2003 Engines and Beyond
Beyond 2003, in the 2004-model year, GM will bring out the Chevy Colorado and GMC Canyon pickups. These will be powered by two new inline engines, both derived from the 4.2L inline-six in the Chevy TrailBlazer et al.
A 2.8L I-4 and 3.5L I-5 (shown) - the first five-cylinder from a domestic manufacturer and largest gasoline five we're familiar with--will be offered, with a choice of the 4L60E automatic or a new five-speed manual. Both share most individual cylinder parts with the 4.2: pistons, rods, front cover/oil pump, valves and valvetrain, etc., but cranks and cams obviously vary by length, as do the oil pans, which don't have an axle shaft passing through them. Construction is the same lost-foam aluminum block and head as the I-6.
Since these engines have fairly large-displacement cylinders, each has a balance-shaft system. These counter-rotating shafts are chain-driven at the rear of the engine and spin at twice engine speed (up to 12,600 rpm) to cancel the unique motions of each engine. Balance shafts were initially developed by Lanchester almost 100 years ago and have seen service more recently in Mitsubishi and Porsche products.
Early engines exhibit the torque you'd expect from a 93mm bore and 102mm stroke at or near peak grunt around 1300-5000 rpm. Peak horsepower is up at 5600, with max revs 6300 for both.