Cycle World's Empulse R vs Zero S comparison

[Richard230]

The November 2013 issue of Cycle World magazine has (starting on page 52) a direct instrumented comparison of the $18,995 2013 Brammo Empulse R and the $15,995 2013 Zero S.  The “shoot out” article, written by Mark Hoyer, was very interesting and contained some comments that I had not expected.

Here are the ups and downs:  The Zero got "ups" for its “killer 30-60 mph surge”, being super quiet and its IPhone app makes for great charge-info/gauge interface.  It's "downs" included its poor styling, poor seat and poor components (for the purchase price).  The Empulse got "ups" for riding like a motorcycle, looking cool and being charging-station ready.  It's negatives included “gearbox makes little sense”, poor suspension set-up (too hard) and “gauge-package range calculation varies so much it's useless”.

Here are the measured hard numbers:

Brammo Empulse R: weight: 471 pounds, range: 45 miles, 0-60 mph: 4.8 seconds, ¼ mile:  13.97 seconds @ 90.19 mph, horsepower (measured on a Dynojet dyno):  52.4 @ 4,900 rpm, torque: 62.6 ft-lb @ 1360, top speed: 103 mph.

Zero S:  weight: 393 pounds, range 62 miles, 0-60 mph: 5.2 seconds, ¼ mile: 14.01 seconds @ 89.65 mph, horsepower: 56.0 @ 4665 rpm, torque: 75.8 ft-lb @ 1088 rpm and top speed: 90 mph.

The Zero was given a “big win” in the range department.  In “normal” use, half surface streets and half freeway cruising in the 70-mph range, the Zero would travel 60 miles with a 15% charge remaining.  However, as the charge dropped to 25%, top speed also began to drop, and by 15% charge, the Zero's top speed was limited to 40 mph.  On the other hand, the Brammo would run at full performance levels, even when its charge level was only 3%, but its range tended to be 40 to 45 miles under “normal” use.  On an identical 34-mile ride, the Zero's gauge showed 37% of its charge left, vs the Empulse' 18%.

The article concludes that electric motorcycle performance deficits have been largely overcome and they are fun, fast and interesting to ride. But price remains an issue in the current marketplace, although plug-in motorcycles will likely find a transportation niche.

[860]

Thanks for the post.  Based on those weight and performance numbers, the transmission took a bike with more weight, a smaller battery, and less powerful motor, and made it so it had better 0-60, better 1/4 mile performance, and higher top speed.

If the Empulse didn't have a transmission, you would expect a single speed Empluse with more weight, a smaller battery, and less powerful motor than the Zero S to perform worse on all of those metrics.

The transmission seems to be delivering what it was advertised to deliver, but I could easily envision a Zero S that is $3,000 more expensive (same price as Empulse R) with more sheer power that might be able to tie the Empulse R in performance, but there would still be the gap in component quality, and styling, and etc between the two.

I wish they would have compared the Zero S and the Empulse E1, just because the prices line up better.

[protomech]

The quarter mile performance is virtually identical.

The Empulse is a bit faster to 60 mph, and has a higher top speed (it continues to accelerate after the quarter, where the Zero has reached its maximum speed). Both of these are improvements that we should expect to see from IET.

However, the other point of comparison is that the Zero is running a smaller motor controller - Sevcon Size 4 vs the Empulse's Size 6.

How much of the performance improvement is due to IET (which carries significant weight, financial, and maintenance costs) and how much is due to the larger controller (which weighs a couple pounds more and costs about $300 more)?

How much does the additional weight of the more powerful charger hurt the Empulse?

We've seen an early preview on the racetrack this year. Without the onboard chargers, the race-ready TTX met with mixed success; Shelina was running midpack in practice at Laguna Seca against the Zeros, Shelina placed midpack at Indy, and then EBoz soundly defeated KK on his modified Zero at AFM Thunderhill.

I think we'll get a more balanced look at the bikes next year.

[BrammoBrian]

The quarter mile performance is virtually identical.

However, the other point of comparison is that the Zero is running a smaller motor controller - Sevcon Size 4 vs the Empulse's Size 6.

Hmmm... are you sure?  The article made no mention of the model year bike that was being tested.  I know that a senior manager at Brammo was offered and then test rode a Zero S that was upfitted with a Size 6 motor controller.  I (Brian's opinion) think that this was the same bike that was tested in this article.

