standard tires on 2.5

[qwk]

One has to remember that while the Roadster applies 100% torque from a stop, it does not apply 100% power from a stop and has the disadvantage of only having a fixed gear.

Remembering that power is force (torque) applied over time, one realizes that one needs to apply maximum power (not torque) over that distance to get there fastest.

Then look at a torque/power curve for roadster, one quickly realizes that off the line while the Roadster produces a lot of torque, it doesn't produce more than 100 hp until you're going around 30 mph and that ideally you'd keep the motor spinning around 8,000 RPM to accelerate the fastest.

Don't forget that with a typical car one can also usually "launch" it (unless you've got a crappy slush-box) in the power band.

Put a 2-3 speed transmission in the Roadster and you'd easily produce better acceleration numbers. While an EV's torque curve is much better than an internal combustion engines, that doesn't mean that performance can't be improved by keeping the motor in it's sweet spot.

You can have all of the power in the world off the line, but with little torque you will not get good 60' times. To get the ultimate track times, you want max torque off the line, and max hp once you get going.

Gearing does have a lot to do with it, but the roadster definately leaves a lot on the table with the current setup as it's engineered for range/reliability.

 

[Dave EV]

You can have all of the power in the world off the line, but with little torque you will not get good 60' times. To get the ultimate track times, you want max torque off the line, and max hp once you get going.

Gearing does have a lot to do with it, but the roadster definately leaves a lot on the table with the current setup as it's engineered for range/reliability.

Gearing has _everything_ to do with it. The motor could produce 1000 ft/lbs of torque but with the wrong gearing you're not going to get to 60' any faster. Why? The motor won't produce any more power!

Torque is meaningless once you bring time into the context. Then all that matters is power.

 

[qwk]

Gearing has _everything_ to do with it. The motor could produce 1000 ft/lbs of torque but with the wrong gearing you're not going to get to 60' any faster. Why? The motor won't produce any more power!

Torque is meaningless once you bring time into the context. Then all that matters is power.

You couldn't be more wrong. It may seem good on paper, but in the real world there are too many variables. With traction not being an issue, gearing can be meaningless as long as you have enough gear to reach the desired distance.

There has to be a happy medium between power and torque to get the max out of vehicle.

 

[Dave EV]

You couldn't be more wrong.

You seem to mis-understand what I'm saying just for the sake of arguing. Here it is in 2 simple statements:

1. Power = work over time.

Thus to travel 60' in the least amount of time you need to either reduce the amount of work that needs to be done (can only be done by reducing weight) or increase power.

2. The Roadster produces less than 100 hp at speeds of less than 30 mph.

Any modern V8 in 1st gear isn't going to have any problem beating that. So no wonder the Roadster doesn't produce stellar 60' times in comparison.

 

[cinergi]

I think it's more accurate to say the Roadster limits how quickly torque ramps up, both for the driver's and the drivetrain's benefit. However, from the logs, it looks like it gets up to maximum torque very quickly. Below is a graph from my best 1/4-mile run.

I don't remember -- do you have a 1.5 or 2.x? I know Scott's gone from owning a 1.5 to 2.5 and mentioned the low-end torque is significantly lower. For me, my butt tells me I'm not at full torque until 20+ MPH. I've yet to measure it or look at logs etc. but it's very limited on the low end.

 

[qwk]

You seem to mis-understand what I'm saying just for the sake of arguing. Here it is in 2 simple statements:

1. Power = work over time.

Thus to travel 60' in the least amount of time you need to either reduce the amount of work that needs to be done (can only be done by reducing weight) or increase power.

2. The Roadster produces less than 100 hp at speeds of less than 30 mph.

Any modern V8 in 1st gear isn't going to have any problem beating that. So no wonder the Roadster doesn't produce stellar 60' times in comparison.

This is a pointless argument. Like I said before, in the real world there are too many variables to make simple paper calculations come true.

