Roadster does a 12.7 quarter mile at Infineon

[graham]

From AutoBlog Green:

Tesla Roadster goes to the drags, does a 12.7 second quarter mile - AutoblogGreen

Proof positive of the Roadster's quarter-mile performance came from a recent trip to the Wednesday Night Drags at Infineon Raceway in California. An Autoblog reader was present for at least one of the orange car's passes down the drag strip and witnessed a time of 12.7-seconds. Anything under 13-seconds in the quarter is quite good and this performance puts the Roadster in firmly in Ferrari territory and bests the Lotus Elise that the Roadster shares many components with. We're not sure if this car was driven by someone from Tesla or if its a customer car, or whether it has the latest version 1.5 drivetrain installed.

 

[TEG]

Looks like manufacturer plates. I think that is VP13 we have seen Tesla people driving all over.

I think at one point it was "the quickest vehicle in the fleet", when it had PEM1.5, but still with a 2 speed. Hopefully now it has full 1.5 with the single speed gearbox, so that the 12.7s 1/4 mile is representative of production cars.

 

[TEG]

By the way, the ABG link takes us back to this story where they said:

...In the course of doing development on the drivetrain for the WhiteStar sedan project, a more powerful motor was needed for the larger and heavier car. In order to achieve this, the team developed a larger diameter motor with a liquid-cooled rotor.
This liquid-cooled unit forms the basis of what's being done for Roadster DriveTrain 1.5. The current air-cooled motor will be replaced by a unit the same size with liquid cooling. This will allow it to run at higher sustained power levels without overheating. Upgraded power electronics will feed more juice to the motor when needed for acceleration. A higher torque rated single-speed reduction gear transmission will handle sending power to the rear wheels...

So, didn't 1.5 actually turn out to be air cooled after all? (And wasn't there a cry for liquid cooling on the autobahn extended top speed runs?)

I am guessing that they thought about liquid cooling the motor for DT1.5, but ended up just adding enhanced air cooling after all.

I am also guessing that the sedan will have a liquid cooled motor.

I wonder if DT1.5 has a "larger diameter" motor compared to 1.0...

 

[graham]

More on the Tesla Roadster's public drag racing debut - AutoblogGreen

Tesla SVP Darryl Siry sent us a scanned copy of the time slip for the run. The car itself was validation prototype #13 and it was driven by Tesla engineer Iain Morrison. The car had the updated 1.5 drivetrain with the high torque motor and single speed gearbox. As an inexperienced drag racer, Morrison's reaction time of 0.764 sec was nothing to write home about, but drag racing turns out to be a lot harder than it looks as I found out last spring. The 2.058 second 60 ft time and 12.757 sec quarter mile time were in the ball park of the best I managed with a 530 hp Shelby GT500 as was the 104.74 mph trap speed

 

[bobw]

JB Straubel wrote in "An Engineering Update on Powertrain 1.5"

that they made changes to reduce electrical resistance, and therefore heat. He did not write that the motor was liquid cooled.

 

[TEG]

I would say this is a great news. They managed to better their estimated 12.9s time even with an engineer driving rather than a professional drag racer.

 

[donauker]

12.7 is good, but what is amazing is that if he would have gotten the reaction time of the driver in the other lane it would have been a 12.1 !!

 

[malcolm]

One of the comments on Autobloggreen made me laugh;

I imagine it sounded something like Satan's Blender

 

[Tdave]

That 1/8 mile time is really excellent, isn't it? Is it correct to subtract the driver reaction time and come up with 7.406 for the car's ability? Is that normal practice? I know little about how these numbers are typically published.

I did find this page that implies the Roadster stacks up quite favorably against other super cars in the 1/8 mile (0- 660 ft) time:

0-660 ft Performance Stats

Compare to 7.406 for the Tesla.

 

[graham]

This site: Tesla Roadster achieves 12.7-second 1/4 mile run is reporting:

The automaker reported today its Roadster model achieved a 12.7 second time down the quarter mile.

I don't see Tesla posting it on their web site. Did they issue a press release? This report is claiming the information came from Tesla itself, and not the Autoblog Green source...

 

[dpeilow]

I'm told that unless it is a professional race, drag strips do not count the driver reaction time. So the 12.7 still stands.

 

[doug]

Tesla Motors - touch

 

[TEG]

“…VP 13, which has powertrain 1.5 and OTHER ENHANCEMENTS under development that we wanted to test…”


So, VP13 has a “litte extra” that the current production cars don’t have yet?
I wonder how close in 1/4 mile time it is compared to production models without the enhancements.

 

[dpeilow]

Where did I recently read a claim of 0-60 in 3.7?

 

[doug]

Where did I recently read a claim of 0-60 in 3.7?

I think it was the Web 2.0 interview where Elon said they're working on a 3.7 or even 3.6 second 0 to 60 time with some "power pack enhancements."

 

[graham]

I would assume this would mean higher capacity, but fewer cells? (the same or greater power and less weight?) While the electronics and motor have changed, to my knowledge the battery has not changed since 2006 or earlier. Batteries have certainly gotten better since then I would hope...

I wonder if they are using any new chemistries, or are just fiddling with newer versions of the same batteries?

 

[TEG]

I would assume this would mean higher capacity...

Not necessarily. Performance could improve even if all they did was reduce the weight. Or a different configuration could offer higher current output, but lower capacity.

 

[TEG]

You could probably drop the 0-60 time from 3.9 down to 3.6 just by installing a limited-slip differential. You wouldn't need to touch the battery or the motor.

I doubt that. Typically there is nearly equal traction on both rear wheels, so a LSD wouldn't offer any benefit in a straight ahead 'drag'. A limited slip is really only most useful when going around corners and the road surface is uneven (for instance sand on the outside of the corner).

 

[GSP]

I doubt that. Typically there is nearly equal traction on both rear wheels, so a LSD wouldn't offer any benefit in a straight ahead 'drag'. A limited slip is really only most useful when going around corners and the road surface is uneven (for instance sand on the outside of the corner).

I'm not a fan of most limited slip differential designs, but an electronic locking differential might be a nice upgrade for the Roadster.

In theory, the traction may be the same for both rear wheels, but in real life the road surface can limit traction for one wheel. With the Roadster's open diff, the traction controller has to limit torque to whatever the one wheel with the least traction can support.

With a locked differential, all the traction from both wheels can be used.

However, the Roadster's open diff is just as good or better than a limit slip unit when going around corners. With an open diff, when you apply to much torque the inside rear wheel will spin, but the outside wheel will not. This allows the outside rear wheel to continue to provide the lateral force required to prevent oversteer (spin out).

With a LSD, torque can be applied to both wheels, requiring more skill to prevent a spin out.

With a locked diff, both wheels will spin. This instantly reduces the lateral force of both rear tires to zero. A great deal of skill and caution is required to drive a car with a locked diff on public roads.

The electronic locking differential is the best of both worlds, completely locked for the 0-60 sprint, and completely open for going around corners.

GSP

 

[vfx]

The torque curve could be adjusted to maximize for 0-60 times.