DETROIT, Mich. — General Motors Corp. says it has found a way to make large engines more fuel-efficient.
In 2004, GM will begin installing in its large trucks and sport utility vehicles V8 engines that will increase fuel efficiency by up to 25 per cent under normal driving conditions, according to spokesman David Roman. The way they will do this is by “displacement on demand.”
Using computer sensors, the displacement on demand technology automatically shuts off four of the eight cylinders during normal conditions. Roman says that usually will happen in third or fourth gear, regardless of whether the transmission is automatic or manual.
“If you’re pulling a trailer it will be in V8,” Roman said. All eight cylinders also are reactivated during acceleration.
When driving conditions return to normal, the engine returns to the four-cylinder operation.
One of the main features of the technology is a special oil pump hydraulic lifter system developed by Eaton Corp. Ken Parker, Eaton’s principal engineer on the project, says the use of the hydraulic lifters allows the cylinders to be activated and deactivated more efficiently, making the transition from four-cylinder to eight and back “smoother” to the driver.
GM’s plant in St. Catharines, Ont., will be one of two plants initially producing the new Vortec V8 engines.
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