a bit, here we’ve got one of the complete downtubes tack welded together, joints sealed up and backpurging gas being piped in, ready for final welding:
And with another fast-forward, full exhaust is finished! Measuring the total length of everything here and comparing to the length needed for an out-the-back exhaust, this side exit exhaust saves me 50 inches of length, approximately 10 lbs:
The downtubes carry the exhaust from the engine down to the bend at the rocker, with a V-band flange pointing straight down the car from there so that the rest of the exhaust is modular. This allows me to easily make different straight sections if I want to test alternate resonators or mufflers.
You’ll also see two cats in the pic above (Wait, cats on a race car? Why??) I wanted to be sure I could fit cats in the system, and since those would be the largest thing I might be trying to fit there I made those first to be sure they fit, and will make a pair of straight cat deletes later that can be swapped in. Cats do a good job of reducing volume, and V8R reports this is a loud motor when you’re on the GO pedal so I’ll likely also use the cats as an option when I need to bring the volume level down at certain tracks, etc.
Installed, the exhaust tucks into the rocker nicely:
Shot from below shows the full route well:
From the perspective we’ll be seeing it from more often, I’m quite happy with how it’s tucked into the car. The exhaust won’t ever be quite as exposed as it is here, since the side skirt will envelope it to direct air, but it will remain like this until it’s up and running:
Speaking of weight, the full 3″ lightweight exhaust that came off this car for the 4 cylinder and turbo was 26 lbs including the downpipe but NOT including the cast iron manifold which was easily 10+ lbs. That exhaust had no cat and no muffler to save weight.
This new exhaust totals 30 lbs all-in, including the cats and everything up to the motor, so somehow in changing to a V6 which has to double everything and adding resonators and even with cats I’ve saved weight over the uber-minimalist turbo exhaust that came off the car. I’ll take that!