Driving GM's Allison 1000 Six-Speed

摘要

Owners of big pickup trucks are not shy about demanding power and torque to handle real or imagined hauling jobs. And General Motors' fans among them will be happy to learn of stronger but more efficient power trains for the 2006 model year. GM's Fleet & Commercial arm recently highlighted improvements for the popular Chevrolet 5ilverado/GMC Sierra 2500 and 3500 series pickups. Included are a new six- speed Allison 1000 transmission and an upgraded Duramax V-8 diesel. The transmission and engine themselves will begin appearing in '06 pickups this fall and early next year. The new "Generation 4" Allison 1000 adds a 6th gear at the very top of the ratio ladder, making it a double-overdrive like bigger Allisons. Sixth is a 0.61 overdrive, which euts engine rpm by 350 at 60 mph and aids fuel economy at highway speeds. All other ratios remain the same as in a five-speed Allison, including a 0.75 overdrive 5th and a 1:1 direct 4th.