EV1 Images, Santa Clara Marriott, August 1998
These images were from a press club meeting at the Santa Clara Marriott
in August 1998. Previously the EV1 tour truck had been at local Saturn
dealers making presentations to potential customers.
EV1 Prototype sets Land Speed Record for Electric Vehicles
On March 11, 1994 Lotus engineer Clive Roberts drove this yellow
EV1 prototype to an electric vehicle
of 183 MPH
at Fort Stockton, Texas.
Roberts was assigned by Lotus to GM's EV project,
which is corporate speak meaning he/Lotus developed the suspension.
(Clive now works for GM.)
Modifications from a standard EV1 are relatively minor,
having two more batteries,
a slightly modified controller, an inch or two shorter ride height,
special Michelin Pilot SX MXX3 tires in 205/50-R15 (a standard size),
3:1 final drive instead of 11:1,
radio telemetry, racing seats, flush aluminum wheel covers,
stripped interior and a roll cage.
Note that the gearing change decreases the torque at the wheels,
but increases top speed. Having a single speed transmission,
the stock EV1 motor normally turns 13,000 RPM at 80 MPH.
One of the images below is a side view of the underside of the race car,
beneath the passenger footwell and behind the front tires.
The right front suspension can be seen at the right of the image.
Presumably the bottom fairings were removed to disconnect the extra
batteries which were in the footwell during the record runs.
Not seen in the pictures below is an aproximately two foot tailcone
added to further reduce drag.
It's not clear if the tailcone was used in the record run.
Please see an extended conversation with Clive below the images.
Click on an image to see a larger view.
Some of the differences between street (red, left)
and race car (yellow, right) can be seen below:
The remaining images were for comparing the standard EV1 colors:
red, silver-blue and forest green.
UPDATE: A Conversation with Clive Roberts
Clive Roberts discussed some more details of the world record car
with me in a conversation on 6 February 2005:
- I've just been looking at your EV1 page, and it stirred some memories.
The tyre size seems very modest now,
when I'm working with 215/40R17 for a fairly modest street car!
- But they were also narrow for lesser frontal area, eh?
- Chosen for a combination of reasons, in consultation with Michelin -
- load capacity
- speed capability
- ability to fit within the packaging space, without too much hacking
- lowest practical width for rolling resistance and frontal area, consistent with the above (of the rolling resistance was high compared with the production tyres)
The suspension was actually less standard than your notes suggest - all the
bushes were changed, and the dampers were valved very tight. In fact I removed
low speed bleed entirely when we started running on the oval, to eliminate a
slight roll-rock on the entry to the banking. I have a feeling we also changed
the rear suspension links and the steering gear, but I would need to dig out
my notes to confirm.
- Did they go with urethane bushes or metal or something else?
Bushes and dampers are also a fairly common thing for weekend
racers to swap out on their cars....
- Just harder versions of the rubber bushes,
pulled out of the tuning bins in the big white trailer.
Apart from the drive unit, batteries and safety equipment,
the car was pretty much put together with what was at hand.
One thing we did not change was the brakes, which made it
interesting to lose enough speed from about 190mph to be able to enter the
next turn - if you work out the kinetic energy compared with the standard EV1
stopping from its maximum 80mph, it shows the size of the problem!
- Did you guys calculate how much of the energy you could recover
through regeneration? I expect the conventional brakes were
needed to do most of the work however.
- I think regen was disabled, not sure how or why
(I left that to the people with second and third degrees).
From experience on the production car I don't think regen
would have dissipated enough energy, fast enough,
to be useful in that situation.
And maybe we wouldn't have wanted all that activity going
on at the front wheels at the entry into a banked turn!
- So it sounds like your corner speeds were about 172mph, equating
the kinetic energy drops from 190 and 80...!
- That was the entry speed under full power at the end of the
back straight, during the run up to the timed trap - any higher just
wasted energy on the banking.
OK in the top lane, but not so good in the lower lanes.
If we got it right the car would reach about 190mph in the trap
before all the energy went away.
Next task was getting round the curve at the opposite end of the oval -
the brakes would drop speed to about 165,
then it was a case of working out how and where to enter the curve.
It took a few runs to work out the technique,
although bad ideas were quickly revealed as such!
Back to EV1 Observations.