M Coupe LTW build

[Michael9218]

So just wrapped up this years winter project. I decided to take a crack at making my own carbon fiber front bumper cover. After getting inspired watching too many YouTube videos I decided to give it a go using the positive mold overlay method. For a one off, this eliminates the need to spend time and effort making a mold. It does, however, mean more work on the back end to get a smooth paintable part. The gelcoat look isn’t practical with this method since the outer surface will not be smooth.

The modified OEM plastic bumper weighed over 15 pounds.



I began by taping the bumper to protect the paint in case this all failed and I needed to go back to this bumper. I also wanted to smooth over gaps. I then used auto body filler to shape and smooth the area around the headlight blanks. I wanted everything to be more aero.



I then used some expanding foam where more changes were desired, like smoothing the kidneys (leaving only an outline of them for visual effect) and decreasing the lower opening.



To get a more smooth topcoat to the foam, I applied a layer of clay.



The next few steps I have no pics, but over the clay I used aluminum foil taped in place. I then sprayed the bumper with a few coats of mold release PVA. I then applied three layers of carbon fabric one at a time, first wetting the part with epoxy, letting it partially set up (about 90 minutes) and then carefully laying a layer on and working it in. This allowed the part to stick to the contours and not lift as it would if wet. This had to be down for each layer. Not a fast process.

Once that set up, I popped it off the mold (well, ok more like wrestled it off) and this is what it looked like, weighing less that 5 pounds!



To prep it for paint, I floated an aircraft body filler (Superfil), which is an epoxy like super light body filler. It looks like crap at this point, but is now smooth. As you can see, the kidneys will be clear coated for effect.



I decided to paint it myself, so I made a makeshift paint booth using my popup tent as a base and used a fan blowing air through three panel filters into the booth and had it exit out a window through more filters. Pretty cool and necessary as the outside temps weren’t cooperative for painting.



Here it is looking much better in primer flat black.



I also went ahead and painted my newly acquired Goke rear hatch. I had to modify this a bit to reinforce it for my wing mounts and I also eliminated the third brake light. A nice little 23 pound savings with this hatch!





I also needed to incorporate an intake ram air scoop feeding a 4” carbon fiber tube I made. Will be interesting to see how this works on track. I will be data logging to provide Josh (pokey britches) with data in case this necessitates a change to the tune.

I started by making a mold with foam and body filler after a lot of careful measuring and sizing up.



Finished part looks the business...



And here is the finished bumper painted a generic gloss black. Doesn’t color match, but is close enough. I was going for a 10’ paint job, so am happy with the results!






So, that was my winter project. How about y’all?

[BookerM3]

Nice Job!

That intake vent must have being a challenge to demold.

[Vanne]

Micheal, man, you keep blowing me away with your carbon skill set mate. That looks freaking exellent, and 5 lbs.. holy Moly thats light.. I absolutely love it... One question i have though, if i may... is the rad going to be able to get enough air like this?

Looks amazing, and cant wait to see your report on how the intake goes with the CLS box.

[Michael9218]

Radiator airflow is actually about the same as I’ve been running for several years. Kidneys have always been blocked off and the portion of the lower inlet that was changed didn’t actually flow air to the radiator. At @100 mph, a small opening can provide plenty of air for the restrictive radiator. Also key to any cooling system is what you’ve got on the back side. My hood vent is sealed to the box behind the radiator and this sucks air through the radiator. Car runs at @190 f on hot summer days.

[Michael9218]

Originally Posted by BookerM3

Nice Job!

That intake vent must have being a challenge to demold.

Since it’s not a structural part, the easy way to demold is to cut a seam on the inside elbow and splay the part out of the mold. You can use a patch to reconnect the seam once out of the mold.

[F360C]

This is super impressive work with the bumper! I love that you kept the look of the Z4M bumper but increased aerodynamic efficiency and dropped some serious weight. Also that intake tube is so sexy... I may need to attempt the same project myself.

What all did you reinforce on the Goke trunk lid? I have been thinking of picking one of these up to mount a wing on.

[Michael9218]

Originally Posted by F360C

What all did you reinforce on the Goke trunk lid? I have been thinking of picking one of these up to mount a wing on.

I reinforced the mount area of the wing uprights with several layers of cf fabric on the underside of the outer skin. Requires that you cut out some access to the inner skin.

