heinzboehmer's 2002 Topaz 6MT Coupe

[Obioban]

3D printer has been the greatest addition to my capability set of anything I can remember. I regret not doing it years ago.

It's pretty much been continuously running since I finished building it. Every freaking project benefits from it somehow. As your project above :P

[heinzboehmer]

3D printer has been the greatest addition to my capability set of anything I can remember. I regret not doing it years ago.

It's pretty much been continuously running since I finished building it. Every freaking project benefits from it somehow. As your project above :P

Completely agree, I use for most projects as well.

[ac427]

Small side project motivated by a comment from karter16: https://nam3forum.com/forums/forum/m...983#post322983

I did notice some weirdness with the ADC on Gauge.S. On a multimeter, the analog output from the AD8495 is rock solid and matches the expected temp (tested with boiling water). On Gauge.S, the voltage readings are offset by 27 mV and they seem to jump around. Annoying, but the offset is easy to fix and I guess I'll just have to deal with the noise.

Just waiting for more wire to arrive in the mail and then I can build a quick harness for thermocouple power and data.

Have you asked Sorek about the Gauge.S readings randomness?

[heinzboehmer]

Have you asked Sorek about the Gauge.S readings randomness?

I have not, but i probably should. I just didn't want to get sucked into another long saga of trying to debug closed source firmware, like what happened with D bus init on the V5 board.

Will reevaluate when all four thermocouples are set up and I've logged some data.

[ac427]

I have not, but i probably should. I just didn't want to get sucked into another long saga of trying to debug closed source firmware, like what happened with D bus init on the V5 board.

Will reevaluate when all four thermocouples are set up and I've logged some data.

I know what you mean about getting embroiled in that sort of misery. Maybe just let them know and leave the with it.

[heinzboehmer]

Thermocouple wiring complete.

Decided on a harness with three "steps":

1. Gauge.S pigtail since getting 3.3V from the board involved soldering to it.
2. Loong harness for each thermocouple.
3. Small "manifold" harness to go between (1) and (2), that feeds 3.3V and GND to the thermocouples and also routes their outputs correctly back to the Gauge.S inputs.

I did make a rookie mistake and only ordered three wire colors. Should have ordered more so that each thermocouple output was easy to identify, but too late. I'll make some labels and attach them to each one before putting them in the car.

Everything seems good electrically, but you can see the weirdness in the ADC quite clearly:



Each thermocouple assembly measures in at 3.2m from tip to connector. Made them long so that they can reach all four brake calipers, in case I ever want to log detailed caliper temps.

Also, slope of the output on the AD8495 works out to be 5mV per deg C, so I'm betting the voltage drop from the long harnesses is messing with the calibration. No big deal, can always boil more water and change the offsets in the Gauge.S config.

Next up is routing everything to the engine bay and I can finally get data on the E86 brace windshield mount.

[heinzboehmer]

Finished up the thermocouples.

First off, got tired of the noise in the readings, so I added four extra parameters that smooth out the last 10 or so readings so that the display doesn't jump around as much. Looks like a moving average to me, but the smoothing is a built in Gauge.S function, so hard to know what's going on under the hood. Also, still gonna log the raw readings just in case.

With that set, I boiled up some more water and recalibrated the sensors. Voltage offsets were small (on the order of tens of mV), but, as discussed previously, this still results in large changes in temp readings. They're not perfect, but good enough for what I need:



Then came running the wires through the firewall. These will not live in the engine bay permanently, so I did my best to make it easy to revert.





And lastly, all four sensors got attached to their chosen probe points. Used double sided thermally conductive tape and kapton tape to fix them in place and ensure accurate readings.

I attached them to the front and rear of the windshield mount, as well as to the passenger side of the firewall plug and the underside of the passenger brace (to roughly approximate the temps seen by the cabin filter housing). Strain relief box got stuffed next to the brake fluid reservoir:







Here's some very preliminary data: https://datazap.me/u/heinzboehmer/e8...ta=19-21-23-25

Cool to see how the engine bay thermocouples heak soak very quickly upon turning the engine off, but the ones behind the firewall stay pretty steady.

This was just a short drive around town at a very reasonable 16 C ambient temp. We'll have to see what temps these things log on track next week.


Also, I somehow managed to find the time and motivation to continue working on the modified cabin air filter housing.

Unfortunately, the first thing I realized is that there is no way the stock filter is going to work. My scan of the engine bay didn't fully capture the edge of the cowl, so I wrongfully assumed that the filter would just barely clear. Test fit crushed my dreams pretty quickly:






Time to find a replacement filter then!

Turns out the E9x M3 uses a set of four smaller filters instead of the big panel filter in the non-Ms. I don't know why, but I find the design so funny. Feels like BMW spent all of their brain power on designing that intake then remembered they should probably do something about the filter that no longer fits (sound familiar?) and just stuffed whatever they could find in there.

Anyway, hopefully they work out?



Well, that's a no. Passenger side is extremely close to fitting, but driver side interferes heavily with the windshield wiper arm linkage.

Did a bit more digging and found 64119237159 from the F25 X3. OE part, activated charcoal, super cheap and can squeeze in no problem:



Area of the faces of both F25 filters comes out to 45% of the area of the E46 filter. BUT, the F25 filters are twice as thick, so there's way more filter material stuffed in there than you would think. I still think they're gonna flow worse than stock, but honestly not too concerned with that.

