VICS Sucks!!!!

[flat_black]

Less manifold = More volume = More air required to keep velocity, since you have to fill that volume to keep velocity high. =) Removing the VTCS butterflies themselves will increase the overall volume, but the flow will be weird.

VICS/VTCS flaps open, the air gets pushed into the plenum by means of air refracting off the butterfly, like so:

VTCS open/VICS closed, the air flows straight across the plate of the butterfly:

So, removing the butterflies, you're not diverting air, and if the air is coming in at a huge boost pressure, it's going to fill the plenum, yes, but it'll all be turbulant air. If the air velocity it high enough, it'll just whisk past the opening like blowing across the top of a bottle.

Physics. =)

Oh, for completion, here's a shot of VTCS in action causing tumble:

 

[TurfBurn]

I was under the impression that the extra plenum didn't have anything to do with actual flow though... that plenum that is getting opened and closed by the butterflies is there only to change the resonance of the overall manifold assembly... it's relying on pressure waves and the air doesn't have to "move" to deal with pressure waves... it's really more about changing the pitch of a drum than anything... So as far as Keola's standpoint, you can remove those butterflies so that they don't impede flow in the other areas... HOWEVER, removing them may make the air somewhat less turbulent which could render the mixture slightly poorer... so it's very hard to tell. I can't run tests on this eithe because a couple fractions of a psi difference will mask which is better... so at the same time that means it would be fine to remove them... Call it weight savings LOL... but the cost to remove them (think welding to seal some of the critical locations) outweighs any potential benefit to just leaving them in tehre.

 

[duMb KeoLa]

are the holes left when removing the vtcs and vics very critical to fill? meaning, do i HAVE to fill the holes when removing the butterflies. i remember talking to dave (pro5) about removing and filling the holes left after the rod is removed, and he recalled that someone said they didnt fill the holes and that it shouldnt really matter. i am going to port the intake mani today and just need to know if its critical to fill the holes.

im also wondering about the vics... less torque on the bottom end would be better for me being that my turbo should spool up pretty quick, and if itll give me better top end thats what i am going after. i really dont want to have to get the manifold taken to someone to have them weld the holes... wouldnt jb weld work fine? i dont even know if im making sense...

thanks

 

[duMb KeoLa]

Less manifold = More volume = More air required to keep velocity, since you have to fill that volume to keep velocity high. =) Removing the VTCS butterflies themselves will increase the overall volume, but the flow will be weird.

VICS/VTCS flaps open, the air gets pushed into the plenum by means of air refracting off the butterfly, like so:

http://www.msprotege.com/forum/attachment.php?attachmentid=46693

VTCS open/VICS closed, the air flows straight across the plate of the butterfly:

http://www.msprotege.com/forum/attachment.php?attachmentid=46692

So, removing the butterflies, you're not diverting air, and if the air is coming in at a huge boost pressure, it's going to fill the plenum, yes, but it'll all be turbulant air. If the air velocity it high enough, it'll just whisk past the opening like blowing across the top of a bottle.

Physics. =)

Oh, for completion, here's a shot of VTCS in action causing tumble:

http://www.msprotege.com/forum/attachment.php?attachmentid=46691

thanks for the help... but im wondering about your first picture... wouldnt it be the same when the vics opens anyway? i dont see how leaving no butterflies would vary from an open vics... the flow should be the same in both instances right? sorry for all the questions

 

[TurfBurn]

are the holes left when removing the vtcs and vics very critical to fill? meaning, do i HAVE to fill the holes when removing the butterflies. i remember talking to dave (pro5) about removing and filling the holes left after the rod is removed, and he recalled that someone said they didnt fill the holes and that it shouldnt really matter. i am going to port the intake mani today and just need to know if its critical to fill the holes.

im also wondering about the vics... less torque on the bottom end would be better for me being that my turbo should spool up pretty quick, and if itll give me better top end thats what i am going after. i really dont want to have to get the manifold taken to someone to have them weld the holes... wouldnt jb weld work fine? i dont even know if im making sense...

