nozferatu
Posts: 575
Joined: Sat Feb 01, 2014 4:47 pm

Re: 2015 Chevy Spark EV specifications

Sun Feb 23, 2014 11:02 pm

Nashco wrote:Other way around, 2014 is 3.17 and 2015 is 3.87, which means if they use the exact same motor torque curve the 2015 will accelerate faster but have a theoretically reduced top speed.

Bryce
It would be quite spectacular if they could improve the acceleration even more-so....I'd hate to lose the phenomenal midrange acceleration of the current car. I really hope they aren't that stupid to reduce the torque after touting about it so much.

Blackmamba
Posts: 24
Joined: Mon Jul 22, 2013 8:47 pm

Re: 2015 Chevy Spark EV specifications

Mon Feb 24, 2014 9:11 am

TonyWilliams wrote:
Nashco wrote:Other way around, 2014 is 3.17 and 2015 is 3.87, which means if they use the exact same motor torque curve the 2015 will accelerate faster but have a theoretically reduced top speed.

Bryce
And probably lower economy at the same speed as a 2014 model. Everything in design and engineering has a trade-off.
Top speed is governed, they just have to bump up the governed limit a bit to match things. And maybe they'll dip into the battery a bit more to match or even exceed the previous range figure.

Like Car & Driver found out, GM dotted all the i's and crossed all the t's when they developed the Spark EV. These changes are just tweaks. No major fault needing to be addressed such as what Nissan still needs to do with the Leaf - get a battery with active temperature management.

Pegasus
Posts: 126
Joined: Fri Jul 12, 2013 12:59 am
Location: Las Vegas, NV

Re: 2015 Chevy Spark EV specifications

Mon Feb 24, 2014 5:02 pm

- Late availability exterior colors for 2LT only: (G6E) Salsa and (G6F) Lime
Aw, for crying out loud! I was whining about this like crazy so I'm glad enough others have so that GM heard us, but I already have my Spark EV in Titanium! I guess I can be happy that it'll soon be a "collectable" color. :lol:

gra
Posts: 249
Joined: Fri Jul 26, 2013 3:52 pm
Location: Inner East S.F. Bay Area

Re: 2015 Chevy Spark EV specifications

Mon Feb 24, 2014 7:34 pm

nozferatu wrote:
Nashco wrote:Other way around, 2014 is 3.17 and 2015 is 3.87, which means if they use the exact same motor torque curve the 2015 will accelerate faster but have a theoretically reduced top speed.

Bryce
It would be quite spectacular if they could improve the acceleration even more-so....I'd hate to lose the phenomenal midrange acceleration of the current car. I really hope they aren't that stupid to reduce the torque after touting about it so much.
Not to mention losing the car's freeway range advantage (if they go with a shorter ratio), which to me is its primary advantage.

Blackmamba
Posts: 24
Joined: Mon Jul 22, 2013 8:47 pm

Re: 2015 Chevy Spark EV specifications

Tue Feb 25, 2014 8:50 am

gra wrote: Not to mention losing the car's freeway range advantage (if they go with a shorter ratio), which to me is its primary advantage.
You are way overestimating the effects of the change. The change difference in ratios is not that great. There still will remain a significant gap in final drive ratios between the '15 Spark EV and any other EV out there. A big gap....

The result is going to be better off the line acceleration with a minimal, if even noticeable, change in range. In fact I'll bet range numbers will stay the same or even go up a tad, as I would guess GM would tap into the battery a bit more in order to keep the EPA figures from falling.

Blackmamba
Posts: 24
Joined: Mon Jul 22, 2013 8:47 pm

Re: 2015 Chevy Spark EV specifications

Tue Feb 25, 2014 9:03 am

Blackmamba wrote:
gra wrote: Not to mention losing the car's freeway range advantage (if they go with a shorter ratio), which to me is its primary advantage.
You are way overestimating the effects of the change. The change difference in ratios is not that great. There still will remain a significant gap in final drive ratios between the '15 Spark EV and any other EV out there. A big gap....

