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Cutaway view of Variable Valve Timing with intelligence on a ZR engine in Techniquest Glyndŵr. VVT-i, or Variable Valve Timing with intelligence, is an automobile variable valve timing petrol engine technology manufactured by Toyota Group and used by brands Groupe PSA (Peugeot and Citroen), Toyota, Lexus, Scion, Daihatsu, Subaru, Aston Martin, Pontiac and Lotus Cars.
Alfa Romeo was the first manufacturer to use a variable valve timing system in production cars (US Patent 4,231,330). [10] The fuel injected models of the 1980 Alfa Romeo Spider 2000 had a mechanical VVT system. The system was engineered by Ing Giampaolo Garcea in the 1970s. [11] All Alfa Romeo Spider models from 1983 onward used electronic VVT ...
The 1GZ-FE is a 4,996 cc (5.0 L) 48-valve DOHC V12 engine with variable valve timing ().Bore is 81 mm and stroke is 80.8 mm, with a compression ratio of 10.5:1. The official power output advertised in Japan per the gentlemen's agreement is 206 kW (276 hp; 280 PS) at 5,200 rpm, though it was advertised as 220 kW (295 hp; 299 PS) in export markets.
The Toyota AZ engine family is a straight-4 piston engine series. The AZ series uses an aluminium engine block with cast iron cylinder liners and aluminium DOHC cylinder head. . The engine series features many advanced technologies including slant-squish combustion chambers, offset cylinder and crank centers, and the VVT-i continuously variable intake valve timing syst
Six times in the past six years NHTSA has undertaken an exhaustive review of allegations of unintended acceleration on Toyota and Lexus vehicles and six times the agency closed the investigation without finding any electronic engine control system malfunction to be the cause of unintended acceleration. [121]
The system has the advantage that it is continuously variable rather than switching in at a set speed. Its disadvantage is the complexity of the system and corresponding price. Other systems will achieve similar results with less cost and simpler design (electronic control). For a more detailed description, see the sandsmuseum link below.
Engines displace from 1.6 to 2.0 liters. Most engines in this family are equipped with Toyota's dual VVT-i technology that optimizes both intake and exhaust valve timing. This engine family is also the first to use Toyota's Valvematic system, first appearing on the Noah and Voxy in 2007 and then the European Avensis in 2009.
The Alfa Romeo Twin Spark engine, introduced in the 1987 Alfa Romeo 75, also uses variable valve timing. [3] [4] The Alfa system varies the phase (not the duration) of the cam timing and operates on the inlet camshaft. [5] Alfa Romeo's variator is a cylindrical chamber that contains a pressure chamber and piston along with helical splines.