I don't think that's the case since the throttle position sensor reports it being fully open (or at least as fully open as it is with the bypass in unmolested form).

 

Yeap its possible that the logic behind whats happening it more computer logic than physical logic. Modern EFI can get really complex. MAP signal based systems (like the MINI's) calculate engine load based on the MAP sensor values. If you change the behavior of the wy the system performs physically, you'll alter the way the computer reacts. If you quicken the response of the bypass you'll be coming off vacuum much quicker which the ECU sees as "load" and probably swaps routines, adds fuel and retards timing.

Downstream MAP, LOAD, Throttle Position are all OBDII logable parameters. Try it out.

 

One more comment;
Is it possible for the bypass valve to be misadjusted and go "over center" so that in the zipped position, its really partialy open? I noticed that on all the other runs there is a slight change in the slope just before reaching max pressure, but not on the zipped runs. In my theory the valve goes past full shut and starts to reopen slightly as the mechanism hits the stop when you zip tie tie it, but under normal operation the mechanism goes to the fully closed position but no farther because there is nothing to drive it past the fully closed position, ie the spring is fully extended.

 

The bypass is closed against the stop when the engine is off. When the engine at idle, the bypass is visibly open (90 degrees from the stop). I'm not sure what position it has during operation (tough to see that while driving). :smile:

It definitely could be possible that the butterfly is overshooting its stop ... that should be adjustable using the stop screw.

 

The same thought had occured to me Andy, but if the butterfly were over-rotating past closed when zip-tied, the same should be expected under WOT no zip tie, right? Unless something holds up the butterfly at closed when it's vacuum driven and you're able to force it past that something with the zip tie (lot's of speculation here).

It's certainly worth a look down the barrel of that bypass valve. You never know, you might have some free boost there, waiting to be recovered! I haven't tried yet; how hard is it to get a look INTO the valve? The HAI should give you a little head start at getting to it. :smile:

James

 

No overshoot:

 

Here are more pics of ye ol' bypass valve:

 

I noticed that when I looked at my bypass valve that there was red loctite or something similar on the set screw.

Andy, it didn't look like yours had that.....if so I wonder if Mini is doing a better job in adjusting them?

My car is a end of April delivery 2004

 

OK, so I fired off an email to a friend of mine, Chris Weisberg, who worked for Turbonetics and Magnuson Superchargers (Eaton) before taking his current job, head of engine development for Carroll Shelby Enterprises. He has an extensive knwoledge of how the blower on the MCS works. I emailed him the link to this thread and this is what he had to say:

The first post is correct, regarding bypass valve operation. What the
people in that thread don't understand is that the bypass valve closes as
it's needed. Meaning, as you put your foot down, the valve closes, and you
have boost. Trying to create part-throttle boost is pointless since the
throttle is partially closed, which prevents the engine from making any real
horsepower in the first place. Besides, if you are at part throttle and you
want more power, step on the pedal more. Also, another downside to closing
the bypass valve at part throttle is that it creates noise and reduces fuel
economy.

That said, changing the preload on the bypass valve can close the bypass a
little sooner in relation to pedal input, making the vehicle feel a little
more snappy in some cases (haven't done it on a Mini yet), but it will not
increase WOT horsepower at all.

Hope this helps,
Chris


Hopefully this helps!

Travis

 

People are saying that they can SEE the valve operate faster with a restricted vacuum line.

Any theories about how this could be?

What are we misunderstanding about how this system operates?

 

I received a BPV in the mail yesterday. The restriction orifice diameter of the hose fitting on the actuating diaphram housing (0.085") is smaller than the restriction orifice diameter of the M7 Device (0.09375). There is more restriction offered by the housing itself than by the M7 Device, which is installed upstream.

Mass hysteria? Draw your own conclusions.

 

mass dysentary.

that is really bizarre then. time to put on the old stocker and try that out again (i installed the HAI and the device at the same time). will report if there is any subjectively perceived difference.

 

Sorry, can't help but laugh.

Some people have seen UFO's. Some have seen Sasquatch and the Loch Ness Monster. Others have seen this device work. Do you believe?

 

Absolutly Come on down and we'll show you too .

Randy
Team M7

 

Sorry for reviving this old thread., I just got a R53 -2004.

Here are my questions:

1. When is bypass valve starts closing ( SC starts supplying boost ) at what RPM?
2. When is bypass valve fully closed ( SC maxed boost )at what RPM?

or please tell at what RPM range is the SC not supplying boost?


Thank you...