Intake Manifolds opened to reveal VIS

*Dv8* · 01-18-03, 02:57 AM

Well its time to do some machine work and what a better time to do it than on my spare engine.

Here i have a TYPE II manifold i just removed from my spare engine. I opened it up to see what if any Port and polish was needed. I had a vuage idea of what the vis system was like, but i had no idea i would find three big flaps all controlled by the air butterflies. (thats why it sounds like a CROSSOVER when i pass 4000RPM one if not all of these flaps open up.

I now have a clearer picture of what LEGENDTYPERKON removed from his....idiot.

Now wait, is he really that moronic or did he actually screw up his idle but eventually for the real race car driver gain more raw hp?

how about removing one plate? i know your ide ,gass etc will goto ****, but im solemly talking performance.

just curious.

what im really curious about, is the seqence of these flaps. when do them open and which ones. Dave you there?

Like DAVE C said the top portion of the 3 peice manifold is very rough, mine had a lot of carbon deposits and some oil in it!?

hoever the other 2 plates are flawlessly smooth with noneed for anything.

please input i want to know how they work and when they do.

~Hybrid

Dave C ver2.0 · 01-18-03, 07:22 AM

Like I said. Extrudehone and port match the upper plenum. You can match the lower plenum and butterfly plate but gains would be very small.

Butterfly actuation is clearly described in the service manual.

IMO removing any butterflys will impair engine operation. Remember they are RPM controlled.

Henyaman · 01-18-03, 10:11 AM

I was thinking the same thing. I was on the NSX forums a while back or something and remember reading that one of them removed and polished the manifold and actually had some decent gains. I will try to find it.
I was looking at mine the other day too, and was wondering the same thing DV8.
Ill look into it.
Peace-
R

ZiGGie · 01-19-03, 01:00 AM

thanks for the pic, i always wonder how the vis function look like

***LegendGS*** · 01-19-03, 01:12 AM

As I understand it, the butterfly valves are for torque control to maintain torque at low and high RPMs.

Of the three valves, I believe that the first is open pretty much all the time. The second (or Low Intake Air Bypass) opens above 3,400 RPM, and the third or High Intake Air Bypass valve opens at 4,300 RPM. These are Type II specs. The Type one opens the low at 3,300 RPM, and the high at 4,000 RPM.

*Dv8* · 01-19-03, 03:51 AM

Quote:

Originally posted by LegendGS
As I understand it, the butterfly valves are for torque control to maintain torque at low and high RPMs.

Of the three valves, I believe that the first is open pretty much all the time. The second (or Low Intake Air Bypass) opens above 3,400 RPM, and the third or High Intake Air Bypass valve opens at 4,300 RPM. These are Type II specs. The Type one opens the low at 3,300 RPM, and the high at 4,000 RPM.

these are type II 's

bothe right and left flaps are controlled by the same butterfly so if one opens the other does too.

middle on is controlled on its own.

i think that they are all closed to start off with and gradually the middle opens as do the left and right a 4300 rpm.

Pics? Anytime.

~Hybrid

***LegendGS*** · 01-19-03, 04:00 AM

OK. I took a closer look at the diagram.

The left and right valves are the low (3,400 RPM), and the middle is the high which kicks in at 4,300 RPM.

I don't think that there is gradual opening. I believe that the valves are either opened or closed.

Henyaman · 01-19-03, 12:49 PM

Basically is changes the resonnant frequency of the incoming air so that it about matches the speed that the intake valves are opening up. That way it lets the engine "breath" a little easier.
By changing the area of the intake manifold, it changes that frequency to match higher RPM's.

I dont think it makes a HUGE difference, but my main questions is once you are pulling in as much power as DV8, for example, so much more air is coming in that it may be starving the engine at lower RPMs until the other butterflys open. So it may benifit to remove it and polish the entire manifold, on the other hand it may always still match the RPM's/Frequency since when you are making that much more power you rev quicker so it still may be in tune.

