Exclusive: GM Exec Says Spark EV’s 400lb-ft of Torque No Misprint

MAY 2 2013 BY STATIK 37

Ever since the Spark EV was first announced and GM threw around the number 400; as in how many lb-ft of torque the Spark EV will have, there has been some question about if they really meant it.

Specs as Listed on Chevy Spark EV Website.  Including the 400 lb-ft Number...Which Is Apparently A Touch Low, Not High At All

Specs as Listed on Chevy Spark EV Website. Including the 400 lb-ft Number…Which Is Apparently A Touch Low, Not High At All

The thinking was that the huge torque rating on the Spark EV could not be the actual motor rating, it had to be measured after the reduction gear…giving the upcoming EV a “real world” torque of more like 150 to 175 lb-ft.

As a comparison, in the Chevrolet Volt, the electric motor has a peak output of 111 kW (149 hp) which delivers 273 lb-ft (370 Nm) of torque, how could the Spark EV’s 100 kW (130hp) put out 400 lb-ft?

This was the debate in the comment section in our article about the Spark EV receiving an official EPA rating of 82 miles of range, and a combined “fuel efficiency” of 119 MPGe.

Then, Peter Savagian, who is GM’s General Director for for Electric Drives and Electrification Systems Engineering, joined the conversation and put the whole issue to bed, saying:

Peter Savagian From GM Takes Some Time To Set US Straight On The Spark EV's Electric Motor Specs

Peter Savagian From GM Takes Some Time To Set US Straight On The Spark EV’s Electric Motor Specs

“I need to disabuse you of the mistaken notion that this motor has less than 400 ftlb of Torque. The Spark EV motor is designed and manufactured by GM.  This motor makes 540 Nm (402 ftlbf) of Torque at stall and out to about 2000 rpm. This is not gear- multiplied axle torque, but actual motor shaft torque.”

But the GM exec was not done there, he kindly offered details on how GM sussed out that rating, as well as why their EPA ratings are so high, and what that will mean to consumers:

“The very high torque is motor performance that we are very proud of, and customers will notice the difference:  (It has a gear reduction of 3.18 to 1, so the axle torque is the product of these two). This is a very low numerical reduction ratio, which has several great benefits – 1) Feels much better to drive.  3.18:1 is less than half of the reduction of all other EVs.  This makes for extraordinary low driveline inertia, less than 1/5 of the driveline inertia of the Nissan Leaf and 1/4 that of the Fiat 500 EV.  Their cars feel like you are driving around in second gear all day long; ours feels like fourth gear. 2) Lower gear mesh, spinning losses, and lower high speed electromagnetic losses mean very high drive unit efficiency.  The Spark EV efficiency from DC current to delivered Wheel torque is 85% averaged over the city driving schedule and 92% when averaged over the highway schedule.  This is the highest in the industry, and that is one of the reasons why the Spark EV sets the benchmark for most efficient car.”

Our thanks to Peter Savagian for ending a long-standing conversation and quesingon about the Spark EV.

It should also be noted that this amount of power has translated into a interested performance result vs the Chevrolet Volt; namely that the Spark EV can blow the doors off it. The Spark EV is teased as having a 0-60 time of “less than 8 seconds,” but Chuck Russell, vehicle chief engineer for the Spark EV says “…it won’t be 7.9 seconds,(thanks to ScottF on the quote) while the Volt takes 8.8 seconds to reach 60 mph.

…now if someone would not mind starting a lively discussion about what the price of the Spark EV will be in the comments section, that would be swell!

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37 Comments on "Exclusive: GM Exec Says Spark EV’s 400lb-ft of Torque No Misprint"

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David Murray

The the motor spinning more slowly, I wonder if the regen can work as well? Typically a motor needs to spin pretty fast to generate a good amount of electricity and the reduction gears typically assist in that so that the motor is spinning pretty fast even when the car doesn’t appear to be.

zilm

Say this to any power station’s generator

Jackson

It would probably say, “Hummmmmmmmm … ” 😉

Hmmm, I don’t quite remember anyone questioning the 400 lb-ft rating here, do you? 😉

Mark H

I thought it was pretty cool of Peter Savagian to jump in on this issue. Our speculations are based on the info we have to work with. I would trust your instincts as much as anyone Tom. As we all know, if you wanna be right all the time, EVs is the wrong hobby.
Nice article Jay.

Yes, it definitely was cool Peter dropped by and explained this. Jay tried to get this straightened out weeks ago and talked to GM reps about it. He even was supposed to have a meeting with a GM engineer (perhaps Peter?) but the meeting never happened which only added more fuel to the speculation.

