407 km/h in a street car?

[sballard]

Pretty amazing video


http://www.dailymotion.com/video/x157l2_bugatti-veyron-at-top-speed

[Porsche-O-Phile]

I want one.

[livi]

Even the giant Brit looks a bit pale.

[masraum]

yep, that video was posted the other day. I liked the revelation "I'm going 407kph. At this speed, the tires will only last for 15 minutes, but that's ok because the gas will only last for 12 min."

[Porsche-O-Phile]

Just out of curiousity, why do the tires only last for 15 minutes at that speed? Either they can take the rotational stresses or they can't. It's not like they're sliding all over the place getting worn down. Is it heat build-up degradation or what?

I do know that the tires are the limiting factor in the governing top-speed of the car. It's actually capable of going faster, but Bugatti limits it due to the tire limitations.

[the]

I wonder how many hectacres per liter you'd get going at that speed.

[livi]

I wonder how big an ordinary bug becomes, caught on the windshield at that speed...

[Gogar]

Just because tires don't experience much lateral friction doesn't mean they don't experience wear.

[Porsche-O-Phile]

But THAT quickly?!?! It's a rolling object for the most part, not a sliding one. Granted very small portions of the tire slide, but enough to reduce the effective life to 15 miles?!?! Sounds like some crappy tire design, IMO, although I'd suspect that's not the case on custom-designed tires for a $1.6M car. There's got to be another reason.

[mschuep]

Originally posted by Porsche-O-Phile
But THAT quickly?!?! It's a rolling object for the most part, not a sliding one. Granted very small portions of the tire slide, but enough to reduce the effective life to 15 miles?!?! Sounds like some crappy tire design, IMO, although I'd suspect that's not the case on custom-designed tires for a $1.6M car. There's got to be another reason.

I don't know if I buy the 15 mile limitation either, but I would think that there would be some serious wear at that speed due to 1) the increased (vertical) downforce, and 2) the massive amount of (horizontal) power being put to the ground to keep the vehicle going that fast. True, the friction coefficient doesn't change, but the forces sure do.

[Porsche-O-Phile]

True - the downforce has to be pretty extreme. . . Probably contributes to the wear.

[rammstein]

The 15 miles figure might be something stated in the Bugatti owner manual, perhaps being overly conservative for lawyer reasons? Yeah, I could see like 2000 miles, but 15?

[Porsche-O-Phile]

The top speed is similarly limited by the tires - probably also for liability reasons. Can you imagine the carnage if you lost control due to a blown tire at 250+ mph?

[masraum]

Originally posted by Porsche-O-Phile
15 miles?!?!

15 MINUTES

Not 15 miles. 15 minutes at ~255 mph is plenty of miles. I'd suspect that at that speed the heat builds up pretty quickly, the centrifugal force is pretty extreme, and considering the power required, and the aero force pushing back on the car those tires are probably pretty highly stressed and probably are slipping a tiny bit.

[masraum]

From wikipedia.org

The Veyron is the quickest production car to reach 100 km/h (62 mph) with an estimated time of 2.5 seconds. It reaches 60mph in approximately 2.46 seconds. It also reaches 200 and 300 km/h (124 and 186 mph) in 7.3 and 16.7 seconds respectively. This makes the Veyron the quickest accelerating production car in history.

It also consumes more fuel than any other production car, using 40.4 L/100 km (5.82 mpg) in city driving and 24.1 L/100 km (10 mpg) in combined cycle. At full throttle, it uses more than 125 L/100 km (2.1 mpg), which would empty its 100 L fuel tank in just 12.5 minutes.

The driver must, using a special key (the "Top Speed Key"), toggle the lock to the left of his seat in order to use the maximum speed of 253.2 miles per hour (407.5 km/h). Theoretically it can go faster but it is electronically limited to 253.2 miles per hour (407.5 km/h) to prevent tire damage. The key functions only when the vehicle is at a stop when a checklist then establishes whether the car—and its driver—are ready to enable 'top speed' mode. If all systems are go, the rear spoiler retracts, the front air diffusers close and the ground clearance, normally 4.9 inches (12.4 cm), drops to 2.6 inches (6.6 cm).

The Veyron's brakes utilize unique cross-drilled and turbine-vented carbon rotors, which draw in cooling air to reduce fade. Each caliper has eight[2] titanium pistons. Bugatti claims maximum deceleration of 1.3 g on road tires. Prototypes have been subjected to repeated 1.0 g braking from 194 to 50 mph (312 to 80 km/h) without fade. With the car's fearsome acceleration from 50 to 194 mph (80 to 312 km/h), that test can be performed every 22 seconds. At speeds above 124 mph (200 km/h), the rear wing also acts as an airbrake, snapping to a 70-degree angle in 0.4 seconds once brakes are applied, providing 0.5 g (4.9 m/s˛) of deceleration.[2] Bugatti claims the Veyron will brake from 252 mph (406 km/h) to a standstill in less than 10 seconds.[2] The braking is also so evenly applied that the car will not deviate from a straight path if the driver lets go of the steering wheel, even with the brakes fully applied starting from close to top speed.

pretty darn impressive for a pig.

[masraum]

Originally posted by Porsche-O-Phile
The top speed is similarly limited by the tires - probably also for liability reasons. Can you imagine the carnage if you lost control due to a blown tire at 250+ mph?

According to the Wikipedia article the theoretical top speed is 257 mph, but the actual top speed is limited to 253. Hardly seems worth it, but at that speed 4 is probably a huge difference. According to the article you can hit 253mph in just under a minute. Yowza.

[mschuep]

yowza indeed, that video made me nervous...seems like a twig in the road would throw off the balance of any car at that speed, much less a small squirrel or bird that wouldn't even have a chance to see it coming.

[masraum]

It'd be scary, but I'd like to have that thing shoot past me at 250mph. I bet that'd be a rush.

[Porsche-O-Phile]

A real rush would be two coming at each other head-on at top speed, only seperated by that little yellow line. . .

Must. have.

[goat]

Originally posted by masraum
yep, that video was posted the other day. I liked the revelation "I'm going 407kph. At this speed, the tires will only last for 15 minutes, but that's ok because the gas will only last for 12 min."

Love that quote!!!!

Amazing Car...