Electric cars

What is instantaneous torque and how does it work in electric cars?

To say that electric vehicles are surprisingly fast is an understatement. Models like the Tesla Model S Plaid can easily accelerate from 0-60 in less than 2 seconds under the right circumstances. This puts them in league with some of the most expensive and powerful supercars. However, the driving force behind the incredibly fast acceleration of electric cars is instantaneous torque, something gasoline-powered supercars lack.

But what is instantaneous torque, how does it work, and why do electric cars have it when their gas-powered counterparts don’t. Answering these questions would be tricky without first explaining what torque is, how it is measured, and why it is essential in cars.

What is torque

Tesla Model S | Getty Images

A simple explanation for torque is that it is a torsion force. You may see examples of torque in everyday life, such as when opening a door or tightening bolts. In these examples, you apply a twisting force to either the door handle or the bolt using a key.

Torque is measured in pound-feet (lb-ft), and in an engine, the twisting force or torque is needed to turn the crankshaft continuously. Torque is then transferred to the vehicle’s wheels, allowing them to handle tough jobs like climbing a hill, tackling rough terrain and towing trailers.

It is even needed to propel the vehicle forward from a standstill. It’s no surprise, then, that the Rimac Nevera, an EV with 1,741 lb-ft of torque according to MotorTrend, also has one of the fastest acceleration rates on the market. Rimac claims the electric hypercar can go from 0-60 in 1.85 seconds.

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How maximum torque is achieved in gasoline cars compared to electric cars with instant torque

With gasoline-powered cars, the maximum twisting force or maximum torque can only be achieved at certain engine speeds, which differ from model to model. For example, the maximum torque of the 2022 Dodge Charger SRT Hellcat Redeye Widebody is 797 lb-ft at 6300 rpm.

For context, engine revolutions per minute (RPM) measures how fast the engine is running at any given time.

It should be noted that the torque will increase or decrease if the car is not at the designated engine speed. Also, if your vehicle starts at low rpm, it takes some time to reach the engine speed required for maximum torque.

Conversely, the maximum torque in electric vehicles is reached the moment you step on the accelerator, hence instantaneous torque. According to Car Throttle, this is mainly due to the fact that there is little or no back electromotive force (EMF) in the electric motor powering the wheels of the car.

Back EMF is a back EMF that increases in an electric motor as it rotates rapidly. Unfortunately, the back EMF also reduces the operating voltage of the car, which in turn reduces the power reaching the wheels of the car. The operating voltage is usually the result of the supply voltage minus the back EMF.

To put this into perspective, if you are supplying 120V of power to a motor and the back EMF is 90V, you only have an operating voltage of 30V. Conversely, if the motor is not spinning, there is no back EMF, which means the full 120V power can be used to create torque.

Since electric motors barely spin before you start driving, there’s little to no back EMF, and as a result electric vehicles always seem to be faster off-line. However, the motors rev faster once you’re driving; therefore, the back EMF is bound to build up.

This creates problems at the top end, so electric cars have trouble accelerating past a certain point, like around 150 mph and above.

Other reasons why electric cars are so quick to start

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There are also other reasons why EVs like the Lucid Air Dream Edition can beat powerhouses like the McLaren Senna to the 1/4 mile mark in a drag race. One is the positioning of the motors, with most EV manufacturers placing them on both the front and rear wheels. The result is extra traction, which means minimal or no wheel spin once you step on the throttle.

Additionally, EVs feature only one gear compared to the multi-speed gearbox of gasoline-powered cars. Therefore, you don’t have to wait for a multiple-speed downshift before engine power can be sent to the wheels. This makes cars more responsive to the throttle.

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