Gen 3 Powertrain Speculation (based on current drive units)

[Kevin Harney]

400hp in a midsize is absolutely mind blowing

+100000 That is in the range of a BMW M3 (425 hp) and with more and instant torque it would blow it away. And the BMW M3 most certainly is not a typical mid size car. Audi S4 only has 333 hp AFAIK. Which is more in line with the BMW 335i coming in about 315 or so. Mustang GT 435 hp.

 

[Yggdrasill]

Can you please give logical reasons why you are all bent on this being FWD ? I believe that you are wrong and have stated many reasons as have others but you have no concrete reasons other than "I said so".

You stated that if they wanted a AWD car that the lesser version should be FWD rather than RWD but WHY? Please elaborate cause I am missing your point. I would need a REALLY good reason to pick a lesser and inferior technology. Can you list some reasons please.....

Several reasons have been stated repeatedly, by myself and others:

- Better space utilization.
- Cost reductions.
- Better regen.
- Better reputation in snowy regions.

AND can you name even one car that will be in the class of the Model 3 that has 700-800 hp please. I think most people with cars this size would be VERY happy with 400 hp. Even the Model S P85D only has 691 hp and that is a MUCH larger car and has AMAZING performance.

Firstly, I said 600-700 hp, not 700-800 hp. Secondly, no, I can't name a single car in the Model 3 class that has 600-700 hp. That's why it's mind-blowing and that's why Tesla will probably do it. (600 hp seems about right.)

 

[JRP3]

First I would say that if the Model 3 would only use the small motors, I'd agree that it would be more likely that the base model 3 would be RWD. But if it only used the small motors, that would be a bit disappointing. It would then have around 400 hp maximum, which isn't mind-blowing. 600-700 hp, however, that would be mind-blowing. (0-60 in 2.8 seconds, anyone?)

Why would you think that Tesla is going to target insane levels of power in their mass market affordable car, even the higher end version? They should leave that for the next generation Roadster, and I expect they will.

Several reasons have been stated repeatedly, by myself and others:

- Better space utilization.

No, as has been explained.

- Cost reductions.

No, as has been explained.

- Better regen.

Slightly better in limited situations.

- Better reputation in snowy regions.

That's what the AWD versions will provide. Besides, the RWD Model S has a pretty good reputation for snow handling.

Firstly, I said 600-700 hp, not 700-800 hp. Secondly, no, I can't name a single car in the Model 3 class that has 600-700 hp. That's why it's mind-blowing and that's why Tesla will probably do it. (600 hp seems about right.)

Not likely, for reasons stated above. Plus with the low end torque provided by electric drive you don't need those types of HP levels to provide great acceleration numbers, especially in a lighter vehicle.

 

[Yggdrasill]

Why would you think that Tesla is going to target insane levels of power in their mass market affordable car, even the higher end version?

Because they can. Because there will be demand. Implementing insane levels of power in an EV is relatively cheap, compared to doing so in an ICE. Playing to one's strengths is just smart.

They should leave that for the next generation Roadster, and I expect they will.

They might. We'll see.

No, as has been explained.
No, as has been explained.

Opinions clearly differ.

 

[tga]

Because they can. Because there will be demand. Implementing insane levels of power in an EV is relatively cheap, compared to doing so in an ICE. Playing to one's strengths is just smart.

They might. We'll see.

Opinions clearly differ.

Several of us have made compelling arguments why the old ICE mantra of "FWD is cheaper" shouldn't apply. I still haven't heard you explain your side, beyond stating "Several reasons have been stated repeatedly, by myself and others" without references (without references, that statement doesn't really count, IMHO).

You seem to feel that if the config is FWD/AWD, then FWD means "small motor in front" and AWD means "add a motor to the rear with the same front motor", and if the config is RWD/AWD, then RWD means big motor in the rear and AWD means (different) small motor in the rear and small motor in the front. Therefore you conclude that RWD/AWD is more complicated because of the need to support 2 different rear motors.

We've seen no evidence to support this argument. I could just as easily state that a FWD car will have a big motor, and and an AWD version will have 2 smaller motors, necessitating supporting 2 front motor sizes.

Whatever. I'm done tilting at this windmill. Others can take up the charge if they care.

