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What is VVTL-i ? Sun Jan 06, 2013 2:11 pm
newcars
Admin
VVTL-i
The new 180hp Celica GT-S (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.
...
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.
source:http://www.celicahobby.com
The new 180hp Celica GT-S (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.
...
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.
source:http://www.celicahobby.com