Theres only one way to find out. Any other input is welcome. I have my intake manifold sitting here as well and I was trying to figure out if that would be better or what.

This is from an NSX page-
VVIS stands for "Variable Volume Induction System," and is explained in the second NSX book on pages 26-29. The VVIS optimizes the air intake for different rpm ranges. For more low- and mid-range power, these butterfly valves remain closed (they look like paddles in the intake system, one paddle per runner). The book says the VVIS is activated by manifold vacuum above 4,800 rpm. By opening the valves, the intake air has acess to a second plenum which provides more "space" for the air- sort of like the Porsche Varioram system.

A note about the NSX variable induction butterfly valves: You can make it run at max volume all the time by disconnecting the hose to the solenoid and capping it, however I didn't notice any difference in performance when I did this (supposedly I should get less low end torque). Makes you wonder if the variable induction is of any real use or if they included it as a techno-gimmick.

Henyaman · 01-19-03, 01:00 PM

Also now that I am thinking about it, that is all tuned for the pressure waves of an NA engine. If you are going to supercharge it, it may be in your interest to remove then since the length of each chanber would need to be changed and tuned for a different pressure level when under boost. So when you are under boost I dont think it will do anything but restrict the ariflow since it is out of tune with the pressure waves. Otherwise if you are staying NA I'd prolly leave it there.
Just my thoughts.
-R

*Dv8* · 01-20-03, 02:16 AM

Well i guess a simple answer to all this is, get my downpipes and you'll see what i mean.

above 4k with the downpipe in place the engine get a big boost of power( a veryvery audible roar of air, very much like VTEC. Something the little paddle coulnt do.) which makes me think the two side flaps open up. If your around N. CA and want to see and hear it for yourself contact me.

once i get everything back up and running i will disconnect the small paddle and surpress the hose so that it remains open, we'll see what happens at the track.

~Hybrid

**B+O** · 01-20-03, 01:29 PM

the stages are

1st stage: all butterflies are closed and the air takes the TEDIOUSLY long route around the back edge of the manifold then around, then back up fron to the runners. thorugh 1500rpm i think, this long tedious tract is optimal for most lowend torque.

2nd stage: the outer flaps open and air flows freely upwards to longer of the runners...

3rd stage THE MOVIE(

inside joke): the middle flap opens to expose a direct run to the intake runners and act as a single plenum instead of a bunch of runners.

sorry i dont know if anyone answered this yet but i saw Dv8 wondering something....that doesn't happen often

i dont have my book with me here, i wish i could scan it...it has the diagram of the stages.

92coupeon18s · 01-20-03, 06:21 PM

i would say take the 2 out that are clean and leave the dirty one but clean it. But i dono

**B+O** · 01-20-03, 06:30 PM

Quote:

Originally posted by 92coupeon18s
i would say take the 2 out that are clean and leave the dirty one but clean it. But i dono

AWESOME TECHNICAL INSIGHT!!!!

j/k

maybe...i might have stage 2 and 3 backwards...dammit i cannot remember the DIAGRAM....

***LegendGS*** · 01-20-03, 08:36 PM

Quote:

Originally posted by Bang&Olufsen DK
maybe...i might have stage 2 and 3 backwards...dammit i cannot remember the DIAGRAM....

Nope. You got it right.

*Dv8* · 01-21-03, 02:27 AM

if its all ture then that little flap carries quite a load.

