P100D, 760HP and Performance Tests

[WarpedOne]

I would think a larger rotating mass would be much less efficient under acceleration but more efficient at regeneration and cruise.

1. Whatever went into rotation will come out when slowing down.
2. Difference in rotor weight is negligible compared to car weight
3. When going with steady speed weight does not make any difference.

So, why lower efficiency of bigger motor at steady highway driving?

 

[TIppy]

Why?
I mean what physical process would result in this lower efficiency?

Because of the aerodynamic efficiency of the model s, it only needs about 15 hp to cruise at highway speed. That's way over on the left side of the efficiency plot. Doubling the horsepower would push it even farther to the left.

So touchy. Why so hostile with the dislike of my post?

 

[St Charles]

Exactly the rimac has 4 motors and 4 gearboxes so it can have 4 wheel torque vectoring. Rimac can make a transmission, why can't tesla? Just because they failed when they were first attempting it? Ever heard of a power glide? 2 gears and very compact and used for launching cars with 3000+hp and equally crazy torque numbers. They cans be built to be strong, reliable, and compact.

Now the argument of does the model s need one, I would say no. The model is is luxury street sedan, not a performance one or a sports car. But if you don't think it would benefit from it or it can't be done reliably, you are delusional. I do maybe think that you should be able to option for a 2 speed trans on the high power model s's.

A Powerglide?! You can't be serious. There are a million reasons why this is a bad idea. But that's not the point. Transmissions are about working around the inherent flaws of an IC engine. Namely, that it must be constantly spinning and has a very limited RPM range. Neither of these are a problem with electric cars.

Let's keep in mind that transmissions are a MASSIVE point of failure. I giggled a bit when you claimed that they could be made to be reliable. They can't; especially in the low volumes that Tesla would need.

Tesla is good at one thing, making batteries. They are OK at making drive units and sort of OK at making cars in general. I do not see the benefit of adding another mechanically complicated component.

 

[Saghost]

Exactly the rimac has 4 motors and 4 gearboxes so it can have 4 wheel torque vectoring. Rimac can make a transmission, why can't tesla? Just because they failed when they were first attempting it? Ever heard of a power glide? 2 gears and very compact and used for launching cars with 3000+hp and equally crazy torque numbers. They cans be built to be strong, reliable, and compact.

Now the argument of does the model s need one, I would say no. The model is is luxury street sedan, not a performance one or a sports car. But if you don't think it would benefit from it or it can't be done reliably, you are delusional. I do maybe think that you should be able to option for a 2 speed trans on the high power model s's.

I'm pretty sure the Rimac has four motors and two gear boxes (depending on what you mean by gearboxes) - the front wheels are on single speed reduction gears like the S and X have (separately for each wheel), while the rear wheels each have what they described as a two speed dual clutch gearbox - which sounds to me like they have all the gears permanently meshed and spinning, and they just switch what clutch is engaged to go from low to high.

In theory the S might benefit from something like this dual clutch two speed if they keep extending the speed range and get stickier rubber. Keeping the front motor smaller and on the single speed means that highway cruise efficiency doesn't have to suffer - in fact, in theory you could clutch the rear motor(s) out entirely and leave it/them stopped during cruise with that setup (though that would mean a slight delay before you could deliver power from it.)

 

[St Charles]

1. Whatever went into rotation will come out when slowing down.
2. Difference in rotor weight is negligible compared to car weight
3. When going with steady speed weight does not make any difference.

So, why lower efficiency of bigger motor at steady highway driving?

I'm mainly going on the effects of flywheel weight on an ICE car. Rotational inertia will have a more profound affect against the total weight of the vehicle. It's realistically a small difference but quantifiable in drag/road racing.

 

[lolachampcar]

We might want to slow down on using Rimac as an example of anything. They are a boutique builder with no track record of producing BeVs. I can only imagine the learning curve they have in front of them if they succeed in producing even a reasonable number of these cars.

 

[theboom1]

A Powerglide?! You can't be serious. There are a million reasons why this is a bad idea. But that's not the point. Transmissions are about working around the inherent flaws of an IC engine. Namely, that it must be constantly spinning and has a very limited RPM range. Neither of these are a problem with electric cars.

Let's keep in mind that transmissions are a MASSIVE point of failure. I giggled a bit when you claimed that they could be made to be reliable. They can't; especially in the low volumes that Tesla would need.

Tesla is good at one thing, making batteries. They are OK at making drive units and sort of OK at making cars in general. I do not see the benefit of adding another mechanically complicated component.

Do you seriously think I mean to actually use a powerglide? Come on now. I was just using it as an example of a compact transmission that can take a lot of power. Electric motors have a flaw to, the faster you go the power drops off significantly, for a performance car that's deal breaking.

