Power To Weight Ratios

Power To Weight Ratios

     While many places online divide the power by the weight, in the 1960s at least one auto manufacturer used an internal standard of 1 horse to 10 pounds, so the more relatable ratio is actually weight to power.

     The problem with historic vehicles and the original advertised horsepower is that the Ford 292 engine with a two barrel carb was quoted as 93 HP in 1955, then in 1956 as 200 HP with the exact same carb. This was the year that auto manufacturers started using gross horsepower as a marketing ploy and no longer cared about the truth. Gross horsepower is measured with the engine out of the car, up on a test stand, with no accessories attached. 

     Sometimes manufacturers would increase the quoted horsepower, or decrease the horsepower, or for arbitrary reasons make it match up to the weight of the vehicle. So the exact same engine would be quoted as 360 horsepower if the vehicle weighed 3,600 lb but if placed into a 3,300 lb vehicle would be quoted as 325 horsepower, maintaining a 1 horse to 10 lb ratio.

     From 1956 through 1972 horsepower quotations were all made up, used purely for marketing ploys, to slip a more powerful engine into a race, or to avoid scrutiny from regulators concerned about larger engines in sports cars. In addition, just to make them appear more powerful, Americans used the gross horsepower numbers in marketing ads from 1956 -1971. 

     By 1972 all U.S. cars were listed with their net horsepower, meaning installed in the car with the water pump and all other accessories attached. The difference is about 25% to 33% lower actual horsepower, so the Ford Torino with the V8 302 is listed as having 210 HP in 1971 but only 140 HP in 1972, and the Plymouth Duster with the Slant-6 225 is listed as having 145 HP in 1970 but only 110 HP in 1972. The weight to power ratios for the 1972 2 door hardtop 302 Torino is 3,616/140 = 25.83 and for the 1972 Duster 225 it is 2,866/110 = 26.05, and the 1972 base Ford Torino 302 is quoted as having a 0-60 of 10.9 seconds while the 1972 Plymouth Duster 225 is quoted as having a 0-60 of 11.5 seconds, neither of which is considered fast now.

     Examples of Ford Power To Weight ratios over more than 100 years: The 1908 Ford Model T was 80 pounds per horse. The 1932 Ford Model 18 was 35 pounds per horse. The 1955 Ford with a 292 V8 was 35 pounds per horse. The 1972 base 302 V8 Ford Torino was 25 pounds per horse. The 2015 Ford F-150 Platinum was 18 pounds per horse. And the 2023 Ford Mustang GT V8 is 8.5 pounds per horse. As long as you can transfer the power to the ground without spinning your tires the lower the power to weight ratio the faster the 0-60 time.