thanks

the hoels between runners aren't that critical... but the big gaping one on the side where the rod goes in woudl be good to fill

Having the VICS butterflies open isn't going to change your top top end... Closing the butterflies could give you more beef possibly in the lower areas... but you are running it open anyway since you didn't wire it to the Microtech at all... It's not really a worthwhile mod... you will lose some torque down low, but with as much boost as you are making and so forth you won't need that torque anyway... I already can break the tires loose at 40 some mph in 2nd gear when I'm rolling along and give it gas... and that's on damn sticky tires... I cringe when I switch tires in a couple weeks!

JB Weld wouldn't work.. would never hold the high boost pressures on the outside edge later... I just wouldn't worry about doing that much... if you are really set on doing it.. then take the manifold apart... take the screws out and cut the butterfly plates in half and then put them back in... then they won't get into the air stream at all.

 

[TurfBurn]

thanks for the help... but im wondering about your first picture... wouldnt it be the same when the vics opens anyway? i dont see how leaving no butterflies would vary from an open vics... the flow should be the same in both instances right? sorry for all the questions

He's indicating that the air will run into the upright butterfly and be forced down into the plenum... which is fine but it'll hit a brick wall and just be a higher pressure zone... with turbulence behind the butterfly... nothing else will change... the dynamic volume of the manifold will still be the same with or without the butterflies in place.. the whole point of the butterflies is the dynamic volume can be changed... when they are closed the volume is "less" which changes the harmonics of the manifold... all has to do with inertia charging and harmonics of what the air does when it runs into the back of the valves and so forth... pressure waves travel at the speed of sound... so you can mathematically calculate your theoretical runner length based on when and how long valves are open etc.

 

[duMb KeoLa]

still confused... damnit... so with our microtechs the vics will be open at all times? im not too sure about what youre talking about, as the stock ecu will still be hooked up, wouldnt that trigger the vics to open and close? i guess im still going to put the vics back in and see what happens... ill also just put the stock actuator thing so i wont need to plug the end of that hole... think its a good idea?

 

[TurfBurn]

still confused... damnit... so with our microtechs the vics will be open at all times? im not too sure about what youre talking about, as the stock ecu will still be hooked up, wouldnt that trigger the vics to open and close? i guess im still going to put the vics back in and see what happens... ill also just put the stock actuator thing so i wont need to plug the end of that hole... think its a good idea?

Go check Dave's car LOL... if you don't see the actuator move when the key is turned on/the car starts up then the stock ECU isn't controlling it... my car is different then everything else on the planet so I can't check myself... As it stand right now I THINK that the stock ECU is not manipulating the VICS in Dave's car... This is a pretty nominal power thing overall... so I'd leave the vics in and the butterflies hooked up properly for now... if you have traction issues it may be useful to disconnect the vac line later.

 

[Spooled]

So let me summarize this:

-Normal driving under 5200 rpm has the VICS activated (diverts the flow into the extra plenum area). This increases the length of the column of air, therefore increasing the inertia and giving you better low-end torque.

-Above 5200 rpm the VICS valve is disabled (closes off the extra plenum area). This gives all of the intake charge a direct shot to the cylinders and smoother flow for high horsepower.

Now, in theory you want to keep VICS for low-end torque and to spool the turbo quickly, but you probably want some control over it. Ideally you want to disable it as soon as the turbo is pushing enough air to out-weigh any advantages that the longer column of air can offer.

What is it exactly that turns the VICS on/off? Is the switch based completely on vacuum, or is it partially ECU controlled? What are all the variables that it relies on? TPS, manifold vacuum, RPM?

 

[peepsalot]

What is it exactly that turns the VICS on/off? Is the switch based completely on vacuum, or is it partially ECU controlled? What are all the variables that it relies on? TPS, manifold vacuum, RPM?