 

[JRP3]

Because they can. Because there will be demand. Implementing insane levels of power in an EV is relatively cheap, compared to doing so in an ICE. Playing to one's strengths is just smart.

In this case it's counter to the purpose of the Model 3, as well as unnecessary.

Opinions clearly differ.

Sure, but you stated cost reductions and space gains as fact, when not only is it not necessarily so but there is good evidence to suggest it's not. The large rear S motor does not impact the usable area of the car but the small front motor does, which is in direct conflict with your premise.

 

[mikes_fsd]

Because they can. Because there will be demand. Implementing insane levels of power in an EV is relatively cheap, compared to doing so in an ICE. Playing to one's strengths is just smart.

They might. We'll see.

Opinions clearly differ.

Lets try facts, Tesla Model S is known and shown to be an AWESOME (this is standard RWD... not the D) winter driving car.
People in Norway know cold, there are many video's on YouTube and there are several articles on this subject, I am just posting a couple links:
Tesla Model S Cold Weather Range Test Norway ENGLISH SUB - YouTube
and
Can a Tesla electric car handle the harsh winter of Norway? : TreeHugger

You do have to watch the videos.... they specifically talk about handling in there.

Please stop with the BS that FWD is better for winter/snowy/icy driving.
Tesla has insane ability to control traction at the sub-second level for each wheel.

Agree that FWD on an ICE (internal combustion engine) car FWD is "better" for winter, but even then you will find cars and people that can prove that statement wrong.

 

[Yggdrasill]

Several of us have made compelling arguments why the old ICE mantra of "FWD is cheaper" shouldn't apply. I still haven't heard you explain your side, beyond stating "Several reasons have been stated repeatedly, by myself and others" without references (without references, that statement doesn't really count, IMHO).

I guess you missed this post, given that you haven't responded: Gen 3 Powertrain Speculation (based on current drive units) - Page 4

Also, in a discussion, the opponent is the judge of whether an argument is compelling.

You seem to feel that if the config is FWD/AWD, then FWD means "small motor in front" and AWD means "add a motor to the rear with the same front motor", and if the config is RWD/AWD, then RWD means big motor in the rear and AWD means (different) small motor in the rear and small motor in the front. Therefore you conclude that RWD/AWD is more complicated because of the need to support 2 different rear motors.

We've seen no evidence to support this argument. I could just as easily state that a FWD car will have a big motor, and and an AWD version will have 2 smaller motors, necessitating supporting 2 front motor sizes.

You haven't quite gotten my position right. I believe that you will have at least two configurations, but probably three configurations.

1. A single small motor
2. Two small motors (could possibly be dropped)
3. Small motor in front, big motor at rear.

And I think it is more likely than not that in the first configuration, the small motor will be in the front. If this is the case, the front of the car will be identical across all three configurations. If the small motor is at the rear, I think you would also need to be able to accomodate a big motor at the rear in the high end configuration, which adds complexity.

 

[Yggdrasill]

In this case it's counter to the purpose of the Model 3, as well as unnecessary.

I disagree that it is counter to the purpose of the Model 3. Tesla shouldn't make a glorified Leaf. The high-end version should be mind-blowing, generate lots of PR and really sell the low-end version. Just like the P85D helps in selling the 85D.

Sure, but you stated cost reductions and space gains as fact, when not only is it not necessarily so but there is good evidence to suggest it's not.

There's no evidence that's been presented in this thread. Some arguments have been made which I have objected to.

That said, I did not present the elements as fact. These are my opinions which I restated at the request of Kevin Harney. (He apparently missed them the first few times I stated them.) It is quite obvious that a thread such as this (as well as this subforum) will be rife with opinion and speculation.

The large rear S motor does not impact the usable area of the car but the small front motor does, which is in direct conflict with your premise.

That's a ridiculous statement. The Model S isn't sold with FWD only, so you have absolutely no idea how much useable space one would get at the back with FWD only. Furthermore, it is a fact that the volume of the rear DU is greater than the volume of the front DU, so it is reasonable to expect that a FWD Model S would get more luggage space at the back than it would lose at the front.

But even if the volume taken up by each DU was identical, there are benefits to having the volume as one big space rather than two smaller spaces. When carrying a big object, it's not too easy to put a third of the object in the frunk and two thirds of the object in the trunk. These considerations will be a lot more important on the Model 3, given that there is less space to work with in the first place. The frunk is a luxury that I think the Model 3 would be better off without.

