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Discussion in 'Electric Vehicles' started by dpeilow, Sep 26, 2008.
German Supertuner RUF Building an Electric Porsche | Autopia from Wired.com
First the Dodge EV and now this.
The trouble with both vehicles is that they just distract potential Roadster customers with promises of jam tomorrow.
Crucially we have no details on gearboxes. Both companies are boasting about more torque, but have they any idea what that will do to the transmission? It's not the maximum that's the problem - it's the fact that an e-motor can change rotational forces very swiftly.
Marrying single speed to expected performance will delay the product. Alternatively using a conventional box will require them to modify the acceleration profile to protect the gearbox from motor torque transients.
Who knows, maybe they'll have to keep the flywheel.
Of course, unlike Tesla, both Porsche and Chrysler can bend gearbox manufacturers to their will, but to be honest I feel that until electrical energy storage improves significantly then the creation of a bomb-proof EV gearbox is just a heavy, expensive and uneccessary development. Why drive faster? You just hit empty sooner.
Tesla - Hurry up and build Model S to get away from these people.
I do agree with you Malcolm but what might happen is one of the big ones like Chrysler og Porsche decides they NEED a gearbox for their high-performance EV and somehow manages to solve the problem. And then after someone has shown how you build a gearbox for the Roadster, and especially if it's one of their contractors we might see a Tesla car with such a gearbox. Might give the Tesla the option of a high max speed.
Of course another possible result might be that one of those big manufacturers fail to create a proper gearbox and they need to eat humble pie just like Tesla did. I bet that would be a very nice boost to Tesla's morale
The "gearbox" isn't the real issue. It is still all about batteries... Price, longevity, reliability, and availability.
Sure the viability of an EV is closely tied to the battery. But Tesla has had no problems with the battery and lots of issues with the gearbox. Hence why I think it's fun to see what other carmakers can do with that problem. The battery is usually not something the carmakers can do anything about anyway. I.e. they are dependant on the battery research and battery producers.
Ruf Electric Porsche: RUF Electric Porsche 911 Concept Finally Revealed
More likely, I think, is that it'll introduce the idea of electric sports cars to more people. It won't take them long to learn about the Tesla Roadster, which is actually available (sorta).
It could well end up being the other way around for other manufacturers.
Tesla put a disproportionate amount of engineering effort on the battery pack, thinking it was the high risk item. The "2 speed" gearbox wasn't typical of what other manufacturers are doing (typically direct drive is much easier).
Tesla patented the way that they did the battery pack, so other companies may opt to experiment with other types of battery arrangements even though we know the "Tesla way" works.
I am curious about the "125 MPH top end" of this car on the Autobahn. Will it be similar to the Tesla where it can only reach that speed for a short time? Will it have enough juice at high speeds to get from one exit to another?
Seems more important for a German car to get this right. Especially since most of the press Tesla received in Germany was negative-ish because of those issues - did they get it right with the Porsche?
True, but part of the "Tesla way" was out of necessity more than being the best way. In this past decade there has been a healthy market for consumer Li-ion batteries, but not one for large-format ones. Tesla has the upper hand today since they have spent an inordinate amount of time making consumer batteries work in a car. As more battery companies get into the game, large-format batteries have the potential to be better. Hopefully Tesla will also continue experimenting as well.
I'd bet on that.
Trouble is motor heat. You can only aircool the stator, cooling the rotory is very very hard. At 120mph the car is burning around 80kW, with 80% efficiency that means 20kW of heat. Some of it in stator, most of it in rotor. If it gets to hot it can deform and even seize up.
It looks like a big lash-up job to me
DVICE: Electric Porsche 911 tries to show Tesla Roadster who's boss
With relatively (compared to the original ICE version) poor acceleration and top speed, this is a pretty bad advertisment for electric power.
Hmm... The original article said "With more torque on tap, the electric version might shave a few ticks off that time and could even beat the Tesla's 0-to-60 sprint of 4.0 seconds."
I guess they decided to gear it for 160mph (Autobahn) top speed rather than low speed acceleration.
I wonder what the range would be at 160 Mph. Anyway, I like the way Porsche looks but this car is a fail. I almost expected to see duct tape under the hood.
Acceleration comparisons on that level of sports cars in milliseconds is as important as faster ejaculation after masturbating on the open.
In a country with (wisely) 90 miles top speed buyer deciding (even wiser) on a car after calculating which model has more cup holders fitting the big Starbucks paper coffeholder - thats overkill.
Looking while at the Paris show at the Porsche & Tesla side by side (they where paraded on a parking lot slowly driving in a circle) the Tesla looks & smells evaporating and killing your nasal receptors as soon as you hit the seat (yes - smells inside - thats also important) like a beta Yugo in finish after a Hippy took a overnight nap with a unwashed overweight girlfriend and for easing that bad choice at the bar - a good smoke.
The Porsche shined in finish & smell comparable polished and perfumed as a gem in the Vatican.
The finish and visible lack in craftsmanship of the Tesla screwyou-on-the-fligh is visible by onlooking even to a self-educated Budukudu nudelbaker.
Finkenbusch writes like a mad lib.
I'd be very surprised if with 200bhp the Porsche could reach or sustain 160mph.
Finkenbusch, what are you talking about?
"milliseconds" - We are talking 3.9 seconds vs 7 seconds. 3.9 is supercar territory. 7 seconds is cheap hot-hatch territory.
Seriously, is this the European fightback that you have been alluding to all this time?
I wonder why Wired keeps quoting 4.0 seconds instead of the stated 3.9? I could understand rounding by claiming "4 seconds", but they always compare it to a car where they specify to the tenth of the second. These are the same folks who claimed the original drivetrain was on par with the Toyota Tundra.
I am sort of surprised this Porsche is getting the press that it is. It has been all over the news the last few days. Almost every article compares it to the Roadster.
Err... for the record: none of the dozen or so Roadsters I have sat inside have smelled. Perhaps he mistakenly sat in a Roaster by accident.
Ruf's electric Porshce powered by UQM motor - AutoblogGreen
Road and Track tests battery-powered E-Ruf 911 - AutoblogGreen
RoadandTrack.com -- Cover Story - 2008 E-Ruf Concept Model A (12/2008)
Ruf's Electric Porsche Hits the Road. Slowly. | Autopia from Wired.com
Odd that the diagram still shows the rear seat in place.
This thing does seem rather kludgey.... oddly routed hoses, dymo labels on the switches... They even just mated the UQM motor to the existing 6 speed tranny, which seems suboptimal for an electric motor. I mean it's fine for a home brew conversion, but kinda lame for a professional tuner.
After reading alot about existing ICE -> Electric conversions I found out trannies are not such a bad idea after all. ICEs need them because of their narrow torque band but electrics will use them to increase efficiency i.e. range.
Electric motor is most efficient at it's top rpm. If you only have one gear ratio good for 120mph top, then you are almost all the time driving at less than half of max motor rpm - producing more heat than it would at higher rpm.
Tesla's range increased because their single gear ratio is now higher than previous 2nd gear - hence v1.5 motor is turning faster (= at higher efficiency) than it did in v1.0 drivetrain.
People report up to 30% higher range after they change their driving style. In an ICE car you increase range when driving at as low rpm (in higest gear) as possbile. When car starts to loose speed or you need more power you downshift to put the engine into higher rpm range. With electric cars this is almost exactly the opposite. You should drive in as low gear (high rpm) as possible for given road / speed limit.
If car starts to loose speed or you need more power you do not down-shift (3 -> 2) but UP-shift (3->4) into higher gear, so rpm lowers to higher torque band.