It's a solenoid controlled by the ECU that opens the path for a vacuum signal. The vacuum is stored in a resevoir with a check valve, so the actuator can get a vacuum signal even when you are at WOT(not making vacuum).

If you want to override it you have to:
1) Leave something in the circuit for the ECU to think the solenoid is still there.(an extra solenoid, or a properly selected resistor would do the trick.)
2) Get an RPM activated switch to control the solenoid yourself.
http://store.summitracing.com/partdetail.asp?autofilter=1&Ntt=rpm+switch&N=%2D118032&part=SUM%2D830449&autoview=sku&Ntk=KeywordSearch

 

[TurfBurn]

and correction... I thought the same as you... but the extra plenum is closed OFF during low rpm's.. and then opens at high... I too thought it was increasing the length... part of why the VICS SUCKS title of this thread because I thought I had reversed the operation and then made more power... but the story actually is you start out with VICS closed, and it opens at higher rpm's..

it is possible that you can optimize it more than what it is right now... but if you look at my graph I had it open until 4500 rpm's and then closed it on the low graph... opposite of how I should have run it... but what you'll see is that the lines cross/change trends at 5200 rpm's... right where mazda normally opens/closes it... which means even under 10 psi of boost keeping it closed until 5200 rpm's seems to be optimal if you are worried about keeping more low end torqe... but as we discussed earlier in the thread.. losing some low end torque is positive because of the potential for some better traction in low gears.

EDIT: The gain between 4200 and 5200 could be a boost thing... but would fit the standard logic belief that VICS has a benefit for low end.

 

[peepsalot]

I still can't make any sense out of those dyno's though.

 

[CasopoliS]

So s*** that was all awesome yet confusing. Someone summarize the pros and cons of altering the VICS system. Does rmoving the vac source on the solenoid still make things better, though you explained the valve(s) in reverse?

 

[TurfBurn]

if you want to drop some low end torque... and need to simplify or remove anything then removing it is good.... the dyno doesn't show a big gain with or without it at the low end of things... but leaving the plenums open (which is what the mazda system does normally) above 5200 rpm's makes a huge difference...

EDIT: General belief is that not having the butterflies closed below 5200 will cause a loss in torque... the dynos do not definitively show that though.

 

[TurfBurn]

I still can't make any sense out of those dyno's though.

Torque and horsepower on there.... back to back runs... notice the horsepower goes to s*** after 5200 rpm's? that is the run where the butterflies got closed at 4500 rpm's... the high peak horsepower one is with the butterflies open... then you can see which torque corresponds to what... but the important thing to notice is there is little difference between any of the curves before about 5200 rpms.

EDIT: Difference may be boost... keep that in mind.

 

[peepsalot]

OK, so the lower HP graph is you running the VICS in the exact opposite of how it should be run?

 

[igdrasil]

You should refer to dyno XX run because im also confused. Although I know what the VICS do.

But basically turbo people will benefit more from short runners and a small plenum.

It will kill some low end torque, but WTF, we dont need it. Besides, if you have a small turbo, or any quick spooler VICS are not needed (or leave them open) if your not looking for BIG HP numbers but resposiveness on the streets.

 

[TurfBurn]

OK, so the lower HP graph is you running the VICS in the exact opposite of how it should be run?

exactly

 

[TurfBurn]

You should refer to dyno XX run because im also confused. Although I know what the VICS do.

03 is with closing the butterflies at high rpm's... in other words the opposite of how it would normally be run by the stock ECU.

1 and 2 the butterflies are open the entire time...

At the beginning of 03 (up to 4500 rpm's) they are left open however... and then closed... so the opposite of how they should be run... so the graph does not show anything of value as far as what happens at low rpm's... only as to what will happen at high rpm's.

 

[igdrasil]

Is that dyno shop close to you???

Do you have a graph of it like stock functionality?? closed before 5200 and then opening it?