Fact Checking
Well-Known Member
I don’t get the 2 speed. What did they get for it? It should have been higher top speed or more efficient.
I believe Porsche went with a 2-speed transmission specifically to maximize Nürburgring-Nordschleife performance - which was probably the only area where they thought to have a chance of beating Tesla's performance.
If you check out the velocity profile of a (mediocre) Nürburgring lap:
It's a pretty fast track where the fastest track ever performed had an average speed of 112 km/h, with speeds rarely dipping below 50 km/h.
An additional complication on Nürburgring is that there's serious altitude drops and increases, 300 meters in altitude change from bottom to top (!):
So in those areas marked 'red' you need a lot of motor power in addition to working against drag, and in the 'blue' areas there's big drops in altitude with a lot of braking, where it's useful if you can charge back your battery pack with regen braking to stay at optimum power output levels - ~7 minutes and 20 kilometers draws a lot of power.
This means that if you use a 2 speed transmission Porsche was probably able to do much of the Nürburgring lap in second gear all the time - and benefit from lowering the EV motor RPM into a higher torque performance regime:
As you can see lowering the RPM of an electric motor can increase its power output, because the power output down-slope starting point can be shifted to the right.
Note that the Roadster 2 is going to have 3 motors, where each motor can probably have a different gearing ratio - this would create a better power output profile at higher speeds too, without having to introduce a transmission.
I have no idea whether a Raven Model S can beat the Taycan on the Nürburgring next week - I really hope Elon knew the result it in advance before tweeting about it.
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