[jong]

That Y-pipe is part of the ACIS system. and both sides are used all of the time. the ACIS control valve is situated in the intake manifold and just moves to change the length of the runners. removing that y-pipe and replacing it with throttle bodies would completely ruin the ACIS effect making it useless.

you will never see 0-5v from the flapper to the ecm. It will always be like .5 - 4.5v or .5 to 3.5v depending.

another thing to consider... The fuel pump is controlled by that flapper. So in your design, make sure that at idle, on of the flaps is opening enough to trigger the fuel pump. If you had some screwy piping design, it would cause one flapper to open more than the either, take the path of less resistance.

another thing to consider.... i have yet to see an SAFC play nicely with our NA flapper. Try to get one to read 100% airflow, even when manually fully extending the flapper... i have yet to see that. but its all relative to what the ECU needs.

someone try it...

 

[MKIIINA]

Did you read the original post?





This means there won't be a restriction on the NA motor...

As for the NA-T guys the website mentioned states "When I had the flowmeter bench tested it flowed ... 300 CFM at 28 inches water." Lets say you're running 14.7lbs of boost (i know thats too much, but the math is easier this way) that puts your air ratio at 2:1, doubling your engine's airflow rate to 586cfm, at 6500 RPM and a volumetric efficiency of 85%. Now, those two airflow meters can flow 600 cfm on a turbo motor... Still giving you enough room to breathe up top. I think that the dual flapper will be a must for the NA-T guys, myself included, as soon as I perfect the setup. The non linear progression thing is making me worry.... But nonetheless... back to the drawing board!

see there is what i was talking about. how would this benefit just the NA guys, not the NA -> T ones. Obviously for the Turbo swap guys its a plus as you can have all sorts of fun adding air in and what not but standard NA's only have so much room to play with. so easy there killer :hug:

 

[Robbman]

That Y-pipe is part of the ACIS system. and both sides are used all of the time. the ACIS control valve is situated in the intake manifold and just moves to change the length of the runners. removing that y-pipe and replacing it with throttle bodies would completely ruin the ACIS effect making it useless.
.

The 7M-GE doesn't have a true ACIS system to begin with... it's just a butterfly valve that is open at idle (to allow the CSI to work), and then closes (yes, closes) at fuel pressure up (FPU). 86.5-88 7M-GEs use two separate VSVs for FPU and valve operation. The 89 and later 7M-GEs used the same VSV for fuel pressure up and to apply vacuum to the butterfly valve.

Replacing the Y-pipe would not render the system ineffective, as both sides of the manifold would still be fed simaltaneuosly...

 

[thescamp]

see there is what i was talking about. how would this benefit just the NA guys, not the NA -> T ones. Obviously for the Turbo swap guys its a plus as you can have all sorts of fun adding air in and what not but standard NA's only have so much room to play with. so easy there killer :hug:

The point was more towords the fact that the Turbo gets a karmen vortex style MAF, not the flapper style. The NA-T guys would definately benefit, even more so then the NA guys! I'm just looking for a solution here...

 

[thescamp]

http://www.carlton24v.co.uk/afmmaf.htm

Verrry interresting....

 

[SlimFastSupra]

first, you need proof that the AFM is a large restriction... I have yet to see any.

Some MR2 turbo people did some testing and found that until 300rwhp+, the AFM did not prove to be a significant restriction.

You can put a VPC on your car (modified one), with 7MGE to remove the AFM.

You can also convert to turbo electronics and use the karmann AFM, higher flowing, or even the lexus for that matter if you were hell bent on squeezing that last ounce of air flow out.

 

[Iceberg319]

first, you need proof that the AFM is a large restriction... I have yet to see any.

Some MR2 turbo people did some testing and found that until 300rwhp+, the AFM did not prove to be a significant restriction.

You can put a VPC on your car (modified one), with 7MGE to remove the AFM.

You can also convert to turbo electronics and use the karmann AFM, higher flowing, or even the lexus for that matter if you were hell bent on squeezing that last ounce of air flow out.

how would a vpc work on NA ??? cuz there is no option for the GE electronics i thought it was only turbos

 

[SlimFastSupra]

modify my man modify!

however spending 600 on a NA just to remove the AFM = :stickpoke

Your money is better spent on suspension or braking. You could build a quick NA that would toast turbo cars in the turns.