~Hybrid

01-18-03, 02:57 AM	#1 (permalink)
Dv8 Get sucked in... Join Date: Jan 2002 Location: CA Posts: 4,753 Car 1: 91' 3.5lt Extreme DV8ED Hybrid 6spd Car 2: 03' G35c Blk on Blk Car 3: 92'Yukon/06'Trailer iTrader: (11)	Intake Manifolds opened to reveal VIS Well its time to do some machine work and what a better time to do it than on my spare engine. Here i have a TYPE II manifold i just removed from my spare engine. I opened it up to see what if any Port and polish was needed. I had a vuage idea of what the vis system was like, but i had no idea i would find three big flaps all controlled by the air butterflies. (thats why it sounds like a CROSSOVER when i pass 4000RPM one if not all of these flaps open up. I now have a clearer picture of what LEGENDTYPERKON removed from his....idiot. Now wait, is he really that moronic or did he actually screw up his idle but eventually for the real race car driver gain more raw hp? how about removing one plate? i know your ide ,gass etc will goto **, but im solemly talking performance. just curious. what im really curious about, is the seqence of these flaps. when do them open and which ones. Dave you there? Like DAVE C said the top portion of the 3 peice manifold is very rough, mine had a lot of carbon deposits and some oil in it!? hoever the other 2 plates are flawlessly smooth with noneed for anything. please input i want to know how they work and when they do. ~Hybrid __________________ AEM EMS Powered. 9 yrs and counting. Results, Where are yours? 12.953@107.865MPH 95 deg. Jun. 07' 3.5 6spd-#55 jet Nitrous 316WHP@5500RPM 345Lb-ft@4100RPM NOS 06-07'N/A 234WHP@5700RPM 229lb-ft@4600RPM 06-07' 13.782@99.135MPH N/A 95 deg. Jun 07' 03' G35c Auto Vortech Supercharged pshhhh 14.3@96MPH-Stock 8 page spread Honda Tuning September 06' issue No Phone or Instant message, PM or Email only. Respect that!** My Legends Website www.2slik4u.com

01-18-03, 07:22 AM	#2 (permalink)
Dave C ver2.0 rh eller Join Date: Jan 2002 Location: Rockville Md Posts: 1,944 Car 1: 92 L sedan and 88 LS sedan (wifes) iTrader: (1)	Like I said. Extrudehone and port match the upper plenum. You can match the lower plenum and butterfly plate but gains would be very small. Butterfly actuation is clearly described in the service manual. IMO removing any butterflys will impair engine operation. Remember they are RPM controlled. __________________ Started rebuilding IC engines in 1968 at the US Merchant Marine Academy. Don't think you know more than me about auto/IC/control systems unless you can document your education.

01-18-03, 10:11 AM	#3 (permalink)
Henyaman Registered User Join Date: Mar 2002 Location: Canton OH Posts: 250 Car 1: 1994 Acura Legend iTrader: (0)	I was thinking the same thing. I was on the NSX forums a while back or something and remember reading that one of them removed and polished the manifold and actually had some decent gains. I will try to find it. I was looking at mine the other day too, and was wondering the same thing DV8. Ill look into it. Peace- R __________________ 1994 Acura Legend Sedan <img border="0" src="http://pages.sssnet.com/delanier/legend.jpg" width="516" height="251"> Custom Greddy Cat-Back Exhaust Full Gound Wire Upgrade HKS Intake w/ Breathers Bypassed TB Coolant passage Clarion Audio Epic Arnage 17" Chrome Wheels 3 Layers of Dynamat (Entire Car) Brand New Paint job

01-19-03, 01:12 AM	#5 (permalink)
*LegendGS* GS Hog Join Date: Jan 2002 Location: SoCal Posts: 6,868 Car 1: 1994 Legend GS-Auto Car 2: 1994 Legend GS-6 spd Car 3: 1993 NSX-6 spd iTrader: (2)	As I understand it, the butterfly valves are for torque control to maintain torque at low and high RPMs. Of the three valves, I believe that the first is open pretty much all the time. The second (or Low Intake Air Bypass) opens above 3,400 RPM, and the third or High Intake Air Bypass valve opens at 4,300 RPM. These are Type II specs. The Type one opens the low at 3,300 RPM, and the high at 4,000 RPM. __________________ Please read the Forum Rules and other announcements

