''Acoustic Control Induction System'', or ACIS, is an implementation of a
variable-length intake manifold
In internal combustion engines, a variable-length intake manifold (VLIM),variable intake manifold (VIM), or variable intake system (VIS) is an automobile internal combustion engine manifold technology. As the name implies, VLIM/VIM/VIS can vary ...
system designed by
Toyota
is a Japanese multinational automotive manufacturer headquartered in Toyota City, Aichi, Japan. It was founded by Kiichiro Toyoda and incorporated on . Toyota is one of the largest automobile manufacturers in the world, producing about 10 ...
.
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 well as provide better
fuel efficiency
Fuel efficiency is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical potential energy contained in a carrier (fuel) into kinetic energy or work. Overall fuel efficiency may vary per device, wh ...
and reduce intake "roar".
The
engine control unit
An engine control unit (ECU), also commonly called an engine control module (ECM), is a type of electronic control unit that controls a series of actuators on an internal combustion engine to ensure optimal engine performance. It does this by re ...
(ECU) controls the position of one or more air control valves based on input signals from throttle angle and engine RPM. The vacuum switching valve (VSV) which controls the vacuum supply to the actuator is normally closed and passes vacuum to the actuator when it is energized by the ECU. By energizing the VSV vacuum is passed to the actuator, closing the air control valve. This effectively lengthens the intake manifold run. By de-energizing the VSV, vacuum to the actuator is blocked and trapped vacuum is bled off of the actuator diaphragm. Toyota ACIS is an On/Off system. The valve (or valves in newer models with multiple valves to create more than 2 lengths) is either fully opened or fully closed.
An example of early single-valve ACIS programming would be the 3.0L 3VZ-FE engine. The ECU actuates the VSV to close the valve when the throttle position is 60% or greater and engine speed is 3,900 RPM or more.
Applications:
*
5E-FHE
*
1G-FE (VVT-i)
*
1GR-FE (Single VVT-i variants only)
*
1GZ-FE
*
2JZ-GE
The Toyota JZ engine family is a series of inline-6 automobile engines produced by Toyota Motor Corporation. As a replacement for the M-series inline-6 engines, the JZ engines were 24-valve DOHC engines in 2.5- and 3.0-litre versions.
1JZ
Th ...
*
7M-GE
*
3S-GE
*
1S-iLu
*
1MZ-FE
*
3UR-FE
*
1UZ-FE (VVT-i)
*
3VZ-FE
See also
*
T-VIS 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 combusti ...
External links
Lexus ACIS
References
{{Reflist
Engine technology
Toyota