Z4M/S54: Euro headers installed

[pal]

Part 1
As some of you know, I installed the European e46 M3 (not CSL) headers on my Z4MC a couple of weeks ago. I just installed the pre-cat O2 sensors on the headers and the 2 post-cat O2s and EGT sensor were not initially installed as there were no bungs for those.

I drove the car around for about 300-400 miles this way and could feel the power gains from a seat of the pants through the rev range. The power gains could be felt in the low end and mid-ramge during part throttle driving which was/is really great esp for the S54 which can use all it can get in this section of the power band.

Since the car was running perfectly fine without the 3 sensors mentioned (there is a check engine light/SES light), I brought the car to a dyno on Monday morning. The results compared to stock are VERY impressive.

Part 2
I brought the car to RRT in Dulles, VA to create a modular wiring harness that would allow relocating the post-cat O2 and EGT sensor connectors to under the car (under the black plastic cowl that hides the fuel filter, TPMS module etc.) or have them in their original location (on top of the valve colver). They used MIL spec wires, OEM black wire tubing, Deutsche connectors and gold pins to do this. James@RRT was meticulous and created an OEM style wiring harness.

He also installed an EGT sensor bung I had a friend make for me onto the secondary cats where the Euro Z4Ms and M3s have it.

Exhaust Gas Temp Sensor Discussion

The other task was to possibly install the post cat O2 bungs onto the secondary cats similar to the European spec Z4M, but we were not sure if the heat shield on the OEM section 2 would get compromised during the install so that part is yet to happen.

Part 3 - Still researching this ....
I want the car to be emission compliant (no SES light) without a flash, if possible. So here are my thoughts/options so far

(1) Find a used Z4M secondary cat section and test that out with the bungs - if someone wants to sell me one, please PM me. The research will help us all at my expense :thumbup:

(2) Find how to source a Euro cat section from a Z4M. North Haven and Tischer dont even list that part #. This will be the easiest and should be plug and play now.

(3) Find a Euro M3 cat section with all the bungs and have the flange that connects to the X-pipe correctly oriented to match the Z4M.

(4) Talk to Fabspeed to see if they will match the flange for our cars.

(5) Find hi-flow OBD2 cats and get a custom section 2 made.

Your thoughts and opinions are very welcome.

Enough words ...

The Euro headers from an e46 M3 race car-


Removed this heat shield and the secondary air pump valve and black plastic tubing.




Under body shield removed


Stock headers exposed



I made sure which O2 sensor connector goes where though BMW has done a good job of labeling as well. 1- post cat O2 for the front bank and 2 - post cat O2 for rear bank. These two connectors were relocated yesterday to under the car along with the EGT one.



Next I broke loose the EGT and O2 sensors and unscrewed them by hand and removed them from the headers.





Pre-cat O2s and EGT out and labeled. Post cat O2s are better removed from under the car.



All out ...


The flanges under the car use an E12 bolt head. I loosened these 4 but did not remove them just yet.


Next I took off the 18 11mm nuts that hold the header to the head. I found a 3" wobble head extension and a 1/4" ratchet to be the close to perfect tool for this task.


Half way there


Headers loose ... now I got under the car and removed the 4 flange bolts and guided the headers out from under the car. I could not take any pictures of this step as I had my hands full with humpty and dumpty.






Comparison picture ... the Euro headers look like athletes compared to the US spec ones.


View from the top. There is tons of space to remove these headers, but I found the easiest is to do it from under the car. F360C pointed me that way ahead of time so it saved me the aggravation of trying to do it from the top.


Install is reverse of removal. I slid the headers up from under the car and lined them up on the studs. Then loosely fitted the 4 E12 bolts on the flanges. Back on the top now to get the 6 new triangular gaskets in place (shiny side goes towards the cyl head) and the 18 nuts snugged up.

Pre-Cat sensors go in. All bolts and nuts checked and rechecked for tightness.