Reliability might be an issue on 6,7,8,10 speeds that a lot of cars are using now but a 2 speed can be almost flawless. If you have it as a dual clutch then the only thing to go wrong other then the shafts or gears just straight up breaking is a clutch to wear out and if designed right, the clutch would last a long time.

Formula e uses multi speed transmissions FYI...

I'm pretty sure the Rimac has four motors and two gear boxes (depending on what you mean by gearboxes) - the front wheels are on single speed reduction gears like the S and X have (separately for each wheel), while the rear wheels each have what they described as a two speed dual clutch gearbox - which sounds to me like they have all the gears permanently meshed and spinning, and they just switch what clutch is engaged to go from low to high.

In theory the S might benefit from something like this dual clutch two speed if they keep extending the speed range and get stickier rubber. Keeping the front motor smaller and on the single speed means that highway cruise efficiency doesn't have to suffer - in fact, in theory you could clutch the rear motor(s) out entirely and leave it/them stopped during cruise with that setup (though that would mean a slight delay before you could deliver power from it.)

Ya that's what I mean. A single speed in the front and a two speed in the back. While I could like tesla to go the 4 independent motor route like rimac, this is not a performance built car so just one for both rear wheels would be fine. If the transmission is designed like you say (I think it it) than other than clutch wearing out, it's flawless.

 

[Cloxxki]

We might want to slow down on using Rimac as an example of anything. They are a boutique builder with no track record of producing BeVs. I can only imagine the learning curve they have in front of them if they succeed in producing even a reasonable number of these cars.

Rimac quickly making friends. They made the Koenigsegg Regera possible.
If they have 3 cars to build, I'm sure they culd get someinsights there, or even borrow some production engineers and planners.

If 1850kg, I suppose that's not too bad a penalty onto the 918 at +200kg. Both AWD.
Rimac has not initial power on tap, like a Tesla versus many "normal" supercars. At higher speeds...we'll have to see howRimac's cooling works. Would 4 motors be easier to cool than 2? Models S tends to dotted-line below 200kW in circuit use. Not enough to go 300kph, let alone more. Very curious to learn what exactly the Rimac can do, beyond the short straight line.

 

[ggnykk]

I have a p100d coming this week with 21 staggered setup, and it is my first Tesla. The wheel situation drives me crazy, as I'm used to having the same diameter front and rears on awd cars. With the Tesla, It seems better to have the taller rears, as I'm considering getting a set of 20's with 245/40 and 275/40 rears, which would be even taller rears. 285/35 would be closer match to front diameter, but if taller rears is an advantage in acceleration given to supreme torque, maybe that is the way to go? Does the speedo correct itself going to taller rears? Thanks

I don't think taller rear means better acceleration. On the flip side, raising the rear means the entire top section of your car will be a giant spoiler, creating drag and down force. The higher your raise the rear, the greater the angle of that huge "spoiler", the greater the drag. Reducing range and efficiency for your everyday driving.

 

[ggnykk]

You don't want tall for best acceleration. You want a small diameter tire. The torque curves were designed for the 19" all season tires. To make use of any more grip, you have to go with a tire/wheel combination that has less rotating mass (moment of inertia) or is smaller in diameter than the 19" tire/wheel combination that comes stock.

Depends on what you mean by "diameter", if you are talking about smaller overall diameter of the entire wheel, then you get WORSE acceleration time coz the contact area with the ground is smaller.

You want light weight for your overall wheel weight for sure, like you suggested.

 

[ggnykk]

Where would Tesla fit a transmission in the Model S? Keep in mind that first they would have to mechanically link the two motors via a driveshaft and the link that to a transmission. All this would come at the cost of space for the battery.

Alternatively, you could just drop the front motor entirely but that seems very counterproductive to the goal.

Given that transmission are a significant point of failure in just about every vehicle ever made, why add one when it clearly is not necessary?

The Model S can barely complete a single lap at full load at almost any road course. Perhaps a better cooling system is the answer.

there is already a one-gear transmission that is sandwiched right between the electric motor and the inverter at the rear axle of the car.

Definitely a very costly re-design if they go for a 2-gear transmission, but it won't take the battery space for sure.

 

[AndreyATC]

We might want to slow down on using Rimac as an example of anything. They are a boutique builder with no track record of producing BeVs. I can only imagine the learning curve they have in front of them if they succeed in producing even a reasonable number of these cars.

+1
It hard to tell how tranny and motors are going to hold up overtime with Rimac
And i believe they use lifepo4 battery pack, which i think is inferior tech to Teslas
It may take a few years before they work out major kinks

 

[St Charles]

Do you seriously think I mean to actually use a powerglide? Come on now. I was just using it as an example of a compact transmission that can take a lot of power. Electric motors have a flaw to, the faster you go the power drops off significantly, for a performance car that's deal breaking.

Reliability might be an issue on 6,7,8,10 speeds that a lot of cars are using now but a 2 speed can be almost flawless. If you have it as a dual clutch then the only thing to go wrong other then the shafts or gears just straight up breaking is a clutch to wear out and if designed right, the clutch would last a long time.