The result is going to be better off the line acceleration with a minimal, if even noticeable, change in range. In fact I'll bet range numbers will stay the same or even go up a tad, as I would guess GM would tap into the battery a bit more in order to keep the EPA figures from falling.
Maybe the old ratio was a tad too tall for the drive motor to operate at peak efficiency.

It just might be that GM engineers determined a slight bump in ratio would move things closer to the car's mechanical 'sweet spot'.

Nashco
Posts: 537
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Location: Portland, OR

Re: 2015 Chevy Spark EV specifications

Tue Feb 25, 2014 10:57 am

I witnessed a presentation GM gave at the 2013 SAE Hybrid and EV Symposium where Steve Tarnowsky (Engineering Manager at GM) gave a presentation which included discussions on the powertrain efficiency versus performance balance and some of the reasons GM used such a unique torque/gearing selection compared to typical EV powertrains. If any of you are curious of the high level points discussed, you can see the presentation on the internet. Of course, there was more discussed than simply what you see in the pdf/powerpoint, but it gives you the highlights.

This is a link to the SAE event guide:

http://www.sae.org/events/hybridev/2013 ... _Guide.pdf

This guide includes a link to the presentations:

http://www.sae.org/events/training/symp ... aheim2013/

User: 2013Hybrid
Password: Anaheim

Which leads you to this link:

http://www.sae.org/events/training/symp ... System.pdf

In summary, there's no clarity to what the gear ratio change will be on performance for production 2015 Spark EV at this time. However, it's obvious that the improvement or reduction in range is directly related to YOUR duty cycle. It's also obvious that acceleration is not only a function of ratios versus speed, but software and hardware limitations as well. We all know that official range numbers are a valuable measurement for simple comparison sake, but that range/efficiency are very related to your duty cycle. If you travel at city speeds a lot, a higher numerical ratio will generally improve your efficiency. If you travel at highway speeds at 55 mph, the ratio change will likely improve your range slightly. If you travel at highway speeds at 75, the ratio change will likely reduce your range slightly. However, until a vehicle comes out with production software and hardware, there's no way to know for sure.

Bryce

nozferatu
Posts: 575
Joined: Sat Feb 01, 2014 4:47 pm

Re: 2015 Chevy Spark EV specifications

Tue Feb 25, 2014 2:22 pm

Nashco wrote:I witnessed a presentation GM gave at the 2013 SAE Hybrid and EV Symposium where Steve Tarnowsky (Engineering Manager at GM) gave a presentation which included discussions on the powertrain efficiency versus performance balance and some of the reasons GM used such a unique torque/gearing selection compared to typical EV powertrains. If any of you are curious of the high level points discussed, you can see the presentation on the internet. Of course, there was more discussed than simply what you see in the pdf/powerpoint, but it gives you the highlights.

This is a link to the SAE event guide:

http://www.sae.org/events/hybridev/2013 ... _Guide.pdf

This guide includes a link to the presentations:

http://www.sae.org/events/training/symp ... aheim2013/

User: 2013Hybrid
Password: Anaheim

Which leads you to this link:

http://www.sae.org/events/training/symp ... System.pdf

In summary, there's no clarity to what the gear ratio change will be on performance for production 2015 Spark EV at this time. However, it's obvious that the improvement or reduction in range is directly related to YOUR duty cycle. It's also obvious that acceleration is not only a function of ratios versus speed, but software and hardware limitations as well. We all know that official range numbers are a valuable measurement for simple comparison sake, but that range/efficiency are very related to your duty cycle. If you travel at city speeds a lot, a higher numerical ratio will generally improve your efficiency. If you travel at highway speeds at 55 mph, the ratio change will likely improve your range slightly. If you travel at highway speeds at 75, the ratio change will likely reduce your range slightly. However, until a vehicle comes out with production software and hardware, there's no way to know for sure.

Bryce
Bryce,

I tend to agree about the acceleration observations. I would venture to say that the current acceleration capabilities of the Spark EV are limited electronically rather than mechanically.

