She’s real fine, my 209 (-mph ‘Vette)
On the occasion of the Genovation GXE Corvette’s official coming-out party at CES 2018, we sat down with the folks responsible for turning politely powerful Corvette Grand Sports into positively pugilistic 800-hp, 700-lb-ft electric record-breakers to learn a bit more about how they did it. Here are the nitty-gritty details behind this $750,000 green hypercar.
The project started four years ago, when the chassis folks at Dana gifted the Rockville, Maryland-based Genovation team an aluminum chassis for a C6 Corvette with the only stipulation being “you can’t put a gas engine in it.” They started shopping around at various trade shows in search of the suppliers best able to help them transform the Corvette into an electric car capable of breaking speed records. They ended up with AMRacing motors (two of them mount up front, twisting the same shaft) and power inverters from Rinehart Motion Systems (both from Oregon). These are fed by a 61-kW-hr battery pack from Lithos Energy under the direction of powertrain control systems designed by from Stafl Systems (both from the Bay Area). The cylindrical-style batteries utilize nickel-cobalt-aluminum/nickel-cobalt-manganese chemistry optimized for power delivery rather than energy density. Genovation’s latest computer simulations predict an EPA range of 175 miles (so long as those miles don’t probe the car’s 209-mph EV speed record or claimed sub-3-second 0–60 performance).
The batteries are arrayed in a horseshoe shape around the front motors (which nestle beneath the two inverters that are visible through the hood’s Plexiglas window), in the central tunnel, and under the raised trunk floor behind the seats. The operating voltage is 700–800 volts, and charging via the 10-kW onboard charger and SAE J1772 plug takes 7 hours. The fact that the operating voltage is higher than that of most DC fast chargers presents a challenge for fast charging at the moment. The powertrain is heated and cooled by three cooling loops, with direct oil cooling of the permanent-magnet motors.
Now, about those performance claims. The GXE Corvette is rear-wheel drive, but it’s way lighter than a Tesla, and its (stock Z06 Michelin Pilot Sport Cup 2) rear tires are wider, so Genovation says it can approach dual-motor Tesla Ludicrous rates of acceleration. Testing to date has been on the six-speed C6 prototype, which retains the Corvette’s stock transaxle and gearing but features a reinforced differential.
The optimal launch speed is 2,500 rpm in second gear, with upshifts occurring at a very gas-Corvette-like 6,500 rpm—well shy of the motor’s 10,000-rev limit. The motors enter a constant-power regime beyond that point, so there’s no reason to press on. Wheelspin is a big issue until fourth gear, and the traction management programming is all Genovation’s. A shift light indicates the optimal rpm, which can vary as the state of charge and nominal voltage drop.
The 209-hp speed record was measured on February 16 at Johnny Bohmer Proving Grounds located at Space Florida’s Shuttle Landing Facility, Kennedy Space Center, Merritt Island Florida, establishing a new land speed record for street-legal electric cars. Genovation actually claims a top speed of 220 mph on longer tracks than Kennedy’s.
The production car is obviously based on the C7 Corvette and will hence feature the seven-speed manual or eight-speed automatic. Genovation retains all the stock safety systems and onboard LAN communications bus but adds a dedicated CAN bus to connect the 11 control modules and the bespoke instrumentation, which includes a Volvo-esque vertical touchscreen. Genovation also adds a Harman ultra-high-fidelity sound system and its own navigation and 4G LTE Wi-Fi system. Over-the-air updates will be offered. The Corvette’s stock CAN bus is fed just enough information to trick it into thinking there’s a perfectly functioning powertrain onboard. Stafl surely had fun making all of this work.
For packaging reasons primarily, the composite leaf springs are removed in favor of a set of DSC Sport adjustable coil-over shock units. Carbon-fiber wheels are from Carbon Revolution (Ford GT and Shelby GT350) and shave 10 pounds of unsprung rotating mass per corner.
Interested customers must bring a new (or very gently used) C7 Corvette Grand Sport to Genovation (which recommends a build combination that ensures you don’t pay for optional items that will just be removed). The plan is to build coupes, but if someone insisted on a convertible, Genovation can build one. The conversion takes place at Prefix Corporation in Auburn Hills, Michigan (the company once contracted to paint new SRT Vipers). The build includes new front and rear fascias—the latter incorporating classic-look round LED taillamps, numerous carbon-fiber trim pieces from Nowicki Autosport, GXE badges, a completely retrimmed interior, and a new custom paint job. We’re told that no two of the 75 cars planned will be the same color. Aero upgrades for top speed stability include a front splitter, rear diffuser, and wing. Adjustable elements including the front splitter can increase downforce for handling-circuit use. New low-drag mirrors include light pipes that, along with those in the front fascia, communicate the charging status when plugged in.
Genovation promises to give Motor Trend and Randy Pobst a go in the GXE Corvette later this summer, shortly before deliveries begin in late 2018.