It wouldn’t surprise me if GM let this issue stew for a while to get people talking about it – and it worked. I know BMW does that. They could give us the technical details on the range extender now but they don’t. They want to see us speculating on how much power it will have, will you be able to climb hills with it, etc just to keep us talking about it.

Agreed. Thanks for putting this article up Jay. I would not have caught Mr. Savagian’s comments. It was great that he came by to clarify.

His points about low drive-train inertia are interesting. EVs in general feel like they have shed 95% of an ICEs drivetrain. I really wonder how this will feel compared to my LEAF.

Unfortunately I might be able to test drive a Tesla in Texas before one of these…

Tom, you’re a stand up guy for coming back and saying that!

Nelson

Leaf Pricing from MSN.com autos:
MSRP(Price it with options)
$28,800 – $34,840
Invoice
$26,986 – $32,635

SparkEV pricing better look like the below:
MSRP(Price it with options)
$26,800 – $32,840
Invoice
$24,986 – $30,635

NPNS!
Volt#671

Anderlan

Now if only GM sold it within a thousand miles of my house!!! This limited market BS is BS.

Anderlan

And it would also help if they sold more than a negative number. That’s what it seems like. Just did some searches on sales sites. Nada. Zilcho. Infinite miles from my zip code = crickets. I’ll have great luck bargaining when there’s one in my entire region. No, oops, one NOT in my entire region. Compliance BS. Beat some suppliers into submission and make an EV at *VOLUME*, GM.

taser54

@anderlan perhaps you missed the FACT that the Spark EV has not gone on sale yet? Don’t let that get in the way of your rant.

Raymondjram

You have a very short memory. GM did the same market limitation with the Volt in 2010. It wasn’t until 2011 that it was sold nation wide. So there is a new BS :”Better Solution” to the personal transportation.

zilm

Do you have a picture of motor? It should be an axial drive with such specs.

See here film:

zilm

This one looks like casual radial drive, I wonder how do they get such torque!
These two looks very interesting

and

They have very few turns per pole and using copper bars instead of wire, so it’s their key to big efficiency with low RPMs which gives them lower ratio needed for gear.
Very interesting!

zilm

These two photos:

Anderlan

My local Nissan dealer–their Leaf-pimp salse rep. specifically–hit somebody with his Leaf. He blames the instant torque. It was in stop and go traffic. He says he got going too fast and in an ordinary car would have had some extra hundreds of milliseconds to stop himself before connecting. I believe him. I kept imagining what I would do to the wall of my carport if I started off in the wrong gear. Less of a bump at 3 feet off the line, more of a bang.

Aaron

With the torque multiplication effect of the 3.18:1 rear end, does this vehicle have more torque at the wheels than the Tesla Roadster?! Something is fishy…

taser54

You should check your conclusion about the Tesla torque after the gear.

Aaron

Tesla Roadster: 295 ft/lb torque
Reduction gear: 8.27:1
Multipled torque: 2439.65 ft/lb torque
Zero to 60: 3.7 seconds

Chevy Spark: 400 ft/lb torque
Reduction gear: 3.18:1
Multiplied torque: 1,272 ft/lb torque?!
Zero to 60: <7.9 seconds?

Mitsubishi i-MiEV: 133 ft/lb torque (for comparison)
Reduction gear: 7.065:1
Multiplied torque: 939.645 ft/lb torque
Zero to 60: ~13 seconds

I guess it is possible… still odd that the Spark's motor has more torque than the Roadster. It's also odd they would allow it to accelerate 0-60 faster than the Volt. Even MORE odd that GM says a lower gearing is better for energy efficiency than ALL the other EVs. What do they know that the others don't?

Ted

I think they’re looking at the energy costs of changing the inertia of the driveline itself. If you can drive the car while spinning the motor at a lower RPM, the energetic cost of changing the motor’s rotational speed will be less than with a high RPM motor.

Joseph Wallace

Very interesting. Do you have specs on the Chevy Volt reduction gear? It feels so so 0-10 mph, but after 10 mph I can beat a lot of cars.

