Chevy builds the fastest production ‘Vette to-date...

GM’s supercharged LS9 produces 638 horse from the box

Whatever happened to the days of car-building camaraderie, when nearly anyone with the money on-hand could order nearly any unthinkable, off-the-wall performance package for nearly any make of car? During these times, even station wagons could be ordered with motor/trans combos typically associated with COPO-optioned Chevelles and Camaros, such as a 427/4-speed option. These were the days when GM and the other “Big 3” of the American muscle scene had what many motor enthusiasts would describe as free reign; the American car makers, for several years, had had the space and resources to spend extra money and build cars that were more rare, but were so because that much more research and craftsmanship had been put into each individual unit.

And now we arrive in 2011, a time in which a muscle car “renaissance” has arose. The car-buying market here on the home soil has, for one reason or another, suddenly regained an interest in dealer-available race cars, something that hasn’t been seen the early ‘70s. Chevy and GM have, in turn, created a response to the renewed sense of horsepower Americana.

The ZR1, with a bottom-built and supercharged LS9 under it’s see-through hood, has earned the title as Chevy’s fastest production Corvette to-date, a title held for years by the 427-powered Stingray from the 1967-69 era. In the late ‘60s, the fastest ‘Vette from the factory that could be ordered was the 500 plus-horse, ZL1, a limited-run ‘Vette that featured Chev’s L72 big block, a rare, all-aluminum variant of the 427 that was underrated at 435 horsepower. The new ZR1, on the other hand, produces 638 real brake horsepower, again from an aluminum motor.

 The use of an aluminum motor, in the case of the new ZR1, reinforces a 40-some-odd-year tradition that, during its peak, was harnessed by such famous builders as Dana and Yenko.

The ZR1 does differ dramatically in architecture, even from the ZR-1 that was introduced into the C4 generation of ‘Vettes from ’90-’95. Indeed, the supercharged, all-aluminum LS9 motor is radically different from the conventional small block of yesteryear. Here’s why:

• Most conventional V6 and V8 motors have been cast iron; the LS9 is aluminum

• The Eaton TVS R2300 supercharger features a four-lobe impeller design, as opposed to the three-lobe design used on most superchargers

• The four-lobe design is said to be the most efficient

• When running under optimal conditions, the Eaton supercharger produces a max boost of 10.5 PSI

• The blown LS9 produces 638 BHP with a 6600 R redline.

The LS9 featured in the ZR1 is also said to be the first factory ‘Vette motor to be built with actual cylinder walls, and though the LS3 bore is smaller than that of the LS7, the walls are still more durable because of their considerable density. The heads are made from a special heat-resistant alloy, the inlet and connecting rods are titanium and the amount of valve lift has been reduced to accommodate the intercooled supercharger.

Even with the technological advancements found on the new generation of ZR1 ‘Vette, there will always be a place in the heart for the original 427 cars. But even in this context, the 427s of yore never used the kind of cutting-edge tools now implemented through the LS platform.

- Sal Alaimo Jr., B. A. (6/30/11)

S. J. A.