M3 S54 exhaust manifolds for ZHP M54

[GoGators]

after you read the title your first thought/question is probably "why?" if your first thought/question isn't "why?" you probably have tried building for SCCA class STX.

STX (all of street touring) per SCCA rules requires Cats to be within 6" of their OEM location. I have personally challenged this via SCCA's official channel for rules changes, rejected, no rationale provided by SCCA. Headers are STX legal, but must conform to the aforementioned Cat restriction. this (obviously) eliminates off the shelf headers for ZHPs. essentially, the cat rule makes german cars the only one that cannot run header in Street touring...

I am getting real close to attempting to modify factory S54 exhaust manifolds to fit my M54. the cat locations are similar, the OEM manifold is tubular and though I have no way to compare the flow improvement, visually, it appears substantial. consider, they are designed for a 0.2 L larger engine spinning at ~1000 rpm higher = lots more air flow....

i should note that i am attempting this bc cost is low. S54 manifolds go for less than $200. reproduction flange on ebay ~$100.

plan would be to use either OEM or reproduction flange for M5X, cut off S54 flange from S54 manifolds, weld, then use M3 section1 tubing connection and reduce from 60mm to 50mm exhaust tube under the car...

below are things I have considered... and some associated risks. if you can think of something I have missed, please post to this thread!!!

-exhaust ports are round vs oval, based on reproduction flange available from kniseleyperformance, I think this will be a non-issue. note, per pictures on eatsleeptinker.com's spec E46 engine build, S52 manifolds fit M54. so the kniseley flange should mate fine.

-bore spacing, according to the forum posts, bore space is 91 mm for M54 and S54. this makes some sense.. but hate to trust forum posts...

-exhaust port angle, I have no way of knowing whether the angle of the ports on the head is same, but i think there is a chance to modify the angle by adjusting the S54 pipes where they will be welded to the flange..

stud/bolt access, this could be an issue as the flange bolt patters are substantially different. i am hoping... there will be room to access the nuts/bolts... (hope is not a plan, but its all i got)

-Cat space, i am assuming that if they fit an E46 M3 coupe, they should fit an E46 coupe/sedan..

-section 1 pipe on M3 is 60mm. it 'appears' to run in the same location as E46 non-M3. hope to be able to simply reduce using a small section of 2.25" pipe..

-O2 sensors, i don't see why this wont be plug and play.


pertinent thoughts? educated concerns?

[NoVAphotog]

I think you'd have better luck with the E36 M3 engine (S52 or S50) headers...same improved design on basically an engine that is the M54...

http://e46fanatics.com/forum/showthread.php?t=861866

[GoGators]

I think you'd have better luck with the E36 M3 engine (S52 or S50) headers...same improved design on basically an engine that is the M54...

http://e46fanatics.com/forum/showthread.php?t=861866

I surely agree that would be easier, but it doesn't solve my primary problem. S52 cats are located under the car, several feet from the cat location in E46.

[NickZHP]

Since it will still have the cats will there really be much improvement? I guess you can weld in racing cats to increase hp.

[GoGators]

Since it will still have the cats will there really be much improvement? I guess you can weld in racing cats to increase hp.

there wont be a dramatic difference. 4-5% hopefully. M3 manifolds are tubular, far superior design to ours. I don't think installing high flow cats will be practical, but use of the M3's should still be an improvement since they were designed for higher flow rate.

I will post a pic of 330 vs M3 manifolds when I pick up my donor set of 330 manifolds. found a set locally for $40. picked up an M3 manifold and section 1 pipe set for $150 this weekend.

[NickZHP]

Awesome, keep us updated on the project I'd like to hear how it goes. I recently finished installing my Active Autowerke headers and I definitely feel an increase in power and a nice improvement in sound. I can't be in STX anymore but I just do it for fun anyways so I'll gladly eat dust in Street Prepared ;)

[GoGators]

i now have a 325i manifold and an M3 header and sectio2474424745n1. here are some comparison pics of the short manifolds.

[GoGators]

2474624747comparison pics of the long manifolds

[GoGators]

now having looked at the two (off the vehicles for the first time) a few things are apparent that I wasn't expected. neither the exhaust port flanges are welded on, they appear to be some sort of press fit (this might make disassembly easier for me). the 330 casting-like manifold is heavy. the O2 sensor bungs on the M3 exhaust are a lot long than the 325 manifold. i presume this would make the O2 sensor not go in as far, for the after cat sensor that seems fine. for the important O2 sensors, ones before the cat, this seems like it might present a problem. will do some research, but i am leaning towards shorting the bung so the sensor is more in the exhaust stream.
2474824749

[GoGators]

i plan on starting to remove the flanges soon. i probably wont be able to put the car on jackstands and remove it from service for the week or so this will probably take anytime soon. hoping for May timeframe to start the fabrication process.

[BMWCurves]

This is very interesting, looking forward to seeing what you end up doing.

[GotZHP]

Any updates? Hows this project coming along

[GoGators]

a mere two months later... I have removed the flagnes from both sets. this was primarily a hack-saw job on the M3 set, a cutoff wheel job on the non-M set.

I also switched my MIG welder wire from standard to SS wire. I cut some slots in the non-M manifold/header tube to practice welding them up - I hadn't ever used the SS wire before.

Next step will be to make the round M3 tubes slightly oblong to more match the port shape of the non-M3 head and header flange.. After, I will be opening up the bores of the non-M flange so that the M3 header tubes slip inside. I hope to have them fit in about 1/8" so I can seal weld in the inside, then grind off the weld excess. then fillet weld the external diameter... prior to full welding I will do a test fit with the just tack-welded... hopefully, next week!!!

[slater]

very cool... looking forward to seeing the results!

[GoGators]

25655
progress thus far.. I intend on working the tubes to a more uniform oblong shape... then grinding the bore/port openings on the non-M flanges to suit.

[GoGators]

made some progress on the short/aft header. it took a ton of die grinding to open the bores enough to fit the m3 header tubes. one of the pics is a side by side with the flange I have not opened up next to the one I did grind open. the m3 header tubes slip in about 1/8" into the flange.

