[SUMOM3]

By no means Am i an engineer or anything, but have many years playing around with SC/Turbo applications.

After much debate and people bringing up the issue of BOV lag issues, I thought of a new project. Few enthusiasts thought of a modification to help relieve the throttle plates slapping clsed due to the pressure not completely being relieved by the AA BOV that is provided. I am assuming that many think that the BOV diameter is "too small"???

Well, Im going to do some testing and measurements of the AA BOV and the Vortech MONDO BOV.

As it stands "Rumors are, that the AA BOV was orginally designed to a capacity of 4-6 psi.

As it stands, looking at Vortechs site, it shows the MONDO BOV being rated 0-10 psi (up to 12).

Now if this is simply the facts and its true... Well im thinking of just cutting out the flange and getting the vortech flanged welded on.

Things i need to find out:
1. I need measurements on the overall size of this MONDO BOV, and the air inlet.
2. Try and see if it will even fit in the tight spot were the BOV is currently in.

3. Try and find a used Vortech BOV

Thoguhts, Advice, Opinions are welcome.

[mm28]

Originally Posted by SUMOM3

By no means Am i an engineer or anything, but have many years playing around with SC/Turbo applications.

After much debate and people bringing up the issue of BOV lag issues, I thought of a new project. Few enthusiasts thought of a modification to help relieve the throttle plates slapping clsed due to the pressure not completely being relieved by the AA BOV that is provided. I am assuming that many think that the BOV diameter is "too small"???

Well, Im going to do some testing and measurements of the AA BOV and the Vortech MONDO BOV.

As it stands "Rumors are, that the AA BOV was orginally designed to a capacity of 4-6 psi.

As it stands, looking at Vortechs site, it shows the MONDO BOV being rated 0-10 psi (up to 12).

Now if this is simply the facts and its true... Well im thinking of just cutting out the flange and getting the vortech flanged welded on.

Things i need to find out:
1. I need measurements on the overall size of this MONDO BOV, and the air inlet.
2. Try and see if it will even fit in the tight spot were the BOV is currently in.

3. Try and find a used Vortech BOV

Thoguhts, Advice, Opinions are welcome.

sounds straight forward enough, i think is going to work

[MSpired]

Good idea. I believe CA Automotive in the UK has replaced a few AA BOV's with some Blitz units. Try contacting them and getting some info if they are willing to share.

[SUMOM3]

So i did some additional searching and found some nice info reading in some mustang forums.

There are actually several different BOV's we can choose from but it all boils down to size.

1) Vortech MONDO BOV: Its a tad bit taller than a coke can, but much bigger than a coke can in circum.... Keep in mind, the flange will add addition length over...Price: $275 (Satin) $306 (polished)

Info:
Vortech Maxflow Bypass/Blowoff Valves improve supercharger operations by opening to relieve unwanted pressure during deceleration, this reduces heat build-up and eliminates compressor surge. These units feature a "rolling diaphragm" design which provides ultra-quick valve response along with unmatched reliability.

2) Tial: makes a very nice 50mm opening (claims to be the biggest openeing available of all BOV's). $243

info:For use on turbo-charged and super-charged applications (Paxton, Vortec, etc.). The body and all internal components are CNC-machined from 6061 aluminum alloy. It features a large 1.98 in (50.5mm) valve; we believe this is the largest valve available with the highest flow capacity. The V-Band design aluminum mounting clamp gives a very clean and unique appearance. The clamp is anodized and uses Stainless Steel hardware for a long lasting, corrosion-free appearance.

The blow off valve seal utilizes a Viton O-ring that is clamped in place to prevent the possibility of sticking to the seat and pulling out. The valve stem and guide are teflon-lubricated, hard anodize-coated for wear resistance.

The Blow Off Valve also comes with a machined aluminum banjo-type air fitting and bolt, with over sized 10mm hose barb for quick actuator response. The actuator has a high temp silicone Nomex-reinforced diaphragm for long life.

3) ATi Procharger BIG RED (best reviews so far as far as performance &Quality) $360-$415

I havent seen any info in depth about this unit yet. Im not too sure about what psi rating this unit has. I also have not seen the size of the unit as well. But it looks HUGE!