 

[DeanMarcum]

I tried the "dual flapper AFM" mod on my N/A + T. No benefit. Remember, the majority of the restriction in the AFM is because of the flapper door spring tension, NOT the meter itself. You must cut the tension in half on each AFM to make the system "flow" any more (if you keep the same spring tension then you will more half as much air through each AFM which will give a very lean reading). With that loose of spring tension though (1/2) the car would run VERY rich at anything but idle because the flapper would swing open all the way almost immediately whenever throttle was applied. I unltimately ran a VPC with the GE electronics (yes, it can be done just think about the MR2 turbo with flapper door meter). If you can make it work, good for you but IMHO you would be better off using a MAFT with the proper conversion. Much simpler to do.

 

[thescamp]

I tried the "dual flapper AFM" mod on my N/A + T. No benefit. Remember, the majority of the restriction in the AFM is because of the flapper door spring tension, NOT the meter itself. You must cut the tension in half on each AFM to make the system "flow" any more (if you keep the same spring tension then you will more half as much air through each AFM which will give a very lean reading). With that loose of spring tension though (1/2) the car would run VERY rich at anything but idle because the flapper would swing open all the way almost immediately whenever throttle was applied. I unltimately ran a VPC with the GE electronics (yes, it can be done just think about the MR2 turbo with flapper door meter). If you can make it work, good for you but IMHO you would be better off using a MAFT with the proper conversion. Much simpler to do.

Actually, the wind drag is caused by the fact that the AFM's hole is 2" wide, compared to the 3" air tract that the intake has, although yes, the flapper's spring tension does cause some drag. I think that the dual VAF theory has been disproven. So now on to other options... the DIY Maft on the prior page... With this lil unit you can even create your own fuel curve...

Or for the people that arent that DIY... Perfect Power has the SMT6 for about 450 bucks that will allow ignition and fuel tuning, along with replacing the AFM with MAF, hotwire or a MAP sensor, removing it completely. The translator is built in... I've been doing some reading on this unit, and it is definately on my list of future power mods... Can you say 6 throttle body'd MAP sensor NA? hmmm.....

 

[jong]

The 7M-GE doesn't have a true ACIS system to begin with... it's just a butterfly valve that is open at idle (to allow the CSI to work), and then closes (yes, closes) at fuel pressure up (FPU). 86.5-88 7M-GEs use two separate VSVs for FPU and valve operation. The 89 and later 7M-GEs used the same VSV for fuel pressure up and to apply vacuum to the butterfly valve.

Replacing the Y-pipe would not render the system ineffective, as both sides of the manifold would still be fed simaltaneuosly...

sorry to disagree... but thats incorrect.

The 7m-ge does infact have a true ACIS system. The Butterfly valve in the manifold changes the effective length of the intake runners. One mode extends from immediately behind the throttle body with the ACIS control valve closed for long runners. The second mode, with the ACIS control valve open, begins in the middle of the manifold to the runners, short runners. If you would replace the Y-pipe with throttle bodies, you would eliminate the "long runners" that is utilized with the Y-pipe, making it a short runner system. the ACIS control valve would do little to nothing because the shared intake air volume is coming from primarily the same spot.

the 7m-ge has almost the same system as the 2JZ-GE.

read here...
http://www.supraforums.com/forum/showthread.php?t=227121&highlight=ACIS+jong
http://www.geocities.com/mwsupra2003/acis.html

Why do you say that the 7mge doesn't have a true acis? It changes the length of the intake runners, which is what ACIS is supposed to do. The system on the 7mge does everything that ACIS does on current toyota models with the ACIS system.

 

[NashMan]

i was think of this back wheni was a na


all i needed was a fule reg and injecotrs and sfac and up the comption

 

[Robbman]

sorry to disagree... but thats incorrect.

