To destroke an engine is to install a crankshaft with a shorter throw, which reduces the distance the pistons travel up and down the cylinders. This modification decreases the engine's overall displacement. Builders typically destroke an engine to achieve a higher safe rev limit, altering the rod-to-stroke ratio to favor high-RPM horsepower over low-end torque.
We decided to destroke the big block to build a high-revving screamer for the track.
Destroking is less common than stroking, usually reserved for specific racing classes with strict displacement limits or when chasing extreme RPMs.
Related terms
Overbore
To machine an engine cylinder to a larger diameter than its factory specification.
Over square
An engine design geometry where the cylinder bore diameter is larger than the piston stroke length.
Under square
An under square engine has a cylinder bore diameter that is smaller than its piston stroke length.