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How To Drivetrain :: Operation Vacuum Gain System (VGS)

  #76  
Old 03-16-2005, 01:05 PM
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I'd plumb in a boost gauge to see what's up. I haven't noticed or measured any boost loss with this setup.
 
  #77  
Old 03-16-2005, 02:29 PM
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if there was less pressure sucking the bypass valve closed because of having a smaller diameter connector, would that effect how quickly the bypass valve closed at different rpm's? Because i can definitely feel the difference when i am around 4500 rpm's in 2nd gear and then floor it. The boost hits much faster than it did without the VGS, but slowly feels to loose its emphasis the higher gear i go, doing the same procedure as before. Does my train of thought make any sense? or is this just the nature of higher speeds with more drag, running out of oomph etc... any explanation would help, cheers
 
  #78  
Old 03-17-2005, 10:18 AM
Cooper S IRE
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wow this is a great mod
well done Andy
the car feels so smooth
had it done in 30 mins
well worth it
cost me 10 euro
 
  #79  
Old 03-18-2005, 11:47 PM
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The vacuum opens the valve....

So, the vacuum opens the valve, and we're moving the vacuum source from in front of the supercharger to after the supercharger....
So, in the condition that you take your foot off the throttle and create vacuum, since the SC is a compressor, then the valve should open later.

When the valve opens, it allows boost to leak back in front of the SC. This would lower manifold pressure after the SC, causing the valve to open more, and the transition should be faster than stock.

Think about when the vacuum source is in front of the SC. Then, when vacuum is high just past the throttle body. So the valve starts to open. But now, compressed air can go through the bypass, raising the pressure in front of the SC. And the valve starts to get more closed. This would explain why the yo-yo occurs, and why this SHOULD fix it!

Now, a restriction in the vacuum line limits how fast the air can go into and out of the diaphram. But it doesn't change what the final pressure would be. If you do electronics, the diaphram volume is like a capacitor. The restriction is like a resistor, the air flow throught the tube is the current, and the pressure is the voltage. A smaller tube just means it takes longer to charge the capacitor, but it will go to the same voltage!

Earlier in the thread, there was speculation that a longer tube would act like enough of a resistance to flow that it might dampen the yo-yo. One guy has an insert that has a tiny hole (0.027 inches or so, I think). this sure will increase the time constant and damp the yo-yo partially, or maybe even totally! But this is a very small hole, and the tee you used has a much bigger through diameter.

another bonus is that boost will INCREASE the force from the diaphram closing the valve.

Matt

Originally Posted by Soul Coughing
if there was less pressure sucking the bypass valve closed because of having a smaller diameter connector, would that effect how quickly the bypass valve closed at different rpm's? Because i can definitely feel the difference when i am around 4500 rpm's in 2nd gear and then floor it. The boost hits much faster than it did without the VGS, but slowly feels to loose its emphasis the higher gear i go, doing the same procedure as before. Does my train of thought make any sense? or is this just the nature of higher speeds with more drag, running out of oomph etc... any explanation would help, cheers
 

Last edited by Dr Obnxs; 03-18-2005 at 11:56 PM. Reason: Comments on tube diameter.
  #80  
Old 03-19-2005, 06:26 AM
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As an early experiment, I replaced the bypass valve's ~5" vacuum line with one about 36" long (coiled up in the space formerly occupied by the stock airbox). I didn't feel any difference at all, Yo-Yo was just as bad as stock. No point in logging that since I wasn't planning to stick with it.
 
  #81  
Old 03-19-2005, 10:40 AM
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Diaphragm longevity, and check valve

Is there any indication of the stock bypass valve diaphragm's tolerance to boost pressure over the long term? Because in the factory design the diaphragm isn't subjected to boost, it may not have been designed to handle it. Some indication could be had by opening one and looking at the internals. If it's a simple diaphragm design, and peak boost differs from atmospheric pressure by no more than peak vacuum does, the diaphragm will probably last.

