EasysBox

When i reinstalled by SC, i decided i would try something, i disabled the boost bypass valve... First impression, the car seems to actually drive smoother, gear engagement doesn't feel as jerky, drives as smooth as it did NA. The jury is still out on gas milage, after my first tank i will post up MPG numbers... Method behind the madness: Since the SC essentially acts like artificial displacement by blowing air into the motor and not compressing it, i am assuming my gas milage may not be hurt that bad as long as i continue to drive like normal, the SC will only get as much air as i let pass through the throttle. The way i see it, it is like driving with a bigger motor under the hood... yeah, anyways, ill continue to post up my results on this and ill post the MPG numbers when i get them...

IowaSciontist

Isn't the bypass supposed to let air out when you let off the gas. Like a BOV for a turbo? what will happen if you hammer on it then let off? Have you tried that yet?

EasysBox

the bypass valve bypasses the boost when you aren't in need of it. ive actually gotten on it with no ill effects, just feels, smoother...

moderngti

On other cars that did this with Eaton blowers.... they didn't have any ill effects until they cooked the bearings in the blower... as it's ALWAYS spinning fast / working at cruise... the bypass takes wear / tear / heat out of the blower.

I'll give this mod 20K until you need a new S/C'er.

EasysBox

...the bypass valve does nothing to affect blower speed...

moderngti

Not peak speed... but average speed... yes it does.
The lobes are always being forced to paddle-wheel air into the engine.

With the bypass, the air can find a less restrictive way into the intake without stressing the blower itself as much... hence why it's there.

For better blower response, at least on the MP62's, we'd pull the little brass pill / restrictor out of the bypass valve vaccum line...

See if yours has this and try the car with it removed...

Steve60

Easy, do you know where to get BPV parts? Shaft, bearings, plate???

Steve60

Moderngti, is right. 20k might be a little on the short side for bearing life, 40k is what I've seen with direct drive 471's - no BPV. "the bypass takes wear / tear / heat out of the blower" = Exactly.....
Easy, why did you disable the BPV?
FYI when the BPV sticks, it's the "O" rings in the bearings, on this SC anyway.

EasysBox

sorry it took me so long to reply, i havent been on the site in awhile, kinda got burned out... anyways, i disabled, or rather removed the bypass actuator because i was bored and wanted to "experiment", however, the noise at idle started to drive me crazy after the first day. so i reinstalled the actuator. when i was installing the actuator, i noticed that the rubber diaphram was damaged, so this is why i was noticing poor response. i called magnusonproducts.com and ordered a new actuator, it cost me $20 shipped. you can get other eaton products from them as well, ie the bypass parts. anyway, i have the bypass working working now and have noticed a 2-3 mpg increase on the freeway...

Steve60

Easy, there are many people that disable the BPV only to find higher IATs, not that there is any way to measure IAT in this setup. BUT, trust me on this. Way better to have the BPV active than not. You can find many articles on the BPV & why it's a good thing.

moderngti

try looking for / removing the brass pill in the diaphragm line... there should be one there on the MP45... it'll improve response big-time!

Steve60

The diaphram can not be taken apart. If you mean the reducer on the, in side, of the spud - diaphram housing, I've tried that without any luck ( you could drill it out ). Yes the responce would be quicker.....

EasysBox

i have removed the brass plug when i installed the new actuator, came off with a set of pliers, however, i reinstalled it into the new actuator, just a little worried that the extra force of not having it there might tear the diaphram again, better safe than sorry...

Steve60

Easy the force remains the same. The pill is there to slow the opening of the valve by reducing the actuator air flow.
I could not get mine out. Figured it was "barbed" in or bonded to the spud... I'll need to try harder.
As moderngti says this is a good mod, done it with some other valves but they were inside the actuator. Some actuators can be taken apart, springs modded, reducer removed ( pill ) etc. The biggest deal is, how closed is the valve? Some are closed more than others & that can make as much as 2 lost lbs of boost...... All this time you thought closed meant closed...... well maybe.... or not.

EasysBox

i know that the hg/psi will be the same, but the force on which they act upon the actuator will be more forceful without the brass plug, thats why i reinstalled it... not like this is a race car anyways ;)

BoogieQ

I had to login just to tell you how completely wrong you are.

The supercharger is a direct belt driven device. The supercharger in question (mp45), and the one you mentioned (the Eaton M62) do not have a clutch to allow variation of speed.

No matter what you do to the bypass, at X rpm on the motor, the blower WILL spin at Y rpm. I don't care if it's a leap year or you found the missing pink sock you have been looking for since grade school, it will NOT change.

To the OP: Leaving the bypass closed is just a stupid idea. They didn't invent it because they were bored. Let it do what it is supposed to do and go about your life. If it runs 'better' that way, then fix what is wrong with your install causing it to run like crap with the bypass actually bypassing the supercharger.

Steve60

The BPV does many jobs none of which slow the rotors.

a- it reduces the parasitic loss when there is no boost

b- it reduces heat produced from stuffing the air ( stuffing rather than compressing ) when boost is not needed. This produces lower intake air temps reducing posible detonation

c- the BPV is an on demand switch that is intake manifold vacume operated so optimal boost is atained when needed

EasysBox

the reason it "seemed" to run better, as i stated, was because i had a bad actuator, the diaphram was damaged... and it is fixed... besides, leaving it closed just to see what happens was just s bored experiment, there is nothing wrong with trying new things...

Steve60

Easy, I don't think BoogieQ was addressing you. There are plenty of people that have disabled the BPV with Mini "S" cars with no problems & they did NOT run like crap before or after.... Just lower IATs ( BPV working ), you can see them on a Mini via any good scanner. There is a sensor on the intake manifold.

EasysBox

maybe, i just assumed "OP" meant original poster.... but yeah, it was just an experiment, i learn best by doing... the biggest problem i had was just the noise was annoying, too loud at idle, i did learn one thing though... the high pitched squeal when the throttle is at a certain position did not go away, i originally thought it was the bypass valve opening and closing, but now i know it is not, next theory.... maybe it is because the TB's are so small, it makes a whistle as the air is drawn through at a certain point... seems to happen between 5hg and 1 or 2psi on the gauge... food for thought...