heinzboehmer's 2002 Topaz 6MT Coupe

[heinzboehmer]

Life got busy, so haven't had too much time to work on car stuff. I did manage to chip away at the HVAC plastics design, though.

Firewall plug is basically done. Here's what it's gonna look like:



Sealing is bit of a challenge with this design. This part needs to seal against the firewall, the removable insert (dark blue part), the filter housing and the braces. Gonna be printing out TPU gaskets for all of that. Here's a clearer view of most of the sealing surfaces and the associated gaskets (light blue and grey):



The removable insert still needs some work. Need to model in the gaskets for the braces and the fastening point to the cabin air filter housing. Should be fairly straight forward to do.

Plan is to have the insert be held up against the firewall plug with magnets, then fastened to the filter housing using the OE hardware.

Printed the firewall plug (no insert) out of PET-CF. My mind is blown every time I see this material get printed, surface quality is just nuts:



As mentioned previously, the whole thing is too big for the printer, so I sliced it up into three parts and printed some dowels to locate all the pieces together. I made the dowels separate parts so that they could be printed in a favorable orientation:



All glued up:



And installed (gaskets still to come):



This is where I should have stopped, but I'm doing a track day at Thunderhill tomorrow and it's forecasted to be >90 F, so I definitely want some thermal insulation. Cabin air filter housings are like $30 on eBay, so I horribly hacked mine up to fit:



Sidenote: I forgot to swap the blade on my oscillating cutter and accidentally confirmed that the material that the part is made of is definitely glass fiber reinforced



Absolutely does not seal, but at least it'll protect against most of the radiant heat:



Also, this is really cool. First sneak peek at the fully assembled engine bay:



I'm honestly really, really happy with how inconspicuous it is.

More to come...

[heinzboehmer]

Why not just use ASA?

What George said!

Another thing is that ABS/ASA are kind of a pain to print without deformation, so probably not the best for this test fit. Also not sure ASA would survive the heat, I measured 80 C at the firewall on a cool day with none of the HVAC plastics in place. I think it can easily get past 100 C back there.

[George Hill]

Why not just use ASA?

Because this is the cheapest filament I have and since it’s printed it costs me nothing more to find out.

Heinz and I chatted about filament material already. We both know PETG is not the right material here but I’d rather throw away $7 of petg vs $20 of something else if the file wasn’t 100% on.

[Obioban]

Yes I am, I am also curious to see how it holds up too. I have PETG printed part in an intake system of a car that's been going for 2-3yrs now and its holding, but I think that one is not in as high of a heat affected zone as this part.

Why not just use ASA?

[heinzboehmer]

Pretty sure it won’t 😜

Yeeeah I don't really expect it to survive the Texas summer, but still a fun experiment.

[George Hill]

Thanks!

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

Yes I am, I am also curious to see how it holds up too. I have PETG printed part in an intake system of a car that's been going for 2-3yrs now and its holding, but I think that one is not in as high of a heat affected zone as this part.

[Obioban]

Thanks!

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

Pretty sure it won’t 😜

[heinzboehmer]

It did look 90* but I didn't spend a bunch of time staring at.

When it cools down outside I'll pull it apart and compare to a stock one.

Thanks!

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

[George Hill]

It did look 90* but I didn't spend a bunch of time staring at.

When it cools down outside I'll pull it apart and compare to a stock one.

[heinzboehmer]

Its in and it fits 99%. The only point of "issue" is the center tab for the microfilter is to high. But because its been glued together and printed in multiple pieces I don't know if this is the design or just the way I assembled it creating this extra clearance. Either way though its in!

Hell yeah, that's awesome! Thanks a bunch for testing.

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.

[George Hill]

Its in and it fits 99%. The only point of "issue" is the center tab for the microfilter is to high. But because its been glued together and printed in multiple pieces I don't know if this is the design or just the way I assembled it creating this extra clearance. Either way though its in!

[George Hill]

It fits!

I don't have a spare seal so I've just got it laid up on the firewall opening as is. This afternoon I'll fully assemble it into Eileen.

[George Hill]

glued and drying

[heinzboehmer]

Awesome! Excited to see how it fits.

[George Hill]

After a couple of failed prints (filament tangled on the spool) we now have (3) pieces... tomorrow we glue!