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Corvette lifts curtain on its power pack

Published December 7, 2012

General Motors small block V8 engine has a history that is inextricably linked with the company’s flagship performance car, the Chevrolet Corvette. This motor has made its way into other GM cars over the years, but the Corvette is where its performance credentials have been burnished into the stuff of legend, both on road and track.

In 1955, the first of the company’s family of “small block” engines, a Turbo-Fire 265 cubic-inch V8 was installed in the Corvette. Since then, the overhead-valve, pushrod small block (the small block moniker differentiates these motors from GM’s big block V8s found in many of its cars and trucks) has powered every single Corvette through four distinct generations, each of which has produced its own variants.

In fact, this motor has been so successful that on November 29, 2011 the 100 millionth unit (an LS9 supercharged variant) rolled off the company’s Performance Build Center in Wixom, Mich., marking an impressive milestone spanning nearly six decades of service.

With the seventh generation (2014) Corvette set to debut at the 2013 North American International Auto Show in Detroit in January, GM wisely chose to whet consumer appetite by unveiling the all-new Generation 5 Small Block V8 that will power it a few months early.

To mark the occasion, GM assembled all of the previous generations of the small block family at its global powertrain engineering centre in Pontiac, Mich. (the now-defunct brand’s former headquarters), including a pristine version of the 1955 Turbo-Fire V8, kept under glass.

At the centre of the room, mounted on a stand under a black shroud was the guest of honour: the all-new 6.2 L V8. Dubbed the “LT1,” the engine is a marvel of efficient packaging that, despite having a larger displacement, is 17 kg (38 lbs.) lighter and 111 mm (4.3 inches) shorter than BMW’s 4.4 L turbocharged V8 and still delivers an extra 50 horsepower (450 vs. 400) and has the same torque output (450 lb.-ft.). GM stressed that the output numbers are based on preliminary testing and won’t be finalized until early next year.

Compact, yet powerful efficiency are the hallmarks of the LT1, according to GM. It features an almost entirely new design (GM claims it’s 99.9 per cent new) that incorporates a slew of technologies including direct injection, active fuel management, continuously variable valve timing and a new combustion system with an 11.5:1 compression ratio.

The technologies are designed to work in concert with one another: direct injection helps to produce better combustion efficiency, active fuel management (a first for Corvette) saves fuel by shutting off half of the engine’s cylinders during light acceleration and continuously variable valve timing works with both systems to improve performance and efficiency and reduce emissions. The 11.5:1 compression ratio is achieved through a smaller chamber size compared to the outgoing engine, a new sculpted piston design, a reversal of the intake and exhaust valves and revised spark plug locations aimed to deliver improved better combustion.

Early testing suggests the LT1 is on track to deliver improved performance, with slightly better horsepower and torque numbers than the LS3, which has served as the Corvette’s base engine since the 2008 model year. The preliminary 450/450 output figures best the LS3 by 20 horsepower and 26 lb.-ft. respectively. While GM can’t say for certain that these figures will match final production output, it expects that they won’t be any less.

With increased horsepower and torque, the 2014 Corvette is expected to deliver improved acceleration, with a 0-60 m.p.h (0-96 km/h) time predicted to land south of four seconds. The outgoing model has posted a 4.2 second 0-60 time.

According to GM, improved power output will not come at the cost of fuel efficiency. The LT1 is expected to exceed the U.S. EPA estimate of 26 m.p.g. (9.05 L/100 km) on the highway.

“The power and efficiency of the Small Block V-8 are hallmarks of Corvette performance. But, the compact size and great power-to-weight are just as important for the overall driving experience. The all-new LT1 will play a huge role in making the all-new Corvette a world-class sports car, in terms of technology, performance, and refinement,” said Jordan Lee, chief engineer and program manager of small block engines.

Waiting another two months to get the lowdown on the car will be tough for Corvette fans and aficionados, but if it holds as much promise as its engine, it should be well worth the wait.

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