- - - Updated - - -

Lets try facts, Tesla Model S is known and shown to be an AWESOME (this is standard RWD... not the D) winter driving car.
People in Norway know cold, there are many video's on YouTube and there are several articles on this subject, I am just posting a couple links:
Tesla Model S Cold Weather Range Test Norway ENGLISH SUB - YouTube
and
Can a Tesla electric car handle the harsh winter of Norway? : TreeHugger

You do have to watch the videos.... they specifically talk about handling in there.

Please stop with the BS that FWD is better for winter/snowy/icy driving.
Tesla has insane ability to control traction at the sub-second level for each wheel.

Agree that FWD on an ICE (internal combustion engine) car FWD is "better" for winter, but even then you will find cars and people that can prove that statement wrong.

I never said the RWD Model S was bad on snow. I merely said that FWD has a better *reputation* on snow, just as RWD has a better *reputation* for sportiness. Actual handling characteristics may vary.

 

[stopcrazypp]

That's a ridiculous statement. The Model S isn't sold with FWD only, so you have absolutely no idea how much useable space one would get at the back with FWD only. Furthermore, it is a fact that the volume of the rear DU is greater than the volume of the front DU, so it is reasonable to expect that a FWD Model S would get more luggage space at the back than it would lose at the front.

But even if the volume taken up by each DU was identical, there are benefits to having the volume as one big space rather than two smaller spaces. When carrying a big object, it's not too easy to put a third of the object in the frunk and two thirds of the object in the trunk. These considerations will be a lot more important on the Model 3, given that there is less space to work with in the first place. The frunk is a luxury that I think the Model 3 would be better off without.

I think JRP3 already alluded to the reasons in a previous post. The front motor necessitates a more vertical (higher) positioning of the motor because of proximity of the steering components.
http://www.myperfectautomobile.com/wp-content/uploads/2012/02/Tesla-Motor.jpg

On the other hand, the RWD drivetrain fits low between the rear axle. You might be able to gain a bit more space under the load floor right behind the rear seats, but you need a rear axle there anyways, so the savings look to be very minimal.
http://www.wired.com/wp-content/upl.../images/2105testimages/electriccars_large.jpg

In daily use, a frunk seems to have more use because it's a convenient enclosed space that's relatively high up in the vehicle (perfect for groceries).

Also in terms of commonality, they would have to specially carve out the extra space there too to accommodate the trunk space vs AWD version. How is this different from accommodating the space difference of a smaller motor vs a larger one (which actually has a much smaller difference)?

 

[Yggdrasill]

I think JRP3 already alluded to the reasons in a previous post. The front motor necessitates a more vertical (higher) positioning of the motor because of proximity of the steering components.
http://www.myperfectautomobile.com/wp-content/uploads/2012/02/Tesla-Motor.jpg

On the other hand, the RWD drivetrain fits low between the rear axle. You might be able to gain a bit more space under the load floor right behind the rear seats, but you need a rear axle there anyways, so the savings look to be very minimal.
http://www.wired.com/wp-content/upl.../images/2105testimages/electriccars_large.jpg

It's obvious from the first picture that with a slightly different sized battery pack, you would be able to rotate the front DU back, so that the widest portion is facing down, at an angle towards the battery pack. From the second picture it is obvious that if you didn't have the rear motor there, you could lower the load floor by about as much as the radius of the inverter, and get more space in the main storage area. Of course, the issue is not how things are currently in the Model S, but how they will be in the Model 3. Tesla has a lot of options for moving things around to utilize the space as optimally as possible. Tesla doesn't have to use a straight rear axle if they go for FWD. It's currently more common to go for a split axle, allowing you to use the space at the rear all the way down.

Tesla has a lot of freedom, but the primary limitation is the space requirement of the DU, which is similar regardless of where you place it.

In daily use, a frunk seem to have more use because it's a convenient enclosed space that's relatively high up in the vehicle (perfect for groceries).

The question is, how big would the frunk of the Model 3 be? I would guesstimate that the frunk of the Model 3 would be tiny; maybe big enough for two bags of groceries. Is it worth it, at the cost of a smaller luggage space at the back? I'm leaning towards no.

 

[Yggdrasill]

Actually, when I think about it, doesn't the Model S already have a split axle? So, once you rip out the drive axle, you can use the space all the way down with minimal modification.

