Project FR-S: Rocking Functional Aero from Kognition, Afterhours Automotive and Seibon

by Mike Kojima

As the SEMA Show approached, we knew we had to do something a bit different.  We knew that the show would probably be flooded with tons of FR-S's and BRZ's.  We also knew that most of these cars would be sporting either 5-Axis or Rocket Bunny aero kits.

At MotoIQ we are not the guys that build show cars so what could we do to stand out amongst the scores of nearly identically modified cars?  We figured we would stick to what we knew best and try to build something functional and not worry about the looks, hoping that by following the old adage that form follows function, we could come up with something appealing in a shot time.

Read all about our FR-S here!

Of course we had to have a rear wing. Being MotoIQ we couldn't just put some ricer shopping cart handle on our car.  In time we want our FR-S to make around 400 whp so we planned accordingly with our wing.  We turned to Kognition Design who built our custom rear wing for us.  Kognition makes the rear wings for many of the leading Time Attack cars most notably the GST Imprezza.

Knowing our planned horsepower output Kognition sized our wing and gave us mounting recommendations while supplying us with the adjustable wing mounts.  The wing generates well over 100 lbs of downforce at 100 mph while only producing about 17 lbs of drag.  The wing is placed so it runs in non turbulent air and as far back as practically possible.

Kognition strongly recommended that we attach the wing directly to the chassis as your typical trunk lid cannot take the stress of a real wing.  Since Project F-R-S is currently a frequently street driven car. We needed to retain a working trunk lid.  Matters are further complicated by our use of a Seibon lightweight carbon fiber trunk lid.  Brian Kono of Afterhours Automotive came to our rescue by reengineering the rear trunk lid. 
Brian reinforced the area between the hinge mounts and wing mounts with additional layers of carbon, epoxy and honeycomb.  The reinforcement is thick and super strong but didn't add much weight to the trunk.
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Wednesday, November 06, 2013 10:48 AM
Can one buy a cut-to-fit splitter like that? Or are there pre-made universal pieces waiting to be had?
Mike Kojima
Mike Kojimalink
Wednesday, November 06, 2013 10:52 AM
Real splitters have to be fabricated.
Wednesday, November 06, 2013 3:44 PM
Looks great.

I hadn't thought about it much before and always preferred the look of the front airdam being flush with the bumper when doing a splitter like this. It makes sense though the way it is done here as it increases the area of the splitter that the stagnation pressure can act on. For classes limited on how far out the splitter can be, seems like a pretty effective way to increase the downfore the splitter can produce. Not to mention it keeps the overhang shorter for a dual purpose car.

SEMA show cars have got nothing on the MotoIQ FR-S!
Mike Kojima
Mike Kojimalink
Wednesday, November 06, 2013 3:55 PM
That was the idea behind it. Funny thing the car is at SEMA now!
Wednesday, November 06, 2013 4:17 PM
I wonder if you could incorporate the exhaust and do a blown diffuser? It would be interesting to measure how much if any affect a blown diffuser makes. Is any one using exhaust blown diffusers outside of F1?
Mike Kojima
Mike Kojimalink
Wednesday, November 06, 2013 4:20 PM
On a sedan a blow over diffuser usualy works better. On a street car is sort of not practical.
Der Bruce
Der Brucelink
Wednesday, November 06, 2013 7:46 PM
I'm a sucker for the way the Red and Black come together to give it a REAL nice aesthetic! Still think Project FR-S needs a time warp to Fastest FR-S in NA!!
Wednesday, November 06, 2013 9:39 PM
I like the new wheels. Are these for the track or did you ditch the old ones?
Dusty Duster
Dusty Dusterlink
Thursday, November 07, 2013 6:18 AM
WTF is a "Rocket Bunny"?!
Thursday, November 07, 2013 9:06 AM
Thinking about it a bit more, spacing down the splitter like that likely means a (nearly) equal pressure is applied to the bottom of the bumper cover as well, canceling out the downforce from the added splitter area?
Dusty Duster
Dusty Dusterlink
Thursday, November 07, 2013 9:15 AM
Also, this is some serious Aero we've got going on. Mike, when are we dropping an LS in there?
Mike Kojima
Mike Kojimalink
Thursday, November 07, 2013 10:04 AM
We didn't design it not to work!
MikeG www.bestexhaust.com.au
MikeG www.bestexhaust.com.aulink
Thursday, November 07, 2013 1:50 PM
Hey Mike, all looks good but without underbody cowling to ensure turbulence free airflow beneath the car, the aero will be somewhat compromised. Just look at just about any serious German car (eg. BMW M3, Audi S4, RS4) designed for the Autobahn - the underbody is covered with smooth plastic panels, to ensure airflow to the rear diffuser is smooth.

P.S. Next time you want an exhaust system for one of these project cars, I'd be happy to talk about sponsoring the project.
Mike Kojima
Mike Kojimalink
Thursday, November 07, 2013 2:46 PM
Well no kidding! :)
Thursday, November 07, 2013 4:08 PM
I wasn't saying you made something that doesn't work. I was more thinking out loud about the impact of the airdam being set back like that and was interested in your thoughts.
Mike Kojima
Mike Kojimalink
Thursday, November 07, 2013 4:16 PM
I thought we did a pretty good job of that in the text.
Thursday, November 07, 2013 10:49 PM
Car is awesome!

I have a S13 stock bumper + splitter. It creates a similar airdam with an overhang like on the FSR. Runing without a splitter will slow down the air and create lift on all parts with front overhang. To cancle out the lift you need a splitter with a bigger surface area than the overhang of the bumper!?
But the ideal thing would be to have a bumper without overhang.

These thought has bothered me fore some time now...
Mike Kojima
Mike Kojimalink
Friday, November 08, 2013 9:33 AM
Thats not how a splitter works.
Tuesday, November 19, 2013 10:52 AM
Fantastic read! I learned a lot from this. Do you know anything about the carbon yarn? What about.the material makes it.fitting for the front lining of the lip? Thanks
Mike Kojima
Mike Kojimalink
Tuesday, November 19, 2013 11:43 AM
The yarn is called carbon tow and it is readily available. It is soaked in epoxy resin and placed on the leading edge of the splitter when the carbon is being laid up. Then it is vacuum bagged it is squished in place real hard and cures into a very strong edge.
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