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Newer P90DL makes 662 hp at the battery!!!

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#2,801
St Charles said:
Also, there is A LOT of tire design that goes into drag racing that we are completely ignoring in these discussions. In short, a 21" performance tire can easily produce worse results than a 19" all season. What makes for a good tire for cornering generally makes for very poor straight line performance. That said, it seems to make little difference in our cars which I think has to do with AWD more than anything. I'd be interested to hear what @lolachampcar has to say on tire performance.
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All very good points.
 
#2,803
TIppy said:
We're considering a hypothetical situation where the coefficient of friction doesn't change when the tires lose grip.
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The difference in static and dynamic co-efficient of friction is effected by tire design, tread pattern, tire shape, tire temperature, road surface, road temperature and a thousand other variables.

The point being is that if the tires loses traction and regain without traction control stepping in, there's still a small penalty in acceleration which has been shown recently by several vbox graphs in this thread.
 
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#2,804
the best ETs thus far have been on the 21"s...



St Charles said:
Also, there is A LOT of tire design that goes into drag racing that we are completely ignoring in these discussions. In short, a 21" performance tire can easily produce worse results than a 19" all season. What makes for a good tire for cornering generally makes for very poor straight line performance. That said, it seems to make little difference in our cars which I think has to do with AWD more than anything. I'd be interested to hear what @lolachampcar has to say on tire performance.
Click to expand...
 
#2,810
sorka said:
The difference in static and dynamic co-efficient of friction is effected by tire design, tread pattern, tire shape, tire temperature, road surface, road temperature and a thousand other variables.

The point being is that if the tires loses traction and regain without traction control stepping in, there's still a small penalty in acceleration which has been shown recently by several vbox graphs in this thread.
Click to expand...
I still don't agree that traction control hasn't stepped in. I think there might be two levels. The first level kicks in when slip is first detected. This looks to be, perhaps a pre-computed, slowing of the increase in power giving the car a chance to catch up with the spinning wheels. If this isn't successful, then the torque is abruptly lowered. This was revealed in the close up of the can bus data of wheels slipping in an earlier post.
 
#2,811
sorka said:
Agree with this but that will delay acceleration as the energy that was going to accelerate the vehicle was instead wasted as heat.
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I agree that there is energy being wasted, but the fact that the wheels are spinning doesn't change the thrust imparted to the car. This is power over and above what the non-spinning wheels can handle or the rpm's wouldn't be increasing, so the acceleration is the same as the non-spinning wheels because we've assumed a constant coefficient of friction. We're wasting the power, but the car still has the same acceleration with the wheels spinning or not.
 
#2,812
TIppy said:
I still don't agree that traction control hasn't stepped in. I think there might be two levels. The first level kicks in when slip is first detected. This looks to be, perhaps a pre-computed, slowing of the increase in power giving the car a chance to catch up with the spinning wheels. If this isn't successful, then the torque is abruptly lowered. This was revealed in the close up of the can bus data of wheels slipping in an earlier post.
Click to expand...

What canbus data? The only data I saw did not show what you're describing.
 
#2,813
By the way, I drove through standing water about 5" deep today, and then did a 0 to 80 max acceleration run. The wheels stuck just fine on the completely dry pavement. If the road is even a little damp, then I have problems with traction. I've also noticed that I almost always loose traction when I'm at 100% SOC with a warm battery just off the charger.
 
#2,814
TIppy said:
I agree that there is energy being wasted, but the fact that the wheels are spinning doesn't change the thrust imparted to the car.
Click to expand...

The problem with that is that even if the co-efficient of friction is the same after slipping, the fact that RPMs are increasing without power increasing means torque drops and the difference is wasted as heat. Am I sounding like a broken record yet:rolleyes:
 
#2,816
sorka said:
What canbus data? The only data I saw did not show what you're describing.
Click to expand...
blow-up-png.193677

Just as the acceleration drops, dip in the green speed curve, the torque begins to drop rapidly. The current and power continue to rise until the break in the decreasing torque curve. At this point the current and power slopes level off. They go from being convex upward to concave upward.
During the time that the power and current continue rising, the torque x rpm is also rising. So clearly the wheels are spinning and the rpm is increasing at a rate to match the increased power being fed to the motors while the torque decreases. The inverter is trying to increase torque but can't because of loss of traction. The leveling off of the current and power looks like the controller has detected that the wheels are spinning and is waiting for the speed of the vehicle to match the speed of the spinning wheels before slowly increasing power again.
 
#2,817
sorka said:
The problem with that is that even if the co-efficient of friction is the same after slipping, the fact that RPMs are increasing without power increasing means torque drops and the difference is wasted as heat. Am I sounding like a broken record yet:rolleyes:
Click to expand...
The problem with this is that if the coefficient of friction is the same, the rpm's can't increase without power increasing. Why would the rpm's increase? Where is the extra torque coming from to accelerate the wheels?
 
#2,818
fiksegts said:
I have two sets of the 21" Arachnid wheels coming so I ordered the car with the 19"s, I'll be putting on my aftermarket wheels while I wait for them....
Click to expand...

TIppy said:
Are these lighter than the regular staggered 21" wheels?
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Yes, the Arachnid wheels are staggered widths and lightweight forged alloy. Looking forward to weighing my set soon ... :cool:

21″ Arachnid Wheel
upload_2016-9-27_21-40-11.png

Size: 21X8.5″ front, 21X9.0″ rear
Offset: +40 front, +40 rear
PCD: 5X120
Center Bore: 64.1mm
Lug Nut Spec: 13/16 Hex, 14X1.50 Thread
Lug Nut Torque Spec: 129 lb-ft.
Price: $ 7,600.00
Details: This wheel is not available when ordering a Tesla Model S.
It can be ordered as a wheel and tire package for the price above from the Tesla store.
 
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