The fact of the matter is that upping the torque in the roadster gets you better acceleration times. Otherwise the Sport would have similar acceleration to the base model. There is no doubt in my mind that Tesla limits the torque on takoff. Like Cinergy pointed out above, there is even a difference between older and newer firmwares, as well as the 1.5-2.5 models.

As soon as the cars start coming out of warranty, I'm willing to bet there will be tinkering happening, and we will see exactly what can/cannot be done.

 

[Eberhard]

you miss the most important point: Even if you would have 10 times the power and/or torque, you cannot do it not really better, because you are limited by the drag force. This mostly depends on the gravity or/and artificial down force by using air wings.
Because of that, the downforce momentum by gravity is nearly equal to the max torque output of the ac-motor up to around 40mph.

 

[tomsax]

I'm not saying your graph is wrong. It just baffling that an ICE with similar power and way less avg. tq/hp, can get much better 60' times. A high 12 second car trapping 100+ definately does get better 60' times than 2.0+. The rule of thumb is that you shave off about .2-.3 sec in the 1/4 mile for shaving off .1 sec in your 60' time.

My mistake, I was thinking 0-60 mph times, not 60-foot times. Still, the log data shows the car gets up to 90% of full torque before I even lift my foot off the brake, so the car's performance is not being held back by some artificial torque limit.

Gas cars that get better 60' times have huge sticky tires and are using engine and shaft inertia to multiply their engine's output on launch at the expense of their clutch. In the Roadster, I can race all night long, blowing away most cars. The ones who can beat the Roadster can only race a few times before their clutch blows up.

The amazing thing about the Roadster is that you don't have to be an expert driver and you don't have to put outrageous wear and tear on your drivetrain to crank out the spec 0-60 or 1/4 mile time over and over again. I can race the quarter mile, get a time in the high 12's, spend $0.25 on electricity and not even squeal the tires. The gas burners are spending as much as $5 on fuel and orders of magnitude more than that on tire and clutch wear.

If we could totally open up the drive, I'm sure we could get a lot better performance, but that's White Zombie, not a production car with a warranty.

 

[qwk]

My mistake, I was thinking 0-60 mph times, not 60-foot times. Still, the log data shows the car gets up to 90% of full torque before I even lift my foot off the brake, so the car's performance is not being held back by some artificial torque limit.

Gas cars that get better 60' times have huge sticky tires and are using engine and shaft inertia to multiply their engine's output on launch at the expense of their clutch. In the Roadster, I can race all night long, blowing away most cars. The ones who can beat the Roadster can only race a few times before their clutch blows up.

The amazing thing about the Roadster is that you don't have to be an expert driver and you don't have to put outrageous wear and tear on your drivetrain to crank out the spec 0-60 or 1/4 mile time over and over again. I can race the quarter mile, get a time in the high 12's, spend $0.25 on electricity and not even squeal the tires. The gas burners are spending as much as $5 on fuel and orders of magnitude more than that on tire and clutch wear.

If we could totally open up the drive, I'm sure we could get a lot better performance, but that's White Zombie, not a production car with a warranty.

If there wasn't an artificial limit on takoff, the roadster would easily spin the tires. Trust me, it has more that enough torque to do it. It's not like the tires used on the roadster are super sticky or wide(yes, even the sport model).

Many moons ago I had a stockish 13 second car that trapped around 100mph(like the roadster), and it would easily get 1.8X 60' times with street tires. The stock clutch lasted over 4 years and 100+ 1/4 mile passes, so while your statement maybe true for a few, it definately generalizes. The car then morphed into an 11 second car trapping ~125mph with the same clutch and adding to that 100+ time slips. It now runs bottom 10's, with an automatic trans. I can drive 200 miles to the track run 20+ times and make it the 200+ miles back with no problem, getting 25mpg on the highway. It can definately be done very easily in an ICE.

