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Electric Hummer Performance Specs

1842 Views 5 Replies 4 Participants Last post by Tom E-Tron, Oct 23, 2020

JimsH3

Discussion Starter · Jan 30, 2020

GM has given us a small taste about home much power the electric Hummer is going to have.

According to their press release, it will have:

1,000 horsepower
11,500 lb/ft of torque
0-97 km/h (0-60 mph) in 3 seconds

Based on these numbers this Hummer is going to come with MASSIVE batteries and is going to be very heavy. It also leads me to believe that it's going to have at least a dual-motor setup, but hopefully it'll have a quad-motor one.

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Oakwood

· #2 · Jan 31, 2020

1,000 horsepower and 11,500 lb/ft torque is just absurd to me. Do you think that torque number is what we'll actually get at the wheels??

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JimsH3

Discussion Starter · #3 · Jan 31, 2020

Oakwood said:
1,000 horsepower and 11,500 lb/ft torque is just absurd to me. Do you think that torque number is what we'll actually get at the wheels??

Automobile Magazine gives an interesting breakdown trying to unpack that 11,500 lb/ft torque number. They believe that the Hummer will have a 4 motor setup with 250 horsepower at each wheel. For torque they say it's how it's delivered, so each engine could either have 2,875 lb-ft if they were direct drive or 295 lb-ft if they use the same 9.73:1 reduction ratio Tesla uses in the Model S.

Now, let's unpack the whole 1,000 horsepower and 11,500-lb-ft torque ratings. Those are new, and both seem really huge, right? A number as high as that lb-ft figure is bound to represent torque applied at all four tires. Since the industry doesn't typically quote torque figures that have been multiplied through any transmission and axle gearing (i.e., for engines, we quote torque from the engine, before it is multiplied by, say, a torque converter), we figure that GMC's Hummer will fit four electric motors, one per wheel, with each rated for 250 horsepower. As for each motor's torque, that figure depends on how it's delivered to each wheel. If the motors were direct-drive in-wheel hub units, that'd mean each one would produce a whopping 2,875 lb-ft; if each motor were instead mounted inboard and spun a half-shaft axle through the same 9.73:1 reduction ratio Tesla uses in the dual-motor Model S (as an example), the torque rating would be a much more "normal" sounding 295 lb-ft per motor.

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Len

· #4 · Oct 23, 2020

JimsH3 said:
Automobile Magazine gives an interesting breakdown trying to unpack that 11,500 lb/ft torque number. They believe that the Hummer will have a 4 motor setup with 250 horsepower at each wheel. For torque they say it's how it's delivered, so each engine could either have 2,875 lb-ft if they were direct drive or 295 lb-ft if they use the same 9.73:1 reduction ratio Tesla uses in the Model S.

Now, let's unpack the whole 1,000 horsepower and 11,500-lb-ft torque ratings. Those are new, and both seem really huge, right? A number as high as that lb-ft figure is bound to represent torque applied at all four tires. Since the industry doesn't typically quote torque figures that have been multiplied through any transmission and axle gearing (i.e., for engines, we quote torque from the engine, before it is multiplied by, say, a torque converter), we figure that GMC's Hummer will fit four electric motors, one per wheel, with each rated for 250 horsepower. As for each motor's torque, that figure depends on how it's delivered to each wheel. If the motors were direct-drive in-wheel hub units, that'd mean each one would produce a whopping 2,875 lb-ft; if each motor were instead mounted inboard and spun a half-shaft axle through the same 9.73:1 reduction ratio Tesla uses in the dual-motor Model S (as an example), the torque rating would be a much more "normal" sounding 295 lb-ft per motor.

Have you considered how many electric watts are involved? One HP is equal to 745.7 watts. 1000 HP means 745700 is supposedly being utilized. Taking into consideration the IR losses and heat generated and that no electric motor or system runs at 100% efficiency, then more than 745700 watts is actually required to attain a mechanical 1000HP. Sounds like a bunch of hype to me.

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Oakwood

· #5 · Oct 23, 2020

Len said:
Have you considered how many electric watts are involved? One HP is equal to 745.7 watts. 1000 HP means 745700 is supposedly being utilized. Taking into consideration the IR losses and heat generated and that no electric motor or system runs at 100% efficiency, then more than 745700 watts is actually required to attain a mechanical 1000HP. Sounds like a bunch of hype to me.

Welcome to the forum @Len! We'll have to wait and see once people start actually testing the Hummer's power but I don't think they'll be far off from 1000 hp for the three motor Edition One.

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Tom E-Tron

· #6 · Oct 23, 2020

Len said:
Have you considered how many electric watts are involved? One HP is equal to 745.7 watts. 1000 HP means 745700 is supposedly being utilized. Taking into consideration the IR losses and heat generated and that no electric motor or system runs at 100% efficiency, then more than 745700 watts is actually required to attain a mechanical 1000HP. Sounds like a bunch of hype to me.

There are a few ways to look at this,

Are you disputing the motors are 250 kW ea? I am attaching a photo taken at GM's drive unit test facility, clearly these motors have been run on the dyno, so GM knows the output capability.

Or do you dispute that the battery can discharge at that rate? So the Hummer EV has a 200 kWh battery, so discharging at 750 kW, would be a 3.75c discharge rate which is fully within reason for short bursts.

for reference Tesla Model Y Performance outputs 336 kW from a 75 kWh battery for a 4.5c discharge rate. So as you can see the Model Y makes the case that there is no issue with the discharge rate.

Another interesting thing I saw in the Hummer demonstration is engaging the WTF mode, seems to take some amount of time, are they charging a capacitor for a power boost during this time? Possible, and would lessen the strain on the battery.

I do not think GM is going to BS about the output as they know customers are going to take these right down to their neighborhood chassis dyno, and likely break the dyno..

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