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Discussion Starter · #1 · (Edited)
Acoustic Control Induction System -- ACIS--

There are a lot of people that haven't a clue what ACIS is or what it does. So, i did some research at work using our Toyota Technical Information System (TIS) and i dug up some technical training for the ACIS system. I then took that published information and created a webpage with text, diagrams and pictures. There is a wealth of information out there, the trouble is finding it. So i will do my best to describe the system, its operation, and the role it plays in performance.

http://www.geocities.com/mwsupra2003/acis.html

the above link has all of the information below. please goto the link for helpful diagrams and pictures. :)


---Theory----
Using laws of inertia, thermodynamics and physics the toyota engineers discovered that the opening and closing of the intake valves creates acoustic energy pulses that bounce around inside the intake manifold and chamber. They then developed a system, called ACIS, to control and manipulate those acoustic pulses to create a "supercharging" effect.

By varying the length of the intake runners through the use of valves, the toyota engineers found a way to time the acoustic pulses so they enter the cylinders through the intake valves. This means that after an intake valve closes and creates this acoustic pulse, the pulse bounces off the intake runner and chamber and then is timed to enter at the next intake cycle so the valve is opened with a pressurized acoustic wave being forced into the cylinder.


---Application---
Toyota has many NA engines that utilize the ACIS system. (7m-ge, 2jz-ge, 2jz-fe, 1mz-fe, ect, ect) In our case, the 7mge, there is a butterfly valve (intake air control valve(IAC)) placed in the middle of our intake manifold behind the union of the Y-pipe. This valve is controlled by an ACIS actuator. The Actuator is controlled via vacuum provided by the either the throttle, VSV's or the ECM ( or all three). There is a vacuum storage tank located beneath the intake manifold and that is connected to a port near the Intake air control valve.


---Operation---
I'm not sure on the switchover throttle position for the 7mge, but the activation RPM is 4200. Before that point at WOT, the Air control valve is closed, meaning that the cylinders are getting shared air from just behind the throttle body. This means that the engine is utilizing long intake runners. Under WOT, past 4200 rpms, the air control valve is opened and the cylinders are now getting shared air from the center of the intake manifold, meaning the engine now has shortened intake runners. ( see diagram on site)

On the 2JZ-FE engine, there is an activation rpm of 4,500 and a 30% throttle crossover map. meaning....

low throttle... ( less than 30%)
<4500 rpm = valve open ( short runners )
>4500 rpm = valve close ( long runners )

high throttle... ( more than 30%)
<4500 rpm = valve close ( long runners )
>4500 rpm = valve open (short runners )

This system ( two stage acis) essentially gives you two torque curves. The valve is timed to open on the downfall after the first peak, so the engine has potential to make equal or more power later on throught the power band.


--- Modification ---
Modifying the ACIS system is not recommended because it has been tuned for the specific engine. But the thought does provoke interest. If by changing the activation RPM and/or throttle %, could you tune where you want your torque to peak?

I have the ACIS system on my now turbocharged 7M-GE and remarkebly it has still provided two torque curves between the designated 4200rpm. I plan to do some experimentation with ACIS during my next trip to the dyno. I will perform runs with the valve closed ( long runners), with the valve open ( short) and then multiple runs using different activation RPMS. If this system can yield more power because of its changing attributes, then it may be a desired modification for mid-power performance enthusiasts.


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feel free to add anything i missed. :)
 

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Discussion Starter · #3 ·
no problem. I'm hoping to get this moved into the FAQ section

*hint hint*
 

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yeah man... that's some good stuff. even though i dont have an n/a.
 

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This subject has been covered a few times, in fact I brought it up a year ago, concerning the advantages/ disadvantages of changing the ACIS crossover point, but no conclusions were reached. I am glad to see such a thorough coverage of this info- Thanx
: )
 

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seriously, i was just talking to my friend that once i get over 4g's, i can feel a stronger pull, almost like vtech, and im like why the fuck does it do that, and now i know.
 

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Discussion Starter · #9 ·
i'm glad you guys like it. i know the system has been discussed, but its always been kinda grey and i just wanted to throw out some sound information so people can start thinking of ideas.

hope it helps :)

ps. glad i amaze you TRD91whtMK3 ver.2 :p :D
 

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I always wondered what that butterfly was there for, I knew it was for better airflow just wasn't sure how it was operated.

BTW it's the same technology as Mitsubishi uses on their Cyclone Intakes.

From what I understand it works good on stock power/stock flow applications, otherwise it looses it's efficency quickly.


Art


PS: If anyone asks you what is this ACIS for, just say it's like a little sonic charger, creates sound waves which give more power :lol:
 

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Discussion Starter · #11 ·
ya, mitsu calls it VIC, variable intake control
 

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The butterfly valve on the 7M-GE is solely controlled by a VSV (from the canister), in turn controlled by the ECU. It's normal state is open (it has to be, otherwise your cold start injector would only feed cylinders 4-6 at idle), when vaccuum is applied it closes.
 

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hoser813 said:
seriously, i was just talking to my friend that once i get over 4g's, i can feel a stronger pull, almost like vtech, and im like why the fuck does it do that, and now i know.

VTEC!!!! aight peace :chicken:
 

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I'm wondering if he ever made those trips to the dyno he talked about. I'm curious about the out come.
 

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on my 86 celica gt-s it has T-VIS - i beleive it is called twin valve induction system. sorta along the same lines
 

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I have a manifold that we removed ACIS. But after talking it over and reading this thread, I found the need for it. Some of the older DSM guys use the Cyclone intake and modify the switch over with a Hobbs switch to match their needs. I decided to find a bigger intake since you can only port the 7M so much. So I will be using a 2J N/A upper with Y pipe. The 2J ACIS looks like the 7M on steriods. I'll post pics of the upper as soon as I dig them up.

Allan:cool:
 

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Discussion Starter · #17 ·
i'm interested in seeing the 2J acis system. I'm doing a lot of work on my car and i'll probably be ditching my manifold for a custom. So.. bye bye ACIS. Too bad the HG never made it to this summer when i was planning on dynoing it
 

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jong said:
i'm interested in seeing the 2J acis system. I'm doing a lot of work on my car and i'll probably be ditching my manifold for a custom. So.. bye bye ACIS. Too bad the HG never made it to this summer when i was planning on dynoing it
It's huge, funny thing is the 2J upper is the same size (slightly larger) than the 7M lower. This could be the mod of the century for the N/A and N/A-turbo cars!

Allan:cool:
 

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Iceberg319 said:
bolt-on affair?
No it's a modify deal just like the Turbo guys do, cut and weld. Cut the flange off the Y pipe for a Q45 throttle body. I found some pics of the Y pipe. I'll keep looking for the manifold pics, but from the Y pipe pics you can get the idea how big the 2JZ is. The 7M Y pipe is ported also.

http://www.villagephotos.com/pubbrowse.asp?folder_id=1267173

Allan:cool:
 
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