Micro sprints also have bash bars on the sides of the cars to protect the engine and driver and help prevent interlocked wheels. The Indoor Auto Racing series also mandates a U-shaped front bumper. All of these bumpers and bash bars get quite a workout so they are bolted in for easy replacement. Most teams elect not to replace the bash bars until they break: most cars we spotted were running with dented bumpers.Since the cars use motorcycle engines, micro sprints also use motorcycle gearboxes. Gearboxes are gutted and only 1st and 2nd gear remain. This is due to the short length of the tracks: the circuit laid out in Trenton is only 1/10 of a mile long so speeds are generally low. Drivers start the race in 1st gear, then shift into 2nd. Removing the top gears reduces weight. It also makes the transmission more efficient as those gears are no longer creating drag losses inside the transmission. For simplicity, all cars use a hand clutch.The maximum engine displacement for these engines is 637cc. Induction is unrestricted and cars can use either carburetion or fuel injection. IAR requires a standard header and muffler must be used to ensure noise levels are not too extreme. 112 octane race fuel or methanol are allowed, though 2-stroke engines are not. When properly tuned these engines can make 150hp. You can also see the chain drive to the rear axle. All of the cars we spotted ran spool rear ends with no differential. This is fairly common in oval racing.The rest of the cockpit is equally barren. Most cars only have a tach, water temperature, oil pressure, and kill switches. We also noticed a number of cars had adjustment knobs. These are remote adjusters for the front shocks allowing the driver to tune the handling in the middle of a race.The routing isn’t always pretty but it works! Also note the screen to help keep the worst of the dirt clods and debris out of the driver’s face. A proper windshield would not work since it would get covered in mud within a few laps.
