Dedicated Exhaust Discussion

[JRowe]

I've seen a few solutions in other threads about exhaust manifold solutions. I thought it would be nice to put them all into one place.

To my knowledge, I've seen three options

- Modify S54 exhaust manifold
- Use factory N52 manifold
- Modify aftermarket N52 header

It would be great if people can post what they've done here (maybe even link to the post). This seems to be the most difficult fabrication needed for this swap. Would be great to come up with a simpler solution.

[hoveringuy]

I used S54 headers because all the BMW DOHC motors have the same cylinder spacing (outside the M30...) so I suspected they would work.

[hoveringuy]

Advantages. They were CHEAP, I think I paid under $100 for them (still needed the flanges...). They're AWESOME, nothing like hydroformed factory tubing. They look baller.

Disadvantages. Alignment on the flanges that go into the ports is critical, if they get slightly skewed the headers are hard to fit. Interfere with the A/C compressor, routing is completely wrong to keep the A/C. "some assembly required"

To construct them I got short sections of the proper diameter tubing for the head, then expanded one side in a press so the header tubes would slip in (kinda like a swedge?) I didn't have the Z4 mounts when I fabricated these, I had to clearance the mount a hair but if I had fabricated them with the mount it wouldn't have been an issue. #2 runner also comes to within 10mm of the engine bay wall.

Other notes. I'm not a huge fan of V-band clamps particularly at the header. The flanges here are perfectly parallel so the exhaust mid section slides in cleanly. Makes exhaust work super-duper easy!

[e30davie]

That is a very nice job. Lots of effort gone into that.

[JRowe]

Perfect solution other than the complexity of fabrication. Has performance and retains AC. Would be nice if there were a simpler solution that did the same.

[hoveringuy]

Perfect solution other than the complexity of fabrication. Has performance and retains AC. Would be nice if there were a simpler solution that did the same.

No A/C, #1 is in the way.

[82eye]

wow that looks good

[FredK]

Where might I be able to buy the $300 Polish headers that someone referred to in another thread?

[Striker01]

Where might I be able to buy the $300 Polish headers that someone referred to in another thread?

Here are the ones I ordered. $315 shipped to OK.

https://fmic.eu/174005-exhaust-manifold-header-bmw-n52-e90-e92-328i-2006-2011-fmic-exh-bb17.html

I'm hoping they will fit with the Z4 arms, if they ever arrive.









Front set is very close to the engine block, not sure it it will be ok or not.



Rear is not even close with the stock 328i engine arms. I've tried every way I could think of to get them on, I'm either not smart enough or they just don't fit.

[hoveringuy]

I'm hoping they will fit with the Z4 arms, if they ever arrive.


Rear is not even close with the stock 328i engine arms. I've tried every way I could think of to get them on, I'm either not smart enough or they just don't fit.

Here's where the engine mount bolt on my Z4 arm sits compared to yours, it's forward of the #4 cyl by 1/2-3/4" and probably close to 3" from the 328i in your photo. I don't see an issue there.



My merges look more like shorty headers than yours, yours extend back much further. mine are staggered front/rear a bit and yours are side by side. The real issue will be how these fit between the transmission and the CAB. As long as the merges clear you can always change the routing of the tail piece.

Your pipes almost look like they come down from above the CAB a bit. They may just fit as-is. Finding off-the-shelf headers that fit the e30 would be game changing!

I will also add that yours are potentially better because they are more equal-length. My forward bank has a longer secondary than the rear bank.

[Striker01]

[QUOTE=hoveringuy;n10107800]

Here's where the engine mount bolt on my Z4 arm sits compared to yours, it's forward of the #4 cyl by 1/2-3/4" and probably close to 3" from the 328i in your photo. I don't see an issue there.

That's good to know, I figured the Z4 arms were right around the #4 from pics, further forward is even better. These are advertised for an e90 328, I don't see how they would fit.

My merges look more like shorty headers than yours, yours extend back much further. mine are staggered front/rear a bit and yours are side by side. The real issue will be how these fit between the transmission and the CAB. As long as the merges clear you can always change the routing of the tail piece.

Yeah tail piece shouldn't be tough but if the collector interferes I'm in for a lot more work.

Your pipes almost look like they come down from above the CAB a bit. They may just fit as-is. Finding off-the-shelf headers that fit the e30 would be game changing!

That would be awesome!

I will also add that yours are potentially better because they are more equal-length. My forward bank has a longer secondary than the rear bank.

I just measured the from the cylinder to the collector to see how close they are to equal length.

1-40cm
2-34.5cm
3-27cm
4-34cm
5-36.5cm
6-34.5cm

front collector to flange-31cm
rear collector to flange-17cm

I don't know enough about exhaust to know how any of that will affect performance but it has to be better than stock manifolds and they were fairly cheap so worth a shot.

[JRowe]

The e90 guys seem to report good experiences with those headers. Should work for our application as well. That’s what I’m trending towards using.

[FredK]

Here are the ones I ordered. $315 shipped to OK.

https://fmic.eu/174005-exhaust-manifold-header-bmw-n52-e90-e92-328i-2006-2011-fmic-exh-bb17.html

Cool, thanks.

hoveringuy, where did you source the head flanges for your custom header build?

[hoveringuy]

Cool, thanks.

hoveringuy, where did you source the head flanges for your custom header build?

I think they were SendCutSend or similar. hubcapboy?

[Striker01]

Cool, thanks.

hoveringuy, where did you source the head flanges for your custom header build?

If you're planning to order these headers, I will test fit them in my e30 as soon as I get the Z4 arms.

Been waiting 2 months on FCP Euro, tried another supplier yesterday that claims to have them in stock, we shall see.