Gears are a magical thing. They can be used to transfer power in all kinds of ways and by combining gears of different sizes, you can make gear ratios that effectively manage, multiply, or divide your power, rpm, and more so that they can be used most efficiently. These gear ratios help multiply torque, allow for higher speeds, and more but are dependent on the application and the desired us. In a motor vehicle, gear ratios come into play in all kinds of ways. From steering to valvetrain to transmission and rear-end ratios, all of them play a part. But do different engine combos need different rear-end (axle) ratios? The answer is yes. Some high winding naturally aspirated combinations are going to want a LOT of rear gear. Say something in the 4, 5, or even 6.0 range. Other cars with power adders may not want, need, or even be able to use ratios that steep because they will ultimately over-rev and not be able to work properly.
So how do you choose a gear ratio for your particular application? And specifically, a turbocharged engine combination that is being used for drag racing? It might surprise you to find out that a much more “mellow” rear-end gear is required in a turbo car and that means they are much more suited to street driving than some other combinations might be.
In this video, Doug from Motion Raceworks is going to teach you about gear ratios for your turbo combination so you can make the right choice the first time. Gears aren’t horribly expensive, but if you can’t set them up yourself then there are some labor charges that can become a factor in replacing them, so why not get it right the first time.