[Vanne]

Thx Micheal, seriously can't wait for the review on the bumper.. just amazing man..

[Michael9218]

I’ve had the car out for a couple track weekends and can say no issues with the bumper or the rear hatch.

I did have my water pump shred it’s impellers. Luckily this happened coming off track on the cool down lap so I didn’t over heat the head. Word to the wise, don’t use the oem plastic impeller water pump. Buy a metal impeller aftermarket pump made for the E46M and use a freeze plug to plug the P side hole for the their overflow pipe.

I also installed a Motorsport T-stat that opens at 155f. Car now runs crazy cool. With 80f ambient after a 30 minute hard charging session my water did not get over 175f.

[racerbruce]

Thank you Michael - this is great insight into future water pump replacements, for sure.

Any thoughts re why the oem plastic impeller became a bit of a grenade??

[Michael9218]

The T-stat wasn’t opening after pump replacement, so I suspect that the T-stat closed at high rpm on track and maybe caused too much pressure for the pump impeller blades. Seems unlikely, but can find no other explanation for both to have failed.

[maupineda]

Originally Posted by Michael9218

I’ve had the car out for a couple track weekends and can say no issues with the bumper or the rear hatch.

I did have my water pump shred it’s impellers. Luckily this happened coming off track on the cool down lap so I didn’t over heat the head. Word to the wise, don’t use the oem plastic impeller water pump. Buy a metal impeller aftermarket pump made for the E46M and use a freeze plug to plug the P side hole for the their overflow pipe.

I also installed a Motorsport T-stat that opens at 155f. Car now runs crazy cool. With 80f ambient after a 30 minute hard charging session my water did not get over 175f.

Would you mind sharing the parts numbers / details of what you used?

[Michael9218]

Water pump:
https://www.bimmerworld.com/Water-Pump-E46-M3.html

Freeze plug:
https://www.bimmerworld.com/BimmerWo...elete-Kit.html

Thermostat:
https://www.bimmerworld.com/Motorspo...6-Euro-M3.html

There may be other sources for the freeze plug where you don’t have to buy a kit, but convenience...

When I pressed in the freeze plug, I buttered up the hole with JB Weld for good measure.

[racerbruce]

Thank you Michael -

[Michael9218]

A long overdue update on my experience with working with Joshua at Severn Tuning.

An outcome of the no start issue I had last spring (turned out to be the instrument cluster) was that the tuner I was using (the guy from Miami) didn’t care to be of much help. So I asked Joshua if he would tune and support my car. This car, as many know by now, is not a once and done type car/project. So I need someone I can work with that is responsive, interested, and flexible. In Sept our schedules aligned and he was going to be in the Atlanta area so we met at a local dyno shop for a live dyno tune. Tuning the MSS70 is a real pain in the ass. Uploads can take up to an hour for each iteration, so pack a lunch! I think we ended up with about 6 or 7 iterations. The final outcome was a solid 336 hp with a very smooth power curve.



Video of a pull. We used 5th gear so those wheels are literally spinning to 150 mph!


How do I get sound?

Josh also wanted me to stay with a MAF based tune for better reliability, but I had just installed my Turner CSL intake. So I decided to modify the CSL intake to accept the MAF. Why? Because that’s how I roll…and I like the shape of the trumpets on the Turner box and it weighed about 5 lbs less. We tested both and the Turner box in this configuration made all of a few more ponies.

To make this work, I needed to fabricate an interface. So out comes the carbon fiber supplies. I used some modeling clay and shaped the cone.





Once on track, he had me do some data logging to make final adjustments to fuel trims and such (maybe he can elaborate). Motor was running strong but I was getting a slight hesitation accelerating through 65 mph in 3rd gear. Weird…. Nothing we tried would make it go away. It was acting like I was lifting. We suspected it might be the brake vacuum control valve so I ordered the CSL specific part which of course was backordered for 4 months (hence this late post on the tuning). Well, this didn’t solve the issue either.

After much patience and perseverance, Joshua had an epiphany. I’ll quote him to best explain:

Tune14 attached. Please make sure it loads correctly and the car starts like it should prior to your track day this weekend.

I spent several hours reconstructing your original file’s firmware based on the read from the Epic file. This wasn’t easy, because your ECU has had its firmware info modified by one of its previous tuners or flash tools. I went parameter by parameter to see what changed, and had to consciously decide which of the 15000 bytes of data differences to transfer over. If I had access to the original firmware info (what BMW calls “software number” or ZUSB), I could have rebuilt the tuned file off of an original BMW file in about 15 minutes.

