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Re: BlueScooby's 06 STI - A little CFD Analysis on the car ;)

Try not to work very hard.
 

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Re: BlueScooby's 06 STI - A little CFD Analysis on the car ;)

Do a video on those mirrors so we can drool.
 

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Re: BlueScooby's 06 STI - A little CFD Analysis on the car ;)

Do a video on those mirrors so we can drool.
unfortunately they don't fold in and out just yet... I've got to run a pair of wires through each door to the new switch first. I will be trying to tackle that next.

In the mean time, I can share the installed (basically the same as USDM because the motors aren't wired) JDM mirrors. The paint was touched up and detailed/buffed out and XPEL was added. Also added the yellow Prova lenses that I had sitting around for a while. So while they don't do the cool folding trick yet, they look MUCH better than the old-n-busted original mirrors...

The Prova lenses are both convex which is great for reducing blindspots but it is taking some getting used to on the drivers mirror. I can definitely see a lot more, but everything also looks much smaller which is a little annoying... I use my drivers wing mirror a lot as it turns out.

The yellow tint really does work at reducing the "glare" or making the intensity of headlights behind you seem reduced. Plus I think it looks super cool ;)




Just look at that smooth paint! you can even see my ugly self in it!


And the obligatory, I-cleaned-my-car-this-weekend-because-it-was-65°F picture:
 

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Re: BlueScooby's 06 STI - Underbody/Diffuser V3 in progress

Well the sheetmetal shop finally got around to finishing my order from two months ago... between all the holidays (dropped off just before thanksgiving) and them getting swamped in December, I've been itching to get these back and start work!

Hoping to get started this weekend. I probably won't do much on the diffuser until I get the other two panels sorted and attached first. I also need to head over to the welder and see if he can do what I'm wanting... I'm planning on using welding rather than riveting for most everything this time.
 

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Re: BlueScooby's 06 STI - Underbody/Diffuser V3 in progress

(I hope yall like pictures... haha)

Made some more progress on the diffuser this weekend. End fences are trimmed trimmed out (preliminairily at least). I will "assemble" the whole thing next and mount and confirm fitment or if more trimming is needed. Once thats done, I will make the final rivets, paint and install. I"m expecting to be able to get most if not all that done by the end of this coming weekend (fingers crossed). My car looks like it is missing something without the old V2 diffuser on there, so I'm pretty excited to finally get the V3 finished up!

After I got the sheetmetal back, I took a V2 versus V3 photo to show the additional width:


I started installing the captive DZUS fasteners:


First shot of the revised panels installed and the diffuser set in place. Notice the lack of bolt heads sticking through disrupting airflow :D


A shot at how wide the new setup is. I actually had to trim a little off the upright for the panel under the gas tank because it was contacting the brake line on the trailing arms at full droop... There is no-more-wide left to be had on that panel :O


Planning out the rear diffuser:


Got the strakes welded in place, and starting to clean up and caulk the joints:


Before and after caulking:



Planning out the fitment/mounting of the diffuser:



And this is where I stopped yesterday. Comparison between the V2 setup and the not-quite-assembled V3 setup:


I want to add more caulk to the joints to round out those inside corners a little more, rather than just sealing them, since a hard square corner is not as efficient. Trying to go all out as much as possible! Ultimately when this is done, it would be really cool to use this a mold for a fiberglass model. You know, to "add lightness" and all that Colin Chapmen stuff. :cool:
 

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Re: BlueScooby's 06 STI - Underbody/Diffuser V3 in progress

Dude, nice work. Very cool. Are you going to leave the strakes that size or trim them down a bit?
 

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Re: BlueScooby's 06 STI - Underbody/Diffuser V3 in progress

Dude, nice work. Very cool. Are you going to leave the strakes that size or trim them down a bit?
The plan is to leave them that large if it doesn't create an issue. I actually used the V2 strakes/end-fences as the template to cut these out, so its fairly likely that I will be able to keep these the size they are now (which is good). Naturally you want your strakes/end-fences to go down as far as possible to actually separate airflows, so I try to keep the trimming to a minimum where possible. I’m planning to finish mounting/hanging the diffuser this weekend, and the first thing I will be testing is ground clearance out of my driveway. :tup:
 

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Re: BlueScooby's 06 STI - Underbody/Diffuser V3 in progress

Low as possible, right. Looks like it doesn't protrude from the car as far either. Good luck on the clearance test :D
 

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Re: BlueScooby's 06 STI - Underbody/Diffuser V3 in progress

Lovin this man. If you need help with CFD let me know. Can't guarantee I'll know the answer but I have an ME degree and have worked with fluid flow for years now designing hydroelectric turbines.
 

