Bypass Valve or Blow-Off Valve??

[VY5Speed]

Howdy, not sure if this is the best place for this but anyway...

In a supercharged system (Particualy a VY V6) can you change the Bypass valve to a Blow-off valve?

I have been doing some reading but im stil not 100% sure...

As far as i can understand, this is possible with a centrifugal supercharger??

Feel free to comment and correct me on any of this.

Cheers,

[Raptorsc]

In a supercharged system (Particualy a VY V6) can you change the Bypass valve to a Blow-off valve?

No, all VS - VY Ecotecs are the same, they have an air flow meter and once it meters the air going to engine you cannot let that air back out to atmosphere, if you do engine will run excessively rich when cruising or may not run at all.

As far as i can understand, this is possible with a centrifugal supercharger??

The same apply's to a centrifugal supercharger installation as well no matter who makes/supplies it.

The only exception is when you remove factory ECU and install a MAP sensed aftermarket ECU, then you can do what you want but plenty of other problems can come along then as well.

Questions always welcome

[kranky_wagon]

so is there any way at all to have the blow off valve a MAP sensec ECU? wat are the other problems you would find?

[Raptorsc]

There is always a way to have a BOV on a MAP sensed system but maybe you mean't MAF sensed.

The problems are very rich on decleration and idle, there are partial plumb back/external vent valves from APS which give sound for a bit (what you want) and then go into plumb back mode, work quite well.

Thats one way to do it, the valves are around $350 but designed for this situation.

[fmlycar]

Quick question. Would a turbosmart kompact dual port bov with adjustable spring tension be suitable for the cetrifugal set up with afm. Trying to get around that pigeon sound

[Raptorsc]

To be honest I do not know if any of these aftermarket valves are a good thing for centrifugal chargers, but you shouldn't have a pigeon sound, do you have the BOSCH valve?

[fmlycar]

I do have a bosch valve but at part throttle cruising and closed throttle decelerating it flutters like it's not holding the correct position either open or closed. Do you think it's possible that it's plumbed the wrong way? As the instructions with my kit didn't say how to install it. Also, Tim, could you PM me your postal address. I've been meaning to send you that paper work and lost your address.

[Raptorsc]

Kurt

To fit the BOSCH valve correctly determine which of the 2 hose fittings has a 10mm x 10mm plastic tab that extends down off the main valve body, the barb that features this little piece is the air IN tube.

It is very strange that it should be producing Pigeon sounds as these valves work faultlessly. It could very possibly be the wrong way around, if not then we can move to next possibility.

Happy to assist as always

[Raptorsc]

Actually just had a second thought on this, you have an intercooler, this means you should be running 2 of them otherwise you will get compressor surge which is heard as "fluttering" and it will eventually take out your Vortech, in fact surge which shows itself as a continous flutter is the very worst type and will destroy any centrifugal supercharger.

[Raptorsc]

Actually just had a second thought on this, you have an intercooler, this means you should be running 2 of them otherwise you will get compressor surge which is heard as "fluttering" and it will eventually take out your Vortech, in fact surge which shows itself as a continous flutter is the very worst type and will destroy any centrifugal supercharger.

[fmlycar]

So then running a dual port valve can only be a good thing then. Just going to see if I can get the one with the correct size inlet. Not sure if it's 20mm or 25mm.

[VN_Luke]

I had a similar issue in my setup (yet to verify that it's resolved) (AFM turbo setup, afm located on the intake side of the turbo)

basically, without the blowoff valve, it would 'flutter' - and you'd get air shooting back through the turbo, and then BACK through the AFM - it could be clearly seen on the logs for the AFM as 'waves' of air (it's a hot-wire afm style sensor, and it was measuring the air TWICE, once ont he way on, and again on the way out during the 'flutter')

Of course with an atmo BOV it was shooting 'measured' air out into the atmosphere, and fuelling for air that wasn't in the system

so what I've done now is run a plumb-back style bov, with a spiraled long (2m?) return hose, and increased the volume between the turbo intake and AFM as much as I can.

hopefully this will be enough to stop the 'blown out' air going back out the AFM (or minimise it enough so it's not an issue)

I also came up with an idea of using ANOTHER AFM on the outlet of the BOV - then 'negating' the value read by that AFM from the other - which should hopefully trick the ecu into fuelling for the correct amount of air.

This might be a good solution if you reallllllly want the BOV sound.

[fmlycar]

My AFM is not far before the throttle body but the bypass valve is before the AFM. Spoke to turbosmart today and they advised that the bosch valve is past it's efficiency and that a dual port with the centrifugal supercharger spec spring is my solution. Once it's all fitted I will let everyone know my result and post part numbers for future reference.

[fmlycar]

Blow off valve and centrifugal spec spring arrived today. Just waiting on the car to come back from the painters and it'll all be fitted.

Repco part numbers

Turbosmart Kompact dual port bov (direct replacement for bosch item) part no. TSFGBOVKTDP25 RRP $553

Turbosmart plumb back spring to suit cetrifugal supercharger part no. FG-BVS-SPKTPB RRP $22

[Raptorsc]

Okey dokey, very interested to hear how this goes, I haven't had much luck with this type of product at all.

Anyone wanting a brand new TURBOSMART BOV with Centifugal SC spring contact me. Going cheap, costs $350 brand new. $150 to the first person to contact me about it. Probably still got the CD that come with it floating around someplace

[Raptorsc]

How is the valve working fmlycar?

[fmlycar]

Still haven't got my car back from the paint shop.........

I will be posting my results and a video on youtube once I get it back.

[fmlycar]

Turbosmart valve works a treat. Got 11psi in the motor without detonation and no more pigeon noise. It did however blow out a exhaust manifold gasket.

[vs-6]

Actually just had a second thought on this, you have an intercooler, this means you should be running 2 of them otherwise you will get compressor surge which is heard as "fluttering" and it will eventually take out your Vortech, in fact surge which shows itself as a continous flutter is the very worst type and will destroy any centrifugal supercharger.

k tim its brad i have just purchased your kit and i have noticed that youve said that u need two bosch plumb backs (which you have sent me)
but i have purchased a blow off
valve and i was told that if u put the blow off valve before the intercooler
near the supercharger itself
and the afm up near the throttle body that you can have it go straight into the atmosphere rather than plumb it back. the blow off valve that i have purchased seems very hard to push up compared to the plumb backs
that you have provided jsut wondering if it will be ok or if i should just try it and see. and how exactly do i mount the 2 plumb backs.

[immortality]

the BOV you ahve purchased is probably fitted with a turbocharger spring. you will need to get a supercharger spring for it? which brand BOV?

[vs-6]

haha just a cheap one off ebay lol ill have to look into this supercharger spring do u know where i can get one from or can i just use the one thats in the bosch plumb back??

[Raptorsc]

Brad

Dun use that ebay thing, will wreck the charger.

You won't be plumbing back your bosch valves, once I show you how to set the IC system up you will find out how it all works

[stocky]

yep ebay BOVs suck. had one on mine and it was too strong. the pressure ended up blowing the whole BOV off the piping.

[vs-6]

yer ok tim was only gonna use it coz it looks better anyway lol but umm what i think im going to do is move the maf sensor up near throttle body (not too close) and then have it as a blow through maf. then i may aswell just use both the plumb backs one on each side of cooler and then just have them going into atmosphere but this means ill need to get some1 to weld up something to the piping

[vs-6]

i didnt listen to tim and i ended up trying my luck with ebay blow off valve tim was right not good enough i have to get soem pipes welded up for 2 plumb backs which kinda sucks but yer i am done and all is good except for a high voltage in temp sensor any1 know how to fix