25659256602566125662

[GoGators]

Encountered the first significant snafu when I went to tack weld the flange to the pipes with the SS mig wire. It reacted poorly to the flange which based on the minimal corrosion I thought was a low grade SS bar. turns out its very magnetic, so it must just be mild steel, hence the SS wire wouldn't bond well. the pipes are definitely SS. So I have a dissimilar metal issue...

this fact may negate any benefit I would get by having some TIG weld it... so, i reloaded my MIG with the mild steel wire and tacked the flange to the tubes. going to consult the TIG welder i was going to use... downside of MIG with the mild steel wire is that it will corrode to some degree and more importantly, the filler material in the wire tends to create very hard, potentially brittle welds...

25663

[GoGators]

today should be test fit day. both manifolds are tack welded, in the event I need to adjust....

2570725708

[GoGators]

fit check on the zhp went well. they fit much tighter to the block than the manifolds did. only one nut is going to be more of challenge to access than they were coming off the manifolds... taking them to a motorcycle fabricator today for tig welding of atleast the interior circumference tomorrow... hopefully install on FRI/SAT then work on modifying the exhaust run to mate with the output flange of the M3header. I do have a set of section 1 pipes from the same donor m3..

2571025711

[slater]

awesome, awesome stuff! amazed at the size differences of the collector tubes!! wow.

really interested to see how the exhaust work goes, and how the end results are! great work. :cheers

[Sockethead]

Something like that should of been on the ZHP to begin with. Great progress! The other folks with e46s in your class are going to be jealous!

[QC_ZHP]

Can't wait to see how this turns out. Great work

[GotZHP]

Encountered the first significant snafu when I went to tack weld the flange to the pipes with the SS mig wire. It reacted poorly to the flange which based on the minimal corrosion I thought was a low grade SS bar. turns out its very magnetic, so it must just be mild steel, hence the SS wire wouldn't bond well. the pipes are definitely SS. So I have a dissimilar metal issue...

this fact may negate any benefit I would get by having some TIG weld it... so, i reloaded my MIG with the mild steel wire and tacked the flange to the tubes. going to consult the TIG welder i was going to use... downside of MIG with the mild steel wire is that it will corrode to some degree and more importantly, the filler material in the wire tends to create very hard, potentially brittle welds...

25663

I've had a few exhaust components over the years that were SS that had been mig welded. One I did myself. There will be corrosion for sure. They will get rusty, but they are under the hood so it wont be an eye sore. Only once did I have a weld crack, and it was on a knock off exhaust for my BRZ. Should be ok with the MIG i think.

Keep the updates coming! I am planning my exhaust set up now and want the Vibrant muffler but with catless headers, every cop in Irvine could here me get into town :eeps

[Aeternalis]

Those look great. Wish they were more of a direct replacement! Would probably be a pretty popular "OEM upgrade" for us M54 guys if so.

Can't wait to see everything all bolted up. :)

[GoGators]

Yesterday, James of street hero customs here in Jacksonville TIG'ed the interior circumference. Obviously, due to the tight interior and vast difference in material thickness, as well as one being stainless and the other carbon steel, it was a challenging job. the result is a nice bead all the way around, that was done in short stiches, this will be the only full seal as the entire external circumference is not accessible... more to follow!
2578125782

[GoGators]

when I got them home, I did as much of the outer circumference as was accessible with my MIG. again, doing about 1/2" stitch welds. they aint art, but they should be functional!

2578325784

[GoGators]

with all the fabricating done I wanted to test the setup.... its an understatement to say that finding a leak after installation would be inconvenient.. pic of test rig:

25785

[GoGators]

video of ~15 psi air test. both passed. my largest concern was actually the upper O2 bungs, I had to cut ~15 mm off of them. then file it flat, which is the sealing surface...

https://youtu.be/bm-l02Ggr1Q

[GoGators]

finished product compared to the ZHP manifolds.

2578625787

[GoGators]

all that's left is the simple chore of installing (haahaahahaa) then mating up the muffler delete 325i exhaust I previously put together with output flange of the M3 headers using a donor M3 section 1 pipe set...

[Sockethead]

Looks great! hard to believe how crappy the m54 exhaust is. Looking forward to you review of them once you get them bolted up and running

[Johnmadd]

Looks great! hard to believe how crappy the m54 exhaust is. Looking forward to you review of them once you get them bolted up and running

+1

[GoGators]

got the aft header installed yesterday. took about an hour. two of the nuts had to be turned 'flat by flat' with an open end wrench... should do the forward header today. I expect it to be much worse. the void where it goes is how I was able to easily access the aft header.

[Aeternalis]

Stock M54 manifolds are such garbage. Ugh. Almost physically painful to look at lol. I think I might get the Bimmerbrakes headers one day after all.

That aside, your S54 retro is coming along great.

[WOLFN8TR]

Very impressive work! [emoji106]

[GoGators]

thanks. got the second (forward) header on yesterday. it took about 3 hours, including a trip to napa to get a crows foot 11mm. two of the nuts had to be tightened with the crows foot and a couple wobbles to a wrench, turning, flat by flat.... not fun. got the underside of the car put back together. today, hopefully, I will get off work in time to start working on modifying the exhaust to adapt to the m3 section one pipe...

[WOLFN8TR]

When I did my headers and sect 1 in my M3 it was a Beouch!! Hours and Hours of frustration but so worth it in the end.

[GotZHP]

Wow, that is the crappiest exhaust manifold I have ever seen! Great progress, like the project.

Definitely putting in catless headers after I pass my next smog. No wonder these cars pick up as much power as they do just by swapping those POS out

[GoGators]

mating the 325i donor exhaust system that I previously 'muffler deleted' to the m3's section 1 pipe is going to be slightly more difficult than anticipated. the distance between the centerline of the parallel tubes is about 2" wider. So, I will have to shorten the inboard 45 deg run that goes to the first resonator. Will also have to fabricate a new hanger that mounts to the transmission since the wider spread will mean the factory hanger will be too narrow...

[Sockethead]

But the hard part is done and you have proven that M3 manifolds can be modified to work... at least physically so far...

