3S-GE ACIS/Beams discussion, Discussion about ACIS, TVIS, VVT-i, etc. applicable to 3S-GE motors Options

[delusionz]

thats alright

how would i go about modding my ACIS?

rather than tell you how to mod it heres a way how not to mod it
http://toymods.net/forums/showthread.php?t...;highlight=ACIS

(also I recommend a new thread for 3SGE ACIS/Beams discussion)

I've been playing around with ACIS recently and I've discovered a few things about it,

The basics ... when the vacuum diaphragm pulls the throttles, the larger diameter in the corner of the inlet pipes open up (under the lid) for high rpm and when there is no vacuum to pull the throttles are free to return to the constricted low rpm position.

A few problems noted with ACIS:

1. When switching between high and low rpm modes, the vacuum diaphragm sometimes get stuck in the high rpm mode
2. The engage point is too late

First experiment was to see how the car behaved with the throttle pull lever tied up with cable ties as to lock the throttles in the high rpm position,

What I observed with the butt dyno was that under full throttle the rpm range where the car would "suddenly get up and go" was lower down, noticed in terms of road speed 65kph before, 55kph after (2nd gear) so in other words 5000-7000 was the get up and go range, without ACIS constriction in the intake the get up and go range was observed from 4000 to 7000.

No loss in acceleration was noticed from idle to 3000 under part throttle, but loss was noticed under full throttle, between 3000 and 4000 I couldn't tell either way in neither part throttle nor full throttle whether ACIS was better in low rpm or high rpm mode....

This suggests to me that 4000 is a better changeover point than 4800 for performance. 4800 is an rpm not reached by normal driving due to speed limits & gear selection thus ACIS seems to exist for the purpose of keeping intake noise down at legal road speeds rather than for improving low rpm torque as midrange torque takes a hit with this setup.

My proposed solution on how TO mod the ACIS, is to gutt the vacuum actuator system and replace it with a motorised cable pulling actuator triggered by a frequency switch relay at 4000 rpm the signal could be obtained by the ignitor right behind there.

[Rusty]

ha sweet finally started a thread, I'd thought I'd start with some Information. This is theory of ACIS

Acoustic 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 well as provide better fuel efficiency and reduce intake "roar".[1].

The ECU controls the position of the intake air control valve 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. Without vacuum, the air control valve opens, effectively shortening intake runner length[1]. This logic is the same as that used on the T-VIS system, the primary difference being that T-VIS actuates at a set RPM value whereas ACIS attempts to maintain a constant powerband by opening progressively.

Anyone who says that ACIS uses compression is WRONG or says it has a form of VVT is WRONG

Toyota Variable Induction System, or T-VIS, is a variable intake system designed by Toyota.

It improves the low-end torque of high-performance, small displacement four-stroke engines 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.

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 flow volume 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 marketT-VIS controller.

VVT-i, or Variable Valve Timing with intelligence, is an automobile variable valve timing technology developed by Toyota, similar to the i-VTEC technology by Honda. The Toyota VVT-i system replaces the Toyota VVT offered starting in 1991 on the 4A-GE 20-Valve engine. The VVT system is a 2-stage hydraulically controlled cam phasing system.

VVT-i, introduced in 1996, varies the timing of the intake valves 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. In 1998, "Dual" VVT-i (adjusts both intake and exhaust camshafts) was first introduced in the RS200 Altezza's 3S-GE engine. Dual VVT-i is also found in Toyota's new generation V6 engine, the 3.5L 2GR-FE V6. This engine can be found in the Avalon, RAV4, and Camry in the US, the Aurion in Australia, and various models in Japan, including the Celica. Dual VVT-i is also used in the Toyota Corolla (1.6 dual VVT-i 124bhp). Other Dual VVT-i engines include the 1.8L 2ZR-FE I4, used in Toyota's next generation of compact vehicles such as the Scion XD. It is also used in the 2JZ-GE and 2JZ-GTE engines used in the Lexus IS300 and in the Toyota Supra. By adjusting the valve timing engine start and stop occurs virtually unnoticeably at minimum compression. In addition fast heating of the catalytic converter to its light-off temperature is possible thereby reducing hydrocarbon emissions considerably. VVT-i Video

In 1998, Toyota started offering a new technology, VVTL-i, which can alter valve lift (and duration) as well as valve timing. In the case of the 16 valve 2ZZ-GE, the engine has 2 camshafts, one operating intake valves and one operating exhaust valves. Each camshaft has two lobes per cylinder, one low rpm lobe and one high rpm, high lift, long duration lobe. Each cylinder has two intake valves and two exhaust valves. Each set of two valves are 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 move up and down with the high lobe without affecting the rocker arm. When the engine is operating below 6000 rpm, the low lobe is operating the rocker arm and thus the valves. When the engine is operating above 6000 rpm, the ECU activates an oil pressure switch which pushes a sliding pin under the slipper follower on each rocker arm. This in effect, switches to the high lobe causing high lift and longer duration.


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, some Toyota models have been discontinued... Celica