Abstract: Reciprocating engine construction wherein a rotating assembly converts the linear motion of the piston into rotational motion more efficiently, therefore yielding more torque and working power while using less fuel. The rotating assembly is three components working together, an interchanger unit with track rollers mounted at both ends and attached at it's center to the connecting rod by bearings allowing it to rotate while reciprocating, a stationary cylindrical unit having opposing wave shaped races (tracks) encircling it's perimeter with slopes of at least 45 degrees to convert the reciprocating motion to rotational motion on a one to one ratio 90 degrees perpendicular to the axis of the interchanger as the track rollers follow the slopes of the races, a rotating carrier that keeps the track rollers aligned and transfers the converted rotational motion to the output shaft by means of gears.