[GoGators]

slide show of the pics from this project. IT IS DONE!!! only driven around the neighborhood to get it up to temp. immediate observation: the muffler delete exhaust I used previously and am using now isn't enough muffling... otherwise, I don't hear any leaks and I haven't romped on it enough to "butt-dyno" it....


https://youtu.be/1ugrjg4L2pE

[GoGators]

https://youtu.be/kKoWfVnwAho

finished up the M3 manifold/header swap on my ZHP. one significant poor assumption. I thought, swapping the OEM manifolds would only increase the decibel level through the exhaust a bit. wrong. its stupid loud. I am using a donor exhaust sys, that I previous had final muffler deleted (still has two resonators). it sounded awesome with the 330i stock manifolds. not so much now.

enjoy the audio and my 3 yr old's assessment.

going to try a vibrant flat black, dual output muffler on it - like Bryant put on his IR. hopefully, it will be enough muffler to take the rasp out...

[slater]

love the comments from your 3-year old!!

i hope the vibrant muffler helps!

[Sockethead]

LOl she knows what she's talking about...

I guess that shows just how restrictive the stock manifolds/cats are...

[Aeternalis]

I bet the Vibrant muffler will make that sound amazing. Stoked for the next video.

One wonders if BMW put those crappy manifolds on the M54 as a sound deadening measure as well...

[GoGators]

yea, I am shocked by the difference in decibel level (considering the M3's still have large cats). hopefully that indicates some improvement in flow performance... will def put another video together after the next iteration of this project; which I hope to be THE LAST!

[Aeternalis]

yea, I am shocked by the difference in decibel level (considering the M3's still have large cats). hopefully that indicates some improvement in flow performance... will def put another video together after the next iteration of this project; which I hope to be THE LAST!
I still have my stock ZHP muffler if you'd like to try that as well/first/instead. PM me if you're interested and I'm sure we can work something out. :)

[WOLFN8TR]

Excellent work even thou it's a bit loud which I'm sure you will figure it out. This video reminds me of when my daughter was 3 and I just installed headers, free flow cats and my SCZA muffler. The first time she went with me she says "daddy the car is too loud, does it need fixed"? [emoji849]

[Sockethead]

I wonder if my twin boys will tell me it sounds cool when I put headers on my car :scratchinghead

[Aeternalis]

I wonder if my twin boys will tell me it sounds cool when I put headers on my car :scratchinghead
Headers with the TSE3 will likely be a pretty intense volume.

[GoGators]

I still have my stock ZHP muffler if you'd like to try that as well/first/instead. PM me if you're interested and I'm sure we can work something out. :)

appreciate the offer, but really want something much lighter, as that was the original goal.... if this fails, I will probably break down and pay someone to rerun the exhaust to a sufficiently large restrictive muffler, locate it in the center of the car and dump it before the rear axle...

[Aeternalis]

appreciate the offer, but really want something much lighter, as that was the original goal....
Right on. The Vibrant muffler definitely fits that bill. Good luck!

[danewilson77]

love the comments from your 3-year old!!

i hope the vibrant muffler helps!



LOl she knows what she's talking about...

I guess that shows just how restrictive the stock manifolds/cats are...

Lmao..

S7 Edge, out

[GotZHP]

Wow that is loud. Love the 3 yr olds comments lol

[GoGators]

though my 3 yr old hasn't given her opinion yet, I am calling this done. I fit up and welded in a stainless y pipe (2 (2") into 1 (2.5")) and a Vibrant muffler, aslos 2.5".. I fit it up tight as possible to the rear valance, looks great in my opinion. Sound is darn good too. this is probably a pretty good comparison for anyone running headers who wants to put a vibrant muffler on, the two mid resonators are installed, though I would expect cat-less headers to be a bit louder/rasp-ier.



https://www.youtube.com/watch?v=J2xhqnQTAtw

[Aeternalis]

though my 3 yr old hasn't given her opinion yet, I am calling this done. I fit up and welded in a stainless y pipe (2 (2") into 1 (2.5")) and a Vibrant muffler, aslos 2.5".. I fit it up tight as possible to the rear valance, looks great in my opinion. Sound is darn good too. this is probably a pretty good comparison for anyone running headers who wants to put a vibrant muffler on, the two mid resonators are installed, though I would expect cat-less headers to be a bit louder/rasp-ier.
That sounds really good. Amazing how much the design of the stock ZHP headers reduces the sound. The M54 is a noisy bugger, lol.

[ProAmAuto]

I am in process of duplicating your headers. I have Ebay headers on my ZHP now, so I don't pass emissions. Do you have a CEL? Or are these working well for you. Thanks!

[GoGators]

I am in process of duplicating your headers. I have Ebay headers on my ZHP now, so I don't pass emissions. Do you have a CEL? Or are these working well for you. Thanks!

so far pretty darn good. I only have about 250 miles on them.

so far, only one SES, it came on after I sat in traffic at idle for ~30 minutes. it threw both Cat efficiency low codes. cleared them and they haven't come back.... I haven't had time to research it further, but I am using my 330i O2 sensors which are not the same as M3s. the precat sensor bungs I cut ~15mm off the bung so that the sensor would protrude into the pipe at the same depth as they did on the 330 manifolds. I did NOT cut the after cat bungs, though maybe I should have. not sure yet. if I were you, I would cut the after cat bungs, it seems likely that might be my issue. I need to research further, but if I continue to get those codes I may try M3 sensors, if I figure out that they will work.

