Dedicated Exhaust Discussion

[Striker01]

These header flanges point down way too far for my taste, they could also be much closer to the transmission. I cut the flange off the rear set so I could actually get them mounted flush on the head. I think the only work required will be behind the collectors. My plan is to get the front set turned towards the rear of the car and moved up and in closer to the transmission then pull the engine to get the rear set matched as close as possible to the front. I want both flanges above the CAB.





Lots of clearance between the frame rail and headers, about 1/2 between the headers and sway bar.


This flange is too low and pointed down too far.

[Striker01]

I finally got my engine arms and test fit the engine. The cheap headers I posted above are going to need some work to fit. First of all the primary tubes that fit into the head were too long on 5 of the 6 cylinders and required a little trimming.


The countersunk holes do not line up on all cylinders and will need some dremel or drill press work to get the nuts on and tightened.





These headers do try an occupy the space where the CAB is, treehouse type may be fine if you want to go that route.



Sorry for the poor picture here, hard to hold the header and get my phone lined up. With the flange against the CAB there is about 1/4 before the header will sit flat against the head. This rear set could've been tucked much closer to the front set.

[hubcapboy]

hubcapboy You have your files on Google drive or something, right? Can you host this DFX?

https://drive.google.com/file/d/1jH2NTVyfXpbvH98rMXtXlgL9ND-waoTZ/view?usp=drivesdk

it’s in my master DXF file I linked from the other thread. I didn’t want to link directly because I didn’t want it to look like new work , but here it is. This has everything I’ve drawn and ordered that shows up in my posts… if anyone wants a specific part they’ll need to copy it out with a dxf editor.

[hubcapboy]

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 chased these for a long time. I don’t think they were on *many* n52’s in Europe. They certainly didn’t seem to be the default. I’ve ordered a lot of car parts from very weird countries just to see if they’d arrive, and I was never able to source a set of these.

[hoveringuy]

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!!

hubcapboy You have your files on Google drive or something, right? Can you host this DFX?

[Striker01]

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

18407568613 & 18407568614

Nice work. I searched ebay.de for every N52 vehicle and never came across those.

I can confirm the cheap AA look alike headers fit fine with the Z4 arm. The left side mount is scheduled for delivery this Friday, depending on my son's soccer schedule I may test fit the engine this weekend.

A couple things to note, these headers came with standard style flat gaskets, not sure if I should use them in addition to the donut ones or just stick with the donut gaskets. The additional gasket will help with clearance for the bell housing bolt hole on the block. The countersunk holes look like a few of them will need to be enlarged to get the flange nuts to sit flush.

[FredK]

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

That's quite a lot of work! Pretty freakin cool Locost, I love seeing these extreme DIY projects.

[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/184725295841?fits=Car+Make%3ABMW&hash=item2b027c52e1:g:DhsAAOSwfDtjhJEV&amdata=enc%3AAQAIAAAA8Fi9f1NyGqSCin3rHf%2F5p01lGg12iPe8ORFas7RxY2yujeqMSU7UlSnI7%2FDpUxhq6qcB78e8Mw7nfcEanHG5pCRKYeaaeFKBgMEIhR9fHOrFyr3VQL8Wg7RjCEPxw83rJU6uAz0EeDZeI5zV9DEJcR1Pl%2FWoc6S3ibinHuQSNbEXiPacqWsmFv7aDKEZZYYp8Oc09wUXJfL36R26p8SYVd4RILb%2BNNzczhPxISlhLU0PPTFqTCSxdOz5kBxUik2NM0UnzLPjg7HXm6Ss8aJaQs%2Fr48eNt6R9p1GNGrrmpQRxohH8jkb4XITOMApTC7PLgw%3D%3D%7Ctkp%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/