Dedicated Exhaust Discussion

[LukeJ]

Here is the DXF for the header flange I created for my equal length headers. The three exhaust ports are about .015" undersize for my design because I put them on a fixture and bore them to exact dimensions. However, they could be used to attach to a set of S54 headers and work just fine. I had my flanges laser cut from 1/8" 304SS, but whatever works for your application will probably be suitable. I have always used OSHCUT for my laser cutting and now they do bending as well. I haven't had any problems with quality from OSHCUT and haven't needed to consider using another supplier.

Well.... I tried to post the DXF for the header flange, but the website won't allow me to do it. Would someone let me know what needs to be done to share this DXF to Rev. Thanks!!

[Habla]

Also stumbled on this nutjob with a homebrew Locost project that seems relevant. Dig deep for an ITB adapter as well...

https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/brunton-stalker-m-spec-bmw-n52/149440/page1/

[Habla]

Did some digging for the euro part numbers today and found these:

18407568613 & 18407568614

https://www.schmiedmann.com/en/product/1955768-used?product=B18407568613

https://www.schmiedmann.com/en/product/1955768-used?product=B18407568614

https://www.realoem.com/bmw/enUS/showparts?id=VE31-EUR---E90-BMW-325i&diagId=18_0741


Or if you're really trying to spend some money:

https://www.supersprint.com/ww-en/bmw-e85--e86-z4/supersprint-performance-sport-exhaust-bmw-z4-30si/manifoldbr-replaces-catalytic-converter.aspx#!/

[JRowe]

Looks like 🇬🇧 UK has an equal length, or at least closer to it, aftermarket option. Not shipping to US though.

https://www.ebay.co.uk/itm/184725295...3ABFBMhJXezfVi

[Striker01]

A solid option might be to get a set of N52 euro headers and de-cat them. Or you could probably even leave the cat...

Why didn't the US get these, I don't know.

I think Lukej or hubcapboy tried to find those but weren't able to figure out the part number or which cars got them. I remember seeing them in one of their build threads.

[hoveringuy]

A solid option might be to get a set of N52 euro headers and de-cat them. Or you could probably even leave the cat...

Why didn't the US get these, I don't know.

[FredK]

Heeeeeey everybody.

The flanges were drawn from a set of the factory e90 manifolds I'm still using as a wheel chock to stop an old truck from rolling down my alley. They're in the master "here's my stuff" DXF linked here:

https://www.r3vlimited.com/board/forum/e30-technical-forums/24v-engine-swaps/n54-n52-swap-forum/10050713-n52-e30-cad-templates-for-oil-pan-engine-arms-and-other-fun-parts

From memory mine were a little tight between two studs, but they fit and they work. The biggest challenge to adapting headers is the "neck-down" you can see in hoveringuy's post. These are necessary when using s54 header tubes for two reasons. 1. you've cut the old flange off, so the primaries are now too short and 2. the n52 gaskets aren't a flat gasket against the head... each primary has a waxy ring that sits around a short length of the primary that extends through the flange and into the head.

I tried as hard as I could to get my hands on aftermarket headers to check fit, but I was pretty confident that all the factory and aftermarket options for the n52 would interfere (severely) with the control arms and bushings. I hope I'm wrong!

Got it. thank you. The way the aftermarket headers don't hug the transmission make me think they won't clear the control arm bushing either. I'm keeping my fingers crossed for Striker.

[hubcapboy]

At some point when my project spins back up I'll be catching up with hoveringuy and the Z4 mounts. I'm concerned that there's a 50/50 shot that the headers I built won't work with them (ours are close but not identical). My plan if that happens is to use a kit like this and actually get them done right:

https://www.gpheaders.com/products/custom-headers/

[hubcapboy]

Heeeeeey everybody.

The flanges were drawn from a set of the factory e90 manifolds I'm still using as a wheel chock to stop an old truck from rolling down my alley. They're in the master "here's my stuff" DXF linked here:

https://www.r3vlimited.com/board/forum/e30-technical-forums/24v-engine-swaps/n54-n52-swap-forum/10050713-n52-e30-cad-templates-for-oil-pan-engine-arms-and-other-fun-parts

From memory mine were a little tight between two studs, but they fit and they work. The biggest challenge to adapting headers is the "neck-down" you can see in hoveringuy's post. These are necessary when using s54 header tubes for two reasons. 1. you've cut the old flange off, so the primaries are now too short and 2. the n52 gaskets aren't a flat gasket against the head... each primary has a waxy ring that sits around a short length of the primary that extends through the flange and into the head.

I tried as hard as I could to get my hands on aftermarket headers to check fit, but I was pretty confident that all the factory and aftermarket options for the n52 would interfere (severely) with the control arms and bushings. I hope I'm wrong!

[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.

[hoveringuy]

Cool, thanks.

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

I think they were SendCutSend or similar. hubcapboy?

[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?

[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.

[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.

[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.