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Tesla Roadster

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Re: Tesla Roadster

#591

Post by runeks »

Unklejoe wrote: post #480

Has the 8 second quarter mile been confirmed to be done in stock trim (i.e., no special tires or other modifications)? The reason I ask is because that is EXTREMELY impressive. I tune EFI systems on race cars as a hobby, and any car in the 8 second range usually needs to run slicks or drag radials to have enough traction. Even all wheel drive cars (GTRs, DSMs, EVOs, etc.) usually run 4 slicks once they get to that sp…

> Even if they had to put slicks on the car to reach that time, that still puts it on par with 1000 HP dedicated drag cars.

Horsepower is a misleading figure, because 1000 HP means a maximum of 1000 HP at some engine RPM. So, in other words, if a gasoline car delivers 100 HP @ 0-2000 RPM, and only delivers 1000 HP between 5500-6000 RPM, we call it 1000 HP.

The Tesla delivers its power constantly, from 0 RPM and — more importantly — its torque is also constant and available from 0 RPM. Add to this the fact that an electronic drive train can adjust the power independently for each wheel 100 times per second, which is simply impossible for a combustion engine (mechanical parts transferring that much power can’t switch that fast).

Re: Tesla Roadster

#592

Post by Unklejoe »

burger_moon wrote: post #584
killjoywashere wrote: post #569

Earlier quoted context omitted.

I suspect Tesla's advantage is in linear acceleration. Those internal combustion cars need a gearbox so the initial acceleration is very high in that first gear. This the same reason the Navy wants to go from steam to electric catapults: you get the plane to the same speed off the cat, but the acceleration curve is straight, so there's lower peak load on the airframe, so your planes last longer. Similarly, the Tesla…

Right but to hit an 8 second 1/4 you're trap speed is 170-190 depending on how fast your 1/8 mile was. There simply isn't even distance to accelerate linearly in 1/4 to hit 8 seconds without leaving the line like a bat out hell. The suspension on most of these cars is also far from normal. There's very few cars in the world which make an8 second pass on independent rear suspension. Most of these cars have straight ax…

There are some IRS cars capable of going 8's. The ones I've seen the most are GTRs, Supras, and the occasional 2JZ/LSx swapped 240sx (I think they swap a Nissan/Infiniti Q45 rear into it or something).

Now that the 2015+ Mustang has IRS, I expect to see more of them as well. I think there's already one in the 8's.

But yeah, IRS is a major pain at that power level. Most (all?) of the performance cars today have IRS, so I expect improvements to come.

Re: Tesla Roadster

#594

Post by Unklejoe »

grkvlt wrote: post #589
Unklejoe wrote: post #491

Earlier quoted context omitted.

Modern high-end aftermarket EFI systems (such as MoTeC) do have traction control, but it's not as effective as one would expect. The main issue I found is that street tires often just don't have the traction required, even under ideal conditions. The result is that traction control has to cut power so much that it ends up hurting the quarter mile times. It does help tremendously on consistency and safety though. Thin…

Wow, the buckling of the tire wall in the last two pictures is crazy. I guess that happens because there is enough friction to stop the wheel moving, and the axle is trying to turn it faster, causing a shear force. With normal tires, I assume they would just slip at that point and spin because they don't have enough friction in the contact patch touching the road.

Yep! The tires are actually designed to do that. It really helps to prevent things from snapping by absorbing some of the shock when the cars drop the clutch or let go of the trans brake.

Re: Tesla Roadster

#595

Post by wazoox »

jfindley wrote: post #397
icc97 wrote: post #366

Earlier quoted context omitted.

From Wikipedia's F1 page [0]: > The 2016 F1 cars have a power-to-weight ratio of 1,400 hp/t (1.05 kW/kg). Theoretically this would allow the car to reach 100 km/h (62 mph) in less than 1 second. However the massive power cannot be converted to motion at low speeds due to traction loss and the usual figure is 2.5 seconds to reach 100 km/h (62 mph) Even adjusting for 60 mph = 2.4s, I don't see how the traction of the T…

I agree, I think this is another case of "well it works on our computer" pre-release specs that will turn out not to get close to real-world performance. The 0-100mph is very suspicious but I think the 0-60 time quoted is simply impossible for a road car, even making allowances for a few years of tech advancements. F1 tires are nothing like road tires. They're not even vaguely comparable - at normal operating tempera…

Have a reality check of a 0-74 mph on the real thing (with 2 people aboard):https://youtu.be/aXWfL-1ieuE?t=3369

Re: Tesla Roadster

#596

Post by clarkmoody »

burger_moon wrote: post #584
killjoywashere wrote: post #569

Earlier quoted context omitted.