[ProAmAuto]

I found this flange on Ebay. I think it would work if I sliced it into 2 pieces in the middle. Might make the conversion a little simpler. I can weld it up no problem. Does anyone know if this will NOT fit the M54 exhaust ports? The ad says it will and they answered an email that said all M5x engines had the same dimensions for exhaust ports and bolts. http://www.ebay.com/itm/M50-s50-M54-Exhaust-Manifold-Flange-M5x-s5x/252079861500?_trksid=p5713.c100284.m3505&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D12 %26asc%3D20140905073823%26meid%3Dcb514f6bc8624e128 e87e9b64302b045%26pid%3D100284%26rk%3D1%26rkt%3D11 %26sd%3D252079861500

[Sockethead]

looks legit... if the M3 headers minus the flanges fit in that flange, that would save you some work

[GoGators]

I found this flange on Ebay. I think it would work if I sliced it into 2 pieces in the middle. Might make the conversion a little simpler. I can weld it up no problem. Does anyone know if this will NOT fit the M54 exhaust ports? The ad says it will and they answered an email that said all M5x engines had the same dimensions for exhaust ports and bolts. http://www.ebay.com/itm/M50-s50-M54-Exhaust-Manifold-Flange-M5x-s5x/252079861500?_trksid=p5713.c100284.m3505&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D12 %26asc%3D20140905073823%26meid%3Dcb514f6bc8624e128 e87e9b64302b045%26pid%3D100284%26rk%3D1%26rkt%3D11 %26sd%3D252079861500

the port spacing should be fine. prior to starting the project I found these, or similar on ebay. the company would make a SS version for $150. I chose to use the M54 set bc I got them for $40.

all you are really gaining is you don't have to cut the manifold off the flange, which only took ~15 minutes with a cutoff wheel and sawzall. however, its always nice to start with a fresh machined piece rather than ~10 yr heat cycled metal...

[GoGators]

looks legit... if the M3 headers minus the flanges fit in that flange, that would save you some work

the challenge is access for welding... the external side of the flange, for the forward header is extremely restricted. I don't think its impossible, but I would like to see how someone did it!!! this is why I chose to have the interior tig'ed. I put a fillet weld on the exterior where accessible primarily to improve strength.

so, either flange (new or used) I think you will have to die-grind out the bores to accept the tubes as a slip fit (to accommodate the interior weld).

[Sockethead]

Saw these on Vibrant Performance website Pretty pricey though:
http://vibrantperformance.com/catalog/index.php?pseudocatlevel=BMW&cPath=1022_1124_1406

Mild Steel version:
http://vibrantperformance.com/catalog/index.php?pseudocatlevel=BMW&cPath=1022_1124_1407

[GoGators]

Saw these on Vibrant Performance website Pretty pricey though:
http://vibrantperformance.com/catalog/index.php?pseudocatlevel=BMW&cPath=1022_1124_1406

Mild Steel version:
http://vibrantperformance.com/catalog/index.php?pseudocatlevel=BMW&cPath=1022_1124_1407

yea, about ~$100/ea on jegs. same problem still exists though, challenging external fillet weld. so if you plan to interior weld, like I did, you will have to immediately grind away a lot of the material on that $100 flange...

[Sockethead]

yea interior weld is the only way to get a seal on it

[terraphantm]

so far pretty darn good. I only have about 250 miles on them.

so far, only one SES, it came on after I sat in traffic at idle for ~30 minutes. it threw both Cat efficiency low codes. cleared them and they haven't come back.... I haven't had time to research it further, but I am using my 330i O2 sensors which are not the same as M3s. the precat sensor bungs I cut ~15mm off the bung so that the sensor would protrude into the pipe at the same depth as they did on the 330 manifolds. I did NOT cut the after cat bungs, though maybe I should have. not sure yet. if I were you, I would cut the after cat bungs, it seems likely that might be my issue. I need to research further, but if I continue to get those codes I may try M3 sensors, if I figure out that they will work.

I wonder if the M3 being a LEV car rather than ULEV makes a difference here. IIRC M3 cats are less dense than most of that vintage (200 CPI vs 400 CPI). Don't know if that's enough to throw off the readings.

You won't be able to use M3 pre-cat O2 sensors since the ZHP has wideband precat O2 sensors while the M3 uses narrowband.

[Aeternalis]

Saw these on Vibrant Performance website Pretty pricey though:
http://vibrantperformance.com/catalog/index.php?pseudocatlevel=BMW&cPath=1022_1124_1406

Mild Steel version:
http://vibrantperformance.com/catalog/index.php?pseudocatlevel=BMW&cPath=1022_1124_1407
Details say that the part number includes two flanges. So about $65 each; not too bad.

http://vibrantperformance.com/catalog/product_info.php?cPath=1022_1124_1406&products_id=2719

[GoGators]

I wonder if the M3 being a LEV car rather than ULEV makes a difference here. IIRC M3 cats are less dense than most of that vintage (200 CPI vs 400 CPI). Don't know if that's enough to throw off the readings.

You won't be able to use M3 pre-cat O2 sensors since the ZHP has wideband precat O2 sensors while the M3 uses narrowband.

I need to put my fluke on the post cat sensors see what mV they are putting out. my OBDII reader will only read real time output of the pre-cat sensors. the SES has been coming on regularly now for the cat efficiency codes.

[terraphantm]

You should be able to get live readings with INPA. And Testo should be able to log them

[GoGators]

still trying to solve this problem without the necessary tools... I don't have INPA/NCS, heck I don't even own a laptop now (use ipad).

I bought a second hand M3 post-cat O2 sensor, cut and soldered the leads to a non-m3 post cat plug and tried it out. light came back on after several miles of driving, both banks (one running the M3 post-cat O2 sensor, the other running the non-m3 O2 sensor).

I am obviously more than a little surprised the M3 sensor didn't work. does anyone know if its possible that the threshold (in mV) that OBDII would flag would be different from a 330 to M3 (possibly attributed to the LEV/ULEV rating)???

I couldn't read the mV from the sensor readily bc of the plug, it has male ends on the sensor lead. I am going to use the non-M3 sensor that took the plug off and strip the wires and use the fluke to see what the output is... though, I am not sure what that data will tell me!

[Sockethead]

Is there a reason why you can't have someone code out the post cat 02 sensors? I had someone code out that along with the SAP when I installed my headers... problem solved

[GoGators]

honestly, I have looked into that very thoroughly. I don't know of anyone local to me that has that ability... but, that is certainly one possible solution.

[Sockethead]

I had to send my DME out to have it done but it was worth the $$/time without the car... post cat sensors gone, SAP gone and port blocked off with a block off plate which, I got from the dealer. It's a BMW part...

