American Racing Headers

[Beedub]

For me??

the Euro headers are that nice, theirs no fitment issues, personally..... wouldn't touch this with a 50ft pole.... waste of money and clearly never intended for the smaller z4 chassis. Thanks for trying tho OP, much appreciated , the community is better for people like yourself!

[bananabun]

Originally Posted by Beedub

For me??

the Euro headers are that nice, theirs no fitment issues, personally..... wouldn't touch this with a 50ft pole.... waste of money and clearly never intended for the smaller z4 chassis. Thanks for trying tho OP, much appreciated , the community is better for people like yourself!

Thanks, Beedub! Learned a lot from you guys when I just bought the coupé earlier this year, so happy to give back a little

[Taskmaster]

Op was banned?

[WeekendWarriorz]

Originally Posted by TheAxiom

Op was banned?

Guess so, was a great guy.

[Twixboy]

Originally Posted by TheAxiom

Op was banned?

Originally Posted by WeekendWarriorz

Guess so, was a great guy.

bananabum doesn't look banned to me

[RossBMWZseries]

Why was he banned? Failed group buy..?

[AriuSen]

Originally Posted by RossBMWZseries

Why was he banned? Failed group buy..?

Lolol. I would be banned few times if that was the case.

[rueyme]

what was the latest on this? did they ever get anywhere? looking for some project to squeeze any extra gains out above the euro headers so was considering this but haven't heard any follow up.

[pokeybritches]

Originally Posted by rueyme

what was the latest on this? did they ever get anywhere? looking for some project to squeeze any extra gains out above the euro headers so was considering this but haven't heard any follow up.

I suspect they won't work due to the way the ECU calculates fuel trims. Here's some background:

The MS43 ECU has a parameter that controls the number of O2 sensors the ECU uses for fuel trims. The logic exists to reduce that number all the way down to a single O2 sensor, which is perfect for 6:1 turbo manifolds or applications like this.

The MS45 ECU (2003-2005 6-cyl BMWs, including the non-M Z4) does not have the same logic built into the ECU. The only way to run a single O2 sensor is a change to the program code, which is significantly more complicated. If a single O2 sensor is used without such a change, one cyl bank will attempt to control all the fuel trims while the other will sit at 0%. So, if fueling was 10% rich, the ECU would compensate by removing 20% fuel from one bank while the other would have no trim.

Placing both O2 sensors into a single exhaust pipe next to each other has even worse results. Each bank's fuel trims will fight with each other and diverge. One bank will go full rich while the other will go full lean, even though overall AFR will look ok. This has to do with each sensor reading slightly differently and the ECU reading each sensor separately at a different time.

BMW N54 ECUs have the same challenge that must be overcome when installing a single turbo 6:1 manifold. As far as I know, the only solution for those cars involves 6:2:1 manifolds. The MSS54 ECU in the E46 M3 has the same challenge too. NickG was able to overcome it with a program code change.

I assume the MSS70 ECU in the Z4M has the same issue. It would be easy to test, since the parameter for O2 sensor configuration exists and can be modified. If the logic exists and the parameter can be calibrated so the ECU only uses a single primary O2 sensor, then one bank will show no fuel trims while the other will show trims with both sensors plugged in. This can even be tested with stock headers. However, considering that no other Siemens ECU after MS43 has the logic built in, it's doubtful MSS70 has it programmed in.

[rueyme]

Thanks for the helpful information. You gave me some technical knowledge on how these cars work to better help my quest to squeeze out gains.

[Sergio19]

Bumping this as there has been some renewed interest in 6-1 headers for the sound. Sounds so much better than the typical S54 rasp.

Do we know if the ECU problem can be overcome?

Sound clips / dyno here:

https://thebuildjournal.com/reviews/...ts-and-review/

[pokeybritches]

I’ve spent a lot of time digging into single O2 sensor conversions since my post a few years ago, and unfortunately I was correct- the logic does not exist in MSS70 without program code changes. I have gotten these to work with some compromises, but it’s a lot of effort and not very straightforward to dial in.

[bananabun]

Ah man, I realized that I never responded to this thread. Back then, ARH wanted a car to test on but we couldn't figure that out and also there wasn't much interest so I never pursed this further. I also crashed my M coupe at the track shortly after this thread so was distracted by that.

pokeybritches thanks for the foresight on ECU changes.

Sergio19 I had almost no rasp with the DKF mid section, SS x pipe, and SS powerloop catback. Car sounded incredible.

And no I'm not banned. Still very much here but moved on to an E92 M3 track car. I do miss my crazy M coupe sometimes, though. It's now in good hands with an owner in the mid west who tracks it quite a bit

[Sergio19]

Appreciate all the feedback/updates, looks like this header is a no-go.

Might be getting off-topic now but has anyone else noticed that all S54 header designs have unequal length secondaries (the pipe following the 3-1 merge)? Perhaps addressing this and equalizing the lengths in section 1 before the X-pipe crossover will clean up the sound.

Kind of similar to what the S55 guys are doing. https://f80.bimmerpost.com/forums/sh....php?t=1675268

I have been looking at V6 engines that sound nice and one thing I find in common is equal length per bank. Obviously this is a lot easier to do on a V6 than I6, hence maybe BMW left that out when they designed the exhaust.