Have we been misled about the efficiency of the IC piston engine ?

prospero · #1 03-23-2010, 09:54 AM

For many years we have placidly believed that the IC piston engine has an efficiency of about 20% - 25%. This in itself is bad enough, it is like buying a cold drink on a hot day and then throwing 80% of it away. But what if the actual situation is much worse ? What if the efficiency of the IC piston engine is only about 1% to 2 % ? Wouldn’t that be an eye-opener ? We would be throwing away 99% of the drink and keeping only a few drops for ourselves ! I am aware that the majority of readers may not be familiar with technological terms but hopefully the moderators of this forum are, since the forum IS after all mainly concerned with the exploration of new technologies. I am sure that if the moderators see anything in this post that they know to be wrong they will immediately point it out.
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 is that even taking into account piston speed etc., the efficiency of the IC piston engine is very low b’cos of these two factors. As an example taking actual figures given by an automobile manufacturer of a maximum 39.5 bhp at 5500 rpm and max. torque of 79 N-m at 2500 rpm. Bore: 6.82 cm, Stroke 7.2 cm : The argument is that pressure on piston head after combustion equals 35 Kg/cm^^2 (figures quoted from text book on automobile engineering) 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) (quoting Archimedes) it would have resulted in a torque of 383.25 kgm (3755.85 N-m ) being generated. Yet the manufacturers figure of 79 N-m maximum torque means that the torque generated is always much lower than this.
This mean that compared to possible output the IC piston engine has only (79/3755.8) x 100 = 2.1% efficiency using this very basic configuration, more complicated configurations could result in an even lower efficiency for the IC piston engine. Could this be right, is there something truly wrong with the IC piston engine around which much of our world revolves ?
If so is there an alternative solution that would allow us to use a far greater percentage of energy in fuel than we are at present utilizing. The answer is a resounding YES, if permitted to do so, I shall explain this new technology over the next few posts. .

prospero · #2 03-23-2010, 10:53 AM

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 this be right, is there something truly wrong with the IC piston engine around which much of our world revolves ?

What has been stated is theoretically correct since power is a function of torque and engine speed. This is shown by the relation: Bhp = (torque (ft lb) x 6.28 x rpm)/33000
And in metric: Kw = ( torque(N-m) x 6.28 x rpm )/ 60000. Thus in the example quoted as Manufacturers figures : Bore 6.82 cm, Stroke 7.2 cms : Max torque = 59 N-m @ 2500 rpm. This torque would result in : ( 79 N-m x 6.28 x 2500rpm) 60000= 20.671 Kw. = 27.7 hp. However using figures of a 30 cm ( 1 ft ) crank throw and with the force applied at right angles the resulting torque would be, 3755.85 N-m . Using this amount of torque and the same rpm of 2500 rpm. The power generated would be : ( 3755.85 Nm x 6.28 x 2500rpm) 60000 = 982.780 Kw = 1318 hp ! Thus efficiency of the IC piston engine using these figures would be: (27.7/3755.85) x 100= 0.7 % approx. So the efficiency of the IC piston engine is illustrated here as being under 1% ! Unfortunately using a piston and crank combination it would not be possible to ever reach such a configuration, thus the kind of efficiency resulting from such an arrangement is unattainable. Or is it ???