heinzboehmer's 2002 Topaz 6MT Coupe

[heinzboehmer]

Oh! Pictures from the last track day were released recently. Here's some slow racecars trying to catch up to the PT3RS:



My favorite picture of the day by far.

[heinzboehmer]

Next up some projects I stole from Bryson.

Harness made to grab CAN from the steering angle sensor:





This will be used for the wideband O2, Gauge.S and to bring CAN to the ODB II port.

Installed:




Still need to go the junkyard and grab some connectors with the rest of the Gauge.S harness, so the installation is kinda temporary. Will likely change some of the routing once I install everything.

Wideband O2 installed and harness tucked away to keep it out of sight and away from the headers:




Also printed out the Bryson Gauge.S enclosure and test fitted:



This thing is super cool. Can't wait to have it hardwired and working all the time.

I did find a tiny USB C fast charging board and altered the enclosure design a bit to fit that in:




Supposedly this thing can do 45W fast charging (per port, so total 90W), but I don't trust that there's a boost converter on there for the 20V 45W fast charging. I bet the most it can do is 12V 36W, which I'm totally okay with. Will still be way faster than just hooking up 5V to the USB C ports. This thing is overkill anyway since the wireless charger keeps my phone charged, but I wanted to have fast charging in case I ever get stranded on a super long roadtrip and the only way out is to trickle charge my laptop with the car

In parallel, I modified and installed the Bryson brake scoops. I had previously cut holes in my dust shields for brake cooling hose flanges, so I conformed the scoops to the hole shape in my dust shields.

Flanges removed and ABS scoops test fitted:




Some small tweaks were needed up top, but they fit great. With the fitment confirmed, I also printed these out of PET-CF. Kept the lower scoops made out of ABS cause that PET-CF material has been very hard to get and I only managed to buy 500g of it. Lower scoops should see much lower temps anyway, so I'm not too worried.




Next thing I need to do is visit a junkyard to grab parts for both the M3 and the E82. With those, I'll be able to finish up the Gauge.S harness and then start my DIY engine tuning journey!

[heinzboehmer]

Some small tweaks to the mounting design of the duct. Extended the rear tab down and added a collar for rigidity. I really don't want this thing slipping off the caliper at speed. I also clearanced the front a bit more to make it easier to install:



Printed a slice of it to verify rear fitment. Very pleased with how well the lower surface fits up against the caliper. I just straight up intersected my model with the 3D scan (cause lazy) and it came out great!



Then PET-CF finally showed up, so I printed the first prototype suitable for testing:



This filament is so cool. Feels very futuristic to click a button and have a composite part come out a few hours later.

Very pleased with how it turned out. Next up is temperature torture testing!

While I was in the area I also swapped the fender liner:



This is one of those things that I just kept forgetting to replace. Finally remembered to order one and got it installed. Old one had definitely seen better days...

[bigjae46]

Really? The reason I mentioned CF is because some random website told me epoxy resin was good up to around 300 C. You have more experience with this than me though.

I'm trying to avoid the composite thing because I think it'll be very hard to get right. Hopefully the PET-CF survives.

The carbon will survive but the epoxy is the limitation. There are other processes that can raise the Tg of the epoxy but it would be extremely expensive.

For example… carbon ceramic rotors have no epoxy, made with heat and pressure. Lots of it. There might be an aerospace epoxy but it would also require a lot of heat and pressure.

[heinzboehmer]

I can help you make one sided molds for aluminum or steel ‘stamping’ if that’s where we end up. No problem

Awesome. PET-CF filament is finally back in stock, so I should be able to test it soon

[Bry5on]

I can help you make one sided molds for aluminum or steel ‘stamping’ if that’s where we end up. No problem

[heinzboehmer]

CF will probably do worse than PET-CF unless you use a polyester resin as the matrix instead of epoxy.

Really? The reason I mentioned CF is because some random website told me epoxy resin was good up to around 300 C. You have more experience with this than me though.

I'm trying to avoid the composite thing because I think it'll be very hard to get right. Hopefully the PET-CF survives.

[bigjae46]

Hell yeah. This PT3RS is the only PT Cruiser I've ever driven, so no idea how a stock one drives. But I agree, this thing is way more fun than it has any right to be.



