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Calul putere este prezentat aici https://en.wikipedia.org/wiki/Horsepower.




Daca e sa ne ghidam dupa acelasi principiu in a determina valoarea unui CAL FORTA, vom considera ca un cal poate dezvolta o forta de tractiune de 735 N daca ridica o masa de 75 kg, pentru ca:

G=m*g

G - greutatea (care este o forta)
m - masa de 75 kg.
g - acceleratia gravitationala care depinde de altitudine. Vom lua o valoare de ~9.8 m/(s*s)

Daca luam exemplul unui motor turbo-diesel prezentat in filmul urmator


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caracterizat prin:

80kW(107 Cp) la 4000 rpm
si
240 Nm la 1750 rpm,

putem observa pe axa Y din stanga graficului(care este forta de tractiune in kN)

valoarea de 9.8 kN pentru anvelopele 195/65R15 si valoarea de 10.21 kN pentru anvelopele 195/65R14.

Astfel, vom imparti forta generata de motor+transmisie+roti la forta generata de un cal(animal) explicata anterior:

9800N / 735N = 13.33 CAI FORTA
102100N / 735N = 13.89 CAI FORTA

Analog se procedeaza la turatia puterii maxime.
Fortele nu sunt afisate concret pe grafic, dar cu un raport de 3.8 pentru treapta intai, 3.41 raport final si 190.99 Nm la 4000 rpm (folosind formula Cp=Nm*RPM/7021.55), rezulta 2472.84 Nm la roata. Diametrul rotilor fiind 634.5 mm si respectiv 609.1 mm se calculeaza forta de tractiune la fiecare roata si se imparte cu forta calului de 735N.


Concluzie:

O putere maxima de 107 Cp la 4000 rpm si un moment maxim de 240Nm la 1750 rpm echivaleaza cu:

- o forta maxima de 13.33 Cf la 1750 rpm si cu 10.61 Cf la 4000 rpm in treapta intai cu anvelope 195/65R15

- o forta maxima de 13.89 Cf la 1750 rpm si cu 11.05 Cf la 4000 rpm in treapta intai cu anvelope 195/65R14



Vedeti si Motor termic? Priviti momentul/cuplul! Puterea e irelevanta!

Cal Putere vs Cal Forta - puterea motoarelor termice induce in eroare de peste 200 de ani.




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As exposed here https://marius-ciclistu.ro/pdf/The%20power%E2%80%99s%20mislead%20in%20thermal%20engine%E2%80%99s%20regard.pdf
Power is force multiplied by speed measured in:
W = N * m/s
According to James Watt's reasoning, the horse force is 735 N.

The power is 735N * 1m/1s = 735 W (735.5 according to James Watt, the difference is due to the gravitational acceleration 9.8 m/s*s that depends on elevation).

Then for example 100 horsepower means 100 * 735W = 73500 W that means 73500N * 1m/1s.

When talking about thermal engines, 100HP are reached at lets say 6000 RPM that is equal to 100 rotations per second.
At this rotational speed the engine is producing 117 Nm at the flywheel.
If the flywheel has 1 cm circumference, then in one second it will turn 100 times so the distance that a point on it's circumference does is 100 cm (1 meter).
Now let's calculate the force at the flywheel's circumference:
Circumference is 1cm = Diameter * 3.1415
=>
Flywheel Diameter = 1/3.1415 = 0.318319274 cm

117Nm = 117N*100cm = 11700Ncm

1 cm arm.... has.... a force of 11700 N
0.318319274 cm arm .... has....a force X N
----------------------------------------------------------
X = 11700 * 0.318319274 / 1 = 3724.3355 N

So this is the force that the thermal engine is producing at 100 horsepower at the flywheel in one seccond and one meter.

But wait. 100 horses are generating 73500N in one second and one meter. Where are the rest of over 69775 N ?

The power being energy over time (Watts = Joules / second), 100 Horsepower are equivalent with 73550 W that are equal to 73550 J/s.

In conclusion:
73550 Joules are transformed in 1 second over 1 meter to generate:
* 73500 N by 100 horses
and
* 3724 N by a thermal engine at 6000 rpm and 100HP.