When driving Project FR-S on the track we had noticed that although the car had excellent handling in general, it had understeer in high-speed turns. We also noticed in pictures of the car traveling at high speeds that the back of the car was squatting down. We reduced the squatting by upping the spring rates when we upgraded the suspension with Wisefab and we also trimmed out our Cognition rear wing by drilling some new adjustment holes so we could run it at zero angle. We also decided to add some CFD-designed Aero parts to the front of the car to help add more front downforce from Verus Engineering and Victory Function. As a note, everything we are doing here also fits the Toyota 86 and the Subaru BRZ.
Project FR-S running at Buttonwillow. You could feel the aero-induced high-speed understeer around Talledega after the Bustop. The back of the car was firmly planted but the front would start sliding off line and you would have to reduce throttle. You could also feel this at turn 2 at Willow springs.
Our front end already had some aero aids. We had a sturdy splitter by Brian Kono at Afterhours Automotive. It was a good height from the ground at about 3.5″ and its interface to the front bumper was well sealed. We also had bullnosed front fenders from Victory Function that reduced some of the pressure in the front wheelwells by getting rid of entrapped air at the back of the wheelwell and reduced some of the front tires pumping action through the open backside.
To further improve the air handling, we added some of Victory Functions’ carbon fiber blades or air guides to the rear of the wheel well. These help by guiding the air curling off the front of the car and allowing the fender cutouts to act more like fender vents. This helps reduce wheelwell pressure more and also reduces drag in this area.
Our fenders were drilled to allow attaching riv-nuts to the underside of the fender crease.