heinzboehmer's 2002 Topaz 6MT Coupe

[bigjae46]

Yup, here is the forged carbon version (still have to clean up some wax and clay). Big thanks to heinzboehmer for providing some 3D printed parts.

I am going to bond the two pieces together. I don't need access to the area behind this since I don't have a blower motor or wipers. Also saves money on 4 threaded inserts. I molded in threaded inserts and will insert a stud with loctite in place of the pressed in studs. I could have used studs but those are $21 each.

This main mounting is a good candidate for a forged carbon part and cost about $400 in materials to make. The small stud plate is more difficult. Some of the details are a challenge. Might be worth modifying the part to make a carbon part. I think it would make sense to keep the small stud plate aluminum especially in a street car where the mounting needs to be 2 pieces.

[heinzboehmer]

Man, life has really gotten in the way of car projects these last couple months. And unfortunately, I don't see that changing in the near future. Currently building myself a new garage, so until that's finished, no big car projects for me.

I've been trying to spend some time finishing the cabin air filter housing design, but I really haven't progressed much.

Given that bigjae46 is already adapting my design for use in his own car, I'm thinking that I should post what I have for broader consumption. This basically includes the design and documentation for everything but the custom cabin air filter housing.

If you're interested, be on the lookout for some post by me. Will try to compile everything in the next few days and share.

[George Hill]

I didn't catch that. I was going to ask about the rear door panels. What's the point? 🤣

At the time it was to protect the vapor barriers, but now I have just embraced the water leak.

[bigjae46]

Also, completely unsolicited (and you might do this already when in use), but you should route those shoulder harness straps in between the headrest posts. If those slip off the seat in a crash, you're gonna have a real bad time.

I didn't catch that. I was going to ask about the rear door panels. What's the point? 🤣

[heinzboehmer]

Definitely! That's a pic from like 5yrs ago when I was mocking everything up, still has the 2.5L from looking at the instrument cluster, just the best interior photo I have, lol.

Good to hear!

[George Hill]

Also, completely unsolicited (and you might do this already when in use), but you should route those shoulder harness straps in between the headrest posts. If those slip off the seat in a crash, you're gonna have a real bad time.

Definitely! That's a pic from like 5yrs ago when I was mocking everything up, still has the 2.5L from looking at the instrument cluster, just the best interior photo I have, lol.

[heinzboehmer]

No, but... lol

Right, I forgot about that small detail.


Also, completely unsolicited (and you might do this already when in use), but you should route those shoulder harness straps in between the headrest posts. If those slip off the seat in a crash, you're gonna have a real bad time.

[George Hill]

Yeah, absolutely nothing is square on this part. It made the CAD really annoying to get right. Makes sense because of the injection molding process and how all the parts fit together, but man, it was a struggle.

No complaints! Just feedback.

Hell yeah! Really appreciate the testing and feedback. Did you notice any increase in intake noise? My car is significantly louder in the interior with the 3D printed part.

No, but... lol

[heinzboehmer]

It is not in the same plane or lower, its just a smidge higher compared to the other tabs, but that could be how I split the part. Also all the tabs are a are open just a bit more than 90*, but probably less than 95* with the center tab being the most.

Yeah, absolutely nothing is square on this part. It made the CAD really annoying to get right. Makes sense because of the injection molding process and how all the parts fit together, but man, it was a struggle.

5 weeks later, numerous 100* days and plenty of driving in that temp, the PETG plug is holding up great. No visible degradation at all. I'm putting it back in. 😎

Hell yeah! Really appreciate the testing and feedback. Did you notice any increase in intake noise? My car is significantly louder in the interior with the 3D printed part.

PERG softens starting at140° and warps at ~175°. Hard to believe that’s not going to be an issue in an engine bay….

I've been monitoring the temps that the firewall gets to and surprisingly, I haven't seen it go higher than 80 C. Didn't go above that even at a track day in the 90s, right after a couple fast laps with no cool down.

[George Hill]

🤷♂️ so far so good.

This adapter is also PETG and been on this dedicated race car for 4.5yrs/3400 miles.

[Obioban]

PERG softens starting at140° and warps at ~175°. Hard to believe that’s not going to be an issue in an engine bay….

[George Hill]

Pretty sure it won’t 😜

Are you planning on running the PETG part? Curious how it'll hold up to engine bay temps.

5 weeks later, numerous 100* days and plenty of driving in that temp, the PETG plug is holding up great. No visible degradation at all. I'm putting it back in. 😎

Does the center tab look perpendicular to the mating surface behind it? It's possible that the print warped a bit.

If it is perpendicular (and you have the time), could you measure the parallel distance between the two highlighted faces? Would be nice if you could grab that measurement from both the printed and stock parts.



CAD says the center tab should be 2 mm lower than the side tabs. That looks reasonable to me based on pictures and the scan, but it's possible that I got that measurement wrong.

It is not in the same plane or lower, its just a smidge higher compared to the other tabs, but that could be how I split the part. Also all the tabs are a are open just a bit more than 90*, but probably less than 95* with the center tab being the most. I think its close enough that it could just be something that happened during my print and not necessarily the file so I wouldn't change the CAD model based off of this one experience.

[heinzboehmer]

For such a substantial reduction, this is more a result of the material more than anything, right?

I suspect most of the weight loss comes from the manufacturing method. It's essentially hollow on the inside, whereas the stock one is solid.

Edit: Actually, we can work this out. Let's see.

CAD says the part has a volume of 702.913 cm3 and we know stock weighs 1618 g (ish, I think I took everything off of it, but I can't remember). That gives us a density of ~2.30 g/cm3 for the UP-GF material used in the stock part.

The datasheet for the PET-CF I printed mine out of says it's got a density of 1.29 g/cm3. Had I printed it fully solid, it would have weighed 907 g. The last 500 g or so (the geometry is slightly different for mine and it has all the extra gaskets and hardware, so not apples to apples) of savings come from the hollow interior.

Looks like I was wrong and a lot of the delta is in the material. Very cool.

[YoitsTmac]

For such a substantial reduction, this is more a result of the material more than anything, right?

[heinzboehmer]

Did something I should have done when I finished printing and assembling my modified firewall plug. I weighed it.

Stock: 1618 g
Mine: 436 g

Came in a little higher than my estimates. Guess the extra walls from the splits, adhesive, gaskets, magnets, etc. all do add up.

Still saving 2.6 lbs over the stock part with no downsides, so not complaining!