The New LS7 EngineThe all-new LS7 of the '06 Z06 reintroduces the 427ci engine to the Corvette lineup. Unlike the previous 427 engine, which was a big-block design, the new 7.0L LS7 is a small-block V-8, the largest-displacement small-block ever produced by GM and a tribute to its 50 years as a performance icon. With 500 hp and 475 lb-ft of torque, it is also the most powerful passenger-car engine ever produced by Chevrolet and GM. The LS7 is easily identified under the hood by red engine covers with black lettering.
The LS7 shares the same basic Gen IV V-8 architecture as the Corvette's 6.0L LS2, but the LS7 uses a different cylinder-block casting with pressed-in steel cylinder liners to accommodate the engine's wide, 104.8mm cylinder bores (the LS2 has 101.6mm bores). When compared to the LS2, the LS7 also has a different front cover, oil pan, exhaust manifolds, and cylinder heads.
Internally, the LS7's reciprocating components make use of racing-derived lightweight technology, including titanium connecting rods and intake valves, to help boost horsepower and rpm capability. The rpm fuel shutoff limit is 7,000 rpm.
The LS7's specifications include:*Unique cylinder block casting with large, 104.8mm bores and pressed-in cylinder liners*Forged-steel main bearing caps*Forged-steel crankshaft*Titanium connecting rods with 101.6mm stroke*Forged-aluminum flat-top pistons*11.0:1 compression*Dry-sump oiling system*Camshaft with .591-inch lift*Racing-derived CNC-ported aluminum cylinder heads with titanium intake valves and sodium-filled exhaust valves*Titanium pushrods and valvesprings*Low-restriction air-intake system*Hydroformed exhaust headers with unique "quad flow" collector flanges.
"In many ways, the LS7 is a racing engine in a street car," said Dave Muscaro, assistant chief engineer of small-block V-8 for passenger cars. "We've taken much of what we've learned over the years from the 7.0L C5-R racing program and instilled it here. There really has been nothing else like it offered in a GM production vehicle." All LS7 engines are assembled by hand at GM Powertrain's new Performance Build Center in Wixom, Michigan. The exacting standards to which they are built include deck-plate honing of the cylinders, a procedure normally associated with building racing engines and almost unheard of in a production-vehicle engine. Look for our LS7 engine story in this issue for all the down-and-dirty details on this killer engine.
Z06 DrivetrainThe Corvette Z06's powertrain and drivetrain systems are matched to the LS7's performance capability. The light, four-into-one headers discharge into new, close-coupled catalytic converters and through to new "bi-modal" mufflers. The mufflers feature a vacuum-actuated outlet valve, which controls exhaust noise during low-load operation but opens for maximum power.
At the rear of the LS7 engine, a single-mass flywheel and a lightweight, high-capacity clutch channel torque to the rear transaxle. The six-speed manual transmission has been strengthened to handle the LS7's increased torque load. The transmission includes a pump, which sends transmission fluid to the front radiator for cooling. Upon its return, the fluid removes additional heat from the differential lube before returning to the transmission. The M6 transmission connects to a limited-slip differential with enlarged ring-and-pinion gears. Stronger axle halfshafts with tougher universal joints transmit power to the rear wheels.