Edit: Yes, looking at the schematics, the load-bearing seems to be done by three suspension joints mounted to the drive unit frame. You could dispense with the drive axle without using a solid rear axle. This means that you can remove the guts of the drive unit and use the space for storage. You would need to redesign the drive unit frame and suspension to use the whole width, though.

 

[ratsbew]

Many people are frightened to death of driving a rear wheel drive car in the snow. You can argue about great traction control algorithms and such but it's a big deal and an easier sell in the mass market.

The fact is that FWD DOES perform MUCH better in the snow. With FWD you have power to the steering wheels and they can claw away at the fresh snow. With RWD you have to push non-driven wheels through the fresh snow and they are more like skis. This is a FACT. I'm sure many of you don't have vast experience driving in snow.

I find this whole conversation funny though, because this isn't a track car where you need RWD. FWD is just fine for a mass market car. The AWD model will address those of us (myself included) who want better performance and traction.

- - - Updated - - -

What if Tesla throws a curve ball and moves to independent hub based motors? This eliminates differentials and transmissions all together and would provide SUPERIOR traction control to anything ever seen before. It would be a departure from what we've seen to date and would allow TONS of internal storage volume both front and rear.

This doesn't solve the FWD vs RWD argument, but I honestly think it could be Tesla style of engineering.

 

[Yggdrasill]

The fact is that FWD DOES perform MUCH better in the snow. With FWD you have power to the steering wheels and they can claw away at the fresh snow. With RWD you have to push non-driven wheels through the fresh snow and they are more like skis. This is a FACT. I'm sure many of you don't have vast experience driving in snow.

I find this whole conversation funny though, because this isn't a track car where you need RWD. FWD is just fine for a mass market car. The AWD model will address those of us (myself included) who want better performance and traction.

I unfortunately only have experience with FWD and AWD in the snow, so I can't say anything about how bad RWD is in the snow. But I'm sure the actual experiences will depend on the circumstances. The Model S is reportedly great for getting up hills and such in the snow, because the traction control is great. If we're talking about fine manouvering at low speeds on supersmooth ice covered in snow, like I sometimes have to do when getting out of my driveway, I would expect that the Model S wouldn't be too great. I would expect the front wheels to get covered in compacted snow and be fairly useless.

What if Tesla throws a curve ball and moves to independent hub based motors? This eliminates differentials and transmissions all together and would provide SUPERIOR traction control to anything ever seen before. It would be a departure from what we've seen to date and would allow TONS of internal storage volume both front and rear.

This doesn't solve the FWD vs RWD argument, but I honestly think it could be Tesla style of engineering.

I strongly doubt it. Hub-motors are terrible because of unsprung weight. The top speed would probably also be pretty bad. And I'm not sure if there are any three phase induction hub motors on the market. Tesla might have to toss out all their technology from the Roadster and Model S and start from scratch.

I think the next Roadster could have four (internally mounted) motors and torque vectoring, though.

 

[ratsbew]

I strongly doubt it. Hub-motors are terrible because of unsprung weight. The top speed would probably also be pretty bad.

I was thinking something along the line of a pancake motor mounted to the frame with a short driveshaft to each wheel. There could be a planetary gearset to take care of speed reduction.

I can imagine a Model S sized frunk and a rear storage area that goes under the rear passenger seats.

 

[Yggdrasill]

I was thinking something along the line of a pancake motor mounted to the frame with a short driveshaft to each wheel. There could be a planetary gearset to take care of speed reduction.

Then you're not talking about hub motors, but more a configuration like the Rimac Concept One or Mercedes SLS AMG Electric Drive.

 

[JRP3]

I disagree that it is counter to the purpose of the Model 3. Tesla shouldn't make a glorified Leaf.

Which of course they will not, and to even suggest such a comparison is absurd and only further weakens your argument. 600-700 hp is not necessary to avoid making a "glorified LEAF", which has 110 hp.

That's a ridiculous statement. The Model S isn't sold with FWD only, so you have absolutely no idea how much useable space one would get at the back with FWD only.

Actually you do, it would be some fraction of the rear motor and gear drive volume. That would only provide a small well behind the rear seat. How many people pack their car to the roof where that little bit of space would make a meaningful difference?

