[reprinted with permission from the July 2003 issue of Snic-Braaapp]
At the close of the $2003 Challenge awards banquet, Grassroots Motorsports
Magazine announced their intention to host another event in 2004. Our current
plan here at Team ISOA headquarters is to enter two cars in next year's event.
We plan to return with our supercharged GT6+ (which is running again and now
has a blow off valve salvaged from an old Saab Turbo) and we're currently building
an electric powered GT6 Mk III.
With only a $2000 budget it's beyond our abilities to make a Triumph fast enough
to win this competition. For $2000 you can buy a clapped out Mustang with a
nitrous burning V8 that will rule the drag strip or a rusting damaged all wheel
drive Mitsubishi Eclipse which can out corner anything else in the autocross.
Our goal is to have fun and build an interesting Triumph. Creating an electric
powered GT6 is my kind of fun, and we'll probably earn some press coverage even
if we come in last place.
Why Electric Cars Suck
The reason most of us are not driving electric cars today can be summarized
in one word: RANGE. As much as I love internal combustion engines, they are
heavy, vibration prone, noisy, polluting, and high maintenance machines that
are dependant on a huge fuel distribution infrastructure.
The problem with electric cars is that the only cost effective battery technology
suitable for automotive use is the century old lead-acid battery. Until fuel
cells or some exotic energy storage technology becomes safe and affordable,
electric cars will only be suitable for short commutes or running errands around
town. A typical electric car based on a VW Rabbit electric will carry 1000 pounds
of batteries, get about 60 miles on a single charge, and take hours to recharge
from a heavy duty electrical outlet.
Cars competing in the $2000 Challange series are judged by their 1/4 mile drag
strip performance and their handling around an SCCA style autocross course.
Most cars take between 10-20 seconds to travel a 1/4 mile and between 40-60
seconds to complete an autocross course. There is plenty of time between runs
to top off the batteries from a portable generator, so limited range is not
Horsepower Versus Torque
Your Triumph's starter is a series wound DC motor. It has two windings connected
in series, a rotating armature coil and a stationary field coil. In simple terms,
when you apply battery power to the starter each winding becomes an electromagnet.
The magnetic fields repel each other, turning the armature. If you've ever tried
to start a TR6 in first gear you know that a small starter motor powered by
a single lead-acid battery has enough torque to move a 2500 pound car at a walking
To quote Carroll Shelby, "horsepower sells cars, torque wins races".
Most internal combustion engines produce peak torque somewhere between 3000
and 5000 RPM. A series wound DC motor generates peak torque at stall (zero RPM).
This is a tremendous advantage at the drag strip. I don't remember much calculus,
but I remember this: if two otherwise identical cars accelerate from 0-60 MPH
in 8 seconds, both cars will be going the same speed but the car which reaches
peak torque at a lower RPM will finish in the lead.
We now know that range, the Achilles' heel of the electric car, is irrelevant
for our short course race car. We also know that electric motors have a distinct
torque advantage over internal combustion engines. Tune in next month to see
how we can purchase a car, a large electric motor, and a couple of dozen batteries
for less than $2004.