questa descrizione della pontiac solistice se non errata(perchè a volte su internet si trovasno pure notizie false) indica che i variatori del 2400 ecotec sono uno per albero a camme e a variazione continua, del resto la sigla vvt è usata anche per i variatori continui dei v6 :SOLSTICE POWERTRAIN
Solstice delivers pure roadster performance through a powertrain that drives the rear wheels. It consists of a 2.4L Ecotec engine with variable valve timing and a standard close-ratio five-speed manual transmission. Later in the 2006 model year, an optional Hydra-Matic 5L40-E five-speed automatic transmission becomes available.
The 2.4L Ecotec four-cylinder is rated at 177 horsepower (132 kw) at 6600 rpm and 166 lb.-ft. of torque (225 Nm) at 4800 rpm.* That power is available throughout much of the rpm band, as approximately 90 percent of peak torque is available from 2400 rpm to 5600 rpm. And with Solstice’s curb weight of just 2,860 pounds (1,297 kg), the 2.4L Ecotec engine helps give the vehicle a weight-to-horsepower ratio of nearly 16.2 to 1.
Balanced performance and economy are hallmarks of the Ecotec engine family, with the 2.4L engine offering unique features such as variable valve timing, coil-on-plug ignition, piston oil-cooling jets and integrated engine oil cooler. To accommodate the increased power level of the engine, the 2.4L Ecotec’s cylinder block bulkheads – the areas where the main bearing caps are attached – are enlarged for strength. Other areas of the engine were enhanced to reinforce the structure; the water jacket is deeper for added cooling capacity and improved cylinder bore roundness.
The 2.4L also shares Ecotec family traits that have helped forge a reputation for durability and sophistication:
Dual overhead camshafts (DOHC) and four valves per cylinder
Twin counter-rotating balance shafts for operational smoothness
Electronic throttle control
Low-friction, roller-finger follower valvetrain with hydraulic lash adjusters
Low-maintenance chain-drive for the camshafts
58X crankshaft positioning
Direct-mount accessories, which reduce or eliminate traditional sources of noise and vibration
Full-circle transmission mount to reduce noise and vibration
GM Oil Life System, which can reduce the frequency for oil changes
Innovative cast-in oil filter housing, which eliminates the need to crawl under the vehicle to perform oil changes and eliminates throwaway oil filter cans that retain used oil
Catalytic converter located close to exhaust manifold to speed catalyst “light off,” reducing hydrocarbon emissions
The camshafts of the 2.4L engine have phasers that support the continuously variable intake and exhaust valve timing. They also have cam position sensors, so that the electronic control module can accurately control valve timing. The crankshaft and camshaft position sensors on the 2.4L engine are digital.
The 2.4L engine also has premium features designed to ensure smooth and quiet operation, including a polymer coating and skirt design for the pistons that reduces noise during cold starts. An automatic hydraulic tensioner also is used; it maintains optimal tension on the timing chain, which reduces noise and vibration.