So I started today with the intent of getting some of the main power distribution stuff done, starting with one of the main ground cables. But I pretty quickly devolved into my usual state of overthinking; in this case it was due to the proximity of the ground cable routing and the exhaust. I was considering a different approach to the ground cable, but I kind of needed to know what the exhaust setup was going to look like, particularly the hangers that support the pipes near the firewall.
This is, in fact, something that Van’s recommends when working on the FWF area – to start by getting the exhaust in place, since it’s an object with a pretty fixed position, and the heat it radiates is important to consider.
So I changed gears to the exhaust. I’ve had the upper pipes in place for a while, but not the tailpipes. I did fit them some time ago and briefly tinker with the heat muss and hangers hardware, but nothing major. So today I remounted the tailpipes and started really thinking about how to arrange things.
The hangers are sort of a point of contention among builder. Specifically, there’s the question of whether they should be braced to the engine mount, or the engine itself. An important point here is that the engine mounts are nowhere near solid, so the engine is going to move relative to the mount, whether it’s shaking during startup/shutdown, or sagging under G-load. This all makes sense to me, so I was leaning towards bracing the tailpipes to the engine.
Thing is, it’s not quite that easy. First off, the hangers provided by Vetterman – which are two stainless tubes joined by a piece of high-temp hose to give some flex – are too short to reach the engine sump (the usual attach point). That’s not an automatic show-stopper, though getting past it would require me to acquire or fabricate longer tube pieces.
The real problem emerged when I temporarily put the heat muff in place. There’s really no flexibility as to where to put this, and since the hanger mounts must be behind it, the muff really restricts where the hangers can go. It’s just not possible to route a hanger from the tailpipe mount to the engine sump without it occupying the same space that the scat tubing to/from the muff will go.
So in the end, I tied the exhaust to the engine mount instead. Doing it this way means that the hangers go up, forward, and outboard to the mount, which keeps the right-hand one clear of the heat muff.
The real fun was getting through the spatial reasoning needed to put all this together, At first I thought I was going to have to tweak the bend on the tailpipe attach tabs, but it turned out that it was possible to rotate them to a position where everything worked. I had similar fun getting the forward end of the hangers to properly mate with the adel clamps on the engine mount tubes.
This is all just a temporary setup for now, but seeing how particular the arrangement of everything is, I’m definitely going to be making some match marks between the stainless tubes and the flex hose pieces, to ensure I can easily put this stuff back like it belongs.
Also, it’s worth noting in the picture below that the hangers will have hose clamps when assembled for real; obviously, without that these wouldn’t exactly be functional… I may also add a bit of a flare to the ends of the tube pieces just to help with security.