[GoGators]

so, still trying to mechanically solve the P0420/30 cat eff codes. I made an extension from two spark plug non foulers. drilled one out, cut the other one off and welded them together. installed the extension on the forward bank post cat O2 sensor, same result, both banks threw the codes.

26602

running out of options (short of DME coding - which I am trying to avoid bc of $$). going to remove the extension I made and weld the tip partially closed, say 50% or so. further reducing the amount of fumes that can reach the post cat O2 sensor.

[autom3otives]

so, still trying to mechanically solve the P0420/30 cat eff codes. I made an extension from two spark plug non foulers. drilled one out, cut the other one off and welded them together. installed the extension on the forward bank post cat O2 sensor, same result, both banks threw the codes.


running out of options (short of DME coding - which I am trying to avoid bc of $$). going to remove the extension I made and weld the tip partially closed, say 50% or so. further reducing the amount of fumes that can reach the post cat O2 sensor.

You might need a combination of a longer sensor spacer and a reducer. I'll be installing these in addition to my headers this weekend, the concept might be what you're looking for:

https://www.amazon.com/Vibrant-11619-J-Style-Restrictor-Adjustable/dp/B00AQ7972O/ref=sr_1_1?ie=UTF8&qid=1469739658&sr=8-1&keywords=vibrant+sensor+spacer

[Sockethead]

looks like a very nice piece...

[autom3otives]

looks like a very nice piece...

Seriously! Recommended by Phil at Eurocharged

[GoGators]

I hadn't come across that product, but yeah, that's a nice looking piece. if I cant get the el-cheapo spark plug non-fouler config to work, this would definitely be my next option.

[TWong1200]

Do you think that perhaps the used cats are just bad and your sensors are doing the correct thing and telling you?

[GoGators]

Do you think that perhaps the used cats are just bad and your sensors are doing the correct thing and telling you?

I don't think so. the donor M3 headers came off a car (they went with a full aftermarket arrangement) I know locally and had ~60k miles on them. also, you can the elements at the aft end, they looked great. I have seen ones that have failed and they are all charred and nasty.

[WOLFN8TR]

Excellent work, I love the way it sounds in the last video you posted! How much of a difference did it make performance wise?

When I did my exhaust I removed my stock headers at 95K and they were good. I wonder if you just need to do the proper drive cycle?

http://www.instructables.com/id/How-to-Do-BMW-OBDII-Drive-Cycle-For-Smog-Check/?ALLSTEPS

[GoGators]

Excellent work, I love the way it sounds in the last video you posted! How much of a difference did it make performance wise?

When I did my exhaust I removed my stock headers at 95K and they were good. I wonder if you just need to do the proper drive cycle?

http://www.instructables.com/id/How-to-Do-BMW-OBDII-Drive-Cycle-For-Smog-Check/?ALLSTEPS

there is certainly more pop in the mid-upper range. based on visual design and the amount of noise these make, I really think they flow pretty comparatively with typical M54 long tube headers. the sound is really nice, I don't the video really does it justice!

What I have been doing is clearing the 0420/0430 codes, then putting 5-ish, more abbreviated than that articles describes drive cycles on it, then the codes pop back up on it.

over the weekend, I made a pair of sensor extenders from 4 spark plug non-foulers. cut the threads off of two and welded them to the other pair. so, now there is only a ~1/4" hole at the end of the extender for exhaust to reach the sensor.

I am about outta ideas, so I will surely have them on long enough to accomplish the lengthy drive cycles mentioned in the link.

thanks!

[GoGators]

26665

Made a pair of these, installed earlier this week. I have driven more cycles than it has taken previously to set off the P0420/30 codes, so I don't want to get my hopes up, but this appears to be a possible solution.

[Fenrir]

This thread is a spectacular read. Keep up the good work!

[GoGators]

This thread is a spectacular read. Keep up the good work!

Haha. thanks.

Been driving with both the O2 sensors extension installed about a week now. No check engine light, thus far.

ALmost ready to claim victory on that post cat O2 sensor issue and the project in general.

At this point it has met my original objective to have an SCCA legal header on the car at a very low cost. Howver, I had hoped this config may be a solution for those living in states that still smog test, I don't know if it will work for them considering the difference in ratings of the Cats. But, other than that, runs good, sounds awesome, hasn't broke and so far, no more check engine light!

[WOLFN8TR]

Excellent work!! Congrats!!

http://uploads.tapatalk-cdn.com/20160811/3d247e6fea636264abc70face49081db.jpg

[Aeternalis]

Haha. thanks.

Been driving with both the O2 sensors extension installed about a week now. No check engine light, thus far.

ALmost ready to claim victory on that post cat O2 sensor issue and the project in general.

At this point it has met my original objective to have an SCCA legal header on the car at a very low cost. Howver, I had hoped this config may be a solution for those living in states that still smog test, I don't know if it will work for them considering the difference in ratings of the Cats. But, other than that, runs good, sounds awesome, hasn't broke and so far, no more check engine light!

If only it was simpler to do. :( Lol. Great work, loved following the thread.

[GoGators]

Yeah, I would not classify this as an easy or simple modification. Time, patience and tools. Its miles more challenging than oil pan gasket, which prior to the headers, I had regarded as my least favorite common e46 repair (of which there are many).

[murph]

If anyone is interested in trying this, I wanted to do a similar setup, and so I have a set of headers that I had the M54 flanges welded to... My fabricator did a much nicer job of getting smooth ports on the interior, but screwed up the angle, so mine end up bumping the motor or trans, and I abandoned that approach. If someone wanted to cut it up and get the angle adjusted, I'd give them the set I have for the cost of shipping, just email or PM me.

It sounds like you're happy with your post-cat exhaust setup, but if you decide you want to go lighter and better performing, I'd recommend the bimmerworld M3 exhaust. It should route fine, and mate up to your M3 headers well, maybe with small modifications.

[ProAmAuto]

So, just checking back in on this thread. Now that its been about 3 months since you finished up this project, have you solved the CEL issues? I am just about to pull the trigger on doing this myself. My ZHP factory manifolds were stolen while I had headers on the car. Now I want to go back to cats but still have some of the power gains from the headers....Thanks again and great thread post.

