Watch A Tesla Model S Fool A Dyno Into Thinking It Has All The Torque

The Tesla Model S is a legit sports sedan. Smooth, fast, good looking, and fun to drive. It has the whole combination. But thanks to the lack of a transmission and how it puts power down, it can fool a dyno into thinking it has 2,000 pound feet of torque. Damn.

While the torque was wild, the horsepower was basically flat, showing that it has 436. Tesla says the P85 S has 415 horsepower, so the figure is close. Driveline loss appears to be basically non-existent.

Hat Tip to Brooks!

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DISCUSSION

I would not be willing to trust the torque number as the way these dynos produce a torque number is a mathematical algorithm based on the HP output and the engine RPM. These guys are using a tool known as an optical RPM sensor to grab RPMs off of the rear wheel. It is visible on the magnetic stand covering the center of their phone number on the trailer. This device is meant to be used on an engine crank pulley by placing a piece of reflective tape on a non-reflective crank pulley and counting the rotation. 1 rotation = 360 degrees.

The issue here is that the wheel is a 10 spoke wheel, and is reflective enough to make the optical eye think that each spoke is a rotation. The lowest degree of fire you can set in the dyno software is 90, or effectively, each time the eye triggers = 1/4 of a full rotation. Assuming that the wheel rotates at the exact same speed as the electric motor, this would mean that the RPS would still be off by 2.5 times (10 spokes /4 - 2.5).

Since torque is a calculation of RPM and Horsepower (the HP readings are taken by the acceleration rate of a known mass, the drum, and therefore can not be thrown off by erroneous RPMs), the Torque number is effectively increased by 2.5x while the HP number reads as normal. The dyno software is limited to 2000 hp / 2000 tq (software limitation only) and therefore an actual torque number can not be calculated.