When Polaris introduced the new Prostar 2.0L engine and mentioned the horsepower numbers, they did sound really good, but we did see a pretty good reduction in peak torque from the previous 2.4L Ecotec. We were a little concerned that the new engine might be a little peaky and feel a little gutless while cruising around. However, once the new engine specs were posted on the Polaris website after the reveal, they also posted up the new transmission gear ratios and the new final drive ratios and that's when we started to notice some important changes Polaris made.
Once we saw the changes to the transmission gearing and final drive, it became pretty obvious to us that although the engine would make less torque, we were going to see a faster Slingshot.
To confirm this, we started the comparison by using one of the dyno's of the base 2.4L Ecotec GM has posted over the years that shows peak horsepower/ torque and their RPM's. We put that information into a spreadsheet, then multiplied the engine power by the gear ratios of the transmission, final drive and also factored in the rear tire diameter. We plotted all of those data points, for all 5 gears on a graph below in red lines.