Installation of a check valve has been suggested to eliminate application of boost pressure to the diaphragm. Some considerations for this application might be: If the check valve has a perfect seal, the diaphragm would never recover from the highest vacuum condition. If the check valve leaks some, it will not protect the diaphram from boost pressure, only slow the rate of change of pressure on the diaphragm - though that might still be helpful in preserving the diaphragm.
 
  #82  
Old 03-19-2005, 02:16 PM
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Andy and all:

I got up early this morning and wanted to make my first official mod, Andy's VGS mod! Went to Autozone and Pep Boys, as Autozone had no 5/32" vacuum lines and Pep Boys did.

After reading the posts, and Andy's install notes about 50 times, I felt I was ready to take on the challenge. VW's have been my thing for the last 5 years, so I was hesitant on the MINI.

After locating everything that I was going to have to work on, and comparing the size of my hands and fingers, I decided to attempt to dismember the IC, for easier access. DAYIM, that was EASY! I was expecting something similar to the Turbo setups I was used to on the VW's. The MINI was a 5 minute tear down!

1. I highly recommend removing the IC, just to save you valuable time in locating the components, and working with the small vacuum lines!

Now, it was easy to located the nipple on the manifold and the nipple on the FPR, as well as the nipple on the diaphram for the Bypass Valve.

I found it very easy to take the tube out of the nipple on the manifold by using a straight pair of needle nose plyers to hold onto the nipple, to prevent it from moving too much in the manifold, and using the 11" 45 degree needle nose plyers as suggested previously in the thread, to pull the vacuum line out of ther nipple, makes it VERY easy!

2. As suggested previously in the thread, buy yourself a 11", 45 degree set of needle nose plyers, this was a tremendous help for us people with not so small hands and fingers.

3. I strongly recommend replacing the vacuum line between the FPR and the manifold nipple, not just connecting the T from the nipple to the stock vacuum line. The stock vacuum line is VERY brittle and easy to snap. Being you are working in a very tight place, you may not even know you snapped a corner, leaving you with a vacuum leak.


After replacing the vacuum to the FPR and nipple, I then ran the line under where the IC was along the fuel rail, or close to it. this keeps everything concealed from your MINI service dept, on their routine inspections.

I then simply used my 45 degree plyers to pull the vacuum line out of the diaphram, put a 7/32 plastic extension in on the end of the line left connected to the Bypass Valve, and a vacuum cap on the end of the extension to cap off the Bypass Valve. I then, fed the 5/32 line from the T between the nipple on the manifold and FPR, and BAMM, you are done!

After checking all my connections once more, I put the IC back on and started up the MINI. Checked for idling problems, signs of leaks, and then took the MINI out for a 45 mile cruise, and it ran perfect! No CEL's, no idling flux, nada.

Now being I only have 700 miles on the MINI, I have not got to experience the Yo-Yo effect. What I have experienced was that under very mild vacuum, as described by Andy (0-5psi) the engine feels like it had a dead spot and you would have to give it more gas to get over the hump. Now, with the VGS, I do not feel any jerky hesitation when starting off at the line, after a quick stop, or in mild manor street driving. This VGS mod definitely changed the responsiveness of throttle and smoothed out the feeling while boosting (if this makes sense).

I am very pleased with the quick easy mod. Took me 1 hour, as I was being careful and was double checking everything, as well as familiarizing myself with the MINI engine.

Things to note:
When buying the vacuum line, I bought 10 feet just to be sure, just in case of a tear or puncture in the hose. I ended up with just under 2.5 feet remaining.

I bought a set of Tees and Extensions that had many different sizes, as this helped out getting the right extension to fit into the Bypass Valve's line that came out of the diaphram.

Use the plyers as mentioned above, and take the time to do things right.


A couple of questions for Andy:

1. Will the plastics of the tees, and the thin 5/32 tubing be OK with the heat in the areas I ran the lines?

2. Is there anything similar to the VAG-COM that I can hook up to the MINI and read measuring blocks and such like I do with the VAG-COM on my VW's? Does Ross-Tech make any software that I can add to my laptop with the VAG-COM, and read through the same OBD connector I currently have?

