An oversquare engine has a bigger bore than the stroke.

• A. False
• B. It depends on design
• C. True
• D. Not enough information

Answer: (C)

Oversquare means the bore is larger than the stroke. Since the bore is the cylinder diameter and the stroke is how far the piston travels, having bore greater than stroke defines an oversquare engine. So the statement is true. This design typically supports higher RPM capability and better high-end breathing because the larger bore allows bigger valves and more air flow, while the shorter piston travel reduces piston speed and friction at high speeds. (If the bore were equal to the stroke, it would be a square; if the bore were smaller than the stroke, it would be undersquare.)