01-19-03, 04:00 AM	#7 (permalink)
*LegendGS* GS Hog Join Date: Jan 2002 Location: SoCal Posts: 6,868 Car 1: 1994 Legend GS-Auto Car 2: 1994 Legend GS-6 spd Car 3: 1993 NSX-6 spd iTrader: (2)	OK. I took a closer look at the diagram. The left and right valves are the low (3,400 RPM), and the middle is the high which kicks in at 4,300 RPM. I don't think that there is gradual opening. I believe that the valves are either opened or closed. __________________ Please read the Forum Rules and other announcements

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01-19-03, 01:00 AM	#4 (permalink)
ZiGGie Registered User Join Date: Jul 2002 Location: SJ, CA Posts: 513 Car 1: 91 Sedan iTrader: (0)	thanks for the pic, i always wonder how the vis function look like

01-19-03, 12:49 PM	#8 (permalink)
Henyaman Registered User Join Date: Mar 2002 Location: Canton OH Posts: 250 Car 1: 1994 Acura Legend iTrader: (0)	Basically is changes the resonnant frequency of the incoming air so that it about matches the speed that the intake valves are opening up. That way it lets the engine "breath" a little easier. By changing the area of the intake manifold, it changes that frequency to match higher RPM's. I dont think it makes a HUGE difference, but my main questions is once you are pulling in as much power as DV8, for example, so much more air is coming in that it may be starving the engine at lower RPMs until the other butterflys open. So it may benifit to remove it and polish the entire manifold, on the other hand it may always still match the RPM's/Frequency since when you are making that much more power you rev quicker so it still may be in tune. Theres only one way to find out. Any other input is welcome. I have my intake manifold sitting here as well and I was trying to figure out if that would be better or what. This is from an NSX page- VVIS stands for "Variable Volume Induction System," and is explained in the second NSX book on pages 26-29. The VVIS optimizes the air intake for different rpm ranges. For more low- and mid-range power, these butterfly valves remain closed (they look like paddles in the intake system, one paddle per runner). The book says the VVIS is activated by manifold vacuum above 4,800 rpm. By opening the valves, the intake air has acess to a second plenum which provides more "space" for the air- sort of like the Porsche Varioram system. A note about the NSX variable induction butterfly valves: You can make it run at max volume all the time by disconnecting the hose to the solenoid and capping it, however I didn't notice any difference in performance when I did this (supposedly I should get less low end torque). Makes you wonder if the variable induction is of any real use or if they included it as a techno-gimmick. __________________ 1994 Acura Legend Sedan <img border="0" src="http://pages.sssnet.com/delanier/legend.jpg" width="516" height="251"> Custom Greddy Cat-Back Exhaust Full Gound Wire Upgrade HKS Intake w/ Breathers Bypassed TB Coolant passage Clarion Audio Epic Arnage 17" Chrome Wheels 3 Layers of Dynamat (Entire Car) Brand New Paint job

01-19-03, 01:00 PM	#9 (permalink)
Henyaman Registered User Join Date: Mar 2002 Location: Canton OH Posts: 250 Car 1: 1994 Acura Legend iTrader: (0)	Also now that I am thinking about it, that is all tuned for the pressure waves of an NA engine. If you are going to supercharge it, it may be in your interest to remove then since the length of each chanber would need to be changed and tuned for a different pressure level when under boost. So when you are under boost I dont think it will do anything but restrict the ariflow since it is out of tune with the pressure waves. Otherwise if you are staying NA I'd prolly leave it there. Just my thoughts. -R __________________ 1994 Acura Legend Sedan <img border="0" src="http://pages.sssnet.com/delanier/legend.jpg" width="516" height="251"> Custom Greddy Cat-Back Exhaust Full Gound Wire Upgrade HKS Intake w/ Breathers Bypassed TB Coolant passage Clarion Audio Epic Arnage 17" Chrome Wheels 3 Layers of Dynamat (Entire Car) Brand New Paint job

