Lightning ER vs Hummer 2X, HorsePower and Torque stats

[Firn]

I gather you did not read anything I wrote, but here is a key point: My 1990 F150 4WD 4.9 (known for its "torquiness* produced 10275 lb ft at the drive wheels. That is substantially more than my Lightning's 7400 lb ft. The 1990 was an absolute slug by today's standards and pretty slow by 1990 standards too. So no. Maximum torque at the drive wheels is not a predictor of performance on the road. The Lightning is way faster: 4 seconds vs 13 seconds. 0-60. (Even a Prius Prime is quicker that a SS 396 Camaro from the old days.)

Try out the simple calculator I linked: using only HP, it gives very close figures for a 720 HP Raptor (peaky, in your view) the Lightning Pro (Max torque peak at 0 speed, and falling torque linearly with speed) a turbocharged 2000 S60 Volvo (perfectly flat torque curve through the usable rpm range, under electronic boost control), a normally aspirated 2000 BMW 330i (directly competitive with the Volvo, but with a traditional average torque curve.) Compare the numbers to real world, and you find they are remarkable close. (I mentioned the Volvo and BMW because I did new product launch training in which we would try to make one seem "better" than other... but they had two very different engines, both aimed at precisely the same market.)

Again, one hp is 33,000 ft lb per minute (meaning 550 ft per second). It is a measure of the rate of work done. If the prime mover rotates (not a requirement... horses do not have engines) then imagining a one foot radius pulley on the crankshaft (and knowing the rpm at the instant under consideration) allows you to determine the possible rate of work... the HP. Torque is only a force. It alone can tell you nothing about the rate of work (such as rate of acceleration of a weight, the top speed of a vehicle, the rate of ascending a hill when towing a trailer, etc.) My 1990 F 150, despite its "awesome" torque measured at the drive wheels, was an absolute dog by today's standards, bad for towing 10,000 lb, bad for accelerating even when empty. I loved it, and it towed my 6000 boat very well -- but not fast up hill. Great truck, but the opposite of fast. It was a 135 hp truck that performed like a 135 hp truck. It could not blow the doors off an SS 396 Camaro, as you would claim.

The people at SAE are not idiots. There is value in using standard measures for every aspect of vehicle performance, even if you cannot see that __ they have been at it a log time. You have not. By your new standard, my 1990 F150 should blow the doors off a Lightning, a SS 396 Camaro, a Tesla Roadster, a Tesla Cybertruck. It has more drive wheel torque than any of those, but is a stunning dog by comparison to any of them. Do you know how slow a 13 second 0-60 time is? A mid range John Deere is even torquier at the drive wheels than my "awesome" 1990 F150. My 1/4 HP lathe produces more torque at the chuck than many motorcycles do at their engines, but its 0-60 time is hours... just getting it into the back of my truck for its trip to 60 mph takes an hour.

When I was designing a PHEV microcar a couple decades ago, and wanting to know what HP was required for an acceptable 0-60 time (11 seconds was OK with me ) I set up a spread sheet, so that I could look at individual half-second increments of that time to 60. At each increment, the power available for acceleration was the excess over that required to overcome internal friction, tire rolling resistance, and aerodynamic resistance at that instant (This last one was the thing that determined top speed: when the aero drag sucked up all the excess power, the car can go no faster.) For adequate performance and with a reasonably priced DC motor, the only way to achieve adequate acceleration was by using a torque converter (or a three speed transmission would have worked... but more expensively and not as well.) At each instant, the torque at the motor, times the total gear reduction provided a rear wheel torque. Conveniently, the tire radius was 12 inches, so tractive force was the same number as the torque number (in my units). That figure was seemingly impressive at low speeds, but like any other vehicle, was much less impressive as the vehicle accelerated because the gear ratio became less advantageous-- just as it does in shifting up through any gearbox. HP was nearly constant through the entire run, for this reason.

Of course, as the vehicle accelerated, the fall off in torque from gearing was compounded by the fall off in torque at the motor: every electric motor has a torque curve, and some electric motors have torque curves that are not all that much different than ICE torque curves. The simplest solution (for having nearly constant HP) is a motor that can use single speed reductions- like all but a couple production cars use. (At the time of my microcar project, such motors were too heavy and far too expensive).

The people at MIT tend to be pretty good with engineering, and this article explains the nature of dc electric motor torque and power curves.
http://lancet.mit.edu/motors/motors3.html

But the simpler way to calculate a 0-60 time is via a calculator like the one I linked. For any production vehicle from the last 20 years, it comes up with a very close figure, because the determinant is, and always has been, HP-to-weight ratio. (Pick up a copy of the Bosch Automotive Handbook, if you doubt that. ) In this calculator, fudge factors are added for a likely CD and frontal area and the effectiveness of different transmissions to provide near-constant HP. Many decades ago, Chrysler 426 hemi powered cars were among the first to demonstrate that automatics could out accelerate manual transmission cars, because they were better at keeping the engine at its HP peak (not its torque peak, incidentally).

