T-VIS
Encyclopedia
Toyota Variable Induction System, or T-VIS, is a variable intake system designed by Toyota to improve the low-end performance of multi-valve engines.
T-VIS is intended to improve the low-end torque
of high-performance, four-stroke internal combustion engine
s - by changing the geometry
of the intake manifold according to the engine rotation speed. The system uses two separate intake runners per cylinder
, one being equipped with a butterfly valve
that can either open or close the runner. All valves are attached to a common shaft which is rotated by a vacuum
actuator
outside the manifold. T-VIS does not actually keep one of the intake valves from opening or seal off the port for one valve.
The engine control unit
(ECU) allows vacuum into the actuator by powering a solenoid valve
when the engine rotation speed is low. At higher engine speeds (e.g. 4,200 rpm), vacuum is cut off and a spring inside the actuator causes the butterfly valve to fully open. The idea behind the system is that in the lower engine speed band, the speed of the intake air will be increased because the intake runner cross section
per cylinder is smaller. However, when engine speed increases, the second runner is opened, decreasing airflow speed, but increasing the airflow volume, better matching the engine's airflow needs at higher revolutions. With modified engines it may be desirable to have the T-VIS open earlier than stock, because modifications that improve an engine's power output may do so by increasing airflow per engine revolution, resulting in a high airflow at a lower rpm.
In addition to providing more air at higher engine speeds, the system also creates a swirl in the combustion chamber at lower rpms. The swirl makes for more efficient combustion, and is due to the asymmetric nature of the airflow with one intake runner closed.
Applications:
T-VIS is intended to improve the low-end torque
Torque
Torque, moment or moment of force , is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist....
of high-performance, four-stroke internal combustion engine
Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...
s - by changing the geometry
Geometry
Geometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers ....
of the intake manifold according to the engine rotation speed. The system uses two separate intake runners per cylinder
Cylinder (engine)
A cylinder is the central working part of a reciprocating engine or pump, the space in which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically cast from aluminum or cast iron before receiving precision machine work...
, one being equipped with a butterfly valve
Butterfly valve
A butterfly valve is a valve which can be used for isolating or regulating flow. The closing mechanism takes the form of a disk. Operation is similar to that of a ball valve, which allows for quick shut off. Butterfly valves are generally favored because they are lower in cost to other valve...
that can either open or close the runner. All valves are attached to a common shaft which is rotated by a vacuum
Vacuum
In everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty". A perfect vacuum would be one with no particles in it at all, which is impossible to achieve in...
actuator
Actuator
An actuator is a type of motor for moving or controlling a mechanism or system. It is operated by a source of energy, usually in the form of an electric current, hydraulic fluid pressure or pneumatic pressure, and converts that energy into some kind of motion. An actuator is the mechanism by which...
outside the manifold. T-VIS does not actually keep one of the intake valves from opening or seal off the port for one valve.
The engine control unit
Engine control unit
An engine control unit is a type of electronic control unit that determines the amount of fuel, ignition timing and other parameters an internal combustion engine needs to keep running...
(ECU) allows vacuum into the actuator by powering a solenoid valve
Solenoid valve
A solenoid valve is an electromechanical valve for use with liquid or gas. The valve is controlled by an electric current through a solenoid: in the case of a two-port valve the flow is switched on or off; in the case of a three-port valve, the outflow is switched between the two outlet ports...
when the engine rotation speed is low. At higher engine speeds (e.g. 4,200 rpm), vacuum is cut off and a spring inside the actuator causes the butterfly valve to fully open. The idea behind the system is that in the lower engine speed band, the speed of the intake air will be increased because the intake runner cross section
Cross section (geometry)
In geometry, a cross-section is the intersection of a figure in 2-dimensional space with a line, or of a body in 3-dimensional space with a plane, etc...
per cylinder is smaller. However, when engine speed increases, the second runner is opened, decreasing airflow speed, but increasing the airflow volume, better matching the engine's airflow needs at higher revolutions. With modified engines it may be desirable to have the T-VIS open earlier than stock, because modifications that improve an engine's power output may do so by increasing airflow per engine revolution, resulting in a high airflow at a lower rpm.
In addition to providing more air at higher engine speeds, the system also creates a swirl in the combustion chamber at lower rpms. The swirl makes for more efficient combustion, and is due to the asymmetric nature of the airflow with one intake runner closed.
Applications:
- 1982.08-1990 1G-GEU/1G-GE
- 1983-1989 4A-GEToyota A engineThe A Series engines are a family of straight-4 internal combustion engines with displacement from 1.3 L to 1.8 L produced by Toyota Motor Corporation...
- 1986-1989 3S-GEToyota S engineThe Toyota S Series engines are a family of straight-4 engines with displacement from 1.8 L to 2.2 L produced by Toyota Motor Corporation. The series has cast iron engine blocks and alloy cylinder heads.-Table of S-block engines:-1S:...
(1st generation only) - 1986-1993/95 3S-GTEToyota S engineThe Toyota S Series engines are a family of straight-4 engines with displacement from 1.8 L to 2.2 L produced by Toyota Motor Corporation. The series has cast iron engine blocks and alloy cylinder heads.-Table of S-block engines:-1S:...
(through 1995 in US market, 1993 everywhere else; 1st & 2nd generation motors only)
See also
- Acoustic Control Induction SystemAcoustic Control Induction SystemAcoustic Control Induction System, or ACIS, is an implementation of a Variable Length Intake Manifold system designed by Toyota.Simply put, the ACIS system uses a single intake air control valve located in the intake to vary the length of the intake tract in order to optimize power and torque, as...
- Variable length intake manifoldVariable Length Intake ManifoldIn internal combustion engines, a variable length intake manifold , or variable intake manifold is an automobile internal combustion engine manifold technology...