More Details On Gm's New Inline-Six Vortec Engine
Although inline six-cylinder engines have long been a favorite among truck enthusiasts who favor smooth operation and a lot of low-end torque, I-6 truck engines of the past were hardly what enthusiasts would call a technological marvel since previous I-6 powerplants were made mostly by pushrod design, sporting two overhead valves per cylinder - not what you would call state-of-the-art. Of course, these basic engines were reliable, cost-effective, and produced the amount and style of power that was ideal for commercial trucks and off-road vehicles. For model-year 2002, General Motors has taken a fresh approach to the design and construction of the venerable I-6 layout, and the result is something special: the Vortec 4200.
Slated for use in the '02 Chevrolet TrailBlazer, the GMC Envoy, and the Oldsmobile Bravada, the Vortec straight-six was designed to provide the power of a small V-8 engine with the smoothness and fuel-efficiency of a sixer. High-tech innovations abound on the new straight shooter, including a double overhead cam, an aluminum cylinder head, an alloy block, a 10:1 compression ratio, variable valve timing, coil-on-plug ignition, and Multec II sequential fuel-injection. The six-shooter's output keeps with its advanced design: 270 horsepower and 275 lb-ft of torque, numbers that are definitely in the V-8 category.
The key feature of the Vortec 4200 I-6 engine is its cylinder head. Although a DOHC design is common in exotic performance engines, twin-cam, multiple-valve engines aren't common in trucks. Basically, the DOHC design does away with in-block valve lifters, pushrods, and rocker arms, replacing that type of complicated valvetrain with a pair of camshafts - one cam for the intake valves; one cam for the exhaust valves - that operate roller lobe followers that directly actuate the valves. Airflow through the cylinder head is enhanced through the use of four valves; two intake and two exhaust valves per cylinder are able to flow more air and fuel at a lower lift than a cylinder with a single, large intake and exhaust valve. Additionally, a four-valve-per-cylinder design is light in weight for accurate valve control, the shape of the four-valve's combustion chamber enhances the combustion process, and the centrally mounted spark plug ensures a thorough burn cycle during the ignition stroke.
Big News From DaimlerChrysler
DaimlerChrysler has recently completed its purchase of the Detroit Diesel Corporation and has taken the company private, buying up all outstanding shares of Detroit Diesel at $23 per share. The Detroit Diesel Corporation, which was incorporated in 1987, is a recognized world leader in the design and manufacture of diesel engines for on- and off-highway applications. The output of various Detroit Diesel engines ranges from 22 to 11,000 horsepower, including powerplant generators, and Detroit Diesel engines are sold throughout a worldwide network of an estimated 2,700 dealers.