A new, 6.2L LS3 small-block V-8 is the standard engine in Coupeand Convertible models. It is rated at 430 horsepower (321 kW)* and 424lb.-ft. of torque (586 Nm)* with the standard exhaust system; with thenew, optional two-mode exhaust system, power ratings increase to 436horses / 325 kW and 428 lb.-ft. / 592 Nm. As a result, the standardCorvette is true supercar, capable of 190 mph. The LS3 with thesix-speed paddle-shift automatic is the fastest automatic-equippedCorvette ever, with 0-60 mph capability of 4.3 seconds.
This new iteration of the storied small-block family features a revised,larger-bore cylinder block - 4.06-inch / 103.25 mm vs. the previous6.0L's 4.00-inch / 101.62 mm bores - high-flow, LS7/L92-style cylinderheads; larger-diameter pistons; revised camshaft and camshaft timing;revised valvetrain with offset intake rocker arms; high-flow intakemanifold; high-flow fuel injectors from the Z06's LS7 engine; and a newengine beauty cover.
The LS3 features an aluminum cylinder block with cast iron cylinderliners. In addition to its larger bores, which help create a376-cubic-inch displacement, the block casting also features revisionsand machining in the bulkheads that enhance its strength and improvedbay to bay breathing. But while the bore of the 6.2L engine is increasedwhen compared with the previous 6.0L engine, the engine's stroke remainsat 3.62 inches (92 mm). The pistons for the larger 6.2L engine also arenew and are designed for its high-rpm performance capability.
Breathing for the new 6.2L engine is accomplished via new, high-flowcylinder heads. They're based on the large port/large valve design foundon the LS7 engine and other GM L92 engines, with larger-capacity,straighter intake ports. The design optimizes intake flow to thecombustion chamber and the exhaust ports are also designed for betterflow.
Complementing the larger-port design of the heads are commensuratelysized valves. The intake valve size alone increases from 2.00 inches(50.8 mm) to 2.16 inches (55 mm) - an increase of nearly 9 percent. Theintake valves feature lightweight hollow stems, which enable theengine's 6,600-rpm capability. The exhaust valves also are large,measuring 1.60 inches (40.4 mm) in diameter.
To accommodate the engine's large valves and enable more direct intakeport flow, the intake-side rocker arms are offset 6 mm between the valvetip and the push rod. Actuating the valves is a new camshaft, withintake-side lobes providing more than a 5-percent percent in increase inlift, from 0.521-inch to 0.551-inch (13.25 mm to 14 mm). Exhaust-valvelift remains unchanged from the LS2. The camshaft timing was revised tooptimize performance with the higher-lift intake cam profile.
Ensuring the cylinder heads receive all the air they can handles fallsto a new, acoustically tuned intake manifold. The composite design ismanufactured with a "lost core" process that improves runner to runnervariation and reduces airflow losses. An acoustic foam material is usedto reduce radiated engine noise; it is sandwiched between the outer topof the manifold and an additional "skull cap" acoustic shell. Also newbeauty covers atop the engine shield the rocker covers and also featurea noise-reducing, acoustically tuned insert to provide a more refinedengine sound.
Exhaust system - Optional on '08 Coupe and Convertible models is a new,two-mode performance exhaust system. Similar in design and function tothe system used on the Z06, the dual-mode exhaust uses vacuum-actuatedoutlet valves, which control engine noise during low-load operation, butopen for maximum performance during high-load operation. It is notidentical to the Z06 system; the Coupe/Convertible uses a2.5-inch-diameter exhaust, while the Z06 uses a three-inch system.
With the new, dual-mode performance exhaust, power output forCoupe/Convertible rises from 430 horsepower (321 kW) and 424 lb.-ft. oftorque (575 Nm) to 436 horses (325 kW) and 428 lb.-ft. (580 Nm). Thissystem gives the Corvette a more aggressive exhaust sound character thatwill appeal to performance enthusiasts.
Transmissions and Axle Ratios
The shifting efforts for both thesix-speed manual transmission and paddle-shift six-speed automatictransmissions have been improved in '08 Corvette models. The manualtransmission shifting improvements include a more positive and directfeel during gear changes, with better gate-to-gate location.
The six-speed paddle-shift automatic transmission on Coupe andConvertible is improved with new hardware and a new controllercalibration that deliver quicker shifts. This change bolsters thefeeling of performance and driver control when using the shiftingpaddles.
Also new for '08 models is the availability of the 2.73 performance axleratio with the automatic transmission. It is included with the Z51package.