[SUMOM3]

Info found on e46psi:
As all 6 throttle plates snap shut, the air quickly accumulates in the intake plenum (manifold) causing a significant spike in pressure. This pressure spike was one of the reasons why Active Autowerke chose to not use the brittle and plastic OEM BMW plenum (more info - Forced Induction 101 section III). The Active Autowerke bypass valve then opens and relieves the pressure buildup by re-circulating the trapped air into the system and away from the plenum.
Although sufficient for level I cars (5.5psi), this airflow system is inadequate for higher levels where boost pressures reach in excess of 7.5psi. Having personal experience with this system, I can attest to the delay being as much as a full second on long gear pulls (4th gear and up). In situations where every second counts, this delay can dictate the outcome of your race or pass.

So, what is the root cause of the delayed, “laggy”, shifting? A definite cause has yet to be established, but the general consensus among a small group of dedicated BMWPSI.com members is that the bypass valve is simply ineffective. When open, the bypass valve attempts to re-circulate an enormous amount of air away from the plenum and into the backside of the Rotrex supercharger unit. The bypass valve has an opening of 40mm while the intake on the backside of the blower has a diameter of 30mm. This decrease in diameter causes a “bottleneck” of airflow and leaves unwanted pressure against the butterflies (throttle plates) preventing them from opening - hence the lag.
Fortunately, an Australian BMW enthusiasts and devoted member of BMWPSI.com took the time to document his “fix” for the lag. What follows is a step by step tutorial on how to rid delayed shifting on E46 M3s equipped with an Active Autowerke supercharger system.

__________________________________________________ ________________________


So that settles it! I think I will go with the Tial BOV knowing that its 50.5mm (10.5 bigger than the AA BOV)

[Saintly]

[QUOTE=SUMOM3;3822101]Info found on e46psi:

Fortunately, an Australian BMW enthusiasts and devoted member of BMWPSI.com took the time to document his “fix” for the lag. QUOTE]
I did all the tests here and going bigger will help no doubt but I am running 10.5psi+ and have no issues. It is strange that some do still have the issues and others don't. I believe that there might be something more to it. I will be interested in your findings. Maybe it has something to do with where people are taking their vacuum line from

[odiedog52]

Where do you recommend we take our vacuum from?

I am having the same issue, massive lag between shifts and I did your bypass mod as well. People just think I shift really slow.

I also see spikes of 10, 11, 14 psi, etc at the end of my runs which may be attributed to this?

[SUMOM3]

[QUOTE=Saintly;3822323]

Originally Posted by SUMOM3

Info found on e46psi:

Fortunately, an Australian BMW enthusiasts and devoted member of BMWPSI.com took the time to document his “fix” for the lag. QUOTE]
I did all the tests here and going bigger will help no doubt but I am running 10.5psi+ and have no issues. It is strange that some do still have the issues and others don't. I believe that there might be something more to it. I will be interested in your findings. Maybe it has something to do with where people are taking their vacuum line from

The vacuum source is being taken exactly where AA instructions tell you to do so, which is off the Fuel rail.

Its very awkward... I feel the "pause" in shifts and its very noticeable. Keep in mind though, I still have the CDV valve as well, but if the facts are that the AA BOV is indeed 40mm, and its bottle necking from the manifold, then thats an issue. Also if the kit was only made with the intent orginally for 4-6 psi, then oviously this needs to be changed out.

Afterall... Dont we all strive to gain from little modifications? Reliability, Power, most importantly the need to always make things better...

By all means, the AA BOV is by far a very nice product and is proven to work... But as their intent to make more power was by adding a bigger blower, and injectors for more fuel, maybe the thought of the BOV was there, but not changed due to , "it works just fine"....

You also have to take in consideration that they are/did make available the upgrade at a very affordable cost and then eventually just made it the "current" kit, and Still managed to keep the cost the same! GOTTA LOVE AA FOR THIS!!!

[votE46]

subscribed!

[Saintly]

Fuel rail for vac is correct. I have seen some take it off the intake manifold. I know that some tuners play with the throttle maps and cam overlap to help solve this issue. I am more puzzled at why some do and some don't there must be a reason. My thoughts are that if the lag was the direct cause of a too smaller outlet of the bypass then we all would have the problem, where as this is not the case and I know a few running 11-12psi boost like me with the AA bypass and no problems.