1983 SAE Super Mileage Competition
I went to school for mechanical engineering, in Tucson at the
University of Arizona, graduating in 1983. My senior design project was
to work with several other students, and build a car to compete in the
SAE Super Mileage Competition. I worked on the engine, concentrating on
making an improved cylinder head, while the other students made the
chassis, body, a differently modified engine, etc. We were given a 2 Hp
Briggs & Stratton engine, and we could do pretty much whatever we
wanted to it. I decided that the best approach would be to make a high
compression overhead valve head for it, and operate the car at full
throttle, accelerate then shut off and coast. The car only had to
average 15 mph in the competition, and this type of driving was
allowed. I made a couple cylinder heads from a 2" thick chunk of
aluminum. I still have the first one, but we used the second one for
the competition, as it worked noticably better. I documented the
reduction in BSFC, using a little water brake dyno and a balance. I
also won the design project class competition (a fancy HP calculator
was the prize), because I was the only student who actually tested his
design!
The frame was made of structural fiberglass channel, bonded together.
The body was thin polycarbonate. The nose was made into a bubble by
making a form with a hole in it, heating in an oven until the plastic
was soft, then inflating with air. The seat was just some plastic
webbing, which was not very strong, but it was light. The steering was
by foot, push the right pedal to steer right, and the left pedal to
steer left. I think there was a rear bicycle brake, operated by hand,
but it was not very effective. The engine was started with an electric
motor, driving the B&S ball type clutch that was originally used
with the pull cord starter. We made a sprocket for a toothed belt, and
powered the motor with a motorcycle battery. I think the rear drive
sprocket was made by a previous year team, from aluminum plate, using a
mill and rotary indexing table.
The engine used the stock bore and stroke. I made this head using the
mill, it had angled valves, with a wedge shaped combustion chamber. The
valves were shortened originals, using the bare aluminum as the seats.
There was no cooling system, just the thermal mass of the big chunk of
aluminum. There was no lubrication system, just some grease added to
the valve guides and rocker arms during assembly. I made an adjustable
timing mount for the coil, and the engine had the new electronic
ignition system that B&S had just introduced, so there were no
points to worry about. The intake manifold was just a crude plumbing
assembly, the exhaust was slightly better aluminum tubing, bent to a
gentle curve.
School was over in the middle of May, and the SAE competition was in
the beginning of June, in Michigan. We got the car put together just
about the time school ended, and made some test runs on the track at
the stadium, just before it was time to leave for the competition. Some
quick calculating (using a soda can's metric and US volume measurements
for conversion) showed we were getting about 472 mpg.
I got to drive, and the car was not really set up for high speed
steering, stopping, etc. I managed to crash into a trash can, and did
some serious damage to the car. The nose was crunched, the frame
broken, the wheels bent, the steering broken. The other students pretty
much gave up at that point. We all had raised some money for the trip
from local sponsors, and I ended up getting the money and being the one
to go on the trip.
I had two choices for transportation: my big block powered 59 chevy pickup (equipped with 4.56
gears), and the old family station wagon, a 1967 Plymouth Fury III with
over 200k miles. I picked the wagon, and somehow managed to talk my
fiancee Janet into going with me. We had several hundred dollars, which
we figured would be enough money for gas, a few motel stays, and some
food. I was staying at my brother's house on Grant Road at the
time. I took the mileage car apart, and we loaded up the wagon with the
parts.
The Plymouth had been our family car since 1969. We had taken it on
several vacations to Minnesota, Mexico, and Texas. On three of those
trips, it had lost a rear wheel bearing. We also lived in Mexico in
Baja California in the early 70s, and had driven the car back and forth
several times between there and Tucson. On the last trip, moving the
last of our possessions home, the engine blew, I think near Gila Bend.
Dad bought a rebuilt engine from Montgomery Wards, and had it
installed. A few years later, I learned how to fix cars by keeping it
running when I got old enough (age 14), so I
was pretty familiar with it--I had done a valve job, lots of
ignition/carb work, overhauled the transmission, replaced the rearend,
etc.
Our trip got off to a great start, somewhere in New Mexico, the
Plymouth started to run badly. I played around with various things, we
drove carefully and kept fiddling with the engine, We finally ended up
going to a tune up shop, as I didn't have any test equipment with
me--the points were out of adjustment, and getting the dwell set
properly was mostly all it needed. While we were there, one of the
mechanics noticed there was a bird nest under the hood of the car, near
the radiator.
When we got to Battle Creek, Michigan, home of the Eaton proving
ground, we had to put the mileage car together.
The engine was way too powerful to run the car efficiently at the
required 15 mph speed, and my research with the engine had shown that
best BSFC was at near full throttle operation. So, our plan for running
the car was to accelerate at full throttle up to about 30 mph, then
shut off the engine and coast down to about 5 mph. Janet had a sign and
a stopwatch, and could time how far I'd gone in how long, so we could
tell if I needed to speed up to maintain the required 15 mph average,
and write something on the sign to let me know. We got the car together
and running, and I took it for a first run. I managed to run off the
course, and broke the "seat". After some more repairs, I made a final
run, and made four of the required six laps, and the starter quit
working--the B&S ball starter clutch was not up to the torque of
the electric starter motor, and came apart. We got the DNF...but they
did calculate our approximate fuel mileage at a bit over 500 mpg.
While on the trip, Janet learned that she had been accepted for a
summer job at Ft Huachuca, and needed to get home by Sunday, and it
would take at least a couple days to drive. I dropped her off at the
Chicago airport, and she flew home. I took my time getting home,
stopping to visit several relatives in the midwest--my uncles in
Minneapolis, my grandfather in Glenwood, a great aunt in South Dakota,
another great aunt and uncle in Colorado. Somewhere in New Mexico I had
to buy a tire for the Plymouth, as the old bias tires were not very
good. But I did have enough gas money to make it home.
My brother cut this article out of the local newspaper.
After 25 years the Tucson paper dug up the story for a repeat!
And here are a couple pictures of the head I made, and didn't use on
the car.