I suspect Tesla's advantage is in linear acceleration. Those internal combustion cars need a gearbox so the initial acceleration is very high in that first gear. This the same reason the Navy wants to go from steam to electric catapults: you get the plane to the same speed off the cat, but the acceleration curve is straight, so there's lower peak load on the airframe, so your planes last longer. Similarly, the Tesla…

Right but to hit an 8 second 1/4 you're trap speed is 170-190 depending on how fast your 1/8 mile was. There simply isn't even distance to accelerate linearly in 1/4 to hit 8 seconds without leaving the line like a bat out hell. The suspension on most of these cars is also far from normal. There's very few cars in the world which make an8 second pass on independent rear suspension. Most of these cars have straight ax…

Accelerating at 1.28g (41.25 ft/s2) for 8 seconds will get you to exactly a quarter mile.

  x = 0.5*a*t^2 = 0.5 * 41.25 ft/s2 * (8s)^2 = 1320 ft = 1/4 mi
Under that acceleration, your final speed is 225 mph

  v = a*t = 41.25 ft/s2 * 8s = 330 ft/s = 225 mph

Re: Tesla Roadster

#597

Post by sbko »

Unklejoe wrote: post #480

Has the 8 second quarter mile been confirmed to be done in stock trim (i.e., no special tires or other modifications)? The reason I ask is because that is EXTREMELY impressive. I tune EFI systems on race cars as a hobby, and any car in the 8 second range usually needs to run slicks or drag radials to have enough traction. Even all wheel drive cars (GTRs, DSMs, EVOs, etc.) usually run 4 slicks once they get to that sp…

"I tune EFI systems on race cars as a hobby" How did you get into such hobby? I would be glad to do that as a hobby :)

Re: Tesla Roadster

#598

Post by TimTheTinker »

Sohcahtoa82 wrote: post #590
TimTheTinker wrote: post #141

Earlier quoted context omitted.

This isn’t CGI :-) https://mobile.twitter.com/DavidHodge/status/931391188065705...

God damn....that acceleration is almost cartoon-like. I'm kinda sad about the $200k price tag. I was planning on budgeting $125k for my next car in 2022. Obviously options have yet to be announced, but I'd really like to see a 100 kwh option for a cheaper price. That would give about a 300 mile range which would be plenty for me. Considering they announced 200 kwh as the base though, I'm not exactly holding my breath…

Despair not. The new Roadster will likely have some good competition by 2022.

Re: Tesla Roadster

#599

Post by dntrkv »

wallace_f wrote: post #517
grecy wrote: post #499

Earlier quoted context omitted.

> that still puts it on par with 1000 HP dedicated drag cars I think you'll find it's past those. Even 1200hp GTRs don't run eights.

The OP is right that 8 sec 1/4 is extremely impressive, but he is wrong that there are few production cars that can run 8s. No production car runs anything close. The fastest 1/4 mile production cars are supercars such as the Veyron and 918, which are at or just under a 10seconds. Remember, an increase from 20->18 seconds is roughly a 10% increase in acceleration; 10->8 is roughly 20% increase over an already ludicro…

>The fastest 1/4 mile production cars are supercars such as the Veyron and 918, which are at or just under a 10seconds.

Except for the Dodge Demon, which does the 1/4 in 9.65

Re: Tesla Roadster

#600

Post by tdiggity »

gregornobis wrote: post #574
tdiggity wrote: post #131

Earlier quoted context omitted.

Founder series limited to 1000 requires full deposit, that's $250 mil Base model requires $45k deposit. Not sure what semi requirements are. Even if they are biting off more than they can chew, they can gauge reaction and devote more/less to this. I'm thinking that these ventures give their engineers a space to get really creative and push the envelope. And, these advancements make their way into the mainstream model…

$250mil sounds a lot - until you remember they currently burn through $400mil of cash in a month

oh please. they're putting money into R&D and into the ramp up. Your statement makes it sound like they're using the money to wipe their @$$es. No, they're putting the money to work. And if the analysts and shareholders didn't believe that, the stock would tank.
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