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I'm interested to know how much kilograms force an average car can produce. I made the following calculations to answer my question but I'm not sure if I'm right or wrong!

Imagine we have a 1.8L engine that can produce a max torque of 155 nm @ 4250 RPM.

1st gear ratio = 3.455 Final drive ratio = 4.529 Tire size = 185/65R14 (Rolling Tire Radius = 0.289 meters) It is a FWD car so we have a drivetrain loss of around 10%.

I calculated the acceleration force as follows:

Wheel torque = 155 x 3.455 x 4.529 = 2425 nm Assuming 10% drivetrain loss, we will end up with 2183 nm of torque at the wheels.

Now, to calculate acceleration force, I divided 2183 by tire radius (0.289):

2183 / 0.289 = 7553 newtons of acceleration force.

Finally, to convert newton to kilograms force:

7553 / 9.8066 = 770 kgf

Does it mean that this car can lift 770 kg of weight if its engine and transmission are used as an industrial elevator?

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  • $\begingroup$ Wait... how are you applying gear ratios to torque? Torque should be pretty much constant (with the exception of slight inefficiency). Am I having a brain fart? $\endgroup$
    – Farris
    Mar 2, 2022 at 15:06
  • $\begingroup$ Assuming no inefficiency, I think you would just take the 155Nm max torque and divide that by the radius of the tire to get force. So 536.33 Newtons. $\endgroup$
    – Farris
    Mar 2, 2022 at 15:09
  • $\begingroup$ @Farris - I'm talking about the engine and transmission (gears and differential) as an integrated unit. Therefore, the maximum torque is much higher than 155 nm. $\endgroup$ Mar 2, 2022 at 16:15
  • $\begingroup$ kilogram is mass, not force. Please edit. $\endgroup$ Mar 2, 2022 at 16:35
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    $\begingroup$ Well, the torque-to-force is ok, but in physical space the drive train is not designed to handle longitudinal loads. So at the least you might want to keep the car horizontal, pin one wheel so it can't move (or lock the differential), and use the other wheel to drive the elevator mechanism. $\endgroup$ Mar 2, 2022 at 16:37

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I did not check your arithmetic but it looks right.

One can get any amount of torque or if you will, drag force on the tires, by changing the gears or in case of tire even using a smaller set of tires.

But if you are interested in performance of the car with original set of tires and do not use any modifications to the gears thats the way to go.

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