Thanks for the wonderful Mod that, I am sure, will allow our MINI's a more efficient boosting experience

 
  #83  
Old 03-19-2005, 03:08 PM
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Itsdchz, awesome write up!

 
  #84  
Old 03-19-2005, 03:50 PM
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bypass damage

ok so what are the odds that the supercharger boost will damage the bypass
this is a great mod
but if it is at the expence of my bypass valve im going back to stock
Andy what do you think
 
  #85  
Old 03-19-2005, 04:45 PM
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ITSDCHZ
Excellent write up. Sounds like you duplicated my set up almost exactly. I have lots of pics and should post some. I can't imagine how some of you did this in a few minutes without the long reach plyers. I also took the time to pick up some body color spray paint and painted the intercooler body color and highlighted the raised S with some red touch up paint. Really looks nice I haven't driven mine yet even though I did the Mod a week ago (working the night shift sucks). Anyway first AutoX is tomorrow and I can hardly wait.
 
  #86  
Old 03-20-2005, 07:35 AM
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Itsdchz

Excellent write up!
rataha, Post those picture's soon.
Now waiting on Boost gauge. I'm going to have to get a pair of those 11" 45 degree needle nose plyers too.
IMHO, this is what NAM is all about.
 
  #87  
Old 03-20-2005, 05:14 PM
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Bypass valve longevity

While I don't have a valve in hand to open and look at, I found photos of opened valves here on NAM, posted by Ryephile in "The Yo-Yo Chronicles".

https://www.northamericanmotoring.co...&postcount=133

https://www.northamericanmotoring.co...&postcount=138

From the photos, it appears the diaphragm assembly is simple, and likely the diaphragm will tolerate the boost pressure for a long time. The valve body with butterfly valve and linkage also looks like it would tolerate increased closing force for a long time.

One area it's hard to see in the photos is how the two halves of the diaphragm housing are connected. In the stock application, vacuum would tend to draw the diaphragm into the half with the nipple. In the VGS application, boost pressure would tend to force the diaphragm away from the half with the nipple. The force on the diaphram would be transfered to the other half of the housing.

It's only a few psi, which would make only a few pounds force separating the two halves of the housing, but I'd like to see the how the connection between them is designed to be comfortable the housing connection will last over the long term.

Has anyone looked at how the housing halves are connected?
 
  #88  
Old 03-20-2005, 08:41 PM
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OK,


I just did this mod and those of you who have done it without taking the intercooler off must have hands the size of an infant. I ended taking off the IC, all the air intake hoses and the throttle body.

I did go ahead and remove the bypass valve to adjust the butterfly for proper closing. Mine needed it for sure.

DEfinitely smooth running now. Also the pickup is much quicker than before. Overall, a blast to drive. Coupled with adjusting the bypass valve to close all the way, I had a definite feeling of more power.
 
  #89  
Old 03-21-2005, 10:21 AM
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bypass diaphram

if you examine the bypass diaphram
you will see it is only pushed together
what are the chances the housing will break apart due to the
boost pressure i know it is only a small ammount
maybe there is some way to reinforce the housing
what do you think Andy is there any chance the bypass can get damaged???
:smile: :smile:
 
  #90  
Old 03-21-2005, 10:56 AM
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I really don't know what, if any, long-term effects there will be on the bypass valve diaphragm. Logically, the diaphragm sees 850 mbar of vacuum (150 mbar absolute) on a regular basis. With the VGS, if it sees 850 mbar of boost (1850 mbar of boost, or 12.5 psi), the diaphragm will be feeling the same force, only in the opposite direction.

My thinking is, if the diaphragm were to fail, the bypass would be held closed by the spring and would no longer open (AKA Ryephix#1). So, fuel economy would get worse, but otherwise the car should remain quite driveable. IIRC, a stock bypass costs about $50.
 
