Separate names with a comma.
Discussion in 'Model S: Driving Dynamics' started by fiksegts, Feb 20, 2017.
Tesla Model S P100D Ludicrous Plus Testing on a Mustang Dyno
920 ft. lbs of torque
... on the 9th full power run.
Congrats Tesla engineering team for an INCREDIBLE job !!!
Could we bother you for your battery part number, just so we'll know which batteries provide the power you log on the dyno and the acceleration you show on DragTimes videos?
Those of us with P90DL's want to keep track as we upgrade to P100D's, just in case there ends up being more than one version.
my friend took delivery of a new P100D AP2 car a couple weeks ago and it has the same battery...
The hp number is actually kind of impressive, from a Mustang dyno. For bragging rights you could go to a Dyno jet, they put out higher hp numbers.
If I were in the business of designing dynos, I'd just print out 20% more power than measured, mine would definitely be the most used!
I used to spend a lot of money having my cars modified and had dyno runs done on my cars dozens of times. The HP and torque numbers from any particular dyno, regardless of manufacturer, are mainly only good for comparison against other runs on that same dyno. Dynos use all sorts of adjustments when calculating HP and torque including for things like temperature and altitude. It is very easy to manipulate the numbers by tweaking these variables or by changing the actual testing conditions. Add to that every manufacturer uses different methodologies and technology (e.g. some dynos apply braking force to the dyno wheels to simulate resistance from wind/road surface and others use a free spinning dyno wheel where only the inertia of the wheel itself provides resistance). You end up with completely inconsistent measurements from one machine to another.
While this does seem awesome, was there an RPM pickup on the motor? I'm guessing that wasn't possible. What do the torque numbers mean without RPM? Sure, we expect torque at the wheels to be huge, due to the gear ratio, but I think it needs to be corrected by RPM to be comparable to an engine torque figure. Even then, I'm not sure we can directly compare this number to any ICE car...
I'm no pro at this stuff, but I think torque is torque regardless of RPM. In an ICE you need RPM to derive HP from the torque reading.
n2mb_racing is right, without the motor rpm you can only measure the torque at the wheels. You use that and the rpm of the wheels to calculate hp. Actually their torque number seems way to high, just from looking at the dyno chart, you can say, that they made a mistake, torque seems 50% too high. That's why I don't care about EV's torque numbers anymore, almost nobody gets it right, especially not the tools that own the dynos. Hp it the important factor here and 580 is impressive.
Thinking more about it, the torque could really be any number. If the motor turned at 200,000 rpm with a really high gear ratio, the motor shaft torque might be really small, yet still develop lots of HP and torque at the wheels.
Maybe torque for ice engines was a reasonable metric since they all turned about the same speeds.
Anyway, I'm going to guess it is not that far off, since I think the motor spins at 15k rpm max, so maybe twice the gear reduction of an ICE?
Either way, it's impressive and damn fast.
If it's a single fixed gear ratio without any clutch or torque converter to allow for slip, then don't we know all we need to know?
I believe the gear reduction is ~9.7:1
We do not know the fudge factors the dyno uses to cook the Engine power and Engine torque values.
Torque is the rotational force. That's what any dyno measures. HP is calculated using the measured torque at a certain RPM. So in order to get correct HP numbers the torque has to be correct.
HP really isn't the right measure for a car. Torque is. Torque is how strong the wheels spin. That's what makes the car go.
Both numbers are important. Problem is the industry got used to reporting torque at some RPM of the engine.
What is really meaningful is wheel torque at different speeds. That is what you feel in the car (adjusted by car weight).
Well, you don't know those regardless of what you've strapped to the dyno.
My point was that it was mentioned above that they didn't capture engine RPM. Given a single fixed gear ratio, we can derive that from wheel RPM.
True the car's weight makes a big difference. What matters is acceleration. That's what you feel. 0 to 60 in 3 seconds is an absolute value. 600 HP without the car's weight doesn't tell you anything about how quick it is.
well, there are Diesel-Electric locomotives with upwards of 6500 horsepower but they can't do a standing quarter mile in under a minute.
traction and gearing seem to be the limiting factors, though. put some racing slicks on the thing and it might get interesting.
Yea but they "measured" 920lf-ft of torque, which can't be at the wheels, or it would take some 14 seconds to get to 60, nor can it be at the shaft, otherwise power would be higher.
They measured peak torque at 50mph, which, knowing that the motors spinning at about 6800 and 7000rpm at 60mph, is at least 5600rpm, so power would be more than 970hp. So 920 lf-ft is just wrong at either the wheels, or at the shaft.
Knowing that an electric motor has a flat torque plateau until peak hp and then a hp plateau(not exactly flat but relatively), hp is a lot more useful number than torque. The Model S motors aren't that torquey, but because they can hold peak torque to a relatively high rpm and rev really high they can be geared really high, which makes them great for acceleration.
A dyno isn't all that complicated. It's a large and heavy drum. They measure the rate of acceleration of the drum which let's you calculate the power very straight forward. It's really simple math. By default, that's at the wheel.
If you put the car in N (neutral) they can also calculate the losses on the drive train up to the clutch and subtract that. That's how they make statements about power at the wheels vs at the shaft. (Since the Tesla doesn't have a clutch, you would be able to calculate the losses in the reduction gears and be able to make a statement about how much power is at the motor).