Quick update then. Still no kitchen ceiling BUT I do now have a nice (but rather short) box hedge around the front of the house.
Anyway… been working on my downpipe/exhaust recently and I'm back as far as the centre of the car.
Since the standard cat/downpipe (2.25” bore) sits in the the same place as the brake master cylinder, and in any case is broken at the turbo flange, I needed to modify/make something to replace it with. For this purpose I bought a secondhand 3” bore stainless decat with the intention of cutting and rewelding it to suit.
Main problem here is that on a RHD 19, the brake master cylinder is sitting where the downpipe/decat needs to go. Due to the position of the turbo outlet on the standard manifold, options are limited here. The downpipe needs to thread between 3 things:
The corner/edge of the scuttle panel
The manifold
The master cylinder (fucking RHD!)
It’s just too big to fit down past the master cylinder and even if it did, it would need so much chopping and so much welding that it made no sense to do it that way rather than just starting from scratch.
So making up a custom downpipe using 2.5” stainless mandrel bends and the turbo flange (which handily is also stainless) from the original cat converter is the order of the day. Bits:
Ground back this little lug thing on the manifold for a bit of extra clearance
Clearance on the scuttle and master cylinder, just. Gonna need some heatshields here!
Mocked up with the engine out of the car to get approximate shape and position.
Then some (read: a lot of) crawling around under the car fettling and adjustment with the engine in.
I’ve tried to think ahead a bit here. I’m using a manual steering rack now but want to keep my options open for fitting power steering in the future. The PAS rack is obviously bulkier and has various pipes coming out of it. With this in mind, while mocking up the link pipe, I’ve fitted the megane PAS rack mounts and the little heatshield that they carry. If I keep my link pipe in the remaining space available then I should hopefully be future proofed.
Rather than have the downpipe to mid pipe join with a flange in the usual place I decided to put a V-band joint in the lower leg of the downpipe as it travels across before it turns to run backwards through the gap between the floor and subframe.
This is for 2 reasons:
1 - There’s not a lot of room down there in that gap to fit any kind of joint (either v-band or normal flange joint)
2 - This way allows the mid pipe to rotate up and down on the v-band joint before clamping up which makes alignment through that gap a bit easier.
Immediately after the V band joint the mid pipe turns 90 degrees then down 45 degrees and back, via a flexi pipe which is realistically as close to the engine as it can go. Then it’s straight back to… not sure yet.
I’m yet to make some bracketry to brace to the OE cat mounting point on the manifold (had to drill out and retap to M6 the remains of the original bolt - being unsupported was probably why the original cat broke off in the first place) and the rubber damped one in the bottom corner. Will probably get all this finally TIGed up before doing that in situ on the engine.
I’m trying to make a decent-ish job of all this as it's such a pain in the arse that it takes so much time and effort even to bodge it so might as well spend the extra time to try and get it right in the first place and hopefully not have to touch it again. That's the plan anyway.
For the rear section though I just need to get something in place so I can start the engine, finish the rest of the work and drive it somewhere to get an MOT etc. I had a go last weekend at making a temporary back section from the original megane system chopped up and a clio 172 back box. Didn't work out very well. Just so hard to thread it round the rear beam and tank etc. using a hotch potch collection of random bent pipe bits. So I gave up.
Other possible solutions are:
1: Cut a suitable flange to mate to the 2” stainless system I could borrow from my 16V. Again just to get the thing running/drivable.
2: A quick and dirty sidey just in front of the passenger side rear wheel. That would be relatively easy to knock up.
I had planned to get a bit more done yesterday (bank holiday) but my heart just wasn’t in it, I’ve had enough of crawling around on the floor, grinding and getting covered in shite for now so I went and sat in the garden with a pack of beers instead. I regret nothing.