The 7m-ge does infact have a true ACIS system. The Butterfly valve in the manifold changes the effective length of the intake runners. One mode extends from immediately behind the throttle body with the ACIS control valve closed for long runners. The second mode, with the ACIS control valve open, begins in the middle of the manifold to the runners, short runners. If you would replace the Y-pipe with throttle bodies, you would eliminate the "long runners" that is utilized with the Y-pipe, making it a short runner system. the ACIS control valve would do little to nothing because the shared intake air volume is coming from primarily the same spot.

the 7m-ge has almost the same system as the 2JZ-GE.

read here...
http://www.supraforums.com/forum/showthread.php?t=227121&highlight=ACIS+jong
http://www.geocities.com/mwsupra2003/acis.html

Why do you say that the 7mge doesn't have a true acis? It changes the length of the intake runners, which is what ACIS is supposed to do. The system on the 7mge does everything that ACIS does on current toyota models with the ACIS system.

I read that, even posted in the thread. To recap (and to repeat what I posted in that thread)

The normal state of the butterfly valve is open, not closed. if it was closed, the cold start injector woud only feed cylinders 1-3.

When vaccuum is applied, the valve closes. The valve activates at 4200 RPM, thus it closes at 4200 RPM, creating the long runners, not short (same time as the fuel pressure up VSV activates, which is interesteing, becuase on later 7M-GEs, the FPU and butterfly are controlled by the SAME VSV, which means there is not multiple open/close operations of the valve as on a true ACIS system))

This is completely at odds with what you wrote about the ACIS system on the 1MZ and 2JZ (and I'll note, you have nothing on that page that shows the 7M-GE system, just the 1MZ and 2JZ)


Replacing the Y-pipe with throttle bodies would not ruin the long runner/short runner effect either. The throttle bodies simply become part of the 'long runner'. When the butterfly valve is open, you still have a short runner...

 

[thescamp]

So does this mean that one side of the Y feeds the long runners, and the other one feeds the short runners? If so, at 4200rpm you'd effectively double the amount of flow the motor would see, kind of like mashing the throttle from 1/2 throttle to full, it'd be jerky and not fluid at all. And the power differance from below 4200 to above would be huge. It is supposed to give two torque peaks, not one little one then another big one...

 

[Robbman]

No... it means that when the valve is closed, cylinders 1-3 are fed from one side of the y pipe, and 4-6 are fed from the other. The chamber in the upper manifold effectively becomes part of the runner.

When the valve is open, the chamber becomes the starting point of the runners.

 

[DavidTT87]

::quote::The valve activates at 4200 RPM, thus it closes at 4200 RPM, creating the long runners, not short ::quote::

Why would toyota make long runners in the high rpms where we dont need the torque???

 

[thescamp]

No... it means that when the valve is closed, cylinders 1-3 are fed from one side of the y pipe, and 4-6 are fed from the other. The chamber in the upper manifold effectively becomes part of the runner.

When the valve is open, the chamber becomes the starting point of the runners.

*lightbulb* I get it. So two throttle bodies would be beneficial!

 

[jong]

I read that, even posted in the thread. To recap (and to repeat what I posted in that thread)

The normal state of the butterfly valve is open, not closed. if it was closed, the cold start injector woud only feed cylinders 1-3.

When vaccuum is applied, the valve closes. The valve activates at 4200 RPM, thus it closes at 4200 RPM, creating the long runners, not short (same time as the fuel pressure up VSV activates, which is interesteing, becuase on later 7M-GEs, the FPU and butterfly are controlled by the SAME VSV, which means there is not multiple open/close operations of the valve as on a true ACIS system))

This is completely at odds with what you wrote about the ACIS system on the 1MZ and 2JZ (and I'll note, you have nothing on that page that shows the 7M-GE system, just the 1MZ and 2JZ)


Replacing the Y-pipe with throttle bodies would not ruin the long runner/short runner effect either. The throttle bodies simply become part of the 'long runner'. When the butterfly valve is open, you still have a short runner...

alrighty... well then toyota must be misinformed about their ACIS system, because i took all of that information directly off our TIS computer database. There was no information directly relating to the ACIS on 7m-ge, BUT... There was a wealth of information regarding the ACIS system on the 2JZ-GE/FE and in there, toyota said, " This ACIS system is identical to the system found on the 7m-ge." if you want me to download all the .pdf 's so you can read them yourself, then i will.