Now don't get me wrong, I love EV's and hate gas burners, but there is no need to exagerate the shortcomings of an ICE at the track. While the Roadster is a very impressive EV, it definately won't break any drag time records while being pooled in with even very cheap ICE cars. The aftermarket for the ICE is HUGE! Not so for EV's.

BTW, while the zombie is very impressive, there are tens of thousands of STREET LEGAL ICE cars accross the country that would make it look silly.

On another note, I don't think that anybody with a roadster sport has made any passes with a full performance mode charge, so that 12.6X record could possibly be easily broken if someone would just try.

 

[tomsax]

BTW, while the zombie is very impressive, there are tens of thousands of STREET LEGAL ICE cars accross the country that would make it look silly.

Really? There are tens of thousands of street-legal ICE cars that can pull a 10.4-second quarter mile? White Zombie is a 9-second car and still has headlights, tail lights, a passenger seat, a radio, carpet, etc. When John is ready, his team will break the 10-second barrier, then be banned from sanctioned drag racing because of the required safety upgrades (certified driver, certified frame, parachute).

On another note, I don't think that anybody with a roadster sport has made any passes with a full performance mode charge, so that 12.6X record could possibly be easily broken if someone would just try.

James Morrison did exactly that on July 25th, 2009, in a brand-new Roadster Sport (delivered two days earlier) with Tesla's high performance tires. In my experience, you don't necessarily get the best time with a full pack, there are too many other factors, like pack temperature, PEM temperature, tire temperature, etc. You have to be charged up high enough that you're PEM-limited, but I don't think there's anything magic about 100%.

 

[qwk]

Really? There are tens of thousands of street-legal ICE cars that can pull a 10.4-second quarter mile? White Zombie is a 9-second car and still has headlights, tail lights, a passenger seat, a radio, carpet, etc. When John is ready, his team will break the 10-second barrier, then be banned from sanctioned drag racing because of the required safety upgrades (certified driver, certified frame, parachute).



James Morrison did exactly that on July 25th, 2009, in a brand-new Roadster Sport (delivered two days earlier) with Tesla's high performance tires. In my experience, you don't necessarily get the best time with a full pack, there are too many other factors, like pack temperature, PEM temperature, tire temperature, etc. You have to be charged up high enough that you're PEM-limited, but I don't think there's anything magic about 100%.

Absolutely, It's not that difficult or even expensive to put an ICE into single digits anymore. Go to LS1tech.com and see how many turbo ls1 cars exist. This isn't 1980 anymore.

Here are some link to what James(current roadster sport recold holder posted). Read Post #3.

Motor Trend: 2010 Roadster Sport

Now read post #1

Tesla Roadster Sport NEDRA record 12.643 at 1/4 mile

So a 75% charge will get you the best times? I really doubt it. That was the state of charge for the record breaking run BTW.

 

[tomsax]

So a 75% charge will get you the best times? I really doubt it. That was the state of charge for the record breaking run BTW.

That's my point exactly. James didn't start his runs at 75%, his state of charge was higher than that on many of his runs, but he got his best run at 75%. My experience in a 2008 is similar: I can start at the top of Performance mode and my times get better as the car warms up.

Your statement was that someone should try with a full Performance mode charge. We have. It's a good place to start, but it isn't the only factor in getting the best time.

You can doubt all you want, but you're arguing with someone who has actually spent a fair amount of time at the track with a number of other Roadster owners trying all sorts of things to improve our times with help from people who have years of experience drag racing.

 

[qwk]

That's my point exactly. James didn't start his runs at 75%, his state of charge was higher than that on many of his runs, but he got his best run at 75%. My experience in a 2008 is similar: I can start at the top of Performance mode and my times get better as the car warms up.

Your statement was that someone should try with a full Performance mode charge. We have. It's a good place to start, but it isn't the only factor in getting the best time.

You can doubt all you want, but you're arguing with someone who has actually spent a fair amount of time at the track with a number of other Roadster owners trying all sorts of things to improve our times with help from people who have years of experience drag racing.