Yeah, it's been pretty fun so far! Prototypes have been ABS, but the duct I'll test with will be PET-CF: https://us.store.bambulab.com/products/pet-cf

Heat deflection temperature of 205 C, so just barely enough based on what I've measured on track. Hoping that the fast moving air helps even further with having it not melt, but we'll see. Worst case, I'll print a mold and make it out of actual CF or stamped aluminum or something.

CF will probably do worse than PET-CF unless you use a polyester resin as the matrix instead of epoxy.

[heinzboehmer]

That's hilarious and awesome lol. We used to have a SRT-4 when I worked at Modified Magazine in a former life. The turbo PT Cruisers have the same engine. Honestly it was way more fun than I thought it could be.

Hell yeah. This PT3RS is the only PT Cruiser I've ever driven, so no idea how a stock one drives. But I agree, this thing is way more fun than it has any right to be.

The ducting is a cool project! what material are you planning on printing the final version out of?

Yeah, it's been pretty fun so far! Prototypes have been ABS, but the duct I'll test with will be PET-CF: https://us.store.bambulab.com/products/pet-cf

Heat deflection temperature of 205 C, so just barely enough based on what I've measured on track. Hoping that the fast moving air helps even further with having it not melt, but we'll see. Worst case, I'll print a mold and make it out of actual CF or stamped aluminum or something.

[karter16]

The ducting is a cool project! what material are you planning on printing the final version out of?

[Nate047]

That's hilarious and awesome lol. We used to have a SRT-4 when I worked at Modified Magazine in a former life. The turbo PT Cruisers have the same engine. Honestly it was way more fun than I thought it could be.

[heinzboehmer]

Can we talk about that PT Cruiser though, how did that thing do

Lol it was there getting a shakedown. Was hilarious to drive. Much more fun than expected.

It's fully racecar'd btw. TC design cage, zero interior anything, bucket, six point harness, fire suppression, etc. Pretty sure that a good part of the reason why it was fun to drive on track was because it's so light. Extremely slow though.

[Nate047]

Can we talk about that PT Cruiser though, how did that thing do

[heinzboehmer]

Friend asked me how the duct mounts to the caliper, so I took some screenshots of the CAD to explain. Figured I'd share here as well for future reference.

Basically, the duct has two tabs that go around that black pad securing pin on the calipers. Problem is that the pad spring clip needs to be compressed for the pin to get installed and then a cotter pin needs to be installed on the pin, so the duct can't be in the way of any of that. To solve this, I made the front tab a separate part. I was originally going to go with a removable top (seen in one of the prototypes above), but the locating features ended up being too small to print reliably. Install process is as follows.

First, the caliper is assembled with just the front mounting tab in place:




Note: this tab also serves to locate the caliper front/rear so that it can't move around and slip off, hence that boxy feature up front.

Then the duct is installed, making sure that the rear tab goes over the rear protruding part of the pad pin:




After that, the duct simply slips over the front tab and gets secured to it with a cotter pin (identical to the one used in the pad pin):



Very easy to install, but we'll have to see how those tabs hold up to vibration and heat cycles. Especially true for the front one, as it needs to be pretty thin to not interfere with the pad when the pistons are fully retracted.

[heinzboehmer]

Track day went awesome. Weather was perfect (cool all day, no rain) and there ended up being a great group of people there. Tons of fun.

M3 friends:




And of course the girodisc dust boots did not survive. Found a melted one on each front caliper:




Also, got my 3D printer and continued with the brake duct development. First prototype on the left and latest on the right:



Test fitted the third one from the left:





Fits great! Newest version has the fan clocked differently for better clearance and has a slightly different front mounting tab design, but is otherwise the same.

Speaking of the fan, I decided that it would be much easier to test the duct performance with one, so I went this route instead of the originally planned passive vacuum generation. I'm still not sure if the fan will live on the duct or if it will live in the belly pan and be connected to the duct with some hose. The fan itself isn't too heavy, but it spins up to 16k rpm, so it puts a decent amount of torque on the duct when the wheel is turned. Having it in the belly pan means I can go to a more powerful fan too if needed. I'll have to do some (destructive) testing and decide if I want to move it or not. More to come