Joseph Wallace

Nevermind, saw it below. One question though. Is that Tesla spinning so much at high speeds with that reduction ratio? Or does it have an overdrive that kicks in like the Volt at 70 mph when the second electric motor kicks in.

scottf200

Credentials — Google search turned up:
http://www.sae.org/servlets/techSession?REQUEST_TYPE=AUTHOR_BIO&PROD_CD=13EM-0002&PRESENTATION_TITLE=OEM+Reports%3A+The+Chevrolet+Spark+EV+1ET35+Drive+Unit+-+Performance%2C+Efficiency%2C+and+Drive+Quality
Peter Savagian (suh vah’ jhin) – General Motors
OEM Reports: The Chevrolet Spark EV 1ET35 Drive Unit – Performance, Efficiency, and Drive Quality
Pete serves as Engineering Director of GM’s Electrification Architecture and Electric Motor Release Center. For the past 12 years, in various roles, he has managed product development and advanced engineering for GM’s hybrid systems, including hybrid architecture development, electric drive component development, systems engineering, systems analysis, and control algorithm development. Pete has worked on electric vehicle systems since 1990. Prior to his current assignment, Pete was Chief Engineer for GM’s EV1 Electric Vehicle Drive Unit and Power Electronics at General Motors and at Delco Electronics. In the past, he has worked at Hughes Aircraft Company and Sundstrand Aviation in various engineering roles.
Pete holds a BS in Mechanical Engineering from the University of Wisconsin, a MS in Operations Research Engineering from the University of Southern California, and an MBA from Duke University.

GeorgeS

Like I said before we need the whole toque speed map to actually model the 0-60 time but we can roughly estimate it by ratio of torques at the wheel and by car wt.

Volt gear ratio= 3.24X2.16
Spark gear ratio=3.18
Volt wt=3850
spark wt=3000
Volt 0-60 time=8.5 sec
Volt wheel=17 inch
Spark wheel= 14 inch (?)

8.5 times (270×3.24×2.16)/(400×3.18) times 3000/3850 times 14/17=8.07 seconds

They say it’s less than 8 seconds and NOT 7.99

I would say 7.8 seconds

It sounds like 540 Nm is “instantaneous torque” & not “continuous torque” rating. The torque of an electric can be varied by amount of current to drive windings. High currents for small periods is OK, but the motor heats up. A e-motor will draw more power to increase acceleration (or climb a hill), and draw less wen operating at steady speed. Both “instantaneous torque” & “continuous torque” are useful comparison values & shouldn’t be confused. “This motor makes 540 Nm (402 ft-lb) of Torque at stall and out to about 2000 rpm”, and “has a gear reduction of 3.18 to 1, so the axle torque is the product of these two”. Given the Spark EV has 15-inch wheels, we can that calculate 540 Nm (402 ft-lb) holds over the 0 mph — 28 mph speed range. [ (2000 rpm * 60 min/hr / 3.18) / (5280ft/mile / (15 in / 12 in/ft * 3.1415)) = 28.06 mph ] A graph of torque vs. rpm, (or vs. mph) would be better for comparison. A 540 Nm (402 ft-lb) torque just tells part of story. The data point is useful when going 0–60 mph in under 8 seconds, but means less when… Read more »
KeiJidosha

Spark EV – 402FtLb torque thru 3.18:1 drive = 1,278FtLbs axle torque
Fit EV – 189FtLb torque thru 8.05:1 drive = 1521FtLbs axle torque
LEAF – 207FtLb torque thru 7.94:1 drive – 1,643FtLbs axle torque

Re; Torque is flat to 2,000RPM

185/55-15 tires = 908 revs/mi
2,000/3.18 = 629 axel rev/min
628/908 = 0.6927 mi/min
.6927 x 60 = 41.5 mph on the Spark EV.

This is where Spark should make up time in the 0-60. Field weakening knee is at a higher mph speed. Spark will drive like an electric Diesel

GSP

Very interesting calculation. The Spark will have full motor torque to 41.5 mph. I’d like to drive one!

GSP

Raymondjram

I want to test drive one, too!

Bill Howland

I would assume its all dependent on whether they are talking about the motor itself, or after it goes through all the gear reductions. If it takes a while to go from 0 – 60 mph that’s all I’m concerned about.

@Keijidosha

Maybe its a country custom or something but in the states we usually only talk about field weakening on a DC motor. Unless you mean a lowered Volts/Hz ratio at higher speed cruising.

mike h.

hopefully not —- but I’m guessing the price will be $40K before any Govt credits, so it will not be a hot seller IMO.

Raymondjram

You missed by over $12,000! The base price is $28,000 but with all the incentives and tax credits, you can buy the Spark EV in California for less than $22,000.

I hope by 2014 the prices drop to keep it competitive against all the imports.

Raymondjram

I have a new question: The Spark EV has a “L” position in addition to the “D” position on the shifter. Is this identical to the Volt, such that “L” only gives more regeneration?

And why put in a mechanical shifter if there is no real gear change? Why not put in a pushbutton shifter?

Loboc

Or a paddle shifter like ELR.

Floor shifters give us older drivers some sense of normalcy. It’d be like switching to a joystick for steering. Not ready for that.