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Old 06-27-2022, 12:58 PM   #391 (permalink)
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Originally Posted by aerohead View Post
The original spoiler conformed to a streamlined pathway, and simply extending it, at the downward angle it would project if you laid a straight-edge on the back of the car's centerline, theoretically, would suffice. Your up-kick design would over-accelerate the flow, lower its pressure, and kill it's direction towards the wake.
Below, just following the bottom of the rear quarter panels for the diffuser would put it at nearly an ideal angle for upsweep.
The August 2022 MOTOR TREND, PP. 70,71, has an article on the 2022, M-B EQXX. Mercedes-Benz is extending it's diffuser back almost 8-inches, while dropping down 3-degrees, above 35-mph, for a 10-count drag reduction.
I'm not trying to be a buzz-kill, but I see 'trouble'.
Whatís trouble with the eqxx diffuser? I thought it reduces drag

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Old 06-27-2022, 01:11 PM   #392 (permalink)
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EQXX

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Whatís trouble with the eqxx diffuser? I thought it reduces drag
It reduces drag by ten counts. So, no trouble there.
Your rendering of the proposed diffuser mod on the previous page though, has a 'mysterious' bulge coming out of the bottom of it. I don't know how to interpret what I'm looking at.
Same for the spoiler.
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Old 06-27-2022, 03:19 PM   #393 (permalink)
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Quote:
Originally Posted by aerohead View Post
It reduces drag by ten counts. So, no trouble there.
Your rendering of the proposed diffuser mod on the previous page though, has a 'mysterious' bulge coming out of the bottom of it. I don't know how to interpret what I'm looking at.
Same for the spoiler.
Oh the spoiler was just me trying to fix the previous bad photoshop. Ignore that. As of right now Iím just leaving the spoiler stock until I do the wheel skirts and diffuser

As for the diffuser part, that buldge isnít a buldge. Itís supposed to be the flares coming off the rear wheel spats merging into the diffuser. Iím not a good digital artist haha. Essentially itís supposed to look like the eqxx diffuser but the side start at the wheel skirts
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Old 06-27-2022, 04:27 PM   #394 (permalink)
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You weren't here for the schicimism over which of three Holy Templates was canonical.
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Old 07-07-2022, 12:25 PM   #395 (permalink)
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Soooo update…

I jacked my car up and got a super good look underneath, other than fixing up the current front belly pan or getting a new one, I doubt I can do much more for a smooth underbody. The whole line of site is super straight. Sure it’s not smooth, but it’s flat and straight. Even the placement of the gas tank and rear muffler is extremely flush. Smoothing everything out with expensive panels will probably make almost no difference except saving a few Pennie’s over a year of driving. Not worth it. I’m going to focus effort on building a rear diffuser and closing in the rear parachute gap between the muffler and bumper

Also got the full rear wheel spats cut out! Just need to sand down the sharp edges and screw them into the body panels!
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Old 07-07-2022, 01:36 PM   #396 (permalink)
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diffuser

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Soooo updateÖ

I jacked my car up and got a super good look underneath, other than fixing up the current front belly pan or getting a new one, I doubt I can do much more for a smooth underbody. The whole line of site is super straight. Sure itís not smooth, but itís flat and straight. Even the placement of the gas tank and rear muffler is extremely flush. Smoothing everything out with expensive panels will probably make almost no difference except saving a few Pennieís over a year of driving. Not worth it. Iím going to focus effort on building a rear diffuser and closing in the rear parachute gap between the muffler and bumper

Also got the full rear wheel spats cut out! Just need to sand down the sharp edges and screw them into the body panels!
On the Audi 100-III, the shallow-angled diffuser was good for a 20-count drag reduction, but that was dependent upon having all the belly pan ahead of it. Potentially Cd 0.21 for the IONIQ with the upstream belly panels and diffuser by themselves. Nearly your total aero target!
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Old 07-07-2022, 02:38 PM   #397 (permalink)
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Also got the full rear wheel spats cut out! Just need to sand down the sharp edges and screw them into the body panels!
Let us see what you come up with.
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Old 07-07-2022, 10:39 PM   #398 (permalink)
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Anyone know why companies don’t just cover the full under body? I mean clearly it’s possible even with gas engine cars. So why not do it from the factory? Cost?

I’m kind of bummed though that it won’t be practical to fill in the small gaps around the underside. I can see a huge potential for the diffuser though. The Ioniq simply doesn’t have one? Again, why not? Why wouldn’t Hyundai do one? Even the Prius has one( doesn’t extend past the body). Hyundai was literally designing the Ioniq to “ beat the Prius”.

I saw a few YouTube videos showing that you don’t need a fully smooth undertray for the diffuser to work. In all the tests, yes the smooth underbody had lower drag, but only by a super small amount. Biggest drag reduction by far was adding a diffuser to any of the under floor types.
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Old 07-07-2022, 11:32 PM   #399 (permalink)
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Manufacturers operate under other constraints, serviceability for one.

The Original Gangster VW Beetle had a flat floorpan, but the seats eventually needed more than wingnuts for hold-downs. The sliding mechanism added wedge shapes to the underside.

Here's a Type II on a rotisserie:

The center section has panels that fill the ladder frame, but they were only used on some models
Quote:
https://www.thesamba.com õ vw õ forum õ viewtopic.php?t=471948
TheSamba.com :: Split Bus - View topic - Belly pans?
Belly pans are only found on Bus's; specifically, Bus's that have a sunroof or a door mobile, or a double door. When you cut a hole in the roof, the belly pans provide the strength and rigidity that is missing from the hole in the roof. They were body strengtheners put on Sunroof buses, and buses with the double doors both sides.
I think by door mobile, they meant Dormobile.
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Old 07-09-2022, 09:30 PM   #400 (permalink)
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Rear wheel skirts officially jigsawed out and shaped and edges sanded

Black dibond. Extremely stiff and light weight but can be shaped if you man handle them.

Will be drilling them in later this week and then play around with them

After I have them installed, Iíll probably insert some river nuts or pop rivets to work better long term and avoid winter rust. Once I get that Iíll be doing a factory black paint job with a glossy clear coat

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