Vehicle speed (mph), engine speed (rpm), tire diameter (inches), trans gear ratio, and rear axle gear ratio are all interrelated. If you know four out of five of these values, you can determine what ...

What if-and believe me, this is a hypothetical-you were trying to put a wild, rare, 200-hp naturally aspirated Autech SR20DE from the hottest of the nonturbo S15 Silvias into a first-generation Miata, ...

Why is the Gear Vendors overdrive so popular on HOT ROD Drag Week? Racers know it will live behind 4,000 hp, can be installed in a weekend, and doesn't share fluid with your transmission so it won't ...

Even good cars only give the driver two speeds to monitor: engine speed and vehicle speed. And while it’s the engine that ultimately does the work to turn the wheels and move a vehicle, a lot goes on ...

Truck engines are designed with an operating range in mind, a band of engine rpm where they operate at peak fuel efficiency for the work they’re doing. That “sweet spot” varies across different makes ...