- T-VIS
"Toyota Variable Induction System", or T-VIS, is a
variable intake system designed byToyota .It improves the low-end
torque of high-performance, small displacement four-stroke engines by changing thegeometry of theintake manifold according to the engine rotation speed. The system uses two separate intake runners per cylinder, one being equipped with abutterfly valve that can either open or close the runner. All valves are attached to a common shaft which is rotated by avacuum actuator outside the manifold.The engine control unit allows vacuum into the actuator by powering a
solenoid valve when the engine rotation speed is below 4200 rpm.Above this engine speed vacuum is cut off and a spring inside the actuator causes the butterfly valve to fully open. The theory behind the system is that in the lower speed band the velocity of the intake air can be improved because the intake runner cross section per cylinder is smaller. However, when the engine gains speed, the required air flowvolume is more significant so the second runner is opened to improve the flow. With upgraded engines (more flow) you may want to have your T-VIS open earlier than stock because it begins to choke the airflow at a lower RPM, since the airflow per RPM is greater with upgraded turbos, intakes, and exhaust. There is now a T-VIS controller on the market [http://www.pampeperformance.com/t-vis_controller T-VIS controller] .ee also
*
Acoustic Control Induction System
*Toyota M engine
*Toyota VZ engine
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