If it\’s got an engine. . .

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Archive for the ‘Efficiency’ Category

Maximum Efficiency

Posted by ifitsgotanengine on September 12, 2006


It seems to me that the best engine from an efficiency standpoint is a single-cylinder engine. Practical experience bears this out – my Suzuki Savage 650 (single cylinder) got 70 mpg, while my Yamaha Maxim 650 (four cylinder) gets 48. Less moving parts mean less friction. less friction means more of the energy in that gallon of gas goes to moving the car down the road.

Less moving parts also means less parts to break.

Why do we not see three-liter singles in family sedans? Or five-liter singles in sports cars?

If you know anything about engines, you already know the answer to this. A large single-cylinder engine would vibrate so badly that it would shake the car apart.

What I propose is a hybrid single-cylinder engine. Couple a large single-cylinder engine up to an electric motor/generator. The electronics controlling the motor/generator would have to be fast enough to switch from motoring to generating every other engine revolution.

When the engine is on its power stroke, the motor/generator is acting as a generator, charging a capacitor (think really fast battery). On the other three strokes, the motor/generator is acting as a motor, since the engine isn’t doing anything productive.

The hybrid motor/generator isn’t there to improve efficiency through regenerative braking, as in other hybrids, it’s just there to smooth out the big single’s power pulses, allowing it to be used in civilized transportation.

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Posted in Efficiency, Engineering | 4 Comments »