[terraphantm]

I might give this a try. I think my ZHP has bad cats, and I don't want to go catless. I think I still have my M3's original headers somewhere...

[GoGators]

Sounds like you have all the major components you need (set of M54 flanges and S54 manifolds).

Since I haven't posted a follow up in a while.... since I put the post cat o2 sensor bung extensions on I have gotten a couple CEL over the course of the last 5-6 months. its seems to only happen when the car idles for a prolonged period of time, typically, for me that has been while sitting in grid at autocrosses. Its so infrequent I do not plan on further troubleshooting. Otherwise, performance, operation and sound are still A+.

[terraphantm]

Sounds like you have all the major components you need (set of M54 flanges and S54 manifolds).

Since I haven't posted a follow up in a while.... since I put the post cat o2 sensor bung extensions on I have gotten a couple CEL over the course of the last 5-6 months. its seems to only happen when the car idles for a prolonged period of time, typically, for me that has been while sitting in grid at autocrosses. Its so infrequent I do not plan on further troubleshooting. Otherwise, performance, operation and sound are still A+.

Yeah I have the major pieces, but what I'm missing is time. We'll see.

If I do end up going this path, I'll try to figure out the o2 sensors stuff. I think taking parameters from the Z4m software may do the trick (its dme is much closer to the ZHP DME than the M3 DME is)

[Raptorman5174]

wow I just read this whole thread, great job you did on the exhaust manifolds and they sound good to :thumbsup:

[GoGators]

wow I just read this whole thread, great job you did on the exhaust manifolds and they sound good to :thumbsup:

THANKS!

[ZHPizza]

@GoGators thank you so much for documenting your journey here. I've been looking for a catted header solution for the M54 and this looks to be the most reasonable solution, despite the headaches involved. I picked up a set of M3 headers the other day and am hoping to do this project over the winter.

Also just came across these SS flanges with 3 machined bores for mating to round tubes. I'll have to measure the tubes on the S54 headers to see how they match up to the bores before ordering, but they look pretty nice.

https://www.ebay.com/itm/K-Precision-M50-s50-M54-Split-Exhaust-Manifold-Flanges-M5x-s5x-Stainless-Steel/253008577732

[Sockethead]

Good find on those flanges.. hopefully they’ll do the trick. If I was still in Jersey, this is the route I would take.

[GeorgeH]

Any thought on using S54 Euro headers and cats?

[ZHPizza]

Any thought on using S54 Euro headers and cats?You would definitely have to code out the O2 sensors with the cats being that far from the engine, but I don't see why it wouldn't work. Still have to change out the flanges of course.

[GeorgeH]

You would definitely have to code out the O2 sensors with the cats being that far from the engine, but I don't see why it wouldn't work. Still have to change out the flanges of course.

The S54 gets away with the cats that far away, why do you think that would be a problem for the M54?

[az3579]

The S54 gets away with the cats that far away, why do you think that would be a problem for the M54?

Different DME, perhaps?

[GeorgeH]

You would definitely have to code out the O2 sensors with the cats being that far from the engine, but I don't see why it wouldn't work. Still have to change out the flanges of course.


Different DME, perhaps?

Yes it is a different DME, but you said "You would definitely have to code out the O2 sensors with the cats being that far from the engine" I was just wondering if you had data for that statement? I will probably end up with some kind of header setup on my ZHP inspired HPDE wagon, but I want to retain cats so moving them downstream is likely in the cards. I don't have a problem coding them out, but would prefer not to if I don't have to.

[ZHPizza]

Yes it is a different DME, but you said "You would definitely have to code out the O2 sensors with the cats being that far from the engine" I was just wondering if you had data for that statement? I will probably end up with some kind of header setup on my ZHP inspired HPDE wagon, but I want to retain cats so moving them downstream is likely in the cards. I don't have a problem coding them out, but would prefer not to if I don't have to.

Just because of the different DME, really. The primary O2 sensors that set your fuel trims will still operate just fine. The M54 stock cats are right up on the block, so the DME is looking for a signal there from the secondary O2 sensor. If you remove the cats or move them down the line, then it won't look right to the DME and throw a CEL. People that add headers or move the cats downstream have to code out the secondary O2 sensors. No big deal, really. I may even have to do it with the OE S54 manifolds.

[DeathTrap]

See if you can get some secondary O2 logs from M3 guys running the Euro cats. I was also interested in running a cat in that location with aftermarket headers while retaining the stock DME coding and hardware.

[GeorgeH]

I would think if anything you may not be able to get the cat hot enough. But there are plenty of S54 guys who have run Euro headers and cats with stock US tunes. I don't know how the DME would know if the cats are 10" in from the header or 40", that's why I was curious to see if that same theory would apply to the M54. Also keep in mind that aftermarket cats may not be as efficient as a BMW cat, so if they are used down stream I'm not sure that means the cat location is the issue.

[JETSET303]

Although I haven’t done this with my ZHP, I had this issue with a full custom exhaust in my 2001 Jeep XJ Cherokee. Had to move the cats further back which threw a code. Pulled the header out and double wrapped it. Problem solved. The header wrap kept enough heat moving down stream that it allowed the cats to work. Granted not a BMW, but a hot running straight 6 none the less. I was thinking about trying this when I get a header for the ZHP. Anyone tried this on their BMW?


Sent from my iPhone using Tapatalk

[DeathTrap]

I don't think it matters how far down the cats are as long as the mixture reads the same as stock. Now there is response time that would probably play a sizable role in whether the DME likes the new setup.

I'm just going to use an Innovative LC-2 when that time comes.

[JETSET303]

I don't think it matters how far down the cats are as long as the mixture reads the same as stock. Now there is response time that would probably play a sizable role in whether the DME likes the new setup.

I'm just going to use an Innovative LC-2 when that time comes.

Cats require heat to function properly. If they are too far down stream, the dissipation of heat can result in a fault in the post-cat O2 sensor. Not reaching their designed operating temperature results in inefficiency which results in readings that are outside parameters. Hence why they are so close to the exhaust manifolds in nearly all cars from the factory.