Also... the ridiculously low range that they achieved on the Empulse was due to this demo unit having the wrong firmware in one of the battery modules. Since the display reports the lowest state of charge from the stack of modules, it unfortunately resulted in the rider being displayed a SOC that was well below what was actually available.  This was discovered when one of our techs rode about 10 miles on 0% indicated SOC. I'm not going to cry about that one, though, as it was clearly within our power to make sure the bike was tops when we handed it over.  i.e... We screwed up and this is the penalty. I guess it just means they'll be very impressed with how far we've come when they test the 2014 bike.

Also... you forgot to mention that Shelina won the ReFuel event against Zero production bikes modified with Size 6 motor controllers...

[protomech]

I haven't read the report, just Richard230's excellent summary. It would be extremely dishonest for Zero to send a Size 6 2013 to be reviewed without explicitly disclosing this, since it's not an option available to customers from the factory.

I'd also expect a Size 6 Zero to make a bit more power on the dyno, be a bit faster at the top end, and be markedly quicker to 60.

I'll pick up a copy of the magazine and read it for myself.

[BrammoBrian]

I haven't read the report, just Richard230's excellent summary. It would be extremely dishonest for Zero to send a Size 6 2013 to be reviewed without explicitly disclosing this, since it's not an option available to customers from the factory.

I'd also expect a Size 6 Zero to make a bit more power on the dyno, be a bit faster at the top end, and be markedly quicker to 60.

I'll pick up a copy of the magazine and read it for myself.

What I think is most strange about the article is that there are no model years designated for either bike.  They could've been testing a 2012 Zero against a 2013 Empulse for all we know.  I wonder if this provided the justification needed for Zero to "sub-in" a 2014 bike.  I don't think anyone would be surprised if Zero at least provided an option for a size 6 to their customers in the future.

*EDIT* - I think I'm probably wrong about this.  I've looked at some Youtube videos of dyno testing on the 2013 Zero S, and they do seem to be getting close to the quoted performance in the article.  Very impressive.  I'd still take an Empulse though...

[protomech]

Okay. I've read the article now.

Yeah, no model years are listed. Odd.

No pictures are available of the Zero's rear, unfortunately, which should definitively show a Size 4 or Size 6 controller. The front pictures show a 2013 component that I have reason to believe will be replaced for the 2014 Zeros. I don't think they snuck in a 2014 bike, but that doesn't mean other shenanigans aren't taking place.

Claimed metrics, presumably at the motor output:
Zero claims 54 hp, 68 ft-lb torque
Brammo claims 54 hp, 66 ft-lb torque

Dyno measurements, presumably at the rear wheel:
Zero measured 56 hp, 75.8 ft-lb
Brammo measured 52.4 hp, 62.6 ft-lb

I assume CW is backing out motor torque calculations based upon the rear wheel dyno plots. I'd love to see those dyno plots, not just a maximum measurement.

Why is the Zero's torque measuring 11% higher at the rear wheel than the specs indicate? Here are possibilities that I envision, ranging from most damning to least damning:

1. Zero shipped CW a 2013 bike with a Size 6 controller.
2. Zero shipped CW a 2013 bike with a hot controller map on the Size 4 controller.
3. The 2013 Zeros vary significantly in torque output, Zero knowingly shipped CW a "hot" bike
4. The 2013 Zeros vary significantly in torque output, Zero unknowingly shipped CW a "hot" bike
5. CW boned up the motor torque calculation.
6. CW's bike is a representative sample from Zero, Zero's specifications listed on their website are wrong/outdated.

Scenario #1 doesn't make any sense (power should be higher), I suspect scenario #5 is most likely.

[Richard230]

It is really hard for me to believe that the Zero was a 2014 model.  The test must have been performed a couple of months ago and there is no way Zero is going to allow a 2014 model out in the fresh air (much less into a magazine editor's hands) before the new models are announced at a major motorcycle show.  I doubt that there are any 2014 models running around right now.  When I visited the factory in late December 2012, they only had one or two pre-production test bikes in the factory and none were being produced on the assembly line at that time.  I can see them tweaking the controller programming, but installing a size 6 controller would be kind of obvious.  Those things are big, compared with the size 4 unit.

[ttxgpfan]

Yeah Brian, I have to say you stepped in it a bit.  One because the Zero guys really are pretty nice and straight forward guys.  And two, at the same time I have a hard time believing that any company that has that many issues with their bikes as is demonstrated by the electric motorcycle forum has enough time on their hands to do anything devious.  And lets not forget their bikes are on back order according to Hollywood Electric's Facebook post.

