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Discussion Starter · #1 ·
I wanted to gain deeper insight and find possible improvement for the S2 exige's aero. People were all talk but almost none were able to back up their claims with data. Sometimes canards were claimed to be a great front downforce generator, and sometimes referred to as vortex generator to block the sides of the car. I wanted to see concrete results with my own eyes and be able to find the right solutions.

All the models available online were a no-go; they were either too low in resolution, or contained sizable amount of polygons but did not retain correct curves. So I initially opted to do manual line sketching. It was a crude model but was greatly improved after several iterations.

I was able to test various diffuser designs with different angle and length. Observed the effects of "bumper cutting", canards, side skirts and so on. However the results lacked credibility due to it not being a real model.

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That's when Lotus Korea stepped in. They offered me an opportunity to do a 3d scan of my vehicle. I was so proud that I decided to leave the "positioning stickers" all over my car.

Finding the right recipe to do a fluid dynamics test on a big 3d scanned model was a challenge and I spent the last two weeks struggling. I finally got a breakthrough. Initial tests are stable now and I have to do some work on internal air tunnels. But I'm pretty sure things are back on track for many many tests to come.

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I would like to thank @JKDENTAL from Lotus Club Korea for connecting me to Lotus Korea represtatives. Thanks to Lotus Korea, of course. And special thanks to @forkmeupscotty for his support.
 

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2006 Exige
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871 Posts
This is very cool!

Really all we ever had to go by was the 3 part series in Racecar Engineering by Simon McBeath.

Is it possible to get the 3d scaned files from you?
 

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I wanted to gain deeper insight and find possible improvement for the S2 exige's aero. People were all talk but almost none were able to back up their claims with data. Sometimes canards were claimed to be a great front downforce generator, and sometimes referred to as vortex generator to block the sides of the car. I wanted to see concrete results with my own eyes and be able to find the right solutions.

All the models available online were a no-go; they were either too low in resolution, or contained sizable amount of polygons but did not retain correct curves. So I initially opted to do manual line sketching. It was a crude model but was greatly improved after several iterations.

I was able to test various diffuser designs with different angle and length. Observed the effects of "bumper cutting", canards, side skirts and so on. However the results lacked credibility due to it not being a real model.

View attachment 1286743
View attachment 1286744
View attachment 1286745
View attachment 1286756


That's when Lotus Korea stepped in. They offered me an opportunity to do a 3d scan of my vehicle. I was so proud that I decided to leave the "positioning stickers" all over my car.

Finding the right recipe to do a fluid dynamics test on a big 3d scanned model was a challenge and I spent the last two weeks struggling. I finally got a breakthrough. Initial tests are stable now and I have to do some work on internal air tunnels. But I'm pretty sure things are back on track for many many tests to come.

View attachment 1286741
View attachment 1286750
View attachment 1286751
View attachment 1286742
View attachment 1286752


I would like to thank @JKDENTAL from Lotus Club Korea for connecting me to Lotus Korea represtatives. Thanks to Lotus Korea, of course. And special thanks to @forkmeupscotty for his support.
Great project! It will be interesting to see your results and maybe some products down the line.
 

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Awesome. There is a series of articles by Simon McBeath where he puts an Exige in a wind tunnel and tries some reverie parts. Give it a search.
 

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I will tell you the preliminary flow around the windshield is spot on. Put your hand in the little space between the mirror and the door, and there is a little stream of hot air, as predicted, the center of the windshield is also cooler than the areas to the left and right.
 

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Super. Have waited and waited to see some data.
 

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Very interested to hear what the results are.
 

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Discussion Starter · #10 · (Edited)
Starting to get some initial results.

The "Stock" model has the following conditions
- BSK carbon kevlar rear hatch
(ロータス エリーゼ・エキシージ エクステリアパーツ・エンジンフード S2エキシージ■BSK■)
  • BSK wide side scoop
  • Sideview mirrors omitted (can be added later)
  • Wheel size modelled after 225/45R15 and 255/35R17 on GRP 6UL wheels
  • Underbody rear wheel cutout sealed
  • Added a Difflow style generic diffuser due to using BOE exhaust
  • Ride height 10cm

Now Lotus claimed 93lb of downforce at 100mph for later style (2008~2011) S2 exige [citation required].
My stock model got 381N of downforce which equates to 85.8lb of downward weight.
While keeping in mind that my "stock" model has some differences from the real stock Exige, it seems quite close.
It doesn't necessarily have to be same as the real world figures since what I am going to observe is the "relative change" rather than absolute figures, but it still is good to be reassured that what I am working on is not too far off from Lotus' claim.

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Now as a sneak peek of what's about to come.
I added GRP's race style side sills.

397.48N downforce VS 381.38N stock (approx. 4.2% increase)
753.77N drag VS 758.03N stock (approx. 0.6% decrease)

I tend to get better numbers as I increase simulation resolution, but I will stick to the current setting for the time being and compare things under the same condition.

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07 Aspen White Exige S - MT
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978 Posts
Do aero skirts facing down not out. Basically a skirt running full length / straight at front then follow curve of rocker to rear wheel. 2 inches down towards the ground. Love to see that data vs “barge boards”
 

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I bought one of the $90 models of an Exige found online. It is a mesh scan, perhaps taken from a game, that needs to be surfaces to make the CFD work. I was trying to use Solidworks CFD module before I gave up. I did some research on renting a scanner, there are several companies that rent them. But what little I could find online implied that I would just end up with another mesh model. I would be curious how you created the surfaces and I'd be willing to commit some funds to be able to do the same what if CFD analysis.
 
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