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Re: BlueScooby's 06 STI - Underbody/Diffuser V3 in progress

Lovin this man. If you need help with CFD let me know. Can't guarantee I'll know the answer but I have an ME degree and have worked with fluid flow for years now designing hydroelectric turbines.
Thanks man! I definitely have more to learn, although my biggest obstacle is getting a model that actually resembles my car. I basically used a single profile extrusion previously since that was the main thing I was interested in, but it would be great to get a pretty realistic model...
 

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Re: BlueScooby's 06 STI - Underbody/Diffuser V3 in progress

Thanks man! I definitely have more to learn, although my biggest obstacle is getting a model that actually resembles my car. I basically used a single profile extrusion previously since that was the main thing I was interested in, but it would be great to get a pretty realistic model...
Funny you say that. I am 98% sure that I have a full 3d rendering of an STI. I'll have to double-check when I get home

Sent from my SM-G955U using Tapatalk
 

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Re: BlueScooby's 06 STI - Underbody/Diffuser V3 in progress

So I did get the diffuser mounted, tested ground clearance and have been driving around with it for a couple days now. I think I managed to mount just a hair lower than the previous V2 setup, despite literally using all the pieces as a template to build the V3... I mounted it slightly different though, and thats probably it.

I'm really pleased with the outcome, especially how the design of this one allowed me to have zero bolts/rivets/airflow-interruptions on the under side of the diffuser. Those cause a lot of drag which reduces the effectiveness of the diffuser, so smooth is best!

I'm also excited to see how the lateral expansion I added plays into the diffuser effectiveness. Now that I'm done building it, I'm a little torn on whether I think it will have actually been a good idea or not... Once I can get a good rain to drive through (tomorrow maybe) I will be able to check to see how the water acts with the diffuser. If it is still fully-wetted after driving around, thats a good indication that I'm not suffering from any stall (thats the main reason I built the V2 setup from the V1). I know the angle isn't too steep to cause stall since the V2 didn't suffer at all (that I could tell) and the V3 is maybe 1 degree less steep.

In any case, I'm sure you really just want to see some pictures ;)

One small complaint about the diffuser first though. Welding the strakes on the diffuser did cause it to warp a touch, so the lines at the back aren't quite as crisp as I hoped. Its not much but you always see your own imperfections...

Starting the process of finishing the hanger bracket for the center:



Once the bracket was welded, I added to support rods to the end-fences and painted it.


Here is the "clearance" test coming out of the driveway :eek: This is where I think the V2 was slightly higher by 1/2" or 1" but I also designed the V2 for a steeper driveway...


And some "finished install" pics:



Lastly, some look-how-smooth pics ;)

 

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Re: BlueScooby's 06 STI - V3 Diffuser/underbody finished/installed

Got my first decent rain-drive after installing the V3 diffuser, and all is well! Diffuser is fully wetted (minus the inside edge of the strakes/end fences but that's to be expected for water).

I saw a lot of water coming up, and believe it or not, at times I could even see vorticies forming off the endfences. It was hard to see in the mirror, but at times, I was definitely able to see curling airflow(water) on the ends. That is the coolest thing I've seen yet. The only thing better would be renting a wind tunnel:naughty:
 

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Re: BlueScooby's 06 STI - V3 Diffuser rain test video

Video from the rain this weekend. Its hard to really capture the rain on camera, but having realized the "effect" is most pronounced in the center of the car's wake, I tried mounting the camera on the trunk this time.

You can clearly see the spray coming up, all though it still doesn't seem as impressive as seeing it in person. I can start to see the wisps of water around 40mph, but at 50-55mph, its starts to get really thick. It appears to be reaching upwards of 6ft or so in the air now (definitely above the top of the car).

Youtube link, incase imbedding fails


I replaced my old-n-worn karboy endlinks this weekend with the Whiteline Ball-socket endlinks. No more clunking, or sway bar preload!

Also, I just signed up for a track day at NCCAR on the 16th! Man I'm excited to be back out on track!
 

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Re: BlueScooby's 06 STI - V3 Diffuser rain test video

Interesting to see how the aero will work on track.

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