Time to sit down and actually finish the CAD this time around.

[YoitsTmac]

I love this project so much. Also makes me want to build some thermal read to all my brakes

[heinzboehmer]

I love this project so much. Also makes me want to build some thermal read to all my brakes

Oh man, I'm geeking out over having access to this telemetry.

Will for sure need to figure out a way to route the thermocouples to the calipers once this testing is done. That sounds like awesome data to have.

[heinzboehmer]

Oh forgot to mention this filter, which is another candidate: Chrysler 68033193AA

It just barely squeezes in and will likely require some trimming of the cowl to work. Surface area is a bit bigger than the X3 filters, but it's 10 mm shorter and it doesn't come in a variant with activated charcoal. Sooo I'm sticking with the X3 filters.

Also, I know I can get the Mann version of the filter, but I just don't think I'd be able to live with having a Chrysler part on the car. X3 filters it is.

[heinzboehmer]

So, turns out Corteco makes two versions of the F25 filters. One activated charcoal and one not. Of course, I bought the one without activated charcoal:



FCP shows the activated charcoal version on their site and a recent review mentions that they are indeed the activated charcoal version:




Gonna try ordering those and see what I receive. Fortunately, these things are ultra cheap.

Also, CAD is done! Pretty cool to finally see the whole assembly put together.



The hole in the top of the cabin air filter housing is there to provide tool access for the middle fastener.



Found this appropriately named plug to cover it. Funnily enough, this one can also be found on an F25 X3.



Printing out a prototype in ABS since the PET-CF filament I ordered did not arrive in time for my track day. Based on the temp data from yesterday, ABS should survive, but guess I'll be putting that to the test.

Roughly 24 hours to go on the prints, so will update in a bit

[Bry5on]

What’s the hole diameter needed for that plug? I need something for mine as the body plug has crumbled and I don’t want to load the printer with TPU just for that.

[heinzboehmer]

What’s the hole diameter needed for that plug? I need something for mine as the body plug has crumbled and I don’t want to load the printer with TPU just for that.

Ha, I had the exact same thought process with the printer.

Hole diameter is 40 mm.

[heinzboehmer]

Man, modern 3D printers are unbelievable. Look at how well mine was able to replicate the "held together with duct tape" look:




Clearly, there were some fitment issues with the prototype.

Since the triangle that the braces form is wider in the front than it is in the back, the filter housing has to have extra clearance for install. Thought I had given it enough, but I was mistaken.

Images above are post modifications and the housing fits pretty great like that. I've scanned the hacked up piece to use as a reference and will design V2 around that.

Everything else fit up perfect first try though:





Don't think I can feel too much of an airflow difference with this housing vs the stock one with the fan at full blast. But all I did was stick my hand in there and judge based on that, so not a scientific claim in the slightest.

Pretty happy with this first attempt. Couple tweaks and it should be good to go!

[heinzboehmer]

Track day done. Some ups, one big down.

Let's start with the good stuff.

HK amp was really dying, so I picked a used one up, did a quick refresh on it (cleaned up and refreshed the thermal paste) and swapped it in:



And wow! I can't believe I had been putting up with the old amp for the last couple years. This thing sounds so much better. I kept having to turn the music down on the drive to the track cause I would hear details that I hadn't heard before and would think they were coming from the car. Pretty happy with this.

Then came a bit of CAD work. Scanned my hacked up filter housing prototype and made the changes necessary for installing:



I have to say that the 3D printer + scanner combo is incredibly powerful. Iterating on this piece would have taken way, way longer had I not had access to these tools.

Test fit piece printing now. Once that is validated, I can move on to printing the entire thing out of PET-CF.

Also, good news is that I didn't see the windshield mount temp go above 70 C, even after letting the car heatsoak in the sun for an hour or so. I'll pull the data later and grab the actual numbers.


But now, the bad news. During one of the afternoon sessions, I came in a bit too hot into Phil Hill and completely missed the turn. Landed with the left tires in the dirt and the right on the pavement, which means I hit the curb at the bottom of the hill pretty hard against the undercarriage. I then drove back onto the pavement for a second and lost it again, spinning out into the dirt on the left side of the track.

Fortunately, the aluminum shear plate took ALL of the damage. I still can't believe I got as lucky as I did. Absolutely nothing else was damaged (including the brake and fuel lines right behind where I hit the car on the curb) and the car stayed right side up.



Having used up all of my luck, I decided to call it and spent the rest of the day cleaning the car up, which wasn't exactly fun. This is what the interior looked like immediately after coming into the paddock:



Vacuumed out what I could, then used compressed air from the tire shop to blow out the rest. Still needs a serious detail (which unfortunately involves removing a ton of the interior trim pieces to get behind them), but all in all, not a terrible result:



Replacement parts ordered. Will spend some hours this week disassembling and cleaning up the car, then can analyze the thermocouple data.

All in all, not the best track day experience I've had, but very glad it wasn't worse. Car drove straight for the entire four hour drive home, all fluids stayed in their places, E86 braces survived and most importantly, no one was hurt.