  #91  
Old 03-21-2005, 10:56 AM
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The check valve concept is to install the check valve backwards in the bypass line so that vacuum could suck it open but boost would push it closed. I ran this setup on my supercharged dakota to keep the MAP sensor from seeing boost it didnt know what to do with.

--
Cheese
 
  #92  
Old 03-21-2005, 11:17 AM
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great thanks

that sounds good to me
thanks Andy
and well done this is a great discovery
 
  #93  
Old 03-21-2005, 11:24 AM
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Andy from my previous post:

A couple of questions for Andy:

1. Will the plastics of the tees, and the thin 5/32 tubing be OK with the heat in the areas I ran the lines?

2. Is there anything similar to the VAG-COM that I can hook up to the MINI and read measuring blocks and such like I do with the VAG-COM on my VW's? Does Ross-Tech make any software that I can add to my laptop with the VAG-COM, and read through the same OBD connector I currently have?

Thanks for the wonderful Mod that, I am sure, will allow our MINI's a more efficient boosting experience
 
  #94  
Old 03-21-2005, 11:32 AM
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2. Is there anything similar to the VAG-COM that I can hook up to the MINI and read measuring blocks and such like I do with the VAG-COM on my VW's? Does Ross-Tech make any software that I can add to my laptop with the VAG-COM, and read through the same OBD connector I currently have?



obviously you haven't heard of BIM-COM
thousands of MINI people are awaiting the release eagerly
and i cant wait it will be a great tool
from ROSS TECH
there is a forum especially for this on yahoo
ill post the link
http://autos.groups.yahoo.com/group/BiM-COM/messages/
 
  #95  
Old 03-21-2005, 12:07 PM
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After driving a little more today, all I can say is WOW. The stumble is very much lessened now and I can drive in a parking lot without yo-yo.

It seems like there is so much more power now because the throttle response off the line is improved. In some ways, the butt-dyno feel is simlar to that of when I first put the pulley on.

Itsdchz, as far as the vacuum lines go, I would think there is no problem with heat as there are already both hard and soft vacuum lines all over these same areas (and plenty that are hotter) of the engine in stock trim so adding some should not be a major problem. I also agree that the 11" pliers would be the ticket. I did not have some and used regular needle-nose but it would have been much better with the long ones.

Also, the aluminum casting on the drivers side of the intercooler (right where the boot attaches) is very sharp on top. I cut the crap out of myself on that thing.
 
  #96  
Old 03-21-2005, 12:13 PM
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Yep, what those guys said. :smile:
 
  #97  
Old 03-21-2005, 01:15 PM
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  #98  
Old 03-21-2005, 04:57 PM
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Something else I just thought of as far as the lines and temperature. When I had the IC out I noticed that there sure is not much place for the air to go underneath it and it made me wonder how much better the thing might work if the IC had a free flow pattern.


This also means that if the vacuum lines are under the intake runner, the air flowing through the IC must be going down in that area and out so it would be cooled by that as well. I'm sure the air is picking up some heat or the IC would not be doing its job but it must be cooler than the engine.
 
  #99  
Old 03-22-2005, 12:11 PM
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[email protected] said
My thinking is, if the diaphragm were to fail, the bypass would be held closed by the spring and would no longer open (AKA Ryephix#1). So, fuel economy would get worse, but otherwise the car should remain quite driveable. IIRC, a stock bypass costs about $50.
It seems that a failure of the bypass valve diaphragm and/or housing would open a path from the intake manifold to atmosphere through the vacuum line installed as part of the VGS setup. I think that would act like a vacuum leak under low boost conditions, and would cause idling problems. Of course, the stock setup could also fail, causing idling problems.
 
  #100  
Old 03-22-2005, 12:50 PM
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You make a good point. If the diaphragm failed, you could have a small leak (the vacuum line) but the big hole (bypass valve) would be plugged by butterfly in the bypass valve, which is held closed by the spring. Of course if the spring broke, all bets are off.
 

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