as I was poking around my car after a road trip this weekend I found a few things that I need to address. #1 being the bpv set screw.. what does the set screw adjust with the bpv ? I can obviously tell mine has been played with and I've already found MULITPLE THINGS DONE WRONG with my car so I wanna make sure that my set screw is set correctly. I've ALWAYS felt like my car should make more boost as I only ever see 15lb MAX with 17% pulley and all other bolt ons and tune..
if I adjust the screw downward to press more against the lever on the bpv , will that then cause it to do what ?
my bpv has good resistance , car runs GREAT but like I said. P.o did some questionable things and the screw has obviously been moved as i can..

 

UPDATE: finally found exact info I needed about bpv.
Soooo I found a bunch of threads from 05 and read them all..unfortunately none explained what I was asking in the 1st post above..
but OMG OMG OMG I went out and adjust the screw counter clock wise so I allowed more travel of the arm and now I went and test drove it only 5min and it didn't make any more boost which I hoped but It had absolutely NO YOYO what so ever..also when it was on boost and I let go of the throttle before the car came off boost kind of hard and if I didn't ride the gas rite it would buck a little and going under 10mph sometimes too it would yoyo if I let off the gas to coast.
NOW IT DRIVES BUTTER SMOOTH . I will test drive it tomorrow as with my job currently i do abit of travel. So I hope it stays this smooth..
BUT can someone tell me how this is effecting the engine? I'm going to try and turning it along clockwise just to see what effects it has...
I will also try it both ways as is and with the vgs mod and see which way performs the best by the butt dyno and runs the smoothest.

 

Smoothest: without VGS mod
Aggressive: with VGS mod (due to direct vacuum)

 

It’s a set screw to adjust the flap opening. Don’t just guesstimate it. Take out the BPV and hold it up. Adjust the screw until you don’t see a light through it. Want it closed. Hope this helps

 

Jep, thats the correct answer. To be honest, the flap does not close for 100% in my case. Not with the original BPV or the aftermarket BPV I ordered. It has some miniscule gaps on the side of the flap.

If it doesn't close well, then you will loose boost meaning lower power off course. it doesn't show on the picture below, but if you take it out and shine with a flashlight from behind the flap, you will see light seeping through. The mission is to minimize this "seepage".

 

If nothing else impacting supercharger speed, 15 psi at top end of RPM is "approx" what you get. Stock on the Mini, it put out 10-11 psi. Other stuff to consider:
1. If you are chasing max boost then you also need to take a look at the accuracy of the gauge you use. Typical accuracy of a 2"/ 52mm pressure gauge is +/-4 % of indicated value; at 15 psi that means the gauge is off no more than +/- 0.6 psi.
2. Intercooler, charge pipe BPV, Intake, etc Seals, gaskets, yep, change em if in doubt. And tuning out the BPV for full closure of the butterfly is a good thing (Probably what DT does on their improved BPV).
3. Otherwise, the M45 is only so big (theoretical 45 cuin / .74 cu liter per rev) and the intercooler, charge pipe, etc. have fixed volume.
3. Keep in mind, higher the s/c speed, higher the Intake Air Temp. At the top end of the RPM range this increases potential to run lean, burn valves, other bad stuff, etc. Not gonna happen on the first time you max, but after repeated maxed out shifts in the summer the intercooler doesn't have a chance to recover. I run a 17% pulley with stock crank damper diameter, I burned a valve after repeated max rpm shifts one hot summer day.... That's with 380 cc JCW injectors.. Now I keep my shifts down to max of 6200 Rpm in the summer. Or give the intercooler about 10 min recovery after a max rpm run through the gears, Generally speaking 17% works for the street, but its on edge for IAT's unless you live in Sweden.

 

Was this with stock intercooler?

 

Yep, 15 psi with stock intercooler is max what I get with a 17% pulley, 4th gear, rpm around 6500. Don't know exact RPM for that, usually kind of busy watching the road/gauges/etc...I have since acquired the infamous "Hack" GP intercooler and it seems to max out around 14 psi. Eventually Ill get around to testing IAT's on both....

Read through this post, its all interesting, but around post #41 - #45 is where s/c RPM vs Engine RPM is laid out.
https://www.northamericanmotoring.co...and-boost.html

 

Im kinda new to this Mini thing, what is the "hack" GP intercooler? I know about the GP intercooler, but havent seen the "hack" reference before.

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Interesting thread! Thats why I like forums like these, becuase of the knowledge and knowledge transfer