If you saw my previous post were I shared the start of this project, building a stainless steel exhaust for my friends Ferrari 308 quattrovalvole, you may recall it was left unfinished until the rest of the car restoration work was completed. With the car recently back on it’s wheels, I went over for a visit and we finished up the exhaust.
All that remained was the very careful alignment of the tips and the exhaust pipes from the mufflers back. Getting everything perfect takes a lot of careful alignment, measuring and welding.
We ended up cutting the tack welds off twice in an effort to get everything exactly lined up and picture perfect. Working on a Ferrari is a bit different then on a modern production car. Each one of these cars was hand built by some Italian Ferrari employee. The fiberglass is a bit off from side to side as is the alignment of bumpers etc. This means you can not rely on measurements alone but also need to do careful visual inspection from a variety of angles.
We enlisted the aide of my friends wife to help check the appearance of the tip location. We also took some time away from the garage when we thought we had it aligned perfectly. It is good to separate yourself a bit from a project and then come back to it when it requires visual and aesthetic perfection.
When everything was perfect, I added a few more spot welds, then we carefully pulled the complete exhaust out of the car and I finished welding up the joints with it removed from the car.
The finished exhaust looks pretty good. It will get the welds ground down and then be polished up as time permits but for now it is back on the car allowing it to be driven.
When all is said and done, I’m proud to say I built this exhaust. It looks good. As for how it sounds, well that will have to wait. The battery was completely dead when we went to fire it up after putting the exhaust on the final time. I promise to share a video with the sound of it when I get the chance to take one. It’s almost car season here in New England. Soon enough I’ll meet up with my buddy for a cruise night or car rally and will get a video clip to share.
A friend came to me asking about building a custom exhaust for his Ferrari 308. Of course I said we could do it and that it’d be a fun project. I put together a rough price list/cost estimate for him and he decided to go ahead with the project. We were not reinventing the wheel here but instead just copying one of the commercially available units with some minor changes like original style dual exhaust tips and keeping it 100% stainless steel throughout.
Before we got started we took careful measurements of the exhaust tubing size and did some tracing of the exhaust mounting flanges. We did look extensively online to buy the flanges but nothing was available in mild steel, forget about in stainless steel. Being a Ferrari they are of course very much not a standard part. I drew them up in CAD, generated the G-Code for my CNC milling machine and banged them out. I say that like it was trivial but the piece of stainless steel stock was nasty. It had some internal work hardened spots from shearing which ate up a few carbide end mills. I then fabbed up some exhaust tips, polishing the tubing on my metal lathe prior to welding them up. I hammer formed the 2 to 1 sections and they came out reasonably well. I did use a tubing expansion die at the end to form the perfectly circular opening for the tubing by stretching it out the last little bit.
The Ferrari 308 in question was also undergoing a complete suspension overhaul at the same time. You can see my buddy in the back doing some cutting.
I’m beveling the tubing edges prior to tack welding. I find that beveling the edges of tubing results in a much cleaner final weld that can be metal finished easier. My buddy claims he will metal finish all of the welds and polish this thing up someday. The pic on the right is me welding up the exhaust bits we are satisfied with off the car. Only after checking multiple times that everything is in the correct spot and fits well did I do any final welding. There are spots on the exhaust I wouldn’t be able to weld up fully if I waited till the entire unit was tack welded together so we built it in stages.
With any sort of custom exhaust fabrication process, it’s important to tack weld and check everything often and repeatedly. I bet we took the exhaust on and off the car over 50 times during this build. Carefully measuring, checking level, angles, and fitment each time we made a change. Here you see one side all tack welded in place during the build process.
When the car is back down on the ground I’ll take a video clip of it running and taking off so you can all hear the glorious sounds this thing makes. Ferrari engines have a beautiful sound and this exhaust brings out the best of that. This project is continued and completed in this second post titled, finishing up a Ferrari 308 custom stainless steel exhaust.