Last Saturday was the monthly "First Saturday" impromptu car and bike show at 95th and Arapahoe just east of Boulder, about 5 miles from my house in Lafayette. I rode my Plum Crazy socially unacceptable B50 road bike which because of a shortage of bikes actually attracted a few questions. Of course there were the usual gaggle of Ferraris, Lotus's, Lamborginis, Porsches, a few hot rods and old American Iron, a Ford Daytona coupe, a brand new S&S V-twin powered Morgan replica, etc. etc. But what interested me the most was the display by a few University of Colorado students showing off their Shell Eco Marathon cars. They have two, the elder 6 year old 50cc pushrod Honda powered carbon fiber monocoque framed 3-wheeler and a new 35cc overhead cam Honda powered tube framed model.
The first was pretty thoroughly developed with a homemade throttle bodied fuel injection system with their own design engine control system using an AFR controlled fuel injector. What kind of air throttle control are you using I asked? "None - we just control the pulse width of the injector." Sounds a little primitive, you say, but only gets about 1700 miles per gallon of gas. Mileage is calculated over several laps of a .6 mile course in Houston at a minimum of 15mph. "We actually only run the motor for part of the lap and coast the rest of the way" reported one of the students. "Was that a winner" I asked? "No - - the students from Laval University in Quebec got over 3,000 mpg" (plug for Canada.)