The top picture is of a Briggs engine with a TAV (CVT). Most of the time mini drag cars are doing Bracket racing an not actually going for top speed. TAV's are super consistent and are adjustable for when the power and how much will come on which is perfect for Bracket racing. The engines these guys are using in there minis are the same engines the Mini Drag cars are using but a 1/3 of the weight. Less weight = Faster and unpredictable power.
89 Honda Elite E 48cc bbk and gears all broken in... I get to 35 mph (gps) full out and Im 240 lbs. Need more speed