For the uninitiated Lemons is the poor mans 24 Hour of Le’ Mans. You take $500 car, race prep it, and go put in as many laps as you or the car can handle. Since NJMP doesn’t have lights on the track it works out to a 14 hour endurance race. This was our 3rd year racing our 1999 BMW 323is and we had a couple things to improve on the car.
Items to knock out:
- Front tires over heat when driving at the limit causing severe under steer.
- Brake rotors have a ton of micro cracks which is a sign of over heating and can cause failure as well as reduce the life of components/ cook your brake fluid.
- Body roll reduction.
I decided we could kill two over heating birds with one air duct. This journey started with picking up a Revopoint Pop 2 which is a affordable-sh consumer grade 3D scanner. It almost ended there as well as consumer grade doesn’t begin to describe it. After about 7 hours of messing around with it, in which I did get a hand full of useable scans, I downloaded a scan of the front bumper off of Grab Cad and put my investment back into its box.
I modeled a fog light with two brake ducts using every mm to space available to me. It was a real tight fit to get the polyurethane cooling ducts hose clamped on. Duct holders where printed and riveted to fit into the wheel liner and brake dust shield and painted white to reflect heat so that the plastic doesn’t melt or become too soft.
The second approach to managing tire temps and body roll was some handling upgrades. By adjusting the cars understeer coefficient we can move some of the work back to the rear wheels. The car was fitted with H&R front and K line rear adjustable anti roll bars. Front was set to soft to maximize front grip and the rear was set to stiff to reduce rear grip. This shifts how the car handles. This allowed the the driver to use the brakes and throttle to help rotate the car into corners at the cost of making the car a lot more twitchy and reactive to small inputs.
Conclusion:
The vents worked perfect. Front tires never got too hot through out the race and the rotors had very few cracks at the end of the race. Great success! The anti roll bars helped us dial in our understeer coefficient to what the team was comfortable with helping us improve our lap times and consistency. On the other hand the body roll is still too much, after doing some research it seems by lowering the car we set up the suspension geometry in such a way that it increases the distance between the center of roll and the center of gravity increasing body roll.
Goals:
Lower the front subframe and raise the car a little to improve body roll characteristics. Add lots and lots of aero! I want to aim for that LMP car look with a vertical tail. Figure out a way to cool the cool suits with out needing ice making it cheaper and more comfortable. Add wheel arch vents and hood vents to reduce drag. And last but not least more power!
Nazar Kovch 