01-20-03, 02:16 AM	#10 (permalink)
Dv8 Get sucked in... Join Date: Jan 2002 Location: CA Posts: 4,753 Car 1: 91' 3.5lt Extreme DV8ED Hybrid 6spd Car 2: 03' G35c Blk on Blk Car 3: 92'Yukon/06'Trailer iTrader: (11)	Well i guess a simple answer to all this is, get my downpipes and you'll see what i mean. above 4k with the downpipe in place the engine get a big boost of power( a veryvery audible roar of air, very much like VTEC. Something the little paddle coulnt do.) which makes me think the two side flaps open up. If your around N. CA and want to see and hear it for yourself contact me. once i get everything back up and running i will disconnect the small paddle and surpress the hose so that it remains open, we'll see what happens at the track. ~Hybrid __________________ AEM EMS Powered. 9 yrs and counting. Results, Where are yours? 12.953@107.865MPH 95 deg. Jun. 07' 3.5 6spd-#55 jet Nitrous 316WHP@5500RPM 345Lb-ft@4100RPM NOS 06-07'N/A 234WHP@5700RPM 229lb-ft@4600RPM 06-07' 13.782@99.135MPH N/A 95 deg. Jun 07' 03' G35c Auto Vortech Supercharged pshhhh 14.3@96MPH-Stock 8 page spread Honda Tuning September 06' issue No Phone or Instant message, PM or Email only. Respect that! My Legends Website www.2slik4u.com

01-20-03, 01:29 PM	#11 (permalink)
B+O G2BMC Join Date: Mar 2002 Location: VSC Moderator Posts: 12,089 Car 1: why? iTrader: (1)	the stages are 1st stage: all butterflies are closed and the air takes the TEDIOUSLY long route around the back edge of the manifold then around, then back up fron to the runners. thorugh 1500rpm i think, this long tedious tract is optimal for most lowend torque. 2nd stage: the outer flaps open and air flows freely upwards to longer of the runners... 3rd stage THE MOVIE( inside joke): the middle flap opens to expose a direct run to the intake runners and act as a single plenum instead of a bunch of runners. sorry i dont know if anyone answered this yet but i saw Dv8 wondering something....that doesn't happen often i dont have my book with me here, i wish i could scan it...it has the diagram of the stages. __________________ "Untainted by Concept of Limitation" -BozzSpeed -Reiko my baby -The MAIN person Thank you Leon. Your words help God said it, and it was so. Forum Rules *flossin,* breakin off the intersection crossin RL'in, ackin a iz-ass on them bosses Last edited by B+O : 01-20-03 at 01:39 PM.

01-20-03, 06:21 PM	#12 (permalink)
92coupeon18s Registered User Join Date: Jan 2002 Location: ATL Posts: 3,116 Car 1: 12sec E36 M3 iTrader: (0)	i would say take the 2 out that are clean and leave the dirty one but clean it. But i dono

01-21-03, 02:27 AM	#15 (permalink)
Dv8 Get sucked in... Join Date: Jan 2002 Location: CA Posts: 4,753 Car 1: 91' 3.5lt Extreme DV8ED Hybrid 6spd Car 2: 03' G35c Blk on Blk Car 3: 92'Yukon/06'Trailer iTrader: (11)	if its all ture then that little flap carries quite a load. ~Hybrid __________________ AEM EMS Powered. 9 yrs and counting. Results, Where are yours? 12.953@107.865MPH 95 deg. Jun. 07' 3.5 6spd-#55 jet Nitrous 316WHP@5500RPM 345Lb-ft@4100RPM NOS 06-07'N/A 234WHP@5700RPM 229lb-ft@4600RPM 06-07' 13.782@99.135MPH N/A 95 deg. Jun 07' 03' G35c Auto Vortech Supercharged pshhhh 14.3@96MPH-Stock 8 page spread Honda Tuning September 06' issue No Phone or Instant message, PM or Email only. Respect that! My Legends Website www.2slik4u.com

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