The Lean Green Cycling Machine

The Combustion Lab where Jim Szybist works is, for all intents and purposes, a garage for gearheads: music blaring on the radio, smell of diesel in the air, overflowing tool boxes, and engines lying in various states of disrepair. But if you pay attention, you'll see computers silently chewing on data and detailed lab notebooks spread open on countertops, and you'll hear the buzz of graduate students—men and women—discussing their engine and fuel-related research.

white motorcycle

This is a garage for academic gearheads.

Szybist, a first year master's student in fuel science, has been working here since last summer. (He doesn't even notice the diesel fumes anymore.) He and his adviser André Boehman, associate professor of fuel science at Penn State, are collaborating with a small Pennsylvania company called eCycle to develop a hybrid-electric motorcycle. The cycle will be powered by a diesel engine and an electric motor working together.

eCycle has already developed an all-electric motorcycle. But it can only go 40 miles before the motor has to be recharged. Their expectation is that the hybrid-electric cycle, with the engine continually charging the electric motor, will go about 160 miles on each gallon of fuel, and reach a top speed of 80 miles an hour.

Szybist's job is to get eCycle's engine running, and then to test it for fuel efficiency and emissions. But, the eCycle team hasn't quite finished building the engine. In the meantime, Szybist has put together a test system consisting of a lawnmower engine, an electric motor, a device called a dynamometer, and sensors hooked up to two computers. The system will allow him to troubleshoot his tests for the real engine. At 125 cubic centimeters (an eighth of a liter), the eCycle engine will be much smaller than the lawnmower engine.

Szybist starts his test system with the touch of a button. "The electric motor started the engine, but now it's just along for the ride," he says, as the lawnmower engine thunders away in the background. (The fuel smell is strong because the lawnmower engine is old and leaky.) In a hybrid-electric system, the engine isn't running all the time. When a rider first starts the motorcycle, the electric motor does all the work. "Electric motors are good at producing low-speed torque," which, Szybist explains, "gives you a lot of power to get things going." The diesel engine doesn't fire until the motorcycle is going at least 15 to 20 miles per hour; it's most efficient at cruising speeds. "At high speed and load conditions both the electric motor and engine will be delivering power to the wheel," says Szybist. During other conditions, such as going down a hill, the engine doesn't need to deliver as much power to the wheels so, instead, it can recharge the battery. A sophisticated computer in the motorcycle will control the delivery of power.

The dynamometer in his test system allows Szybist to put a "load" on his lawnmower engine to simulate a motorcycle going up a hill or a carrying a heavy rider. "It can simulate conditions that are far more rigorous that anything the eCycle would normally experience," Szybist explains. The sensors feed information to the computers, and Szybist instantly gets readings on torque, speed, and horsepower. He pulls a lever marked "throttle" and the engine thunders harder. The numbers on the computer screen jump higher.

Assembling the test system seems to have been Szybist's rite of passage into the gearhead world. "For someone trained as a chemical engineer, putting this together was quite a feat in mechanical and electrical engineering," he says, grinning.

Once he gets the eCycle engine, Szybist will fit it into his system (replacing the lawnmower engine) and test for emissions like unburned fuel, carbon monoxide, particulates, and oxides of nitrogen. He'll attach a sampling line to the exhaust pipe of the engine and use vacuum pumps to flow the exhaust into several different analytical instruments.

The eCycle team claims that their engine will consume less fuel and create less pollution than a typical motorcycle engine. Most motorcycles contain larger "four-stroke" gasoline engines, in which an air fuel mixture is taken into the engine's cylinders, compressed, ignited, and then exhausted. eCycle uses a smaller "two-stroke" diesel engine that has a higher power-to-weight ratio. When the hot air is compressed, and the piston is near the top of the cylinder, fuel is injected into the air. It spontaneously ignites, forcing the piston to the bottom of the cylinder. The exhaust is released at the same time a fresh batch of air enters. Because combustion occurs with each downward stroke of the piston, the eCycle engine is fuel-efficient and powerful for its size. With the proper adjustment of the fuel injection timing (another one of Szybist's jobs), very little unburned fuel will be released with the exhaust, making the system a clean one.

While all hybrid-electric vehicles on the market today use a gas or diesel engine with an electric motor, Szybist is interested in exploring alternative fuel sources. He seems enthusiastic about the work others in Boehman's lab have been doing with vegetable-based fuels (see "Flower Power" in the September 1999 R/PS) and dimethyl ether.

Would Szybist ever purchase an eCycle? He laughs. "I'll say this much: I'm a huge fan of small, very fuel-efficient vehicles."

Jim Szybist is a master's student in fuel science in the College of Earth and Mineral Sciences, 416 Academic Activities Building, University Park, PA, 16802; jps182@psu.edu. His adviser is Andre Boehman, Ph.D., associate professor of fuel science and director of the Energy Institute, 405 Academic Activities Bldg.; 814-865-7839; boehman@ems.psu.edu. This project is funded by eCycle, the Pennsylvania Department of Energy, and the Pennsylvania Department of Environmental Protection.

Last Updated May 01, 2001