An internal combustion engine

An internal combustion engine comprising:

• at least one piston configured to move within a piston cylinder throughout a piston stroke;
• a rotatable crankshaft;
• and
• a piston to crankshaft linkage comprising:
• a piston connecting rod pivotally connected at one end to the piston at a piston pin;
• and
• a crankshaft connecting rod pivotally connected at one end to the piston connecting rod at a connecting rod joint and pivotally connected at another end to the crankshaft
• wherein the internal combustion engine also comprises a control arm configured to direct movement of the connecting rod joint to alter an effective length of the piston to crankshaft linkage as the piston to crankshaft linkage is moved via rotation of the crankshaft to form a working crank angle when the piston is at its top dead centre (TDC) position for a predetermined angle of rotation of the crankshaft;
• wherein a reduction in the effective length of the piston to crankshaft linkage via the control arm reduces the stroke of the piston within the piston cylinder in a low compression position.