The all-new LS7 of the '06 Z06 reintroduces the 427-cubic-inch engine to the Corvette lineup, Hill notes. Unlike the previous 427 engine, however, which was a big-block design, the new 7.0-liter LS7 is a small-block V-8, specically the largest-displacement small-block ever produced by GM and a tribute to its 50 years as a performance icon.
The LS7 shares the same basic Gen IV V-8 architecture as the Corvette's 6.0-liter LS2, says Hill, but the LS7 uses a different cylinder block casting with pressed-in steel cylinder liners to accommodate the engine's 104.8-mm-wide cylinder bores; the LS2 has 101.6-mm bores. And 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.
Hill says the LS7's specifications include:
Dave Muscaro, assistant chief engineer of the small-block V-8 for passenger cars, says, ''In many ways, the LS7 is a racing engine in a street car. We've taken much of what we've learned over the years from the 7.0-liter C5-R racing program and instilled it here. There really has been nothing else like it offered in a GM production vehicle."
Muscaro points out that one of the clearest examples of the LS7's race-bred technology is its use of titanium connecting rods. ''They weigh just 480 grams apiece, almost 30 percent less than the rods in the LS2 V-8. As well as being lightweight, which enhances high-rpm performance and rpm range, titanium makes the rods extremely durable.
The Corvette Z06's powertrain and drivetrain systems are matched to the LS7's performance capability, Muscaro adds. The light, four-into-one headers discharge in to new, close-coupled catalytic converters and through to new ''bi-modal'' mufflers. The mufflers each 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 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, and 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.
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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.
Hill says the LS7's specifications include:
- unique cylinder block casting with large, 104.8-mm bores and pressed-in cylinder liners
- forged steel main bearing caps
- forged steel crankshaft
- titanium connecting rods with 101.6-mm 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 valve springs
- low-restriction air intake system
- hydroformed exhaust headers with unique ''quad flow'' collector flanges.
Dave Muscaro, assistant chief engineer of the small-block V-8 for passenger cars, says, ''In many ways, the LS7 is a racing engine in a street car. We've taken much of what we've learned over the years from the 7.0-liter C5-R racing program and instilled it here. There really has been nothing else like it offered in a GM production vehicle."
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The Corvette Z06's powertrain and drivetrain systems are matched to the LS7's performance capability, Muscaro adds. The light, four-into-one headers discharge in to new, close-coupled catalytic converters and through to new ''bi-modal'' mufflers. The mufflers each 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 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, and 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.