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 ...

Power, power, we all want more power. Naturally, most people think of the engine when upgrading their 4x4, since that’s where the power comes from. Is your rig a slug in the rocks or on the road? Just ...

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, ...

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 ...