860. Seriously, you'd rather spend $3,000 on motor than on quality suspension, tires, wheels, and brakes? 

[860]

860. Seriously, you'd rather spend $3,000 on motor than on quality suspension, tires, wheels, and brakes? 

Hah!  Naw, what I was trying to say is that even with $3,000 more in motor/battery/controller, a Zero S might tie or even beat the Empluse R performance numbers, but they still would be way behind in suspension, tires, wheels, brakes, etc.

I was trying to point out how the multispeed transmission delivered on performance per dollar, and that a Zero S that got the same performance numbers without a multispeed transmission would still be hard pressed to compete with the Empulse R because it would still be behind in all those areas (and in sheer style points). 

It was more a commentary on the whole debate on multispeed vs single speed transmission with a more powerful drivetrain than anything else.

[ttxgpfan]

Whew.  Thought you were going for the forum squid award for a second there.   I'll be sure to read more carefully next time.

[protomech]

The transmission seems to be delivering what it was advertised to deliver, but I could easily envision a Zero S that is $3,000 more expensive (same price as Empulse R) with more sheer power that might be able to tie the Empulse R in performance, but there would still be the gap in component quality, and styling, and etc between the two.

The Empulse is indeed the fastest stock production bike you can buy in 2013. IET + big motor + big motor controller beats single speed + bigger motor + small motor controller.

I suspect the decision to not offering the Size 6 controller this year on the Zeros was a business decision not a technical decision. Edit: I laid out my crackpot theories on electricmotorcycleforum.

There are significant technical merits to IET, no doubt. And if you constrain your options to IET + 40 kW motor vs a 40 kW motor alone - without considering say IET + 40 kW motor vs 60 kW motor - then IET is indeed a winner. However, I suspect again that the driving motivation behind selecting IET was business, not technical.

Just my suspicions. *adjusts tin foil hat*

***

Now, what happens when you fit a Size 6 controller to the Zero?

The price comparison between the Empulse E1 and the Zero S is about $1500, if you figure the Empulse has range somewhere between the two battery options for Zero.

The Sevcon Size 6 costs about $300 more than the Size 4 at online retailers. Figure OEM cost differences are somewhat less. Obviously there's a cost of programming as well - and I hear the Size 6 is significantly more difficult. Cost != price, so we'll see what the option ends up being priced at in 2014. I guess it will be a $1000 option.

I expect a Size 6 Zero with the same gearing would offer about 30% more torque and 20+% more power .. so figure 0-60 times around 4.0 seconds and 100+ mph top speeds. That's a bit more than a tie, at least in a straight line.

Stock gearing for the 2013 Zeros is 28/132 (4.7:1). They have a 25/98 (3.9:1) gearing option for high speeds .. with this gearing option I would expect 0-60 around 4.8 seconds and 115-120 mph top speeds.

I think Zero will fit this taller gearing option for the 2014 Zeros as standard, as I expect it will also help reduce power draw / extend range slightly. The shorter gearing will be available for those that want more acceleration.

Edit: math is hard, okay?

[Richard230]

Everything that I have read says that the 2013 Zeros have an issue with the motor overheating when driven hard for more than a few minutes at top speed, which results in the controller cutting back top speed by about 15%.  So what happens if you stuff a Size 6 controller into the mix?  Would the motor just overheat that much faster?  If that was the case, a Size 6 controller would seem to be a waste of money for anything other than drag or circuit racing, where full throttle is not used for long periods of time, like it might be on the street, when climbing a steep freeway hill against a headwind, while carrying a passenger.   

[protomech]

I'm pretty sure that's the controller overheating first on the stock bikes, not the motor. Example: Ted Rich stuck his size 4 controller in an ice bath when he was racing eRoadRacing. He also added an air duct going into the motor.

Once you put a size 6 controller on, then the motor is the new weak thermal link. And yes, the motor will reach heat soak more quickly with a size 6 controller than a size 4, though I don't know whether a 2014 size 6 would reach heat soak (motor limited) before a 2013 size 4 (controller limited).

Size 6 controller cooling methods, for the racers, varied from naked - no heatsink! - for ElectricCowboy, to stock heatsink (Jay64, Ted Rich at Indy) to forced air cooling (Kenyon).

Every Zero racer also added extra motor cooling. For racing applications the passive cooling is not enough.

On the street you're not going to use full power for that long, 99% of the time. Especially with the larger controller and taller gearing, a 2014 with a Size 6 will hold freeway speeds in adverse conditions noticeably better than a 2013 Size 4.

[Richard230]

Thanks, Protomech.  I am starting to feel better about the Size 6.      Now, all I have to do is get a refrigerator with a ice cube dispenser.