A case in point is if you compare the acceleration times of the Spark EV to the Fiat 500e. Off the line, the Fiat has the Spark beat up to about 50 mph. Not until about 50 does the Spark gain advantage. Given that the Spark and Fiat weigh roughly the same and they have similar top speeds...but the Spark has both more power and FAR more torque...the quicker off-the-line acceleration is, IMO, due to electronically limited power and torque on the Spark EV.

But going back to the minor changes for the Spark EV for 2015, I think the features I mentioned that they left out would have been really nice.

Blackmamba
Posts: 24
Joined: Mon Jul 22, 2013 8:47 pm

Re: 2015 Chevy Spark EV specifications

Tue Feb 25, 2014 3:16 pm

nozferatu wrote: Bryce,

I tend to agree about the acceleration observations. I would venture to say that the current acceleration capabilities of the Spark EV are limited electronically rather than mechanically.

A case in point is if you compare the acceleration times of the Spark EV to the Fiat 500e. Off the line, the Fiat has the Spark beat up to about 50 mph. Not until about 50 does the Spark gain advantage. Given that the Spark and Fiat weigh roughly the same and they have similar top speeds...but the Spark has both more power and FAR more torque...the quicker off-the-line acceleration is, IMO, due to electronically limited power and torque on the Spark EV.

But going back to the minor changes for the Spark EV for 2015, I think the features I mentioned that they left out would have been really nice.
I presume there are electronic limiters that are involved too, but who knows to what extent. The obvious difference between the Fiat and the SParkEV is that final drive ratio where the Spark has long legs which take longer to get rolling, but once rolling it really gets rolling - the Fiat has short legs which start fast but lose it as speed climbs.

Kind of like starting from a standstill on a bicycle with its chain in the big ring up front and the smallest ring in the back (Spark) going against a bicycle starting in the small ring up front and a larger ring at the rear (Fiat). The monster torque in the Spark keeps it from getting totally disrespected at the start.

gra
Posts: 249
Joined: Fri Jul 26, 2013 3:52 pm
Location: Inner East S.F. Bay Area

Re: 2015 Chevy Spark EV specifications

Tue Feb 25, 2014 5:35 pm

Nashco wrote:<snip>
In summary, there's no clarity to what the gear ratio change will be on performance for production 2015 Spark EV at this time. However, it's obvious that the improvement or reduction in range is directly related to YOUR duty cycle. It's also obvious that acceleration is not only a function of ratios versus speed, but software and hardware limitations as well. We all know that official range numbers are a valuable measurement for simple comparison sake, but that range/efficiency are very related to your duty cycle. If you travel at city speeds a lot, a higher numerical ratio will generally improve your efficiency. If you travel at highway speeds at 55 mph, the ratio change will likely improve your range slightly. If you travel at highway speeds at 75, the ratio change will likely reduce your range slightly. However, until a vehicle comes out with production software and hardware, there's no way to know for sure.

Bryce
Agree that an individual's duty cycle is the key to range. For me, the Spark's better range at realistic freeway speeds would be the deciding factor. For what the car is, I can see little practical benefit to a faster 0-60 time, or even improving the 0-30 time. I don't think there's any need to compete even more with the i3; neither car provides the kind of acceleration that a true gearhead will want.

I doubt that many people are finding their BEVs range-limited in all-urban surface street driving. Speeds are too low and there's lots of regen. No, where most people have range issues is with part or all-freeway commutes and similar trips at realistic speeds, and IMO that's where the major emphasis needs to be to make BEVs more mainstream.

Most states have interstate speed limits of at least 65 mph, with most western states having rural interstate limits of 70, 75 or even 80, and actual cruising speeds in unconstrained flow tend to be 5-10 mph over the speed limit. Although it is often impossible to reach those speeds at the height of rush hour, outside of those times it's quite common. For me personally, I'd happily give up a second or two 0-60 (so equivalent to a LEAF or Focus) to gain 10 or 15 miles more range at 65+ mph, and retain or improve 30-50 and 50-70 passing accel. I regard the latter as far more useful in the real world than 0-60 times; I'm not interested in drag racing, but I do have to merge with or pass traffic regularly.

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