Irvrobinson

Irvrobinson

Audioholic Spartan
EV production specs vs planned specs usually never follow through completely. The fact that GM is using crank torque figures is pretty laughable as it is - NO ONE uses that figure, otherwise a Ram 3500 has 35,000 tq.
Now you're starting to annoy me. You really have no idea what you're talking about, do you?

GM is not using a crankshaft figure for torque because electric cars don't have a crankshaft. A crankshaft is used in an internal combustion engine to drive the pistons via the torque arms. Also, EVs don't have transmissions, they are direct drive, so except for driveline losses there is no difference between the torque at the electric motor shaft and the torque fed into the differential, as in ICE cars. In the Hummer GM is using front and rear differentials, the motors will drive the differentials directly, but there will be losses in such big heavy gearing and their lubrication fluid, and additional losses in the drive shafts to each wheel, not to mention the losses from the rotating weight of the wheels and tires.

As for "NO ONE" using crankshaft horsepower and torque for ICE vehicles... WTF are you talking about? Every manufacturer rates their vehicles that way.

I'm glad you brought up Telas. As you can see in your own post, they weigh as much as a F150/etc etc, but can accelerate no LESS that 5.6 seconds to 60 (every model can be optioned up to hit the 3 second range). By your logic, we'd have dead bodies all over the road because they can A.) Accelerate extremely fast, and B.) are heavy vehicles. Thing is, we don't, and it's not like Telas isn't selling, they're creaming the luxury market right now hand over fits compared to their peers. The reason for it is that when people get behind the wheel of cars like this, they stop and think for a second before mashing the go pedal. It's not about how easy it is to physically stomp a gas pedal, it's the fact that when it's sub 3 seconds, you will almost always let off or wait for a gap.
Teslas don't weigh 7000lbs. The heaviest Teslas, the Model X, weighs about 5500lbs. F=MA. And only a small percentage of their production are the Performance models with the 100kWh batteries and the bigger motors. And any Tesla is going to handle a lot better than this massive, truck-chassis Hummer.

I'm done with you.
 
William Lemmerhirt

William Lemmerhirt

Audioholic Spartan
Now you're starting to annoy me. You really have no idea what you're talking about, do you?

GM is not using a crankshaft figure for torque because electric cars don't have a crankshaft. A crankshaft is used in an internal combustion engine to drive the pistons via the torque arms. Also, EVs don't have transmissions, they are direct drive, so except for driveline losses there is no difference between the torque at the electric motor shaft and the torque fed into the differential, as in ICE cars. In the Hummer GM is using front and rear differentials, the motors will drive the differentials directly, but there will be losses in such big heavy gearing and their lubrication fluid, and additional losses in the drive shafts to each wheel, not to mention the losses from the rotating weight of the wheels and tires.

As for "NO ONE" using crankshaft horsepower and torque for ICE vehicles... WTF are you talking about? Every manufacturer rates their vehicles that way.



Teslas don't weigh 7000lbs. The heaviest Teslas, the Model X, weighs about 5500lbs. F=MA. And only a small percentage of their production are the Performance models with the 100kWh batteries and the bigger motors. And any Tesla is going to handle a lot better than this massive, truck-chassis Hummer.

I'm done with you.
Hey Irv. I have no dog in this but just wanted add or question something here. If I’m not mistaken, the crankshaft is actually driven by the pistons and connecting rods. Not the other way around. When the intake charge is fired the pressure pushes down against the crank and the power is delivered through the transmission and to the wheels.

Also, iirc, in the 70’s, they stopped measuring crank horsepower and started using wheel horsepower or brake horsepower because all the 60’s power numbers were taken with all the accessories off the engine, and measured at the flywheel. Measuring at the wheels levels the field since the parasitic loss is already accounted for. Maybe I need a history lesson?
 
Irvrobinson

Irvrobinson

Audioholic Spartan
Hey Irv. I have no dog in this but just wanted add or question something here. If I’m not mistaken, the crankshaft is actually driven by the pistons and connecting rods. Not the other way around. When the intake charge is fired the pressure pushes down against the crank and the power is delivered through the transmission and to the wheels.
You are correct, of course. Poor wording on my part.

Also, iirc, in the 70’s, they stopped measuring crank horsepower and started using wheel horsepower or brake horsepower because all the 60’s power numbers were taken with all the accessories off the engine, and measured at the flywheel. Measuring at the wheels levels the field since the parasitic loss is already accounted for. Maybe I need a history lesson?
The latest standard for measuring horsepower is SAE J1349 Certified Power, which is a crankshaft horsepower standard. There are so many links that describe this, but here's a non-technical one:

SAE_net_horsepower

 

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