The (Not) AC Cobra: “Snake Oil”

AUG 1 2015 BY TDILLARD 9

We like to go sniffing around the backwoods of New England, and in the Great State of Maine, we found this gem – a AC Cobra replica powered with an 11″ DC motor (“DC Cobra”?), built from the ground up by NEDRA member and general madman, Wayne Krauth.  Krauth started this build in 2010, and has had this thing together for a few years now, but is only lately starting to pull the stops out and see what 2000A of battery will do to ETs, as well as various drivetrain parts.  Last we heard, he “turned 4th gear into another neutral …” on an 90% power run, and was replacing the tranny with a slightly more robust unit. He calls it “Snake Oil”.

Here are some shots of the car at work:

"Snake Oil" at 60' vs a nitrous Camaro

“Snake Oil” at 60′ vs a nitrous Camaro

...at 60' against an electric Porsche

…at 60′ against an electric Porsche

...and thrashing a Firebird

…and thrashing a Firebird

Wayne says: “I always admired the look of the Cobra, and when trying to decide what to build for a performance electric, it seemed like a great choice.    It’s light, strong, handles like a go kart and has that classic look.   It had to have the power of a big V8, and maybe more.”

Here are some of the pertinent details:

“2010 Factory Five Racing kit, model Mk4, replica of a 1965 AC Cobra,  same frame, steering, brakes and suspension as the original, British Racing Green.

Built all electric from the beginning, never had a drop of gas in it.

Multiple goals of drag racing, autocross racing and just a fun car to run about with.”

Snake Oil's BMS instrumentation

Snake Oil’s BMS instrumentation

Weight:  2240 lbs (without passengers, but full of fuel, lol)
Motor: 11″ GE motor, custom built for drag racing by Dennis Berube  (aka, the Current Eliminator dragster owner/builder/driver)
Controller:  Zilla 2000 amp motor controller
Pack: 240V lithium battery pack
– currently at 18 kWh pack capacity, which might increase to 280V and 21 kWh
– capable of delivering over 2000 battery amps
Transmission: 2 speed powerglide transmission, converted to manual shift instead of auto
Charger: onboard Manzanita Micro PFC30 charger; car is wired for 120V, 240V and J1772 inputs
BMS: Orion BMS (battery management system)

Instrumentation
– two 7″ touch screens provide
– BMS monitoring and drive map recording, email, browsing, maps, etc
– Zilla configuration, monitoring and performance data logging, also BMS configuration management
– dashboard gauges include gps speedometer, tach,  SOC, motor temp,  and transmission fluid pressure
– artificial engine sounds via a SoundRacer module with choice of 4 engines,   Shelby V8,  Lamborghini V12,  Harley and everyone’s favorite the Jetsons’s car sound.   The engine sound makes a throaty rumble and follows the throttle to the point where it gets a few backfire pops when going from high throttle to low quickly.
– multiple aerodynamic modifications to improve fuel economy and reduce drag at higher speeds, with more mods planned

Performance
– range estimated to about 60 miles per charge, or two trips up Mt Washington
– best fuel economy is 115 MPGe using street tires and driving gently at up to 50 mph
– worst fuel economy is 26.5 MPGe for an afternoon of drag racing

Battery pack and Zilla Controller

Battery pack and Zilla Controller

Motor/drivetrain

Motor/drivetrain

At this point, Wayne says he’s still working through motor break-in so he’s not yet at full power.  He’s got 700 break-in miles on the drag racing motor so far, and has run it at between 60 and 80% power.  It only took 2 seconds at 90% for it to blow the transmission.  As far as his on-track work, he’s only got 5 trips to a drag strip, and still running with reduced power. At 80% power, it runs the 1/8 mile in 7.55 seconds at 85 mph, with his best launch so far was a 1.53 second 60 ft   (est. 0-60 mph in under 2.7 seconds).  He beat 6 out of 7 street muscle cars in the 1/8 mile that were running on gasoline, and he reports it’s ferocious off the line, and often puts it more than a car length ahead of the other vehicle, by the 60 foot mark.

UPDATE from Wayne: “I raced at Oxford last night and set a new record. 1/8 mile. 7.20 seconds at 87 mph, running at 90% power.”

Even in this short time, he’s got some stories to tell – mostly they go like, “…after laughing, and racing me, the nitrous owners declined a second race”.  Our favorite, though, is “one day at Winterport, the Cobra was running quicker ETs than an 1100 Suzuki drag bike.   The only motorcycle that was quicker than the Cobra was a very fast electric that was built and raced by Frank John.” (More on that later…)

The Cobra at Winterport

The Cobra at Winterport

Check out his EV Album page here, where you can see a complete build diary, including “8/24/14 – Set NEDRA XS/B drag racing record for 1/8 mile, while running at 64% power”, and for a neat look at what it’d be like from the back seat (if there was a back seat) check out this over-the-shoulder view from his YouTube channel:

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9 Comments on "The (Not) AC Cobra: “Snake Oil”"

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Pushmi-Pullyu
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Pushmi-Pullyu

It looks very nice, but a DC motor and the need to shift gears is the mark of a limited power, and relatively inefficient, conversion EV.

Critic
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Critic

You don’t know what you’re talking about.

Dorkus Malorkus
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Dorkus Malorkus

60ft = 18.288m
18.288m in 1.53 seconds = 11.95m/s
Going from 0 to 11.95m/s in 1.53s means that he is /averaging/ 0.8g of acceleration over those 1.53 seconds. (The “peak” figure is probably well north of 1g.)

Crikey!

Bill Howland
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Bill Howland

Everyone’s a critic. I think it was a stupendous conversion of a classic roadster.

A very fine polished conversion job.

Its very insulting to people who have done a thorough, fine conversion to have magpies who are not at all conversant with the detail required criticizing a truly unique and FINISHED, Successful job.

Phr3d
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Phr3d

Yep, if I -could- do it, that’s what I’d want — FanTastic job!

Wayne Krauth
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The car is a blast to drive especially at the strip where it can get enough traction to hook the tires. The DC motor is a torque monster and is set to launch at 2000 motor amps. The quickest 60 ft two nights ago was 1.517 seconds.

If you put the 60′ time into Wallace Racing Calculators, it says 1.63 G’s of acceleration.

http://www.wallaceracing.com/g-force-60foot.php

I added 4 more videos on youtube of friday night racing, you can see the instant electric torque versus gas torque on all of the launches.

Phr3d
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Phr3d

“where it can get enough traction to hook the tires”, begs the question:
Thoughts about powering front wheels also? Realize weight and complexity, but it sounds (looks) like grip is a real limitation.

Wayne Krauth
Guest

The rear wheels can do it with the right conditions. The drag strip track is quite sticky and with slicks, the car hooks.

In the video link above it had drag radials which won’t hook at the track above about 80% power. You can hear the tires spinning. I changed to slicks, boosted the power and it’s hooking.

Phr3d
Guest
Phr3d

just shocking , transporter-level acceleration, lol.. suggest a drone with 60fps and time-stamped, then slo-mo’d to really capture that effect, as the car is in a Completely different place in 1/15th of a second on standard cams.
Gotta give an interesting affect to your vision, yes.. does it look like Warp?