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VVTL-i

The new 180hp Celica GTS (USA/CAN) now features the amazing VVTL-i engine developed by Toyota and Yamaha. Based on the standard 140hp 1.8 VVT-i, the VVTL-i has both Variable Valve Timing and Variable Valve Lift. The latter is achieved by an extra cam lobe that is brought into play by the engine electronics via a hydraulic actuator.

Interestingly, Toyota have set up the system so that the extra power kicks in a little over 6000 rpm. The torque curve of a VVTL-i is almost exactly the same as a VVT-i up to that point and then suddenly, where the VVT-i begins to run out of steam and revs, the new engine develops a new lease of life producing the extra 49 bhp right through to its rpm redline. The disappointing thing is that even with the new close ratio gearbox, the engine drops out of its optimum rev range when changing down. It seems very strange to us that the extra horsepower doesn't kick in just below 6000 rpm so that the engine can be kept in its sweet spot - this would almost certainly knock over a second off the already impressive 0-60 time of the Celica, putting it into another class altogether. Perhaps Toyota are saving this extra power for a later date. We expect to see after market chips that vary the valve lift at a lower engine speed, though as yet, none have appeared.

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The diagram below shows the two cams which are both always turning, and the hydraulic actuator that moves the 'Rocker Arm Pin' into place at a preset engine speed.

VVTL-i = Variable Valve Timing and Lift- intelligent
http://www.toyota-europe.com/technology/engines/vvtl_i.html

Toyota's Variable Valve Timing and Lift-intelligent engine goes one step further than VVT-i engines: It automatically adjusts the amount of "lift" on the cylinder's Intake and exhaust valves. In fact, VVTL-i technology has a lot in common with the human body: Athletes train to increase the air volume entering and leaving their lungs.

At high engine speeds Toyota's Electronic Control Unit (ECU) "lifts" the four valves located over each cylinder to increase the fresh air entering and exhaust leaving the cylinder. Increased air Intake at high engine speeds (above 6000 rpm) means more power, better combustion and fewer harmful emissions.

Celica GT
VVT-i, or Variable Valve Timing with intelligence, is an automobile variable valve timing technology developed by Toyota. The Toyota VVT-i system replaces the Toyota VVT offered starting in 1991 on the 5-valve per cylinder 4A-GE engine. The VVT system is a 2-stage hydraulically controlled cam phasing system.

VVT-i, introduced on the 1JZ-GTE/2JZ-GTE engine in 1996, varies the timing of the intake valves 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.[1] Variants of the system, including VVTL-i, Dual VVT-i, VVT-iE, "VVT-iW" and Valvematic, have followed.

Celica GTS
VVTL-i (Variable Valve Timing and Lift intelligent system) (also sometimes denoted as VVT-iL or Variable Valve Timing and Intelligence with Lift) is an enhanced version of VVT-i that can alter valve lift (and duration) as well as valve timing. In the case of the 16 valve 2ZZ-GE, the engine head resembles a typical DOHC design, featuring separate cams for intake and exhaust and featuring two intake and two exhaust valves (four total) per cylinder. Unlike a conventional design, each camshaft has two lobes per cylinder, one optimized for lower rpm operation and one optimized for high rpm operation, with higher lift and longer duration. Each valve pair is controlled by one rocker arm, which is operated by the camshaft. Each rocker arm has a slipper follower mounted to the rocker arm with a spring, allowing the slipper-follower to freely move up and down with the high lobe without affecting the rocker arm. When the engine is operating below 6000-7000 rpm (dependent on year, car, and ECU installed), the lower lobe is operating the rocker arm and thus the valves, and the slipper-follower is freewheeling next to the rocker arm. When the engine is operating above the lift engagement point, the ECU activates an oil pressure switch which pushes a sliding pin under the slipper-follower on each rocker arm. The rocker arm is now locked into the slipper-follower's movements and thus follows the movement of the high rpm cam lobe and will operate with the high rpm cam profile until the pin is disengaged by the ECU. The lift system is similar in principle to Honda VTEC operation.

The system was first used in 1999 Toyota Celica with 2ZZ-GE. Toyota has now ceased production of its VVTL-i engines for most markets, because the engine does not meet Euro IV specifications for emissions. As a result, this engine has been discontinued on some Toyota models, including that of the Corolla T-Sport (Europe), Corolla Sportivo (Australia), Celica, Corolla XRS, Toyota Matrix XRS, and the Pontiac Vibe GT, all of which had the 2ZZ-GE engine fitted. The Lotus Elise continues to offer the 2ZZ-GE and the 1ZZ-FE engine, while the Exige offers the engine with a supercharger. The Toyota Yaris uses VVT-i on its gasoline engines.

Toyota introduced VVT-i in 1996. With this technology
* The timing of the intake valves varies by adjusting the relationship between the camshaft drive (belt, scissor-gear 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 results in improved engine efficiency.

Toyota's Variable Valve Timing Mechanism