When I initially unlocked your ECU, I had to copy a stock BMW file over the data sections of the ECU which were locked. I’m thinking the stock file I used didn’t 100% match (it was maybe a 98% match), and the slight differences are causing the weird behavior.

Joshua Bettis, P.E.
Founder and Lead Tuner
www.severntuning.com

Success! I ran the car this weekend and the hesitation appears to be gone!

Previous tuners had done something to the ecu.

You’re just not going to get from other tuners the level of support and passion you get with Joshua. I mean, at one point I texted him at the end of a track day on a Saturday thinking he would get back to me Monday. He called me that evening and by morning I had a new tune to try.

[Michael9218]

Decided to go with a lighter smaller mirror. This little mirror weighs 4 ounces compared to 2.5 lbs for the big stock mirrors. You can get them in convex or flat. Initially I went with convex on both, but switched the drivers side to flat for better down track visibility. In a race situation, you would want the wider angle for spacial awareness, but for track days I just need to see if someone is closing.

[Michael9218]

So after switching back to stock control arms late last year and using the Condor Speedshop offset poly bushings I can say that I haven’t felt any degradation in performance from the roll center correcting SLR control arms. While I buy into the theory of the roll center correction, both the feel and my data doesn’t support the premise. In fact, I recently shaved nearly 2 seconds off my previous best lap at Road Atlanta (1:33.9). I can say that the front end is tighter and more confidence inspiring.

[F360C]

Originally Posted by Michael9218

So after switching back to stock control arms late last year and using the Condor Speedshop offset poly bushings I can say that I haven’t felt any degradation in performance from the roll center correcting SLR control arms. While I buy into the theory of the roll center correction, both the feel and my data doesn’t support the premise. In fact, I recently shaved nearly 2 seconds off my previous best lap at Road Atlanta (1:33.9). I can say that the front end is tighter and more confidence inspiring.

Also love the updates Michael! Your comments on Josh have me thinking of switching my tune over from EPIC.

If you don't mind me asking what settings (Reb/comp) are you running on your MCS suspension? I am running close to the same suspension (MCS 2 way remotes) with the same rates are you and interested where you ended up with your settings. I know you mentioned way back that the settings recommended by MCS resulted in low grip levels. Aero and weight wise are cars are completely different but knowing where you ended up with your settings would be an interesting comparison.

[Michael9218]

Originally Posted by F360C

Also love the updates Michael! Your comments on Josh have me thinking of switching my tune over from EPIC.

If you don't mind me asking what settings (Reb/comp) are you running on your MCS suspension? I am running close to the same suspension (MCS 2 way remotes) with the same rates are you and interested where you ended up with your settings. I know you mentioned way back that the settings recommended by MCS resulted in low grip levels. Aero and weight wise are cars are completely different but knowing where you ended up with your settings would be an interesting comparison.

I’m running MCS 3 way remotes, but yeah, the rebound and high speed should be equivalent. I’m running the same front and back. Rebound is 7 and comp is 6. (I run the low speed at 5 dry and 2 if damp.). Camber with stock arms is 3.0 front and 1.6 rear. No rear sway bar. 700/850 springs. I also found that I need to run lower psi in the tires than I had been. 33 hot with 275/40/17 Hankooks. Really helped even tire temps across the tire and also resulted in lower lap times.

[Duncan.B]

Possibly the best thread I've ever seen 😍
The craftsmanship that's been put into this is outstanding. Well done mate. And the finished product. 🤯🤯 EPIC.

Forums need more people like you 👏🏼

[yahweh]

Updates!?

[Michael9218]

Yea, time for an update...

I decided to try and improve the airflow coming off the rear hatch. If you notice, Porsche GT cars have a spoiler on the deck lid under their wing to enhance the airflow under the wing and reduce the suction from the stern wake.

I made a simple panel out of carbon fiber (with foam core for strength) and bonded a piece of aluminum angle to create a gurney flat to kick to air up.





This actually made a difference! Looking at my data from the other weekend at Barber, I picked up 3-4 mph at the end of the straights. I saw similar results last weekend at Road Atlanta. The butt dyno also felt it at the end of the back straight. The faster I went the more the car seemed to accelerate. I know, you can't trust the butt dyno, just saying...