POWER-TO-WEIGHT RATIO

'Power-to-Weight ratio' (Specific Power) is a calculation commonly 'applied to' ''engines and other mobile power plants'' to enable the comparison of one unit (design) to another. Power-to-Weight ratio is a measurement of actual performance of any engine (power plant).
The Power-to-Weight ratio (Specific Power) formula for an engine (power plant) is:

POWER generated by the engine, divided by, WEIGHT of the engine as follows:
:$$
egin{matrix}
mbox{P-to-W}&= P/W \
end{matrix}

English system ''units of measure'' are usually horsepower per pound ('hp/lb')

Metric system ''units of measure'' are usually horsepower per kilogram ('hp/kg')

The use of Watts, or kw (kilowatts), instead of horsepower is common (Conversion: 745.7 watts/hp).
Because this is a ratio, the denominator is always singular (1 lb or 1 kg) as in the following example:

250 hp (engine power) / 1,000 lb (engine weight) = 0.25 hp/lb (turbocharged V-8 diesel engine) Specific Power

70,000 hp (turbine power) / 700 lb (turbine weight) = 100 hp/lb (Space Shuttle) Specific Power

Note: When looking at Power to Weight ratio (Specific Power), 'larger' is better.
' Weight-to-Power ratio' (Power Loading) is a calculation commonly 'applied to' ''aircraft, cars, and vehicles in general,'' to enable the comparison of one vehicle performance to another. Weight-to-Power ratio is a measurement of the acceleration capability (potential) of any land vehicle or climb performance of any aircraft or space vehicle).
The Weight-to-Power ratio (Power Loading) formula for a vehicle is:

WEIGHT of the vehicle, divided by, POWER generated by the engine as follows:
:$$
egin{matrix}
mbox{W-to-P}&= W/P \
end{matrix}

English system ''units of measure'' are usually pounds per horsepower ('lb/hp')

Metric system ''units of measure'' are usually kilograms per horsepower ('kg/hp')

The use of Watts, or kw (kilowatts), instead of horsepower is common (Conversion: 745.7 watts/hp).
Because this is a ratio, the denominator is always singular (1 hp or 1 kw) as in the following example:

3,122 lbs (automobile weight) / 145 hp (V6 (cyl) engine power) = 21.5 lbs/hp (2007 Chevy Malibu Is, 5 seats) Power Loading

2,450 lbs ( aircraft weight ) / 160 hp (H4 (cyl) engine power) = 15.3 lbs/hp (9.25 kg/kW) (Cessna 172 airplane, 4 seats) Power Loading

Note: When looking at Weight-to-Power ratio (Power Loading), 'smaller' is better.

Contents

See also

External Links

See also

★ Vehicle metrics

External Links

★ Weight to Power ratio of current automobiles.