Documenting the modifications to Zero S’s at eRoadRacing Laguna Seca 2013

One of the questions about the eRoadRacing grid at Laguna Seca is the relative performance of the Empulse TTX’s and Zero S’s. These are manufactured electric motorcycles from Brammo and Zero, and there’s debate over which approach (transmission versus direct drive) is better. The results of the weekend showed the two makes being relatively equal, and it appears to me to be more about rider skill, as I noted in writing up the qualifying round results. But there is a factoid to accommodate in interpreting those results: All the Zero S’s in the race had modifications, primarily to use a larger (more powerful) controller.

To see the data in tables go here: Performance comparison between Empulse TTX and Zero S at eRoadRacing Laguna Seca

Stock the 2013 Zero S uses a SEVCON Gen4 size4 controller. The bikes ridden by Jeremiah Johnson, Brandon Nozaki-Miller, and Kenyon Kluge all had been upgraded to size6 controllers. The bike ridden by Ted Rich had a size4 controller, but he’d built a special box around the controller into which he poured ice water to keep the controller cool.

Duct work on Kenyon Kluge’s bike

Using the size 6 controllers meant the potential to pump more power into the motors. So is this modification going to make the bikes more powerful. I understood however that they had the controllers turned down, in one case to 50% power. Another item is that they faced overheating issues, especially in the motor. All the Zero S’s had another modification to install some air ducting, generally from Home Depot, to direct air onto the motor to improve the air cooling.

Jeremiah Johnson observed to me that the motor is located BEHIND the battery box, meaning that it won’t have good air flow. In normal riding this isn’t going to be important, but for a race where the rider needs to has to push the bike as hard as he can, cooling the motor and controller is vital. Zero’s design team is aiming for the typical daily rider, not for the needs of the racer. This is understandable because they can sell a lot more bikes to typical daily riders than they can to racers.

I was told that Kenyon’s bike was “stock” except for the upgraded controller, the duct work shown above, and a fan mounted to the controller. Dunno if they tweaked any controller settings.

Brandon’s and Jeremiah’s bikes had some prep work done by Hollywood Electrics, and had the size6 controller. Additionally Brandon has been developing various addons, but one in particular he claims gives him an important speed boost. This is a sound system that responds to various bits of information such as throttle settings and perhaps lean or speed, and makes different sounds based on the conditions. This gives him auditory feedback about the behavior of the bike that’s missing because the bike is naturally quiet. Loud vehicles naturally give us auditory feedback that we naturally use in driving. Brandon believes the auditory feedback helps him take in information audially that he’d otherwise have to receive visually such as reading dials on the dashboard, but because it’s audio input he can keep his eyes focused on the track where they belong.

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About David Herron

David Herron is a writer and software engineer living in Silicon Valley. He primarily writes about electric vehicles, clean energy systems, climate change, peak oil and related issues. When not writing he indulges in software projects and is sometimes employed as a software engineer. David has written for sites like PlugInCars and TorqueNews, and worked for companies like Sun Microsystems and Yahoo.