i've read many many threads on vgs. but i didn't find a definitive answer to this. in the current gen mcs, the factory "yo-yo" is no longer an issue. are its other "merits" real and worth the change? i know its cheap and easy, thats not the point.

will vgs improve an '06 model?

 

I think they fixed the yo-yo in '05.

I have an '05 with the VGS and while I really don't have the yo-yo to fix, you can definitely tell that you are getting boost much sooner. The VGS also pushes the BPV shut with much more force then the stock set up.

Since it's such a cheap and easy mod, give it a try. If you like it... keep it... if you don't... go back to stock.

 

A few things: there was YoYo in some '05s (at least one- mine) so it's not necessarily fixed by then. And many pre-'05s didn't have it, or the owners never noticed it. Also, how does the VGS shut the BPV with more force? The Detroit Tuned BPV uses a stronger spring to close the valve, but I don't see how the VGS with a stock BPV will close with more force. It might close at a different rpm, but the vacuum needed to close it won't change since you haven't changed out the diaphram nor the spring, (unless you change the valve to a DT one.)
If you don't have the YoYo, I don't see any point in doing the VGS.

 

When yo-yo is discussed, what is being defined: the inherent flat spots in the ECU programming or the normal function of a vacuum controlled bypass valve (which are on their third generation and do wear out)?

 

From:
https://www.northamericanmotoring.co...602#post486602

 

I have read through that thread before. However, that is the normal operation of a vacuum controled valve. When people are talking of the yo-yo's I’m not quite sure they are always speaking of the same thing. And that is what concerns me.

 

Oh, sorry, that wasn't in response to your question. I don't know what the yo-yo is either, actually. I just say that I've never had it because I never have experienced something that I would ever describe as a "yo-yo".

 

I have an extremely late model 05, the only differance between my MINI and an 06 is the icon used in the passenger airbag off light (my software has since been upgraded so I'm on par with 06 in that matter to)

I did the VGS, well cause I figured even if it did nothing I was only out $5 which was (and I believe is again) less than the cost of 2 gallons of gas.

It has made a phenomenal HP/torque improvement (esp. in the low end), and the get-up and go factor is much improved (feels like 30 more HP just because you get the use of the SC so much sooner; not actually any HP improvement just where and how the SC kicks in). The biggest differeance I felt after removing it for a day or so, was without it all power is lost between shifts put the VGS back on and the engine holds the power(elimination of yo-yo? because I'm not waiting for the valve to close again) on the up shifts better so acceleration improved in 2nd 3rd 4th 5th and 6th.

Between a CAI and VGS (my only preformance mods thus far); my MINI is more fun to drive than an 05 from the same month fitted with a JCW kit.

I'd say go for it cause its simple there's some great how-tos and it will only put you out $5.

 

shankrabbit: My post *asked how* the VGS creates more force on the BPV diaphram. I don't see how it can, but that's probably caused by my failure to understand many physical phenomena. Simply posting the quote from Andy at RossTech doesn't help me understand the physics here.
thanks,

 

So these oscillations (which are so well depicted in Andy's opening post) are "normal operation?" If so, we need not resume normal operation, because the effect of these oscillations in my stock '05 MCS were incredibly obvious and frustrating/irritating. They were effectively eliminated by the VGS and DT BPV.
cheers,

 

Whoops... sorry, I get what you're asking now.

Here is how I understand the VGS.

The stock vacuum line to the the BPV is located pre-supercharger. So it relys on the vacuum created by the SC to close the BPV.

The VGS switches that line from pre-SC to post-SC, and gets it's vacuum directly from the intake manifold (same place as the fuel pressure regulator), which creates a lot more "suck" then the vacuum from the pre-SC location.

This extra "suck" from the manifold not only closes the BPV sooner, but it holds it shut with much more force.

Instead of waiting for the SC to spin up to a certain speed in order to create enough "suck" to close the BPV (as in the stock system), the VGS uses the almost instant mechanical "suck" created by the pistons in the manifold to shut the BPV.

Is this making any sense?

 

Lets see if I can explain it in the right way.

It VGS creates more force because it changes the source of where is senses vaccum. The post superchager source that is mentioned in Andy's quote is something I understand as being under boost, the pressure is stonger and the pressure Delta is greater. With the stock setup there is less pressure change and it can happen over a greater period of time because the air is moving slower. The slower air can cause the BPV to flutter, the faster pressurized air causes and abrupt change and uses the boosted and vaccum to push the valve with greater pressure change in one way way or another. The increased pressure exerting more "force" on the valve itself.

If I understand it correctly, if not then I'm sure someone will jump in and clear things up soon.

