heinzboehmer's 2002 Topaz 6MT Coupe

[Obioban]

Everyone stop applying logic to hobby time/money, please.

[heinzboehmer]

Ha, I have no regrets about the amount of time/money spent on this project. Learned a ton so it was 100% worth it. And like Obioban said, it's a hobby so who cares. Would rather be doing this than just sitting around.

Still pretty crazy to see that number though!

[heinzboehmer]

Aaand done!




Well, not entirely done. Still waiting to receive the flat gaskets that seal against the plug and the filter cover. Oh and need to make the strut tower brackets pretty. I'll get to those details later.

Printed some retainers for the screws as well, to try and make it harder to lose them.



Not sure yet if they make it better or worse. Middle one definitely helps, but the outer two kinda get in the way. Might end up removing the retainers for those.

Also replaced all the hood seals while I was at it, as they were original to the car and kinda starting to fall apart:



I'll try to get some pictures with better lighting this weekend.

[Bry5on]

New hood seals! Luxurious.

[heinzboehmer]

New hood seals! Luxurious.

Right? I felt so fancy putting them on.

Speaking of fancy, my street tires have been heat cycled out for a bit now, but I was holding out to see if Michelin would finally release the PS5SSS5Super in 18", so I hadn't gotten new ones. But then I noticed this:



Fine, guess I'll swap them out for a new set of PS4Ss. Gave the mobile tire guy who's always at the track a call and he swapped tires for me in my driveway. Not having to stuff a bunch of tires into a car and then drive to the tire shop was truly the ultimate luxury, don't think I can go back.

I did notice this texture on the new tires, guessing it's to enhance contrast for aesthetics.




Fancy all around.

Also, decided to give up on road force balancing. I've always asked for it in the past, but it seems to still result in vibrations at higher speeds (80+ mph). Went with a traditional balance this time around and the car feels perfectly smooth. Good stuff.

Lastly, got a daylight pic of the final final final v3 version of the strut tower bracing. You can barely tell they're not stock. Amazing.

[PipeUy]

Wow bracing and cabin air filter housing looks absolutely OEM, truly an amazing job!! I think I know what the next project will be after finishing the engine swap in the E30

[heinzboehmer]

Wow bracing and cabin air filter housing looks absolutely OEM, truly an amazing job!! I think I know what the next project will be after finishing the engine swap in the E30

Hell yeah! Would be super cool to see these parts on other cars.

[heinzboehmer]

Man, I love this thing. Just a few weeks ago, it was flying off the racetrack and today it hauled a bunch of tile for a bathroom remodel (with working cabin air filtration!).



Who knew that throwing a couple hundred pounds of tile into the trunk was all you needed to prep the car for instagram fame?



What a good car.

[Slideways]

^ You couldn't do that in a McF1

[Obioban]

^ You couldn't do that in a McF1

McF1 has way more space than you'd expect in those side pods.

[heinzboehmer]

Fine, you guys have convinced me. Next time I'll take the F1 to the tile store.

[Obioban]

Fine, you guys have convinced me. Next time I'll take the F1 to the tile store.

🤣

M3 is shockingly practical. Was my only car the first 10
years I owned it. Got work done!

[heinzboehmer]

🤣

M3 is shockingly practical. Was my only car the first 10
years I owned it. Got work done!

It really is! Was my only car the first 5 years I owned it. Took me skiing a million times, moved me a couple times (including one cross country move) and served as a daily for a couple years. Good stuff.

[heinzboehmer]

I've been trying to learn a bit more about air filtration to help interpret my experimental results, but the only thing that has become clear to me is that I have not controlled for nowhere near enough variables to adequately characterize each filter. However, I think we can get an idea of how the system is behaving as a whole.

Let's start with the static pressure data. Experimental setup stayed the same as what I described 30 or so posts back and the data is the average of three measurements. Also worth noting that all filters used in the tests were brand new.

Setup	Differential Pressure (Pa)
Stock Housing + Plug, No Filter	53
Stock Housing + Plug, Stock Filter	80
Modified Housing + Plug, No Filters	73
Modified Housing + Plug, F25 Filters	84

I think we can really only make three observations from this data:

1. Both housings flow worse with filters installed. This is expected and just a sanity check, as any filter will impede flow to an extent.
2. With no filters installed, the modified parts flow worse than the stock parts. This is also expected, as the total opening for the filters in the modified housing is smaller than stock.
3. With filters installed, the modified parts also flow worse than the stock parts, but by a much smaller margin.

The last observation is the interesting one and it's where I think drawing conclusions about the filter properties is not straight forward. Although differential pressure (and thus, flow rate) is very similar between the modified and stock parts, this does not necessarily mean that the filtration efficiency is the same. One possible explanation for the numbers being close is that the filter material in the F25 filters is less dense (driving both differential pressure and filtration efficiency down + flow rate up), but the decrease in area of the housing openings balances this out.

What's tripping me out a bit is that all of the dimensions are different between the stock and F25 filters. F25 filters are significantly taller, so even though their footprint is about 45% that of stock, the total filter surface area is closer. I can probably estimate what the total area is for both filters by counting the pleats and doing a bit of math, but I'm not sure I'm gonna get anywhere with that. I still won't really know how the differential pressure of each filter material compares, since the housing geometry is completely different between the two versions. The only way I can think of accurately measuring this is to cut up both filters, flatten out the material and then run a similar pressure experiment with some bench setup that only flows air through a fixed area. As curious as I am, I don't really think this is a good use of my time/money, as the real world effects are likely gonna be indistinguishable between the two setups.

I think the only thing that (3) tells us is that the power required to move air from outside the car, through the filters and into the cabin, is roughly the same between both setups.

But, actually, I'm okay with that. The system is still operating well within the bounds it was designed for and the only potential downside is that a bit more dust will get into the cabin. Totally happy making that tradeoff considering the massive difference in driving experience that the bracing provides.

[bigjae46]

Fine, guess I'll swap them out for a new set of PS4Ss. Gave the mobile tire guy who's always at the track a call and he swapped tires for me in my driveway. Not having to stuff a bunch of tires into a car and then drive to the tire shop was truly the ultimate luxury, don't think I can go back.

Check your toe

I see road force balancing (RFB) more as a diagnostic tool than something I would routinely do. I used RFB to determine how out of round a wheel was - can't always see it on a dynamic balancer or if the tire was bad (it happens). I never saw a situation where a RFB fixed a vibration issue where a dynamic balance couldn't. In some cases, a RFB made noise and vibration worse. Whoever is mounting a new tire needs to understanding the markings on the side of the tire to orient the high point of the tire with the valve stem which typically optimizes the balance.

IMO, RFB as a routine is the nitrogen of tire balancing - mostly useless, makes the shop more money, and is often "flat rated" by techs. Meaning they say they did it...but didn't do it.