- Joined
- Aug 24, 2019
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- Location
- San Francisco
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- 2018 Tesla Model 3 Performance
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- #1
A two speed transmission could be a game changer for an electric car, or it could be a warranty and reliability nightmare that takes your million mile car with a 500,000 mile battery and puts it in the shop every 50,000 miles, like a classic VW Group DSG.
First, we need to map out the gear ratios. Second, we need to figure out at what RPM it cuts over, or what the gear change strategy is.
Let’s start with Tesla as a reference. I am under the impression the Tesla PSM is 19000 RPM max, electronically limited to 155 MPH (below max RPM), it has a 7.5:1 gear ratio, and it may or may not have a gear-reduction-ratio before connecting to the wheels. The latter is how Tesla slows down the launch of an AWD car, versus a Performance AWD car.
I would think the Porsche system has two purposes. First, to act as an overdrive at 80 MPH and improve efficiency. Second, as a way to separate the “launch gear” from the “track gear”.
First, we need to map out the gear ratios. Second, we need to figure out at what RPM it cuts over, or what the gear change strategy is.
Let’s start with Tesla as a reference. I am under the impression the Tesla PSM is 19000 RPM max, electronically limited to 155 MPH (below max RPM), it has a 7.5:1 gear ratio, and it may or may not have a gear-reduction-ratio before connecting to the wheels. The latter is how Tesla slows down the launch of an AWD car, versus a Performance AWD car.
I would think the Porsche system has two purposes. First, to act as an overdrive at 80 MPH and improve efficiency. Second, as a way to separate the “launch gear” from the “track gear”.
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