nashman69g

iTrader: (3)

I must say the VDI system really makes a noticable difference...As we all know if we take the air pump off the VDI as well as the 5/6th port no longer work on S5 cars...well I wired the 5/6th ports open and that help improve my performace some but hurts the low end--oh well...So today I used a syringe to force the VDI open(temp fix)...low end feel the same as before...at about 3K the 5/6th ports are doing there job and I start feeling the power kick in...at about 5K(before opening the VDI) I would feel the power level off...since the opening of the VDI I can the power kick in the next thing I know the buzzer is going off at 6800 for me to shift at 7K (S4 engine w/ S5 intake manfold on)--I wish I could rev past 7K without the worry of killing my engine (162K on her)!!
The car pull hard at 5K on up when I need to shift!!

So go and get your VDI opened up!!!

nashman69g

iTrader: (3)

bump!!

SleeperZzZ

can you help me about taking my airpump off on my s5, i dont know what to do with the ports, or how to wire them.... im kinda new at this

nashman69g

iTrader: (3)

as far as the ports are concerned just wire them open as I have in the pic!!
u just need to take off the bolts that hold the air pump on and plug the hole to the inlet of the ACV or take the ACV off and get the block off plate for it!! If u still are unclear on how to due it, this topic has been covered about 10,987,675 times so just search for ACV or air pump and you should find something!!

sonic7

iTrader: (1)

10,987,676 to be exact!

nashman69g

iTrader: (3)

lol

RyosukeTakahashi

For any VDI experts out there I have a question. I've written about this before, I have an S4 which I did the VDI swap and the MT true dual exhaust. As you know the RB headers in the exhaust set up use a exhaust back pressure bung to allow for normal 6 por operatation on S4cars. I also did the VDI swap and since I removed the ACV and AP, I basically ran vacuum lines from the BP bung, to a T that spilt into two lines, one went to the 5/6 ports and was T'd again to open the ports and another went to the VDI manifold without the RPM switch, as recomended in the carl davis page. Well I also hooked up an Boost pressure gauge to monitor when I get the 3.5 to 4 psi necessary to open the VDI. It came on rougly around 5000-5200 RPM. So do any of you know on a stock s5 do the short runners close every time you fall below the 5600 RPM range?? I feel that perhaps my open system has premature opening of the VDI and thus losing its benefits. and if I'm driving hard it opens up at very early RPMs so in a Stock s5 is the VDI on long runners until 5600 even when racing or does it open to short runners when you are racing? if that makes sense at all.

rotarygod

iTrader: (1)

First of all wiring the aux ports open will NEVER give you a performance increase of any kind. ZERO, none, nada. It is a physical impossibility in this space/time continuum. They will only serve to hurt low end if non operating. Removing the sleeves and actuator rods from the airstream however will improve performance on the top end but still hurt low end. Leaving the VDI open at all times is also doing in essence the same thing. You are hurting yourself below 5500 rpm or so at the expense of retaining, not gaining, original power of a working VDI system. Saying that however, yes VDI does work. It functions better on more mild porting styles. The more wild the port style the less effective it becomes. On a big streetport or anything larger you would not want this manifold.

Ryosuke: The S4 uses exhaust backpressure (as you already know) to open the aux ports. Under harder driving the increase in exhaust pressure at lower rpms comes from increased load. This will cause your ports to open sooner if you are under power. The S5 however uses air pump air, not exhaust backpressure, to open the ports and VDI. These are triggered electronically through actuators to provide air at the same rpm regardless of load. This is an advantage because under high loads the ports would sometimes open too early and hurt power at that rpm. The S5 should close the ports any time the rpm drops below their set opening.

Jimmy325i

Why does everyone think the air pump has to go?

Unless you have a better way of working things (not known as plummers twine btw) leave the damn thing alone. It doesn't drain much power from the motor (like maybe 1-2hp at most) and isn't exactly in the way of anything, and does its job very well.

I wired my ports open because of the dyno runs and a sticking sleeve and I HATE IT HATE IT HATE IT HATE IT!!!! My car stalls unless you hold the gas till it warms up now. Freeway mileage sucks. Bottom end is gone... There is no benefit from removing the actuation of the aux ports.

Jimmy325i

Oh yeah, and to resolve the actuation issues I have an onboard air system in my living room awaiting a pressure switch for the compressor and an rpm switch for the solenoid valve.

I'll have working aux ports and track side air tools. lol All for the same weight of the air pump. (only located over the rear end of the car instead of the front)

RyosukeTakahashi

okay so if I understand correctly, under WOT conditions, a normal S5's VDI chamber would be closed until hitting the ~5600 RPM range in every gear? is this how the overall torque curve of the S5's is better? or does it stay open under the WOT condition?? I'm debating wether or not I should use the solenoid like in the swap page that way I can control the opening of the VDI, VS letting it open when it has enough backpressure from my system to do so..... I think I need a lot of tuning time for this cars set up.

thanks

rotarygod

iTrader: (1)

The S5 is rpm dependent regardless of load. I would find a way to use a solenoid.

j200pruf

iTrader: (4)

IF you ppl are just going to wire the acuators open, then why not just take them all the way out and get rid of the restriction, either that or make them functional.

RyosukeTakahashi

rotarygod, its not that I don't know how to make this system use the solenoid, I'm just trying to figure out if the system has any benefits to allowing the VDI actuator to open from BP rather than the RPM controlled way.

but thanks for the info.

jacobcartmill

iTrader: (6)

hey i have a question about this topic (sorry to bring it back to life)
but my VDI has never worked on my 91 GXL. i have the stock vacuum rack and all the solenoids, but i was under the conclusion that my VDI solenoid was dead (i had never felt any kind of power come on around 5500-8000 rpms) so i switched the lines from the blue solenoid (the one under the VDI solenoind) and nothing changed. so i took the VDI actuator off and it opens easily with several lbs of pressure (i think 5-7psi?) and the sleeve was nice and smooth and really easy to turn.
i am ****** lost on the VDI stuff, can anyone help me out? i have a cone intake and i can really hear the 6pi opening at 4k so i know they are working smoothly as they should, but VDI has me totally lost.

M5150

it should open at under 3 psi

silverrotor

iTrader: (1)

Why you shouldn't wire open your Auxilliary Ports; https://www.rx7club.com/forum/showth...highlight=port