How to make ACIS and NA Intake Manifold work correctly on a 7MGTE

whitey482

New Member
Jan 2, 2017
8
0
1
Dallas
Hey all,

I've been researching how to convert over to an N/A intake manifold set up and leveraging the ACIS technology on my 7mgte motor. Some people may think why the hell are you doing this in first place? What's wrong with the stock turbo manifold? Why not just go FFIM? Well, my main reason is i dont have the funds to go FFIM and I want to do something different. Personally, I like the looks of the n/a y-pipe set up and it seems that ACIS does have some good hp benefits.

Anyway, back to my question. I have all the n/a manifold parts for the conversion: upper and lower intake manifolds, n/a throttle body, n/a breather tube assembly and soon I'll be getting the n/a vacuum control canister. This is where the valve in the intake manifold is controlled by vacuum. My main question is how is this valve going to be activated properly or even at all? The 7mgte harness and ecu do not have the VSV1 (intake air control valve) signal. I looked this up in my TEWDs. The 7mgte does have a vsv for egr and vsv2 for fuel pressure up. So I foresee the ACIS system not working properly. From my research the actuator is controlled by the ECU and opens based on the position of the TPS and engine speed. If there is no signal that will tell the valve to open then I'm not sure how this is going to work. I may have answered my own question. I could use VSV2 for fuel pressure up. I am upgrading to an AFR set up so wont need that. But I'm not sure this signal will fire at the right time to mimic the behavior of the VSV1 air control valve.

I am wondering if anyone has done this setup and if they were able to get a signal to control the vsv or if you don't need it all?

Here are some threads i researched:

http://www.supraforums.com/forum/showthread.php?224175-How-to-increase-low-rpm-power-from-7mgte&p=2283118&viewfull=1#post2283118

Jong recommended to someone looking increase lower end HP to swap over the n/a intake mani set up.Not sure if that guy ended up doing that. From his post: Transplant the 7mge intake manifold and all the vacuum accessories. The 7mge has ACIS ( Acoustic Control Induction System), basically, the length of the intake runners changes. So you get max power for all ranges. when i dyno'd my na/t the ACIS actually gave me two torque curves. One peaking at around 3.5k and another peaking at 6k. the acis valve opens at 4.2k rpms. there is more info on the forums, but the ACIS system on the gte would be impressive IMO.

From this post http://www.supramania.com/forums/threads/40185-7mge-ACIS-system-questions


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.

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.
 

dexterrogers

Slow worker
Jul 25, 2006
15
0
0
Calgary, AB
How about a msd rpm window switch. It would work more like tvis but youd still get the benefit i think. I think it would solve the vsv lack of computer input problem -


Sent from my iPhone using Tapatalk
 

suprarx7nut

YotaMD.com author
Nov 10, 2006
3,811
1
38
Arizona
www.supramania.com
This is a cool project if nothing else, just as an engineering exercise. So as a preface, I'm all for the experiment.

My question, though, is if there is any evidence to suggest this short runner vs long runner difference has any impact in a boosted application. We know it has a distinct advantage in the NA with the engine intake under a slight vacuum, but I'm not sure that advantage would carry over into a boosted application. Intake and exhaust behave differently in NA vs FI motors. If there was an advantage to the ACIS system in a turbo motor, I would think Toyota would have integrated it into the 7MGTE. They already had it developed and parts made for the NA before they introduced the GTE.

Al this being said, I'm very intrigued to see how it works in a turbo motor! I bet somebody played around with it in a NA-T build, but can't recall anyone documenting it. I helped CRE assemble his NA-T in my garage around 7 years ago and kept in touch as he tuned it, but can't recall what he did with ACIS. He ended up selling it not long after, but that was one responsive motor. Makes me smile just thinking about it...
 

whitey482

New Member
Jan 2, 2017
8
0
1
Dallas
That is a really good question. As we all know the Cressida and non-turbo supra shared the same 7m-ge motor. But they had different intake manifolds. The cressy had a similiar intake as the gte whereas the supra n/a had the y-pipe with ACIS. So there really was no advantage production wise for Toyota to choose one or the other for the turbo supra since both were being produced. I'm not sure if cost impacted toyota's decision to go with the single runner pipe set up for the gte? Anyways, do any of the Na-t guys out there see any significant difference with the ACIS turned on or off?

I found this thread in supraforums where a na-t 2j guy compared power and torque output with ACIS enabled and disabled. http://www.supraforums.com/forum/sh...ake-Manifold&p=6593627&viewfull=1#post6593627.

I did a couple of pulls tonight with and without ACIS and used the math function that FWombat made on AEM fourums. The difference is around 30f/lbs between 3500 and 4000. I think I'll keep it on! :)

So looks like stand-a-alone ems's can control the ACIS. That's how Kurt above toggled between the two scenarios. I am running stock ecu but do plan to get an ecumaster det3 piggy back. I'm not sure if that has the capability.
 

whitey482

New Member
Jan 2, 2017
8
0
1
Dallas
Another post from the same guy. http://www.supraforums.com/forum/sh...ake-Manifold&p=7415603&viewfull=1#post7415603

Started running e85 and pushed the boost to 10psi. When I get bigger injectors I can go higher. Just a little more data to show that the ACIS functions the same with boost as it does n/a. This is a series of six pulls where I was tuning ignition, a total of 6 degrees was added from the 1st to 6th pull. For those of you not using the ACIS system, you're giving up a lot of torque early in the rev range for no reason!

p2098045_1.jpg
 

andrew_mx83

Member
Mar 22, 2008
100
3
18
Melbourne
A simple frequency switch will activate the VSV based on a set rpm, our local electronics store here in oz sells one for about a third the cost of the msd unit.
Or if you have an aftermarket ecu just use a spare output and set it to switch based on rpm and tps