More bottom end out of your 3vz? try the ACIS....

[v-cam]

Ok guys. Im not lying, dont call it placebo. This is for real.

Last night I thought about how Jap engines are designed to rev hard and make lots of top end. Hence why the 3vz pulls so well after 4 grand on the tacho. This is great, but the low rev power isn't something to write home about...

So, I was thinking about the ACIS valve in the intake and wondered what would happen if is was open all the time rather than only after 4 grand? Someone said here that it would cause you to lose all the power down low.... well, you were wrong.

I jammed it open and went for a drive. The power from idle to about 4500 now is incredible, the car is so much more responsive and pulls real hard. The noise it makes is better, like a deep growl as the engine gulps in air... It transformed the engine! The torque hole between 3 and 4 grand is now overflowing with power!

The down side? Well, power tapers off after 5 grand. No longer is the fianl punch before redline as it seems to run out of steam.... could be my stock exhaust not allowing all the air back out quick enough though... Interestingly, the gearbox could sense the lack of power at the top end and shifted at 5 grand, throwing you straight into the power again... you could literally feel yourself pushed back in the seat when it shifted from 2nd to third early! Even when I planted it at low speed, the gearbox stayed in a 2nd gear, using all the newfound torque rather than banging back to first and using the last 1000 revs out of the tacho...

But my car has 250,000 klicks on board, and I prefer not to rev it out these days, but have recently been forced to as thats where the power is... until now

So try it out guys and let me know if you notice a difference, I'm particually interested in those who have y-pipes and zorst systems or intakes... my engine is stock right down to the air filter.

All i did was tie it open with wire.

[Luckynumber5]

You could have just unplugged the vacuum like from the ACIS actuator.... The 3vz was designed with low end in mind, to say that you have suddenly transformed the engine to a top end monster by simply disabling the variable geometry intake is

Sorry man but it is placebo. Variable intake= like 5 horsepower

[v-cam]

No I couldn't have just unplugged it, because it is sprung closed. idiot. Obviously you have no idea what im talking about.

If you read my post, you would see that I said it changed the low end. I also said that the top end tapered off power. So I dont see where you got "top end monster" from.

Im also talking torque not Hp. Do you know the difference? So before you assume that its all placebo, go and do it to your camry and post something with a little intelligence. Also, make sure you read posts properly beofre sounding like a know-it-all idiot.

[v-cam]

Can someone with a little 3vz engine experience post on here what they think? I don't need people flaming me saying its all in my head when they havn't tried it themselves or read my post properly. If you haven't got anything intelligent to add, don't bother posting.

My question is with all this is what is it doing to my a/f ratio? Does the ECU on the 3vz adjust this at all?

[Rdizzle]

you should go get it dynoed. I would like to see what kind of numbers this might have opened up. To bad i'm a 5S.

[bigbird]

Originally Posted by Luckynumber5

The 3vz was designed with low end in mind, to say that you have suddenly transformed the engine to a top end monster by simply disabling the variable geometry intake is

i think hes saying that the "mod" has freed up power from idle to 4500(low end). not that hes got alot more top end power. im not sure what to believe, the idea would be simple to try out but im sure toys will grace us with his knoledge soon

[midnightmach]

Originally Posted by v-cam

No I couldn't have just unplugged it, because it is sprung closed. idiot. Obviously you have no idea what im talking about.

I thought its always open and closes under heavy thottle... heres a pic after i cleaned it...

sprung open

Have you done the ACIS mod? Because if you did you would have known this...

[bigbird]

this came from 2wickedtoyz's origional post on the acis mod.

"1.The ACIS allows the intake manifold to divert the path of intake air into the combustion chamber. Two air intake paths are provided in the intake manifold to allow the option of the intake volume most favorable for the particular engine speed. Optimum performance is achieved by switching the intake air control valve from either the closed postion(for high tourque at low rpm) or the open position(for maximum horsepower at high rpms)."

i believe its open when the car is off because there is no vacume pressure to close it, but i may be wrong. i do believe that it is closed at lower rpms becaust it fallows the logic as i see it, lower rpms needs less air, higher rpms needs more air. but im no expert.

