If you change your car's gearing, can you make it quicker? The simple answer is yes. More aggressive gearing creates a quicker car but not a faster car.
A gearing change will have a noticeable affect on your car. If you swap in taller rear gears, you can gain some top-end speed, making your car faster, but you're going to be a bit slower leaving from a stop. You'll get an opposite result when you swap in shorter gears.
Engineering Explained host Jason Fenske recently changed out the rear-end gearing in his own project Honda S2000. That's good news for you, because he's going to break down the resulting change to his car with the help of math and science.
Jason removed the original 4.10 rear gears in favor of a shorter limited-slip differential packed with 4.44 gearing. To see just how much quicker this setup really is, Jason utilized his VBox data logger and produced a few 10-60 mph runs with his old rear end and the newer one, making sure to minimize the number of variables between the runs.
The newer 4.44 gearing resulted in times that were between 4 and 7 percent quicker. More noticeable, though, was the fact that the peak average g forces felt during those pulls rose by five percent. That's due to the torque of the engine getting properly planted to the tires and the road.
On the far side of his powerband, Jason notes that his car lost some top-end speed. The good news is that we're talking about a Honda S2000 and not a Bugatti Chiron, so it's far better to gain low-end scoot in this scenario.