kevin
Posts: 125
Joined: Sat Jul 27, 2013 9:52 am
Location: Los Gatos

Re: Performance Boost!?

Mon Dec 23, 2013 11:52 am

...

That's because although the spark has 400ft lbs, the software dials it down. It's quite obvious when driving.

I'd love to have performance software for the spark ev. Not only would it fix the annoying power reduction the stock software does when trying to do hard acceleration runs, but it could also help with the torque steer issue which is being caused from the software using stability control to shift which wheel is recieving more power.

Oh and think of the burnouts we'd get if we didn't have the software pulling power there too :)[/quote]

What makes you think the software is limiting the torque?

There are only two reasons form restricting the torque:
1) The traction control detects wheel spin
2) The motor hits the power limit of the battery/inverter system (~100kW)

You can disable the traction control but the maximum power output of the inverter is not controllable.

Up to about 40mph the power output of the spark is torque limited, above that speed the output is power limited and the torque reduces inversely with speed up the max speed.

With the ~3:1 final drive there is only about 1200ft-lbs of torque at the wheels. In first gear most gasoline cars can exceed that because of the ~16:1 torque. For example a my Mazda 3 has ~145ft-lbs torque and ~15:1 ratio in bottom gear, this gives it over 2000ft-lbs at the wheels.

kevin

tarmactrr
Posts: 11
Joined: Thu Nov 14, 2013 8:24 am

Re: Performance Boost!?

Thu Dec 26, 2013 9:28 am

kevin wrote: What makes you think the software is limiting the torque?

There are only two reasons form restricting the torque:
1) The traction control detects wheel spin
2) The motor hits the power limit of the battery/inverter system (~100kW)

You can disable the traction control but the maximum power output of the inverter is not controllable.

Up to about 40mph the power output of the spark is torque limited, above that speed the output is power limited and the torque reduces inversely with speed up the max speed.

With the ~3:1 final drive there is only about 1200ft-lbs of torque at the wheels. In first gear most gasoline cars can exceed that because of the ~16:1 torque. For example a my Mazda 3 has ~145ft-lbs torque and ~15:1 ratio in bottom gear, this gives it over 2000ft-lbs at the wheels.

kevin
The software is a lot like an ESC on a radio controlled car. You're correct, there is a max amperage level that the battery/motor can produce/recieve, but that's not what is happening. If it was, then you wouldn't have a larger surge of power at higher speed than at lower speed. They are limiting torque through the software, and again limiting it above 40mph because at that speed stability control cannot be defeated, so it again limits power through the stability control system. Finally I'll be willing to be that the software is setup not to give the full power allowed by the ESC, which is how they easily built the hotrod spark ev for SEMA, using the same motor/battery system in the production spark ev's.

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

Re: Performance Boost!?

Tue Feb 04, 2014 12:19 am

What's the HP/Torque curve for this car anyway?

I would imagine the real performance of this car can be appreciated in midrange acceleration...not necessarily off the line. Has anyone done or know of performance runs for 20-40, 30-50, 40-60, etc runs?

blownb310
Posts: 70
Joined: Sat May 25, 2013 7:04 pm
Location: Albany, NY

Re: Performance Boost!?

Tue Feb 04, 2014 8:50 am

tarmactrr wrote: They are limiting torque through the software, and again limiting it above 40mph because at that speed stability control cannot be defeated, so it again limits power through the stability control system.
Couldn't the VSC system be turned off completely by pulling the fuse for it?
Mike

https://www.facebook.com/groups/CapitalDistrictEVDrivers/

Nashco
Posts: 537
Joined: Wed May 29, 2013 12:00 am
Location: Portland, OR

Re: Performance Boost!?

Tue Feb 04, 2014 5:11 pm

nozferatu wrote:What's the HP/Torque curve for this car anyway?
Here's a power/torque curve that GM presented last year:

Image

With that said, you'll notice that when you stomp on the go pedal it displays 120 kW peak (rather than the 105 kW indicated on this chart). I haven't been able to get to the bottom of this discrepancy yet; it could be that with ideal conditions you get more power than nominal conditions and GM allows more go, or it could be that the instrument cluster displays something different than motor output. Hard to say without more data.

Bryce

scknogas
Posts: 25
Joined: Sun Jan 26, 2014 7:21 pm
Location: San Diego, CA
Contact: Website

Re: Performance Boost!?

Wed Feb 05, 2014 10:03 am

[quote="tcam999"]Finished Stage I and working on a Stage II performance boost
A little preview
http://www.youtube.com/watch?v=3v2aYpMOn-8/quote]

So, did you ever get a Stage II done? Any news on the Stage I? Pricing? Availability? Power curve? 0-60, etc...
Drive 2014 Spark EV - NoGas since 1/29/14
http://www.voltstats.net/SparkEV/Stats/Details/4463

Drove Volt 645 - NoGas from 1/29/11 to 1/29/14.
Drove 37,015.72 miles, 31,083.80 electric miles. Burned 156 gallons. Lifetime MPG 224.94.

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

Re: Performance Boost!?

