Editing VVT-i (section)

{{Short description|Automobile variable valve timing technology}}
{{Redirect-distinguish|Valvematic|Valvetronic}}
{{Use British English|date=June 2024}}
{{more citations needed|date=June 2024}}
[[Image:Toyota ZR engine cutaways valve gear.jpg|thumb|Cutaway view of Variable Valve Timing with intelligence on a [[Toyota ZR engine|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 [[brand]]s [[Groupe PSA]] ([[Peugeot]] and [[Citroen]]), [[Toyota]], [[Lexus]], [[Scion (automobile)|Scion]], [[Daihatsu]],  [[Subaru]], [[Aston Martin]], [[Pontiac (automobile)|Pontiac]] and [[Lotus Cars]]. It was introduced in 1995 with the ''[[Toyota JZ engine#2JZ-GE|2JZ-GE]]'' engine found in the [[Toyota_Crown (S150)|JZS155 Toyota Crown]] and [[Toyota_Crown_Majesta (S150)|Crown Majesta]].

The VVT-i system replaces the Toyota '''VVT''' system introduced in 1991 with the five-valve per cylinder ''[[Toyota A engine#4A-GE (20-valve)|4A-GE]]'' "Silver Top" engine found in the [[Toyota Corolla Levin (E100)|AE101 Corolla Levin]] and [[Toyota Sprinter Trueno (E100)|Sprinter Trueno]]. The previous VVT system was a 2-stage hydraulically controlled cam phasing system.

VVT-i varies the timing of the [[intake]] [[poppet valve|valve]]s by adjusting the relationship between the [[camshaft]] drive (belt or chain) and intake camshaft. Engine oil pressure is applied to an actuator to adjust the camshaft position. Adjustments in the overlap time between the exhaust valve closing and intake valve opening result in improved engine efficiency.

Variants of the system, including '''VVTL-i''', '''Dual VVT-i''', '''VVT-iE''', '''VVT-iW''' and '''Valvematic''' have followed. [[Direct fuel injection|Direct injection]] systems such as the '''D-4 (VVT-i D-4)''' and '''D-4S''' are also used in conjunction with VVT-i.