So.. with JDM Combe getting even closer.. and far too much on to deal with, we're still battling on!
We've had some pretty late nights this week so far, but we've got a fair amount done and picked up all the flat parts from the laser cutters..
So we'll start with this fully rad picture of the car we took this week.
You've probably noticed the aluminium plates on the front, they go where the original front bumper bar mounts were. When we removed them (because weight reduction) they left the ends of the chassis rails exposed, so we designed these and had them cut.
Before:
After:
We also did some painting while the bumper was off..
With all our flat stuff picked up from the laser cutters we got cracking with the exhaust manifold.
We figured for this part we'd give you a run down of how we make a turbo manifold the DaveFab way..
We start off by modelling the exhaust head flange in Solidworks, and then holding the turbocharger in space where we want it. Once we've measured exactly where we want it to sit we can go about making a 3D model of the manifold like you saw in the other post. This is having modeled all the off the shelf stainless bends we have available.
From this we can get an accurate bill of materials to order as well as any straight length measurements we need to cut. We can also control the length of all the runners individually and explore every available path they can take. For this build we have gone for unequal runners simply because we were unable to package it effectively without cutting things up. If it were a naturally aspirated engine this would be a potential major flaw, but with turbocharged engines exhaust systems work much differently and there is little gain to be had.
Once we had the design sorted we designed a weld fixture around the 3D model of the manifold and had it laser cut.
Which looks like this!
Everything is castellated (like a jigsaw) for accuracy and rigidity, the main flange mating surfaces are 12mm steel, and the rest is 3mm.
We also designed in all the purge plumbing to ensure a strong weld on both sides of the tube. This is essential for pretty much any stainless steel tube welding - an exhaust manifold is no exception. They are subjected to significant pressures at high temperatures so the initial welding process really sets the foundations for a reliable set up.
With that part all set up ready to go we can look at tacking all the individual runners together. For this part we 3D printed our own fixtures designed from the solidworks model to get them all tacked up.
Test fitting..
It's quite far from the cylinder head, but it has it's benefits. As we can still fit a 3" downpipe with no cutting the enginebay, get a fairly straight run with the intake, have one 90 and it's into the intercooler..
and the bonnet shuts with no modification needed too!
Once you've trial tested all your runners the next job is weld preparation. TIG welding is a bit like painting, it's heavily reliant on the prep work.
So if the tubes have huge gaps, you're probably going to have a bad time.
Similarly if the tubes are really dirty and covered in weird metal shop oily badness, you're also going to have a bad time.
You want to be welding stainless, not stainless with some weird scale and residue thrown in the mix.
So with all that in mind, we went ahead and cleaned up the runners.
Once we'd cleaned all the pipes up, it was time for welding. For this part we use some tapered aluminium bungs we had made by a local machine shop to purge the inside of oxygen.
Mandatory weld pictures.
Once we welded all the runners up, we went ahead and welded them on to the main fixture.
It's important at this point to have a think about what order you want to weld them, as you can easily get yourself into trouble here if you don't.
We tend to start with the ones furthest in, and work outwards.
After a little while we had this.
All that's left is to weld the tubes on to the head flange in the morning, and then we'll get stuck into completing the colour change so we can get more of the car back together.
Certainly looking tight for next weekend!
le sigh
Jul 15, 2023 20:03:52 GMT
le sigh
Jul 15, 2023 20:03:52 GMT