Formula e uses multi speed transmissions FYI...

Ya that's what I mean. A single speed in the front and a two speed in the back. While I could like tesla to go the 4 independent motor route like rimac, this is not a performance built car so just one for both rear wheels would be fine. If the transmission is designed like you say (I think it it) than other than clutch wearing out, it's flawless.

You are right, I said the powerglide wasn't the point. It is, however, a very bad example. It was a flawed transmission that had the sole benefit of 20+ years of aftermarket development and support. There is no such thing as a flawless transmission, period.

Formula E is also a bad example as there are only two allowed car configurations. Single motor with a transmission and dual motor without.

 

[ggnykk]

+1
It hard to tell how tranny and motors are going to hold up overtime with Rimac
And i believe they use lifepo4 battery pack, which i think is inferior tech to Teslas
It may take a few years before they work out major kinks

My understanding is that they use Formula One technology. The Koenigsegg Regera hypercar that cost almost 3 million dollars also use Rimac's battery technology. If I am not mistaken, the Formula E racing cars also use Rimac's technology. At least both Rimac and Koenigsegg claims that the battery has the highest energy density in the world and it is super light weight. Rimac got a lot more credibility than you may assume.

 

[lolachampcar]

I'm not saying they are not capable. I just see a huge gulf between a couple off boutique shop and Tesla's putting tens of millions of miles on a large fleet of packs with some rather incredible degradation numbers (to mention just one element). F1 technology sounds fancy but, in the end, that stuff only needs to last a very short period of time. A road car, presumably, will require a little more durability and longevity.

Lastly, I seem to remember that LiOn had the better energy and power density but was significantly more unstable than LiFo. If Rimac is using LiFo, that 80 KW-Hr battery must be absolutely huge.

 

[WarpedOne]

Because of the aerodynamic efficiency of the model s, it only needs about 15 hp to cruise at highway speed. That's way over on the left side of the efficiency plot. Doubling the horsepower would push it even farther to the left.

Again, why?

So touchy. Why so hostile with the dislike of my post?

Nothing touchy i just dislike that which is wrong.

As far as I understand electric motors, for any given power output the motor that is capable of more will be more efficient than motor that is not. i.e. a 100kW motor will have higher efficiency at 50kW output than 50 kW motor.

"Big is inefficient, small is more efficient" is reasoning by analogy, it holds true for ICE therefore it holds true for electrics also. Well, it does not.

 

[ggnykk]

I'm not saying they are not capable. I just see a huge gulf between a couple off boutique shop and Tesla's putting tens of millions of miles on a large fleet of packs with some rather incredible degradation numbers (to mention just one element). F1 technology sounds fancy but, in the end, that stuff only needs to last a very short period of time. A road car, presumably, will require a little more durability and longevity.

Lastly, I seem to remember that LiOn had the better energy and power density but was significantly more unstable than LiFo. If Rimac is using LiFo, that 80 KW-Hr battery must be absolutely huge.

this is all the specs that they say about the battery
Concept_S | Rimac Automobili

• Voltage: 650V nominal
• Capacity: 82 kWh
• Rimac Automobili Battery and Thermal Management Systems

And....
Concept_One | Rimac Automobili

• Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO2) chemistry
• Voltage: 650V nominal
• Capacity: 82 kWh
• Cooling: Liquid
• Milled aluminum and sheet aluminum housing
• Rimac Automobili Battery and Thermal Management Systems
• Several layers of redundant safety and protection systems

"The Concept_One’s battery pack is designed to deliver 1MW of power during acceleration and to absorb 400 kW during braking. A unique liquid thermal management and low-resistance conducting system had to be developed in order to master this challenge. The result is a highly advanced high-performance battery pack that is designed for demanding track-use, high power delivery and safety."



Common Elon, the answer is here "Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO2) chemistry". Please copy it and put it in Tesla cars, haha ;-)

 

[TIppy]

Again, why?


Nothing touchy i just dislike that which is wrong.

As far as I understand electric motors, for any given power output the motor that is capable of more will be more efficient than motor that is not. i.e. a 100kW motor will have higher efficiency at 50kW output than 50 kW motor.

"Big is inefficient, small is more efficient" is reasoning by analogy, it holds true for ICE therefore it holds true for electrics also. Well, it does not.

Did you look at the plot I posted that shows that all induction motors are less efficient if they are used at low percentages of their full load hp?

 

[WarpedOne]

Edit: now I see the plot but cant comprehend it.

What is 120 percent of full load? What is full load efficieny at less then full load?

 

[TIppy]

I see no plot, just IMG.

It's an image labelled "Induction motor efficiency as a function of load" and shows a plot of how the efficiency drops off as you use an induction motor at less than its designed full load.

You don't see that plot?