At 11:34 -0400 16/07/2002, Joseph B. Reid wrote:
>I suspect that the French car manuals use the "cheval vapeur" or "CV". It
>is defined as 75 metre kilogram-force = 735.50 W = 0,986 32 horsepower.
Not really. In fact in most European countries car engines power is
given in two units: kW and "CV DIN", commonly called (in French)
"chevaux DIN". DIN stands for "Deutsches Institut f�r Normung" and is
the German Bureau of Standards who defined the CV DIN or HP DIN as
0.735 kW.
>There is, or was, also the "cheval vapeur fiscal" which seemed to bear no
>relation to CV.
There has been an "administrative power" in many countries, used as
a basis for taxes, and more or less related to actual power. For
instance in the early 19th century in UK, a car had an administrative
power equal to 0.1 liter of displacement (yes, it was metric!).
But true, France had developed very sophisticated formulas to
establish the "fiscal power", this one for example used until 1998:
P = m (0.0458 C/K)^1.48
where m = 1 for gas driven engines and 0.7 for diesel engines
C = displacement in cubic centimeters
K = average of speeds in km/h at 1000 rpm for the different
gear ratios (sorry, rpm, not Hz!)
One immediately sees how the formula was ridiculous: the sport
version of a model, with a 5 or 6-speed gear box, had a fiscal power
lower than the basic version with 3 or 4 speeds, and paid less taxes
and a lower insurance premium (which used to be based on the fiscal
power)!
The present formula is:
P = (CO2/45) + (P/40) where CO2 = CO2 emissions in g/km and P = power in kW.
Incidentally there is no longer any tax on cars (but the registration
tax, only once) and insurance premiums are based on actual power and
cost of the car.
Louis
