The one-cylinder test engine in the basement of a University of Wisconsin-Madison lab is connected to a life-support system of pipes, tubes, ducts and cables. You might think that the engine resembles a patient in intensive care, but in this case, the patient is not sick. Instead, the elaborate monitoring system shows that the engine can convert 59.5 percent of the chemical energy in its fuel into motion — significantly better than the 52 percent maximum in modern diesel truck engines.