This cylinder configuration allows for larger intake and exhaust valves in the cylinder head, improving airflow at high engine speeds. Because the piston travels a shorter distance per revolution, piston speed remains lower, enabling the engine to safely reach higher maximum RPMs. Most high-performance and racing engines use this geometry to maximize peak horsepower, sacrificing some low-end torque compared to longer-stroke designs.
We're building an over square naturally aspirated V8 so it can comfortably spin to nine thousand RPM on the track.
A highly over square engine feels sluggish off the line but pulls aggressively once the revs climb into the upper range.
Also heard as
- short-stroke
Do not mix it up with
- Under square: Under square means the stroke is longer than the bore diameter, which favors low-end torque over high RPM horsepower.
Related terms
Under square
An under square engine has a cylinder bore diameter that is smaller than its piston stroke length.
Overbore
To machine an engine cylinder to a larger diameter than its factory specification.
Destroke
Destroking an engine means reducing the piston stroke length to decrease displacement and alter the power band.