I disconnected the 2 post cat O2s and the EGT and labeled the connectors on the car that go to the DME.


I will post up pics of the EGT relocation and wiring harness extension later ... still not pulled them off the camera. Thanks to James@RRT for being patient and letting me take pictures and ask him a thousand questions. tnsbruce stopped by to check on progress and bought me lunch at this great Kabob place ... and I got to ride in his awesomely quick 530i.

Dyno Plots
These are the 2 clean runs. The dip in the first run was due to the car moving on the dyno in the low RPMs. Once the strapped were snugged up that dip went away so ignore that.

The car dyno'd 313.26 whp/245.26 w tq on Monday morning as the air was nice and cold with low humidity. The SAE corrected numbers were 295.93 whp/232.07 wtq.




For comparison, SAE numbers from a Dynojet are super consistent from run to run and even on different days. Below is my stock plot done on the same Dynojet compared to the one with headers. The gains are consistent with the butt-dyno ... headers are def THE exhaust modification on these cars for a solid improvement all around.





Discuss away.

[Starscream]

I just wish there was a way around OBD readiness for emissions tests (NJ)

If there was I'd be all over this, Its the final piece of my M's mod puzzle,

I talked to Roman when I got my ESS tune and he said he can turn off the CEL but the DME would come back "not ready" when they plugged it in on a inspection, and fail (in NJ)

So that popped my header bubble

[pal]

Starscream - I am working on getting the OBD readiness stuff working without any tune. We have extended the wiring harness for the 2 post cat O2s and the EGT and relocated these connectors to under the car.

Now I need to find a set of cats that are OBD compliant to plug the post cat O2s into and in theory everything should work like it did before.

I have an appointment with Fabspeed on Friday morning for them to see what is involved in adapting their e46 M3 sport cats to our cars. From the looks of it, it may just be changing the orientation of the post cat flanges to meet our x-pipe.

[Starscream]

Keep me posted if it works out

don't we have a set of second cats in the pipe directly after the headers?

[pal]

Originally Posted by Starscream

Keep me posted if it works out

don't we have a set of second cats in the pipe directly after the headers?

Will do.

Yes, we do have a secondary set of cats. The original plan was to install the bungs on that. But there is very little space and we would have had to butcher up the heat shield to install the bungs. Since we were not sure of how that would impact the integrity of the heat shield, I decided not to go that route at this time ...

If someone has a set of OEM cat section for sale, I would be willing to buy them off you for this experiment that will benefit all of us interested in the headers.

[Getssum96]

Waiting patiently to see the results here!!!

[imom]

Pal,
how much was the euro headers and where do you buy them in the U.S.? I too like to see how the M can get a boost on the low and mid range power. Thanks!

[pal]

imom - North Haven sells the CSL ones for around 1700 new. I however recommend (and this is what I did) searching e46 M3 classifieds as a ton of those guys have done this and some are now starting to part out their cars and have parts for sale for awesome prices.

The other option is to look at aftermarket new ones from places like Fabspeed. Those are around 1100'ish I think and gains are comparable, if not more due to the longer lengths of the pipes, from what I have read on the M3 boards.

[imom]

pal... So E46 M3 stock headers or is there a particular "CSL" version that I need to find? Sorry I don't know my BMW history...only got my M roadster recently and don't know what parts fromt he M3 are interchangeable...I know it's the same engine...wasn't sure if the header would transfer over.

I will look at fabspeed... How do these headers compare to say the $300 to $400 headers you seen on forums/ebay/etc. I just want to boost my low end power....while still retaining some decent MPG.

[pal]

Originally Posted by imom

pal... So E46 M3 stock headers or is there a particular "CSL" version that I need to find?

Euro and CSL will fit the Z4M just fine. The CSLs are about 2 lbs lighter, but otherwise I believe they are the same in terms of flow and fitment.

I will look at fabspeed... How do these headers compare to say the $300 to $400 headers you seen on forums/ebay/etc. I just want to boost my low end power....while still retaining some decent MPG.

