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Compared to electric motors, internal combustion engines provide relatively little torque, over a relatively narrow range of RPM. An typical electric motor can

by retrac 4y ago

Compared to electric motors, internal combustion engines provide relatively little torque, over a relatively narrow range of RPM. An typical electric motor can apply its maximum torque, constantly, from zero RPM to its normal RPM. A gas engine just cannot do that. At low RPM it has little torque and power. At high RPM, you can't really transfer that full power with a transmission in the lowest gear, because now it's too much torque. (Stripped gears and/or snapped belts were pretty common before computer-controlled automatic transmissions.) This (idealized) chart may help explain: https://www.researchgate.net/profile/Ronghui-Zhang-2/publication/317051708/figure/fig4/AS:668720569540618@1536446816440/Torque-speed-characteristics-of-electric-motors-and-internal-combustion-engines.png https://www.researchgate.net/profile/Ronghui-Zhang-2/publica...

Isamu 4y ago
Right, electric motors can develop max torque at zero rpm (and with no shifter), this is similar to steam engines. That’s why many diesel locomotives are actually diesel-electric, with a diesel power plant generating electricity for motors driving the wheels.
- deleted 4y ago
  [deleted]
emmelaich 4y ago
Possibly a faster 0-100 would be achieved with an ICE (nitro) driving electric motors.
IgorPartola 4y ago
That chart is… not right. Torque for a vehicle is measured at the crankshaft, before the transmission. For an electric motor it is a flat horizontal line. For an ICE it is almost flat in its power band but rises from much lower before it reaches it. The rest of what you are saying isn’t wrong but that’s a bad chart.
- fdewrewrewf 4y ago
  >For an electric motor it is a flat horizontal line. That's....wrong (or at least, not necessarily true). The torque curve for an electric motor is strongly dependent on the technology used. Induction motor (as used by Tesla): https://en.wikipedia.org/wiki/Induction_motor#/media/File:Torque_electric_motor_AC.svg https://en.wikipedia.org/wiki/Induction_motor#/media/File:To...
fho 4y ago
There is an additional caveat: if you search for "electric motor efficiency map" you will find graphs that show that at low power (rpm x torque) electric motors have low(-ish) efficiency. If I get this right it means you still have an area of rpm x torque where you want your electric motor to be for peak efficiency.
- fdewrewrewf 4y ago
  It's very true. The most efficient speed of a car is the point where the increasing engine + drivetrain gearing efficiency meets wind resistance, and is typically 10-15mph higher for ICE cars.

by retrac 4y ago

Isamu 4y ago

Right, electric motors can develop max torque at zero rpm (and with no shifter), this is similar to steam engines. That’s why many diesel locomotives are actually diesel-electric, with a diesel power plant generating electricity for motors driving the wheels.

deleted 4y ago
[deleted]

emmelaich 4y ago

Possibly a faster 0-100 would be achieved with an ICE (nitro) driving electric motors.

IgorPartola 4y ago

That chart is… not right. Torque for a vehicle is measured at the crankshaft, before the transmission. For an electric motor it is a flat horizontal line. For an ICE it is almost flat in its power band but rises from much lower before it reaches it. The rest of what you are saying isn’t wrong but that’s a bad chart.

fdewrewrewf 4y ago
>For an electric motor it is a flat horizontal line. That's....wrong (or at least, not necessarily true). The torque curve for an electric motor is strongly dependent on the technology used. Induction motor (as used by Tesla): https://en.wikipedia.org/wiki/Induction_motor#/media/File:Torque_electric_motor_AC.svg https://en.wikipedia.org/wiki/Induction_motor#/media/File:To...

fho 4y ago

There is an additional caveat: if you search for "electric motor efficiency map" you will find graphs that show that at low power (rpm x torque) electric motors have low(-ish) efficiency. If I get this right it means you still have an area of rpm x torque where you want your electric motor to be for peak efficiency.

fdewrewrewf 4y ago
It's very true. The most efficient speed of a car is the point where the increasing engine + drivetrain gearing efficiency meets wind resistance, and is typically 10-15mph higher for ICE cars.