If an engine is described as square, what does that imply about its dimensions?

When an engine is described as square, it implies that the bore (the diameter of the cylinders) and the stroke (the distance the piston travels within the cylinder) dimensions are equal. This configuration can have a significant impact on engine performance characteristics. Square engines tend to exhibit balanced performance with an optimal power delivery across a range of RPMs, as the equal dimensions allow for efficient combustion and movement of the piston.

This term contrasts with other configurations where the bore may be larger than the stroke (over-square) or smaller than the stroke (under-square), which can affect the torque and horsepower characteristics of the engine. In an over-square engine, for example, it may achieve higher RPMs and potentially more power, while under-square engines may offer better torque at lower RPMs. Therefore, the description of being square specifically refers to the equality in bore and stroke, which influences the performance and operational characteristics of the engine.