Edit:It appears Ben has beaten me to the explination.

 

Brewhahhaha....

 

"The slower air can cause the BPV to flutter, the faster pressurized air causes and abrupt change and uses the boosted and vaccum to push the valve with greater pressure change in one way way or another. The increased pressure exerting more "force" on the valve itself."
The VGS mod can also cause this flutter with an early car, 02 -04 with the stock BPV. The symptom is a kind of almost shut to shut under normal driving. I believe this is due to a soft spring, on my car anyway. When the mod works right, on other cars I have done, it works great. There is more power where you want it because the valve shuts sooner.

 

Thanks to both motor on and shankrabbit. I suppose I see the BPV as a binary state device: it's open or closed. Once sufficient force is applied to the diaphram to close it, additional force is unnecessary. I can understand how the VGS vacuum takeoff point causes the BPV to close "earlier" but I don't understand what "with more force" means. Once it's closed, it's closed isn't it?
I'm not disagreeing that the stock BPV can oscillate, and I can see how the VGS keeps the valve closed against this oscillation--but not because it has more force, but because the force applied by the VGS is more constant, rather than greater in PSI.
that's all...
cheers,

 

The BPV is not a binary state valve. It's quite variable.
(I can't find the post for the life of me) I've read somewhere that with the softer springs (02-04) that sometimes the BPV wouldn't even shut completely with the stock setup.

But you are right, once it is shut, applying more pressure to it will not make it "more shut".

 

Now, that some BPVs didn't shut completely is another issue, unrelated to the VGS, that plagues the OEM valve. When I replaced my BPV it certainly didn't close when "shut" because of misalignment of the butterfly. I adjusted it to close properly, and some people have done this mod rather than replace it with the DT unit. If the BPV has a misaligned butterfly, some SC pressure will be leaked off regardless of any other modification, VGS included.
Also, are you sure tha MINI replaced the stock spring with the 2005 model year? I have never seen that claim before. When comparing my stock '05 valve with the Detroit Tuned one, the DT spring was stronger.

cheers,

 

"(I can't find the post for the life of me) I've read somewhere that with the softer springs (02-04) that sometimes the BPV wouldn't even shut completely with the stock setup."

I can't find that post either. It does not apply to all 02 -04 cars, just some.

Wow, "more shut" must be much more better, especialy if it means that the valve shuts more than really shut or completely shut. Is "more shut" something like gripsion? Some tires have gripsion, personaly I have never seen any.

 

For drivability purposes the BPV is designed not to shut completely. Remember, we are talking about milliseconds here with respect to the BPV fluttering. I’ve never measured it like Andy did, however, and to me your butt dynos seem rather sensitive.
In effect, what you guys are saying is that the yo-yo effect is normal BPV operation that you don't like. And the VGS and/or Detroit Tuned BPV rectifies the situation.
Of note, I've done a/b testing at the track with the Detroit Tuned BPV and never noticed a difference except in mileage: average 33 to 27.

 

Seeing as we're providing what we in academia call "anectodal evidence", let me add to dmh's data point: I installed the VGS and the DT BPV and my gas consumption remained unchanged. Of course, it has *never* been anywhere near 27 let alone 33--more like 23 on a good light foot day. Anyone getting better than 25mpg in a MCS is not driving it hard enough!
And that's all I have to say about that...

 

I just think the street is not the place to drive it hard. 33 MPG is what I average according to my on board computer. I have a ScanGaugeII and maybe I'll see what that says as well.

 

I know some who have done it on heavyier modded cars and they found no differance whatsoever, on my car I noticed a huge differance; I did the mod about eh same time I added my CAI and noticed a phenominal jump in MPG after the CAI never getting any conclusive # jump with just the VGS change. And its not always milliseconds that are being discussed here. I don't consider what I have to be a yo-yo but simply a delay in getting power, by doing the VGS that 1-2 second delay was eliminated and brought down to a .2 second delay inherient from the electric throttle. I have no experiance with the BPV and cannot comment on that. I do know that mods effect each car a little differently and at least on my ride the VGS made a huge differance, at no measurablesacrifice in MPG.

 

There are many threads disscussing MPG many show the OBC is very overzealous when reporting mpg figures, I use the tradtional trip meter between stations divide by gallons need to fill tank.

 

one other question. https://www.northamericanmotoring.com/forums/showpost.php?p=975967&postcount=29
suggests that there may be temperature concerns. any comments from you guys?

 

Hm... I don't know about having hard factual numbers for you, but I know that after a hard drive around town I can easily put my hand on the inlet of the IC without giving myself a permanent scar.

Granted I have a custom diverter, but if the delta of temp was that extreme I think I'd notice.