News From the Auto Industry

Fully dressed, the engine comes in at just 305 lb.

Number-one relates to the current product initiative, which really started with the Sky, although some could argue that the Vue, introduced as a model year 2002, was really the first domestic small(ish) SUV that was ahead of its time (particularly if you take into account the fact that GM and Honda collaborated on a deal whereby the Vue is being fitted with 3.5 liter V6s sourced from Honda–an alliance, of sorts, way ahead of anything even proposed or thought about with Nissan, as the engine was first offered in the ‘04 model year). Still, overall, Saturn hasn’t had a whole lot going for it, with the mainly forgotten L-Series (though in some ways, it was a harbinger of things to come when introduced in 2000), the Ion (saved from the axe recently by $3/gallon gas), and the Relay, vehicles that don’t overwhelm in the design and/or engineering categories. But now not only is there the Sky roadster, but the Sky Red Line, a version of the base model that takes something that is already a grand execution of the Kappa platform (which is also used for the Pontiac Solstice) and, essentially via some rather impressive powertrain engineering, takes the car to a new level of performance, something that’s not only been sorely lacking at Saturn for some time (some might argue since approximately Day One), but at GM as a whole (taking into account the number of nameplates it has in its portfolio and comparing it with those that make the market sit up and take notice in a positive way; there are, for example, the Chevy Corvette and the Cadillac XLR, but then the pickin’s become rather slim).

1. Good things come to those who wait

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2. Practice makes perfect

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What is the real factor of the Sky Red Line that makes a discernable difference? It’s under the hood. It features a first for GM in North America: a direct-injection engine, a 2.0-liter turbocharged Ecotec. The engine is mated to either a Hydra-Matic 5L40 five-speed automatic or an Aisin AR5 five-speed manual. The importance of direct injection is that by injecting the fuel right into the combustion chamber, there is a more complete burn; one consequence is that it takes less fuel to get the same amount of horsepower achieved by a conventional port-injection system. As regards the horsepower, it provides 260 hp @ 5,300 rpm and 260 lb-ft of torque at 2,500 rpm. This makes it GM’s highest specific horsepower engine ever–2.1 hp/in.[.sup.3] of displacement. A reason why direct injection isn’t more widely deployed is because it is tricky. That is, they can be prone to timing issues (i.e., combusting when not wanted) and it is necessary to have a fuel system that can reliably and repeatably operate at high pressures. In the case of this engine, the pressure is as high as 2,250 psi.

The injectors are located below the intake ports in this engine, which makes it unlike other Ecotecs. Consequently, there is a modified A356 aluminum cylinder head deployed. The intake valves are stainless steel; the exhaust valves have sodium-filled stems for cooling (the sodium liquefies under operating temperatures and serves to conduct heat away from the valve face and guide and down to the stem). There is continuously variable valve timing; intake and exhaust timing are adjusted independently. The 319 aluminum Gen II engine block is common to other Ecotec engines, including a 2.4-liter version. The pistons are also aluminum. The crankshaft is drop-forged steel with induction heat-treated fillets and cross-drilled, chamfered oil passages. The twin-scroll turbocharger generates maximum boost of 20 psi. One advantage of using the direct-injection approach is that compared to port injection, the intake process is cooler, so the engine can operate at higher boost and compression (9.2:1) than is the case with conventional turbo-powered engines. Of course, there is an air-to-air intercooler to reduce the inlet air temperature.