An engine can include at least one piston, a block, a fluid delivery system, and an output shaft. The block can define at least one cylinder. The piston can be received in the cylinder. The piston can be operable to reciprocally move rectilinearly while positioned in the cylinder. The fluid delivery system can be operable to communicate air and combustible fuel to the cylinder. The piston can be operable to compress the air and combustible fuel. The output shaft can be driven in motion by the piston and extend beyond the block to a distal end. The output shaft is limited to rectilinear movement.