Dedicated Exhaust Discussion

[moatilliatta]

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.

[hoveringuy]

Never really considered them, just figured Flanges will work better and be easier to build.



Great idea welding studs. never thought of that!

I love having the studs. It lets me slide the mid pipe up and it just sits on the studs while I secure the back. Plus, just a single ratchet/extension and M13 socket and done. No wrestling with two separate wrenches. It's Lux!

[digger]

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

[Striker01]

why no vbands?

Never really considered them, just figured Flanges will work better and be easier to build.

I had V-bands and now I have flanges.

Much, much prefer the flanges because they're so much easier to align and connect, and they fit a tighter space. With the studs welded into the header flanges, just slide the mid pipe on and tighten the nuts.

V-bands were always a wrestling match for me. hated them!

Great idea welding studs. never thought of that!

[hoveringuy]

why no vbands?

I had V-bands and now I have flanges.

Much, much prefer the flanges because they're so much easier to align and connect, and they fit a tighter space. With the studs welded into the header flanges, just slide the mid pipe on and tighten the nuts.

V-bands were always a wrestling match for me. hated them!

[moatilliatta]

why no vbands?

[Striker01]

So I tried to mock up the exhaust with the wrong engine mounts. My engine was about an inch closer to the driver side frame rail, didn't realize until I tried to fit the intake with the bosch ibooster installed. Lesson learned, Revshift 24 mounts will not work. I got the AKG ones and now that the engine is centered one of the flanges is closer to the CAB than I would prefer. I cut the rear header primaries just past the flange and shortened until the rear set just cleared the front set.

It got rid of the weird bend in the rear set and I tucked the front one a little closer to the transmission.



I should even be able to use the stock heatshield with just a minor modification.

[hoveringuy]

As far as the flex, I'm thinking about doing one on each mid pipe, fairly close to that flange. Reasoning is that I'm pretty sure the stainless will move between tacking and fully welding but I'm open to suggestions, figuring this out as I go.

you don't want two flex pipes, because then it will flex. Constantly. And you'll be replacing cracked flex sections in short order.

You just need one, if any, so you can align the second flange.

[Striker01]

Ugh thank you so much for doing this. Great work, great pictures. Welcome to the "it's really hard to get a picture of this and explain to everyone what's going wrong" club. I LOVE the plate to align the flanges. I wish I'd done that. hoveringuy and I did a bunch of "do we need a flex on one side before they come together?" arguing, so we'd love your thoughts on that.

Is there any hope to match up to an existing catalog rear section or rear and mid?

I think you guys went into a single exhaust, if I remember correctly. My plan is 2" dual with an x pipe before the cats. I want it to match up to my M20 stromung catback. I didn't even look at any of the existing mid section stuff, figure any catalog option will need adjusting so probably easier to just start from scratch. I ordered a 2" "build your own" kit, 2 high flow cats, flanges for the front and a donut/flare connection for the rear. I'm hoping the flare donut thing will work for the rear as the stromung pipes are slightly smaller at 1 7/8" OD. Have to play that by ear as I go, I don't really want to modify the stromung in case decide to go a different route. As far as the flex, I'm thinking about doing one on each mid pipe, fairly close to that flange. Reasoning is that I'm pretty sure the stainless will move between tacking and fully welding but I'm open to suggestions, figuring this out as I go.

[hubcapboy]

Ugh thank you so much for doing this. Great work, great pictures. Welcome to the "it's really hard to get a picture of this and explain to everyone what's going wrong" club. I LOVE the plate to align the flanges. I wish I'd done that. hoveringuy and I did a bunch of "do we need a flex on one side before they come together?" arguing, so we'd love your thoughts on that.

Is there any hope to match up to an existing catalog rear section or rear and mid?

[Striker01]

I mean, that bend isn't the greatest thing in the world but it's not a big deal, either. Oxygen sensors have room, sway bar and CAB clear, room for AC.

This is legit, and I'm guessing it would be easy to duplicate if the motor was out of the chassis once you know where the flanges need to fall.

good job!!

Thanks! It should work fine, i did tilt the O2 sensor more toward the engine just to keep the cable clear of the firewall. I probably could've tried pie cutting sections out of the primaries to get the whole thing tucked closer to the block but this solution seemed easier.

[hoveringuy]

I mean, that bend isn't the greatest thing in the world but it's not a big deal, either. Oxygen sensors have room, sway bar and CAB clear, room for AC.

This is legit, and I'm guessing it would be easy to duplicate if the motor was out of the chassis once you know where the flanges need to fall.

good job!!

[Striker01]

Here is a shot from above




Clearance from the sway bar, about 1/2"



From the side, it doesn't hang down past the frame rail anymore and should give me plenty of room to work around the CAB for the mid section.

[Striker01]

Did some more work on the headers. The front set was just a couple cuts and took a couple inches length out.


Rear set took a few hours of messing with it in the garage. Multiple cuts, tacks, and re-cuts but I think I have them sorted.

Once I had it close to where I think it will work, I drilled a scrap piece of thick sheet metal to mount on the other flange. Clamped the flange to it and tacked it together.



I have no idea how that weird bend after the collector will affect performance but they fit now.

[JRowe]

Great feedback. Thanks for sharing.