Wed Feb 05, 2014 12:25 pm

Nashco wrote:
nozferatu wrote:What's the HP/Torque curve for this car anyway?
Here's a power/torque curve that GM presented last year:

Image

With that said, you'll notice that when you stomp on the go pedal it displays 120 kW peak (rather than the 105 kW indicated on this chart). I haven't been able to get to the bottom of this discrepancy yet; it could be that with ideal conditions you get more power than nominal conditions and GM allows more go, or it could be that the instrument cluster displays something different than motor output. Hard to say without more data.

Bryce
Hey Bryce thanks.

As suspected I figured the best acceleration rates for this car are up to about 50 MPH.

It'd be interesting to see how it's mid-range acceleration compares to regular IC vehicles that have more power than this car. When I drove it, it had great punch from 20-50....but truth be told it didn't' feel like a 400 ft-lb car. Perhaps this isnt' a good example but my friend's 335i really pulls and has less torque than this car. But obvious has way more power.

This validates my long term belief that ultimately power is what is critical for acceleration...at any speed. Torque is simply a gearing translation of that power. So lot's of torque means usable power low down.

Anyway...some acceleration numbers would be great if anyone has them.

emotodude
Posts: 30
Joined: Tue Nov 26, 2013 4:38 pm

Re: Performance Boost!?

Tue Mar 25, 2014 4:20 pm

Nashco wrote:
nozferatu wrote:What's the HP/Torque curve for this car anyway?
Here's a power/torque curve that GM presented last year:

Image

With that said, you'll notice that when you stomp on the go pedal it displays 120 kW peak (rather than the 105 kW indicated on this chart). I haven't been able to get to the bottom of this discrepancy yet; it could be that with ideal conditions you get more power than nominal conditions and GM allows more go, or it could be that the instrument cluster displays something different than motor output. Hard to say without more data.

Bryce
EV power is almost always claimed as "BATTERY POWER". That is the power the battery is delivering. You will lose at least 10% of that in even the most efficient vehicles before it comes out at the contact patch of the tire. The spark motor is probably in the low 90% efficiency range, the controller is probably mid 90%, you probably lost a couple percent in hi-power interconnects (even in the battery itself), and another 5% in mechanical drive-train losses. I would be shocked (pun intended :mrgreen: ) if the Spark EV was getting over 85% Total System Efficiency.

Zero Motorcycles, for whom I used to run R&D, have a very clean drive-train, single stage belt direct from motor to wheel and approach 90% total system efficiency.

emotodude
Posts: 30
Joined: Tue Nov 26, 2013 4:38 pm

Re: Performance Boost!?

Tue Mar 25, 2014 4:27 pm

nozferatu wrote: Hey Bryce thanks.

As suspected I figured the best acceleration rates for this car are up to about 50 MPH.

It'd be interesting to see how it's mid-range acceleration compares to regular IC vehicles that have more power than this car. When I drove it, it had great punch from 20-50....but truth be told it didn't' feel like a 400 ft-lb car. Perhaps this isnt' a good example but my friend's 335i really pulls and has less torque than this car. But obvious has way more power.

This validates my long term belief that ultimately power is what is critical for acceleration...at any speed. Torque is simply a gearing translation of that power. So lot's of torque means usable power low down.

Anyway...some acceleration numbers would be great if anyone has them.
Check this thread, I posted some data which lined up nicely with motorotrends review.

viewtopic.php?f=9&t=3563

To your other point. RPM and Torque are just components of Power. Gearing will get you any RPM or Torque value from any amount of power, but not vice versa ;p EV's do have ginormous motor torque, but (most) are single speed which equate to driving around in 3rd-4th gear in most cars. See how your buddies 335i does leaving it in 4th gear ALL THE TIME.

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

Re: Performance Boost!?

Tue Mar 25, 2014 9:48 pm

EVelyn wrote:OK... I'm surprised that nobody has brought this up yet... But seems that this little tiger of a ride has a lot of potential for a software upgrade to tease out some more of that torque a little faster. I mean, 402 lb ft. of torque seems to be nicely spaced over the range of speed from the factory. Doesn't it seem possible to tune that for super-fast acceleration fun?

Now, I'm not advocating this - it is a Spark after all, and not at all designed for drag racing or high-speed anything for that matter. But wouldn't it be a fun idea to have a little "quick go!" boost mode every now and then?

The fact that souping-up a new technology and modifying electron control for dragster launches is Bad idea (this is a given), but that point aside, Does anyone on the forum have knowledge (or a good guess) on what might be possible to "tune" this little buggy for more quick take-off fun? Is it just software?

Now before any of you tree-huggers out there vote me off the forum - keep in mind, this is a very natural line of questioning; an expected evolution that is consistent with our great nation's love for automobiles. It happened with hot rods, tuner cars, and motorcycles ... It's a natural question to ponder. And, anyone who's driven a Tesla knows the potential fun I'm talking about here. And those motors don't generate 400 lb ft of torque either!! :shock:
I'd prefer even more mid and top end acceleration...I'm not so big on off the line...especially in this car where any additional performance boost would be completely wasted in wheelspin.

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