GM Ramps Up Inline Truck Mills

General Motors Corp., in an effort to increase the performance of its midsize trucks and the Hummer H3 SUV, is jacking up the displacement and power of its Vortec series of inline 4- and 5-cyl. powerplants.

The improvements, which first were applied last year to the Vortec 4200 4.2L inline 6-cyl., are part of GM's recent investment in its Powertrain Div. for 19 new or significantly revised engines and transmissions for the '07 model year.

Since its introduction in '05, the hefty 4,700-lb. (2,132-kg) H3 has made due with GM's Vortec 3500 3.5L inline 5-cyl., rated at 220 hp and 225 lb.-ft. (305 Nm) of torque.

The engine, also available in the Chevrolet Colorado and GMC Canyon midsize pickup trucks, has been criticized for providing the iconic off-roader with rather unspectacular straight-line performance.

For '07, the engine is bumped to 3.7L and now churns out 242 hp and 242 lb.-ft. (328 Nm) of torque.

Similarly, the Vortec 2800 2.8L 4-cyl., which shares 90% of its components with the 5-cyl. mill, is boosted to 2.9L for 185 hp and 190 lb.-ft. (258 Nm) of torque, increasing 6% and 3%, respectively, over the 2.8L unit it replaces, GM says.