heinzboehmer's 2002 Topaz 6MT Coupe

[D-O]

Very well done sir.

[heinzboehmer]

Thanks! I'm pretty happy with how the project came out

[YoitsTmac]

Looks great! Whose intake snorkel is that? I'm looking for a plastic OEM-style one

[heinzboehmer]

Looks great! Whose intake snorkel is that? I'm looking for a plastic OEM-style one

Karbonius snorkel that I had cerakoted. I think Haimus makes one that fits and is plastic?

[heinzboehmer]

Also, some (long) thoughts and a photo dump at the end:

It's been interesting driving the car with the braces and snorkel back on. It's both more and less refined.

The thing that I kept being drawn to this time around is the H in NVH. The car isn't harsher as a whole, but the qualities of the harshness for sure change.

If you imagine plotting the impacts that the driver feels inside the car, the amplitudes would stay the same, regardless of bracing, BUT the shape of the waveform would be very different. Unbraced would be sinusoidal, while braced would be much more triangle-like. In other words, the unbraced chassis extends the duration of the harshness, but softens the transitions, while the braced chassis both absorbs and gets the harshness out of the way much quicker. In qualitative terms, the bracing makes the car feel more "sporty" and less "relaxed". Think this is similar to what Bryson was talking about when comparing it to a spring rate change.

The one exception to this is the steering wheel. The feedback you get through there is for sure harsher, period. Makes sense since, for a given impact: less strut tower deflection -> less energy absorbed by flexing the strut towers -> more energy going into the steering rack -> harsher "jolts" of the wheel in your hands. This is not at all an unwelcome change, though! Makes the front end feel way more precise and again, "sporty".

On throttle, mid corner behavior is still the best part of this mod for me. You give it steering input and the front keeps turning at the same radius, regardless of the amount of throttle applied. It's very fun.

Counterpoint to that is that the front end is significantly less forgiving of imprecise inputs. I didn't even realize I had learned this behavior, but turns out I was using the unbraced, throttle induced understeer to aid in small direction changes. Simplest example that comes to mind is giving it only a little bit of steering angle on the highway to change lanes, then giving it throttle to speed up and letting the understeering front end carry you over to the other lane. If I go to do that with the braced chassis, the car just keeps pointing where I told it to point with my hands. Again, not something I mind because of the more sporty nature of the car, but still something worth pointing out.

The braced chassis demands more attention from the driver in most situations, and especially if you want to be smooth. As mentioned above, it's less forgiving to imprecision.


Onto the snorkel:

This change was immediately obvious: less snorkel, more rowdiness. It's not louder, but the overtones in the noise are slightly higher pitched, which makes it feel louder.

And this isn't just subjective! I have data to prove it.

First, a comparison of the waveforms of a pull from 3k to 8k rpm (same on ramp, similar weather, mic in the same spot, both WOT). Note that the amplitude is basically the same between both.

No snorkel:



Snorkel:



And here's a spectrogram comparison of the same clips.

No snorkel:



Snorkel:



The difference is very obvious in the spectrograms. Notice how much more higher the frequencies are pushed without the snorkel. With the snorkel, they're all bunched up in the low end.

Cool to see, but I think I'll be keeping the snorkel for the sake of those IATs

(also worth noting that this is with the cerakoted snorkel. I'm not sure how much the coating affects the sound, but it sounds pretty similar to what I remember the uncoated snorkel sounding like. I wish I had captured audio of that combo as well, just to know for sure)



Anyway, too much talking. Ending this one with some much better engine bay pictures, in a couple different lighting scenarios.:

[Slideways]

Both brace and snorkel turned out amazing with the cerakote!

The snorkel might need a sticker delete

[heinzboehmer]

Both brace and snorkel turned out amazing with the cerakote!

The snorkel might need a sticker delete

Yeah, sticker is pretty unsightly. I asked for it to get masked cause it has manufacturing info on it, buut all of that came off when unmasking.

Which means that if I do remove it, I have to figure out how to blend the overspray with the raw carbon under the sticker. Soooo I've just been ignoring it.

[George Hill]

My Z4 braces just showed up

And the brace looks sooo good, but that snorkel being cerakoted vs CF is the chefs kiss IMO.