Hopes for Mileage Honors Ride on 65-Pound Frame, 3 Motors
After a flurry of last-minute preparations, a team of 15 California State University, Northridge mechanical engineering students set out for Sacramento on Friday, taking with them a 65-pound car that has a lawn mower motor, wheelchair wheels and a Styrofoam body.
If all goes as expected, they’ll give it a vial of gasoline today, fire up its two-horsepower Briggs & Stratton engine and see what it can do on the California Highway Patrol test track.
In theory, it could get 2,200 miles per gallon of gasoline.
The students built the car to compete with eight other colleges in a two-day mileage competition sponsored by the Society of Automotive Engineers and the Briggs & Stratton Corp.
Through much of the spring semester, they worked side-by-side with another team of CSUN mechanical engineering students who built and raced a mini off-road car in an event put on by the same sponsors in April. That project required a rough-and-ready approach. Strength and speed were the engineering goals.
In contrast, the high-mileage project favors delicacy and ultra-fine tuning.
The car consists of a frame of slender metal rods suspended on three wheels of the type used on racing wheelchairs.
A teardrop-shaped, seven-pound fairing covers the frame. The students made the fairing by hand, using stencils and hot wires to cut thin shell sections out of Styrofoam blocks, then gluing the sections together and sanding the joints.
They’ll use three engines in the competition. One is the stock lawn mower engine issued by the race sponsors. The other two have been modified by the students for better performance.
Student Rich Mountain changed the flow characteristics and carburetion of one engine to lower its internal friction and slightly reduce its displacement.
Another student, Margo Summers, radically modified the third engine, reducing its displacement from 109 cc to only 45. Summers inserted a cylinder sleeve, modified a Honda piston and milled her own connecting rod and head.
Although theoretically the best engine, said James Yannotta, a senior mechanical engineering student, it may not perform up to its potential because Summers ran short on time.
“We weren’t able to do enough tests on a dynamometer to refine the engine and get the perfect settings,” Yannotta said. “We’re going to use our own intuition.”
The competition begins with a technical evaluation this morning. The students will then have the rest of the day to prepare for the seven-hour road test on Sunday.
During the road test, they will be allowed to run their car as often as they want over a four-lap course totaling just under seven miles. The car will be driven by a number of students, all of whom must weigh at least 150 pounds.
For each test they will be issued a vial containing a precise quantity of gasoline. They will connect the vial to the car’s fuel line and drive the course. Then the fuel vial will be weighed to calculate fuel consumption. Only their best performance will go on record.
The students plan to use all three engines.
Any of them, in its most efficient power range, could keep the car moving at far above the minimum required speed of 10 m.p.h. The driver’s strategy to obtain the maximum mileage, therefore, will be to accelerate the car to 25 m.p.h., kill the engine, coast until the speed drops to about 15 m.p.h., then restart the engine.
Using this method, a team from the University of Saskatchewan set the current record of 2,199 mpg, Yannotta said.
The students had hoped to beat that. But, after falling behind schedule during finals and finishing the car in a rush, they have lowered their expectations.
“We really have not had enough time to really do refinements on our engine and racing strategy,” Yannotta said. “We’re probably going to get anywhere from 1,000 to 1,500" miles per gallon.