[EvoFire]

I'm wondering why would it lose power after 5krpms when its suppose to open anyways.

[Razo-E]

Don't fuck with the ACIS; it's there for a reason..

if you can feel a "kick" when it hits a certain RPM (it's 4000 for my Supra, N/A's have ACIS) then it ISN'T working correctly...

[EvoFire]

Originally Posted by Razo-E

Don't fuck with the ACIS; it's there for a reason..

if you can feel a "kick" when it hits a certain RPM (it's 4000 for my Supra, N/A's have ACIS) then it ISN'T working correctly...

My car kicks at 4krpms too..... its not very big, but the tone of the engine changes and the car does seem to accelerate faster.... No I don't have VTEC lolz!

[ag6286]

Closing the ACIS will NOT 'transform' your engine. its mostly in your head. While you're right, it does help close the gap in power from 3-4 grand, the overall gain is not much. I closed mine like you permanently but only because i have done a full port and polish on my 3vzfe, so i automatically lose some low end but have big gains as teh RPM goes up. Luckynumber five is right, it was designed with low end in mind. The torque output is huge at very very low RPM, especially compared to the 1mzfe. Also, you SHOULD NOT lose top end if you keep it open since it opens anyway at 4000RPM till the next shift, so power should not logically change.

[ag6286]

reguarding the KICK, my had a HUGE kick at 4000 b/c of the mods i did, again the only reason i messed with mine was to close the huge gap in power mine had

[Razo-E]

This is taken from SupraMania...

Originally Posted by jong

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.

Originally Posted by NickM

This looks like a nice place to expalin Toyota's air intake control system, or ACIS as it is now called.

First of all, it does not ever "kick in". The default position of the valve is springloaded open, which is high rpm use. Vacuum pulling on the diapragm closes it to boost low RPM torque. The manifold with longer runners aids low end torque, but starve the engine at higher engine speeds. The shorter ones lose velocity, but can fill a cylinder at high RPM.

So the system is set up for high rpm, and closes the valve for low speed torque. If you really feel it kick in, your probably does not work, and the vacuum solenoid is froze. Take a good look at that stock torque curve, and how flat it is.

That is stock and working correctly. Jetjock has posted the parameters for specific opening and closing elsewhere, but now you know why.

Originally Posted by jetjock

Maybe this will help. I don't have one on my car but this is what the tech manuals say:

The ACIS is designed to shift the torque band higher along the rpm range. It does this by responding to changes in the throttle opening angle (VTA signal of the TPS) and engine rpm (NE signal in the CPS). The air control valve is then opened or closed by the ECU via a VSV and vacuum actuator.

The valve is located in the center of the manifold and when closed divides it into two sections - a front chamber for cylinders 1 to 3 and a rear chamber for cylinders 4 to 6. A closed ACIS valve has the same effect as lengthening the intake manifold while an open valve has the same effect as shortening the intake manifold. In other words flow efficiency what's being controlled.

When the ECU turns on the VSV vacuum is applied to the actuator and closes the valve. When the VSV is turned off atmospheric pressure is applied to the actuator and opens the valve. There are four combinations of speed and throttle angle the ECU uses to decide when to open or close the ACIS:

1) Above 60% throttle angle and above 4,200 rpm: VSV off, ACIS open.

2) Above 60% throttle angle and below 4,200 rpm: VSV on, ACIS closed.

3) Below 60% throttle angle and above 4,200 rpm: VSV on, ACIS closed.

4) Below 60% throttle angle and below 4,200 rpm: VSV off, ACIS open.

[v-cam]

^interesting read...

So im actually tying the valve closed? That would explain the starvation of air at high rpms. But if thats the case, why does it release so much more low end when i have it tied if essentially its doing the exact same thing? That means im tying it open?

Now im confused....

Why in stock form does it lack low end then? And if you say the 3vz was designed for low-end, why does it not produce peak torque until a lofty 4400 rpm? Thats contradictory.

Toysrme- im looking for your view on this.