Andy has supplied me with a huge pile of stainless steel mandrel bends. And three beautifully made collectors.
These parts are destined for my exhaust system, as I don’t have the cash to buy a complete bespoke system from Andy. Plus I quite like to make such things myself if I can.
At the bottom of the picture you can see the wireframe model I made previously.
About 2 hours after I took this photo I basically thew it away, and began a long stint of fitting/refitting and dis-assembly. Repeat until nearly comatose.
Basically my planned layout didn’t seem to match the radii of the bends, so I couldn’t use it.
Andy has suggested I aim for a total primary length of 400mm, but 60mm of this is taken up with the conical port expanders, and a nother 0mm or so is in the collectors. This only leaves 265 mm for the actual bends, and with each 90 degree 100mm in length you can see I didn’t have much to play with. Of course you want to get all the headers the same length, but because it is a 4-2-1 system you need to get the collectors in a similar place too, so that the secondaries also end up a similar length.
After much work I ended up with this. It is s no where near perfect and I think with say another 100 hour practice I could make it neater. But each header should be within 10mm of the target length.
One or two of the configurations I’m not happy with, particularly the pipe on No 3. but I expect it will work well enough. As you I didn’t quite manage to get the collectors level, but we are (I think) close enough.
Welding these is a real challenge, it’s thin wall stuff, and if the joints aren’t perfect you have to add welding rod, and this immediately then falls inside the tube.
I’ve just got No 2 to do now, its currently held on with green tape., and then when I know I’ve got spare material I’ll think about doing no 3 again.
But Generally I’m pretty happy as I can now finish the engine mount on this side.