Believe me, I know that there are many factors in getting record breaking track times. I'm not trying to argue, just pointing out very simple things. I used to basically live at the track. I have probably close to 1k passes down numerous drag strips. I know what works and what doesn't. Although I have never taken an EV down the track, a lot of the same things still apply.

Look at post #12 here. It seems to contradict what you are saying. Has anyone really got a run in with a fully warmed up Roadster sport at close to 100% charge? Yes, the sport is much quicker than a base model, so comparing the two and taking it as gospel is not the best idea.

Tesla Roadster Sport NEDRA record 12.643 at 1/4 mile

 

[tomsax]

You're right, James charged up in Range mode then switched to Performance mode to drive, based on advice we got from Tesla. It's the same state-of-charge, but there may be a small difference it how warm the battery is allowed to get in the two modes. Do you know what the temperature difference is?

 

[slcasner]

That's my point exactly. James didn't start his runs at 75%, his state of charge was higher than that on many of his runs, but he got his best run at 75%. My experience in a 2008 is similar: I can start at the top of Performance mode and my times get better as the car warms up.

That's because you burn off some of those heavy electrons so the car is lighter! :wink:

 

[qwk]

You're right, James charged up in Range mode then switched to Performance mode to drive, based on advice we got from Tesla. It's the same state-of-charge, but there may be a small difference it how warm the battery is allowed to get in the two modes. Do you know what the temperature difference is?

No.

Range mode lets the battery run warmer, but doesn't preheat it like performance mode does. Basically, I and others think that the best times will come with a close to 100% charge with the battery warmed up.

The problem is that it would take someone dedicated enough to breaking the record, who would be willing to get a full performance mode charge at the track right before a run. Since that is a lot of waiting around while not making any runs with the car while others are, I'm not really surprised that it hasn't happened.

 

[W.Petefish]

Guys,

Can we stay on topic please??

 

[S-2000 Roadster]

It seems that a lot of Tesla Roadster owners are completely new to the concept of High Performance and Ultra High Performance tires.

I would say that it's fair to call the "standard" tires "High Performance," especially compared to what most folks drive (unless they have autocross experience). The AD07s are called "Extreme Performance Summer" tires and the Sport upgrades are racing tires. From the point of view of the two OEM tires, it's reasonable to call them "standard" and "sport," but when you compare prices, treadwear, and value for dollar versus other street tires, you really need to change your perspective. The standard here is not the same as standard on the typical car lot.

Those readers who run autocross and work with tire shops who cater specifically to autocross clients already know what I'm trying to say. But I see a lot of surprised comments from people in this thread who seem to think that the Tesla Roadster tires are unacceptable from their point of view - and I just want to say that there is a huge market for tires with the same high prices and short lifespans.

I wanted new tires before driving to Portland for drag racing.

I used to shop at Puget Sound Tire for all of my sports cars - alas, they're out of business now. But when they sold me tires for a track day on the week of a race, they always shaved the tires to get the traction up to par. I suppose that a trip from Seattle to Portland might be just enough to wear in new tires, but I'm still a little surprised that you raced on brand new tires. I suppose 175 miles (SEA to PDX) is a bit more than the 50 miles from PST to SIR, but it's well shy of the 500 miles mentioned in some of the postings here.

In other words, I wonder how much your results were affected by running on brand new tires.

... then again, I don't suppose you had a trailer with a second set of wheels and tires, did you?

 

[dsm363]

I just replaced my rear tires with new AD07s after 7,700 miles. I still had 3.5mm tread depth in the rears but the new tires are much quieter and seem to have better grip (of course). I'm thinking I may replace them sooner than I did last time or maybe try some of the other tires people have talked about.

 

[tomsax]

In other words, I wonder how much your results were affected by running on brand new tires.

My statement wasn't clear. I wanted new tires for safety. I wasn't concerned about track performance, I was concerned about hitting wet roads on the trip and getting sideways or upside down. My drag racing times were not stellar on that trip, although others were having problems getting good times as well.