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[DeathTrap]

Cats require heat to function properly. If they are too far down stream, the dissipation of heat can result in a fault in the post-cat O2 sensor. Not reaching their designed operating temperature results in inefficiency which results in readings that are outside parameters. Hence why they are so close to the exhaust manifolds in nearly all cars from the factory.


Sent from my iPhone using Tapatalk

Agreed. That's also why manufacturers are tending toward integrated manifolds. Gotta heat the cat up as fast as possible to reduce the most severe emissions from cold start.

Legally, I know that the position of the cat cannot be more the 3" from OEM location or the EPA will get you, but ehh. :)

The S54 also uses inconel for the header material, indicating that the motor runs really hot exhaust gasses through those tubes compared to the M54.

I think a more relevant question here is how far out of spec can we go before the DME flags the cat?

[ZHPizza]

Well I am trying to move forward on this project and ran into an issue. Just posted on e46f so copying it here in case anyone is considering this...

So I thought I would be able to pull this off without modifying the OE midsection, but it turns out I can't shorten the rear M3 header enough to fit the OE connection. I'll have to modify the midsection too to move the flanges downstream a bit.

S54 manifolds:
https://uploads.tapatalk-cdn.com/20190713/3146dfacad4135f38002cacb485251f5.jpg

M54 manifolds:
https://uploads.tapatalk-cdn.com/20190713/78f9ee14e451301cc7eaece20a47f914.jpg

Front comparison - for this one, the S54 pipe COULD be shortened enough to make the M54 flange location work:
https://uploads.tapatalk-cdn.com/20190713/69d8da682f0e5d0762fd00bdf8f39376.jpg

Rear comparison - but you can't do the same with the rear:
https://uploads.tapatalk-cdn.com/20190713/3ce5f76fd710d6d2fdc7478515fef7db.jpg

The S54 cat extends into where the M54 flange is, hence the need to move the flanges downstream a bit on the misdsection:
https://uploads.tapatalk-cdn.com/20190713/d2c5bbb2483016566939dc5f9658d58e.jpg

The guy on e46f saw this and moved the midsection flanges down and shared these pics of the finished product:
https://uploads.tapatalk-cdn.com/20190713/262e08aaaeaf0b0610d1f1eb1de75f7b.jpghttps://uploads.tapatalk-cdn.com/20190713/8f25f0bc133f7c3d49865f7f0d0cfe7a.jpghttps://uploads.tapatalk-cdn.com/20190713/d866763b56991d3da121a6f470ab909f.jpg

I just sent these to my buddy that's doing the fab work and I guess I'm taking him the whole damn exhaust on Monday [emoji52]

[san]

Well I am trying to move forward on this project and ran into an issue. Just posted on e46f so copying it here in case anyone is considering this...

So I thought I would be able to pull this off without modifying the OE midsection, but it turns out I can't shorten the rear M3 header enough to fit the OE connection. I'll have to modify the midsection too to move the flanges downstream a bit.

S54 manifolds:
https://uploads.tapatalk-cdn.com/20190713/3146dfacad4135f38002cacb485251f5.jpg

M54 manifolds:
https://uploads.tapatalk-cdn.com/20190713/78f9ee14e451301cc7eaece20a47f914.jpg

Front comparison - for this one, the S54 pipe COULD be shortened enough to make the M54 flange location work:
https://uploads.tapatalk-cdn.com/20190713/69d8da682f0e5d0762fd00bdf8f39376.jpg

Rear comparison - but you can't do the same with the rear:
https://uploads.tapatalk-cdn.com/20190713/3ce5f76fd710d6d2fdc7478515fef7db.jpg

The S54 cat extends into where the M54 flange is, hence the need to move the flanges downstream a bit on the misdsection:
https://uploads.tapatalk-cdn.com/20190713/d2c5bbb2483016566939dc5f9658d58e.jpg

The guy on e46f saw this and moved the midsection flanges down and shared these pics of the finished product:
https://uploads.tapatalk-cdn.com/20190713/262e08aaaeaf0b0610d1f1eb1de75f7b.jpghttps://uploads.tapatalk-cdn.com/20190713/8f25f0bc133f7c3d49865f7f0d0cfe7a.jpghttps://uploads.tapatalk-cdn.com/20190713/d866763b56991d3da121a6f470ab909f.jpg

I just sent these to my buddy that's doing the fab work and I guess I'm taking him the whole damn exhaust on Monday [emoji52]

If you manage to make this work then I might do the same...


Sent from my iPhone using Tapatalk

[Chaplian]

Bump, any updates on this? I'm looking into doing the same on my touring for when I do the M54B30 swap.

[ZHPizza]

I abandoned the project for a few reasons:

1. The primaries on the S54 headers are so small that they did not mate up to the stainless M54 flanges that I had bought on ebay. Smaller primaries are a good thing as you don't want the collector to be a smaller cross section than the 3 primaries, but it meant I had to do what others had done and cut the mild steel flanges off of the OE exhaust manifolds and use those.

2. Getting the angles right was harder than I anticipated. I mocked them up on the car and then took the parts to work and barely tack welded the headers onto the flanges, thinking that I could bend the tack welds a bit to massage them into place on the car, then bring them back for finish welding.The fitment was too far off for that strategy. They'll need to be re-tacked in place while on the car. I don't have a welder at home and my car was stuck on the lift with no exhaust manifolds so I needed to get something on it that worked and had already chopped up my OE manifolds.

3. The transition to the rest of the exhaust was going to be a bear with changing the flange placements, and I would have to neck down from the M3 2.25" exhaust diameter to mate with our 2.0" piping. That would probably be fine for this situation, especially since you're coming straight off the cats, but you really never want to neck down in an exhaust system as it will create backpressure.

So with all that in mind and the fact that I had butchered my OE manifolds and couldn't just throw them back on, I ordered a set of 'ebay headers' on Amazon with next day shipping and got those on the car.

The results were...ok. There was a noticeable bump in power, but the ECU seemed to be chasing the fuel trims and of course my car was now catless and just cranking out poisonous gases and honda rasp. I was already this far and liked the extra torque, so I picked up some Magnaflow high flow cats and had them welded in just behind the flanges for the headers (I'll try to grab a pic the next time I'm under the car). The cats knocked down 90% of the rasp, but the cat bodies are 4" diameter, which would be great for a forced induction car, but with NA there is a big loss of exhaust gas velocity there and it sapped away most of the power that I had picked up with the headers.

