Dedicated Exhaust Discussion

[Striker01]

I'll rework the CAB heat shield while the headers and mid section are off for ceramic coating, it clears fine now but doesn't look very good.

[Striker01]

It hangs just slightly lower than the front subframe and transmission exhaust bracket.

[Striker01]

Finished up my new exhaust. Super happy with the fit and how it turned out. I'm sure muffler sound will change as I drive it some but initial impression is that it has a little more bass and is quieter. Didn't notice any drone on my 6ish mile drive. I like the side slanted tips, more like a stock 325. The only place it may touch is where it comes through the rear valance. It's close on the passenger side, I'd like it a little higher in the opening but then I run into more clearance issues with the large tips.

I really like the ball and socket couplers, have to check them after a few heat cycles to see if they stay tight and a couple of the bolts may need to be shortened a bit but no strange sounds on the initial drive.

With the stock straps this thing hung down below the opening in the rear valance. We decided to weld mounts directly to the muffler and modify the stock straps.





Got super lucky here, thought we would have to remove one pipe completely to get the welds done but my brother figured it out with his tungsten out super far.

[Striker01]

It hangs down a little lower than the 2" from the AA headers but we got it tucked as well as we could, I did switch to the treehouse style CABs, fit was too tight with stock ones; headers cleared them but no room for the heat shield.

Clutch job may be a headers off deal going forward but with the sway bar brackets dropped and one exhaust stud removed they will go in without a hassle.

Also got my brother a hand switch for his TIG torch, money well invested. So much nicer than throwing sparks all over trying to tack with MIG.

More to follow....

[Striker01]

Finally getting around to getting the N53 headers ready to go into the car. Headers are almost done, ran out of gas to back purge today, so front set is just tacked for now.

2.5" PLM cats mounted in stock position right after the collectors, then tapers down to 2.36" to mate up to the supersprint E30 S52 swap exhaust. Got a good deal on the supersprint midpipe and rear exhaust but it fits terrible and their claim of full stainless is false. Also how can an exhaust this expensive use MIG, yuck!



Trying out stainlessbros 2.36" ball and socket setup, instead of flanges or slip joints.

[Striker01]

Nice! N53 being a euro-only motor that's an N52 with high pressure fuel injection.

I think that's why hubcapboy couldn't find them. He may have been searching for N52 cars with them, there were quite a few sets overseas when I ordered these.

[hoveringuy]

First pieces for version 2 of my swap exhaust showed up. N53 headers. Primaries are just under 1.5”, 38mm OD. Collector is 2.5” and output from cats is 50mm, just under 2”.

Nice! N53 being a euro-only motor that's an N52 with high pressure fuel injection.

[Striker01]

First pieces for version 2 of my swap exhaust showed up. N53 headers. Primaries are just under 1.5”, 38mm OD. Collector is 2.5” and output from cats is 50mm, just under 2”.

[Striker01]

Looks like Supersprint is offering a complete exhaust for our cars. Expensive but cool aftermarket is producing stuff for this swap.

https://www.supersprint.com/en-us/bmw-e30-n51-n52-n52n-n53-engine-conversion.aspx

[Striker01]

Exhaust is sorted and on the car for good. Was wanting dual all the way back with an X-pipe but the magnaflow cat I ordered is 2 in/2 out single chamber. I'd already put a ton of work into the x-pipe so it stayed even though it's probably totally unnecessary. Gives a good place for both pipes to reconnect before the transmission brace. The M20 transmission brace mounted right up to the 17 transmission and I cut the tab off the old cat to put on my new one.

I mocked this up with the CAT heat shield jacked up against the car, cut the heat shield off after final welding and it left a nice gap for movement.



Here it is mated to the Stromung M20 muffler. I was hoping to leave the muffler unmodified but couldn't get it to work, ended up cutting off the flanges and using slip joints.



Midpipe is ceramic coated and mounted. Lowest exhaust point is where is passes under the rear axle, I'm happy with it. The CAB heat shield isn't touching, just the pic angle.



One of my header flanged warped during welding and was leaking. Found these gaskets, they seem to be great, no leaks when I fired it up yesterday. Sorry no pic before I installed them.





Short video of it running. In a garage with no load but at least give you an idea. No making fun of my slides, was deep cleaning the interior before putting seats back in and didn't want to wear shoes in the car. LOL

https://youtu.be/IDCbeZnhtVE

[Striker01]

Mounted for hopefully the final time!

[Striker01]

Hopefully my last post about these AA look-a-like headers. I'm going to call them sorted and send them out for ceramic coating.

Thanks to digger for talking about gearbox clearance, that's something I wasn't even thinking about and got lucky by just needing a slight modification for them to clear.

In this picture you can see the countersunk holes for the flange nuts. Unfortunately the holes aren't cut very precise and some of the studs weren't centered in all of them. Also the copper flange nuts are too big to fit into the ones that are centered, maybe 1/32" too small. I didn't like how some of the nuts didn't have much material to clamp on so I decided to fill the the countersunk area.



Filled, then lots of grinding and drilling.



I forgot to take a picture after grinding and drilling but here they are mounted, with the proper nuts.



This gap was at least an inch before I decided to shorten the primaries at the flange. It's fairly close now but both headers feel pretty solid and hopefully won't rattle together.



I got lucky here, I hadn't even considered removing the transmission. Just had to cut this little ear off (circled) and it will slide into place with the headers on. I also ran the grinder between the flanges, they were touching after the final welding.

[digger]

I'm don't think I follow what you're saying. I'm not familiar with the post you're talking about. I also don't see any way the exhaust can move an inch, I don't think the stock transmission hanger has the ability to move that much and the 30 some year old M20 mid section I took off is still in great shape.

He’s talking about when disconnecting the exhaust to get it off the stud and that there should already be plenty of play once gearbox mount is removed .Thinking more about it corrosion is probably not your long term friend and a bolt is easier to replace. Each to their own

[Striker01]

If the exhaust wont slide back an inch minimum you don't have enough room for thermal growth.

Kinda like that muffler hanger on the car Garage Welt posted. That'll totally fatigue and break put through some proper paces.

Along with flexy on one side and non flex on a dual exhaust system, to much strain on the non flexy side, till fatigue and crack.. IE a lot of E30 down pipes.

I'm don't think I follow what you're saying. I'm not familiar with the post you're talking about. I also don't see any way the exhaust can move an inch, I don't think the stock transmission hanger has the ability to move that much and the 30 some year old M20 mid section I took off is still in great shape.

[Striker01]

i like the good old flange myself, but IMO you dont want the connection too far downstream from the bell housing otherwise its a headers off job to remove the gearbox.

I would also think about whether adding studs might make it more difficult as you need to the clear the studs to drop it down. it depends on the layout overall

I would love to have the connection closer to the front but that would require significant changes to the rear bank, forward of the collector. That's not something I want to take on. I think I can still get the transmission off, it will be tight though.