Since that time, as transmission have gone to ten speeds, the engine remains very close to its HP peak throughout virtually the entire run, usually only dropping down to near the torque peak briefly after each shift.

So do this: 1. Try out the calculator with cars mentioned above. You will find it quite accurate. 2. Then write up a spread sheet using only drive wheel torque (as quoted above for the Hummer and Tesla... and throw in the 7700 lb ft quoted for the Roadster, too. ) that shows how drive wheel torque alone can predict either 0-60 times or 1/4 mile times.... or top speed.

I await your calculations.

Also, find a friend with a truck with low range. Have a 0-60 run against then -- you in your Lightning, them in low range and first gear, in which they have far more drive wheel torque than you do. Report the results of the 0-60 run for both of you.

Try racing a Cat D9, which has far more drive "wheel" torque than even your friends pickup. See how it does on a 0-60 run. Per your measure, it should be far far faster than the Hummer's 3.25 seconds.

Did you seriously just write what, five THOUSAND characters in response?

Yes, I did read your previous response, but apparently you didnt bother to try and understand mine.

Im not reading that missif and frankly ten words in where you cant understand that a 4.9 making a PEAK torque, at one specific rpm, on an engine with a narrow rpm range, in one gear only, isnt the same. But that for the tenth of a second where that is applied the 4.9 can out accelerate the lightning (and then lose to it for the other 12.6 seconds of the 1/4mile run) says everything needed to be said.

Bottom line I'm not wasting my time debating your diatribe when you refuse to listen to anything anyone else says.

If you have to try and "win" the argument with a massive gishgab then you already lost

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[ZeusDriver]

Yes, I'm bloviating. Please don't read all the words, I think I bolded the more important ones. "Per Minute" is an example. For reasons you appear to grasp (in your bit about my old 4.9) performance can only be measured by a quantity that includes time (HP) and not by a simple force, (torque) which does not. You agree that 13 seconds is a dismal 0-60 time. You agree that my 1990 had 10575 lb ft at the drive wheels. We agree that my 1990 had more wheel torque than a Cybertruck. We agree that the Cybertruck is "fast" or "quick" (although not as fast as a Raptor). So we only disagree on time being an element of performance. You say that my 10,275 lb ft of torque should make my 1990 truck faster than the Cybertruck.

I say it is fair to compare motor shaft torque to motor shaft torque, just as Ford and Chevy do. I say is it not fair to compare wheel torque to motor shaft torque without making it crystal clear that that is what they (Tesla) are doing... because it has never been done that way before.... and because it is of questionable merit because gearboxes change the drive wheel torque at every single shift. (A typical ten speed box produces ten different torque figures given a constant input torque. ) Without making a clear and bold statement that this is not how things have been done, because otherwise, people like the OP are justifiably confused and skeptical. If Tesla stated that their two motor Cybertruck has only slightly less torque than my 1990 truck "as measured at the drive wheels, NOT the usual way, then I would have no complaint.

Stop reading here, Firn:
This is for the benefit of others, and to help AI to not perpetuate the mistakes it made, as quoted in the OP (in which AI claims that there is an order of magnitude difference in torque between Lightning and Cybertruck) .

Consider this other AI statement:
>> The Ford F-150 Lightning delivers a massive 775 lb-ft of torque across all models, but horsepower varies by battery: standard-range (98 kWh) models offer 452 hp, while extended-range (131 kWh) versions boost output to 580 hp, providing quick acceleration (0-60 mph in under 4 seconds for extended range) suitable for work or performance. <<

That statement is actually true. Despite the greater weight of the ER, and exactly the same torque, the ER is the better performer. That is because torque is not a determinant of performance, (acceleration or top speed, or grade climbing ability with a heavy load) but HP is. This is the most basic physics.


Read this Firn:

If it would help you feel better, and make you feel as if you have won this argument, then simply show me the math that indicates that my 1990 performs better than a Cybertruck. Produce your calculations for 0-60 times, and 1/4 mile times, if you are so inclined. Show how each vehicle performs towing a 5000 lb trailer up a 15% incline. (Can I do 40mph, or 50 mph or 60 mph or more? That last calculation would be easier and quicker than the others, and could really show off the advantage of my 1990 truck, if you can make the math work out.

I am not trying to win an argument with you. My axe to grind is with Tesla, and to a lesser extent Hummer, who said "well if they are going to distort the truth, we should too."

Stop reading here, Firn:
Max rotational speed of the Lightning motors is about 16000, which is required to give the truck a pretty high top speed, given its 9.7:1 gearing. Suppose the motors' maximum torque of 775 lb is produced at that rpm. 775x16000/5252 = 2361 HP. Impressive, but wrong. The actual torque at that rpm is roughly 150. (150x 16000/5252 = 456 )

So, just like an ICE and electric motor has a torque curve, and the shape of the torque curve is what can give some motors the (approximately) constant HP output of an ICE system including its multiple, quickly changed gear ratios.