So current state of my car:
Ebay headers (https://www.amazon.com/gp/product/B07JGXTQ94/) wrapped in fiberglass shit
Magnaflow cats (https://www.amazon.com/gp/product/B000XQM36K/) welded in just after the headers, beside the transmission
maybe a little more power than stock...maybe
cats take longer to heat up than OE so startups and first 5 mins of driving are noxious af, after that it's fine

I'm not thrilled with it, and would rather have stock manifolds than what is currently on the car (stock was less rasp, less emissions, same-ish power), but I'll keep working on it. I have a Borla exhaust ready to go on and may try to swap the first canister on it for a 2in-2out cat to see if it the smaller cat body keeps the velocities up.

Lmk if you want to buy some low mileage S54 headers tacked to M54 flanges for cheap:
https://uploads.tapatalk-cdn.com/20200104/cc68e8fba2121f7145f651caa435b0ba.jpg

[BMWCurves]

I had no idea you had attempted this. Shame it didn't work out (yet), but savor that sweet sweet reward of educating the rest of us?

[holyc0w]

Hmmm... it seems like the best way to get these to work would be an S54 swap. :ducking

[Reasoned1]

Great idea--thanks for trying and educating the rest of us! And I think holyc0w may be right...

[Chaplian]

I abandoned the project for a few reasons:

1. The primaries on the S54 headers are so small that they did not mate up to the stainless M54 flanges that I had bought on ebay. Smaller primaries are a good thing as you don't want the collector to be a smaller cross section than the 3 primaries, but it meant I had to do what others had done and cut the mild steel flanges off of the OE exhaust manifolds and use those.

2. Getting the angles right was harder than I anticipated. I mocked them up on the car and then took the parts to work and barely tack welded the headers onto the flanges, thinking that I could bend the tack welds a bit to massage them into place on the car, then bring them back for finish welding.The fitment was too far off for that strategy. They'll need to be re-tacked in place while on the car. I don't have a welder at home and my car was stuck on the lift with no exhaust manifolds so I needed to get something on it that worked and had already chopped up my OE manifolds.

3. The transition to the rest of the exhaust was going to be a bear with changing the flange placements, and I would have to neck down from the M3 2.25" exhaust diameter to mate with our 2.0" piping. That would probably be fine for this situation, especially since you're coming straight off the cats, but you really never want to neck down in an exhaust system as it will create backpressure.

So with all that in mind and the fact that I had butchered my OE manifolds and couldn't just throw them back on, I ordered a set of 'ebay headers' on Amazon with next day shipping and got those on the car.

The results were...ok. There was a noticeable bump in power, but the ECU seemed to be chasing the fuel trims and of course my car was now catless and just cranking out poisonous gases and honda rasp. I was already this far and liked the extra torque, so I picked up some Magnaflow high flow cats and had them welded in just behind the flanges for the headers (I'll try to grab a pic the next time I'm under the car). The cats knocked down 90% of the rasp, but the cat bodies are 4" diameter, which would be great for a forced induction car, but with NA there is a big loss of exhaust gas velocity there and it sapped away most of the power that I had picked up with the headers.

So current state of my car:
Ebay headers (https://www.amazon.com/gp/product/B07JGXTQ94/) wrapped in fiberglass shit
Magnaflow cats (https://www.amazon.com/gp/product/B000XQM36K/) welded in just after the headers, beside the transmission
maybe a little more power than stock...maybe
cats take longer to heat up than OE so startups and first 5 mins of driving are noxious af, after that it's fine

I'm not thrilled with it, and would rather have stock manifolds than what is currently on the car (stock was less rasp, less emissions, same-ish power), but I'll keep working on it. I have a Borla exhaust ready to go on and may try to swap the first canister on it for a 2in-2out cat to see if it the smaller cat body keeps the velocities up.

Thanks for the follow-up! Not the news I was hoping for, but I definitely appreciate your insight and experiences.


Do you guys have emissions testing in NC? I've been thinking about doing your same plan also, but I don't know how happy the post-cat O2s would be if I moved the cats downstream, and we have OBD2 emissions testing here. The other option is the Pypes exhaust manifold that's a slightly improvement over stock.

[DeathTrap]

I thought the car wouldn't care THAT much about gas velocity after the collector?

I have my headers on and the rasp is...an acquired taste. I much prefer the smooth sound of the stock exhaust, but don't want to lose the power either.

Sent from my Pixel 2 XL using Tapatalk

[ZHPizza]

Thanks for the follow-up! Not the news I was hoping for, but I definitely appreciate your insight and experiences.


Do you guys have emissions testing in NC? I've been thinking about doing your same plan also, but I don't know how happy the post-cat O2s would be if I moved the cats downstream, and we have OBD2 emissions testing here. The other option is the Pypes exhaust manifold that's a slightly improvement over stock.

Yep, we have the same testing in NC and my car is due now. I tried many iterations of spacers to make the post cat O2 sensors happy and couldn't, so I'm going to try to move them downstream to somewhere after my magnaflow cats...once I figure out a cat setup that I like. This has been way more of a headache than finishing the S54 headers would have been. Live and learn!



I thought the car wouldn't care THAT much about gas velocity after the collector?

I have my headers on and the rasp is...an acquired taste. I much prefer the smooth sound of the stock exhaust, but don't want to lose the power either.

Sent from my Pixel 2 XL using Tapatalk

Gotta maintain velocity to the tip, my dude. Any place where the gasses slow down means backpressure upstream. It should be fine on the S54 cats since you're necking down from the catalyst anyway - just going down to 2.0" instead of 2.25".

The rasp of the headers without cats on stock exhaust was embarrassing for me. The fumes were even worse - I felt so bad driving through town with kids on the sidewalk or really if anyone was behind me. We've all been stuck behind catless cars breathing that nasty shit because some inconsiderate bro wanted more power. I did not like being that bro.