Ebay headers tend to be hit or miss in terms of fitment and often require modifications for fitment and/or clearance with the passenger side control arm.


Starscream - I did go to Fabspeed today and things look promising. They put the car up on a lift and think it would be a few hours of work to adapt their e46 M3 cat section for our cars. They use OEM style 200 cell ceramic cats for their kit and say that these are emissions/OBD compliant. The other fringe benefit of their cat section is that its a 2 piece with a quick disconnect coupler that allows you to run a set of straight pipes in place of the cats if you so desire. I threw the idea of a possible group buy and they seemed to be open to that as well ...

Lets see how that goes. They will throw some numbers my way next week and if those work I will get this done sometime in early January and dyno the car as well to see if I can get an additional 4.1 whp SAE to get to the psychologically advantageous 300 whp.

The header upgrade seems to be the best bang for the buck though and I would do it again

[imom]

Hi Pal... I'd be interested in a group buy. I see some vendors putting the sensor after section 1 (header area)... Would it make more sense to put them in the secondary cats section?

[fatmatt0116]

Only $7.95 on amazon. Used by e46 m3 post members, should save you some coin and a lot of fuss.

http://www.amazon.com/Guaranteed-Pas.../dp/B0007N1ZPY

[DarkstarZero]

Originally Posted by fatmatt0116

Only $7.95 on amazon. Used by e46 m3 post members, should save you some coin and a lot of fuss.

http://www.amazon.com/Guaranteed-Pas.../dp/B0007N1ZPY

That's interesting...

[imom]

I manage to get a hold of Euro E46 M3 Headers (non CSL) (hopefully will receive my set in a month or so). Pal, any word on the fabspeed section 2 group buy will happen?

I wonder if it's necessary or advised to also have the Euro section 2 cats vs. the stock U.S. section 2 cats? I wonder if the other 2 O2 sensor and the EGT is required for the car to run right?

This is new to me, so I'm still a little unclear about this. Will ESS tune only require the 2 primary O2 sensors in the Euro Headers and skip the secondary two O2 sensors and EGT? My Euro Headers already have the bung available (1 per header).

Finally is it worth JET/hot coat the Euro Headers I'm getting? Is it necessary?

Thanks for the input.

[imom]

Bump on my question

[crfine88]

Incredibly useful and detailed thread.
thank you Pal

[pal]

I did not want to give up on using the stock secondary cat section so I brought it to my trusty muffler shop (Mufflex) this morning and about 2 hours later the post cat O2 sensors were in 90° bungs and plugged into the extended harness connectors under the car. I cleared the codes using Rev on my iPhone and about 3 restarts and 10-12 miles later, there are still no codes and no CEL/MIL light - fingers crossed so it stays this way. In a week or two of driving we will know for sure.

Apologies for the not so good iPhone pictures ... totally forgot to take my camera along.

Window cut into the heat shield - care needs to be taken to not damage the attaching ring and the flat section that glues the top and bottom part of the heat shield.


A view inside ... its hollow and there is no packing in between the cat and the shield. I was worried for nothing earlier. And there is tons of space once the window is cut out.


Holes cut out ...


Denny, the owner at Mufflex at work. He is great and has helped me out with such stuff over the years.


Cut shield bent a bit to clear the O2 sensor body. The 90° O2 bungs in place.

[Diokaef]

Nice

[Diokaef]

...

[Diokaef]

..

[pal]

Diokaef - I don't think cutting the stock headers is a good idea. Needless to say the labor and parts involved to get the right collectors etc. will probably not be cost effective.

[Last Update - As far as I can tell anyways ]
325 miles of commuting miles later, no error codes and looks like the Readiness codes are set properly. Below is the output this evening from the DME using the Rev application connecting to the OBD2 port.

I think this modification is complete. If anything changes down the line, I will be sure to update this thread.

[imom]

Pal, how much was it to get the bungs installed on the secondary cats?