Alternative Energy Forums

I was reading an interesting article that claimed that the efficiency of the IC piston engine, is mainly affected by the very short crank throw and the angle which the connecting rod makes with the crankshaft as it travels down the cylinder. The contention of the article was that even taking into account piston speed etc., the efficiency of the IC piston engine was very low b’cos of these two factors. The article used as an example figures given by the manufacturer of 39.5 bhp at 5500 rpm and max. torque of 79 Nm at 2500 rpm. Bore: 6.82 cm, Stroke 7.2 cm : The argument went like this pressure on piston head after combustion equals 35 Kg/cm^^2 area of piston head equals 36.5 cm^^2 approx. Therefore initial pressure on piston head equals 1277.5 kgf. If this force had been applied at right angles on a lever that was 30 cms (1 ft. long) it would have resulted in a torque of 383.25 kgm (3755.85 N-m ) being generated. Yet the manufacturers figure of 79 Nm maximum torque means that the torque generated is always much lower than this. Could he be right about this, is there something truly wrong with the IC piston engine around which much of our world revolves ?

More importantly can we afford to delude ourselves into thinking that our car engines are 20% - 25% efficient, when in actual fact the figure is much lower ? Can we afford to continue to use an engine that is so inefficient?