I'd like to know how exactly replacing the Y-pipe with throttle bodies wouldn't change the acis effect? The long runners utilize the Y-pipe... if you remove the Y-pipe, then there is no longer any long runners.. its just short. the butterfly would open and close with almost no difference, I'm sure the Toyota engineers had something in mind when they designed the system with Y-pipe, and --although purely speculation-- would agree with me, that removing that Y-pipe, although more than likely benificial in terms of throttle response, would completely change the geometry of the intake manifold, especially during the "long runner" operation, and thus change the ACIS effect. That manifold, INCLUDING the y-pipe, was designed acousticly... Its about the pressure waves, sound. I"m sure you've blown across a bottle once in your life and noticed that different lengths of bottles resonate at different frequencies, or the same can be true about an open end tube over a speaker ( like a bandpass sub box) the tube, depending on length, will create a resonance at a certain frequency and its octaves. That same principle holds true for the ACIS system.... for example...

Lets say you have a speaker producing 120Hz ( speaker = valve in our case) and, a ( wild guess) 2 foot cardboard tube with an I.D of 2". That 2 foot tube will resonate at 120Hz... but... we want to cut that tube down ( remove y-pipe and replace with throttle bodies) lets say we chop that tube down to 1 1/4 foot. That tube will no longer resonate at 120hz. Thus, the "supercharging" effect is lost ( at 120Hz).

If you were to shave 1/8" off that Y-pipe, you would change the ACIS system. any change to that manifold, Y-pipe, throttle, or butterfly valve could easily and probably dramatically change how ( more specifically when) the ACIS system operates. my guess, Toyota optimized the system to give the engine best performance, i doubt there is little room for improvement, and i'm willing to bet you would lose any ACIS gains by altering it.

furthermore, by calling the ACIS system on the 7m-ge anything but a "true" acis system soley on the grounds as it doesn't have "stages" in terms of different throttle % activation, is pure horse manure! Its ACIS, Acoustic Control Induction System, it does EXACTLY what the system is supposed to do, and it does the SAME DAMN thing it does on every other toyota engine, it changes the length of the intake runners to optimize the air flow in terms of acoustic pulses. Ok, so toyota made some improvements on the system over the years, which is understandable, by giving it more features and control by adding more butterfly valves, VSV's, activation RPMS, and throttle % activations. But its all the same! ACIS is ACIS... There is a simple ACIS system, or a complex ACIS system, both are TRUE ACIS!!!! what your saying is like... " A 1990 supra isn't a true supra because it doesn't have a 2JZ..." A supra is a supra, toyota made revisions and changes, are you saying then that a 1990 supra isn't a true supra? COME ON!?

You're comparing apples to apples and calling one an orange!

 

[Robbman]

1. Show me a proven reference that Toyota calls the 7M-GE system an ACIS system. There is almost a decade between motor designs between a 7M-GE and a 2JZ-GE. The 7M system operates exactly opposite to what you wrote about the ACIS system. Either Toyota is wrong, or you are. They are different... period. If you call the 2JZ system an ACIS system you can't call the 7M system an ACIS system. Maybe there's a reason why there was no mention of 'ACIS' until after the 2JZ and 1MZ were introduced (93 and 94 respectively...)

A carburetor and TBI both do the same thing, provide fuel for a motor, but you don't call one the other on that basis do you?

2. Using two throttle bodies, the runners are still separated. The length of the Y-pipe now becomes the length of the throttle bodies. I see where you're getting confues though... I'm saying to attach the throttle bodies directly to the upper manifold.

3. Speaking of comparing apples to an orange...

If there were little room for improvement, and Toyota acoustically designed the 7M-GE, then there would have been no need to change the design so drastically as they did on the 2JZ-GE. Larger diameter runners, larger diameter Y-pipe, different upper manifold design, etc all affect the acoustics of the manifold.

 

[thescamp]

This is true... So, upon the completion of the twin AFM project, why not build a manifold to feed 1-3 and 4-6 with seperate throttle bodies, and remove the ACIS system completely? Is it really that huge of a differance in power? Personally, I would like one power curve to base my shifts off of...

I think that I'm going to open a thread on a VPC system for the NA motor. No one makes ANYTHING like this, so it'd be original definately. Alls it would take is building a microchip to convert the vacuum readings to an analog output using a table that is adjustable by EPROM programming, to get the right fuel curve. From there, modifying and tuning the fuel curve is as easy as reading a wideband O2.