Furthermore, it is a fact that the volume of the rear DU is greater than the volume of the front DU, so it is reasonable to expect that a FWD Model S would get more luggage space at the back than it would lose at the front.

Not that's not reasonable since a single motor FWD S would have to use the same sized large motor in the front for similar performance. Though because of weight transfer a FWD S would not have the same traction and thus less acceleration. There is a reason no drag racers use FWD.

But even if the volume taken up by each DU was identical, there are benefits to having the volume as one big space rather than two smaller spaces. When carrying a big object, it's not too easy to put a third of the object in the frunk and two thirds of the object in the trunk.

Please describe this large object that takes up all the rear space but also drops down into the small well left by the rear motor/gear drive removal.

 

[Kevin Harney]

I guess you missed this post, given that you haven't responded: Gen 3 Powertrain Speculation (based on current drive units) - Page 4

Also, in a discussion, the opponent is the judge of whether an argument is compelling.
You haven't quite gotten my position right. I believe that you will have at least two configurations, but probably three configurations.

1. A single small motor
2. Two small motors (could possibly be dropped)
3. Small motor in front, big motor at rear.

And I think it is more likely than not that in the first configuration, the small motor will be in the front. If this is the case, the front of the car will be identical across all three configurations. If the small motor is at the rear, I think you would also need to be able to accomodate a big motor at the rear in the high end configuration, which adds complexity.

OH I finally see where you are coming from. I would suggest that if this were to happen yes the middle option would be dropped or never implemented in the first place really and you shou7ld have 2 configurations left and larger motor in the rear and an optional smaller one in the front for the AWD version. That being said you argument has no further advantages.

- - - Updated - - -

The fact is that FWD DOES perform MUCH better in the snow. With FWD you have power to the steering wheels and they can claw away at the fresh snow. With RWD you have to push non-driven wheels through the fresh snow and they are more like skis. This is a FACT. I'm sure many of you don't have vast experience driving in snow.

The reason a FWD performs better in the snow is that it has a heavy ICE over the wheels. And this is not true for an EV so that benefit is lost. It is also true that a FWD performs worse when there is not a lot of snow (for most of us 99% of the time). FWD has no benefits here like an ICE. Cost is not saved and winter handling are lost. Be careful what you post as fact when it is mostly blatantly wrong.

 

[Yggdrasill]

Which of course they will not, and to even suggest such a comparison is absurd and only further weakens your argument. 600-700 hp is not necessary to avoid making a "glorified LEAF", which has 110 hp.

The comparison to the Leaf was perhaps an exaggeration, but as others pointed out earlier, the competition has around 400 hp, so Tesla should aim to beat that by a good margin in the Model 3. If Tesla designs the Model 3 to beat the BMW M3 (425 hp) with an equal margin that the P85D (691 hp) beats the M5 (560 hp), the Model 3 should have 524 hp. That would also be sufficiently mind-blowing, in my view. Around 400 hp, however, would be a bit disappointing.

Please describe this large object that takes up all the rear space but also drops down into the small well left by the rear motor/gear drive removal.

Looking at the picture stopcrazypp posted: http://www.wired.com/wp-content/uploads/blogs/magazine/wp-content/images/2105testimages/electriccars_large.jpg

I would estimate that you could increase the size of the space behind the rear seats (between the parcel shelf and the load floor) by around 50%, by dropping the entire load floor right down to the bottom of the car. In my view, that's significant. Now, this would require not only removing the motor/inverter/reduction gear, but you would also need to redesign the suspension and the frame. This is not ideal on the Model S, but completely unproblematic when designing the Model 3 from scratch.

 

[Kevin Harney]

The comparison to the Leaf was perhaps an exaggeration, but as others pointed out earlier, the competition has around 400 hp, so Tesla should aim to beat that by a good margin in the Model 3. If Tesla designs the Model 3 to beat the BMW M3 (425 hp) with an equal margin that the P85D (691 hp) beats the M5 (560 hp), the Model 3 should have 524 hp. That would also be sufficiently mind-blowing, in my view. Around 400 hp, however, would be a bit disappointing..

I do not think 425 hp with instant 400+ ftlbs of torque would be even remotely disappointing. In fact I think it would quite the opposite. Most ICEs in this category have about 400 ft/lbs of torque but it is not instant or efficiently used.