Weight to Power Over A Curve

Power to weight ratios typically compare peak power over weight. This however does not paint the full picture, and we will explore this through comparison of the Honda S2000 and the ND MX-5. The static power to weight ratios are as follows: 

 

Honda S2000: 240hp/1250kg = 0.192 hp/kg 

 

Mazda ND MX-5: 160hp/1050kg = 0.152 hp/kg

 

Looking at the results it would be easy to conclude that the S2000 has more power for every kilogram it has to move. I looked for dyno comparisons of the two cars which were as close as possible and started plotting the graphs below. 

 

The top graph shows the horsepower curve, and the graph below that shows horsepower over weight. 

 

Through the data, we can conclude that the Mazda MX-5 has the advantage in power to weight ratio up till 6,800rpm, upon which the S2000 takes over. Weight impacts all areas of dynamic performance, including consumables wear, braking, and cornering. 

 

 

Other advantages that the ND MX-5 would have is better daily driving characteristics and better fuel economy.  As we can see, power to weight ratios when only measured at their peak can be misleading. 

 

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