I put a alta cold air in my mini and it makes the blow off sound beautifull but i was thinking of doing a diverter valve? is that a smart move? also i was looking to do the new alta boost tubes and turbo inlet tubes? smart or not? Also when i put my cold air in it told me to plug the bost so is it pointless to get the bost tubes. What about a bost guage?

 

Your mini should already have a diverter valve. So I assume you mean a blow-off valve. Whether or not this is a smart move is always controversial, but exhaust depot has the nicest set-up I have seen.

Alta's turbo inlet tube won't fit a factory JCW. I learned this the hard way...

 

As for a BOV it will not harm anything. The turbo system as you now have it has a BOV it just exhaust back into the intake so you dont hear the PSSSST. If you like the sound go for it....

 

atko3, there's numerous mentions in many threads throughout the site that states that this engine/turbo/ecu/etc./whathaveyou setup does not react well to the blow-off exhausting to open air. I never read them as I wasn't figuring I'd be touching that for a long time if ever, so can't offer more. Just dig a bit more around NAM if you're interested in the subject.

 

Most all modern turbo systems have a BOV...you just dont hear them because its a closed system....exhausting it to atmosphere will do no harm...it will also not increase or decrease performance.

 

Harm isn't the same thing as running like crap. I don't have any skin in the game or experience, so I recommend everyone search & read from folks who have experience w/this particular engine.

 

I do and it will run fine and do no harm....

 

Thoought some of you would be interested in what the blow off valve does...
Blow Off Valve (BOV)What does it do:
The purpose of a blow off valve or compressor bypass valve is to prevent large pressure spikes in the intake pipes when the throttle plate is closed while boosting, preventing the turbo from surging. The BOV sits between the turbo and the throttle body and has a vacuum line that is attached to both the other side of the BOV valve and the intake manifold. When you are boosting the pressure on both sides of the valve is essentially equal because the pressure in the intake manifold is the same as in the intake pipes. When you close the throttle plate while boosting all that air slams into the plate and pressure spikes. At the same time the intake manifold pressure drops to a vacuum, and thus so does the pressure on the other side of the valve. The result is the valve opens wide to allow the pressure to vent out. Also included in a good BOV is some form of spring to aid in keeping the valve closed during modulating part throttle situations so that the BOV doesn't open and cause drivability problems.

 

there is a difference in BOV and diverter valve. and that is that with a BOV the air is vented to the atmosphere and with a diverter valve it is rerouted to keep the turbo spooling. I know this because I owned an Eagle Talon TSi AWD. It had the all to infamouse 4G63t 2.0L Turbo (same block that was in the last Evo). now that car had this sequence and I am not sure that the same is true for the R56. Filter, MAF, Turbo inlet, Turbo, Intercooler, intake tube, Throttle plate. Now the diverter valve was on the intake tube and it had a tube that ran from it back down to before the turbo. If the Mini system has those in the same order then I can assure you the engine will run like crap if you vent that extra boost to the atmosphere. What happens is the air that has gone through the MAF the computer has already accounted for how much fuel its going to need. Now if you vent that air off you are going to have a rich situation because the turbo is going to have to pull more air in and that will cause a rich situation. When I would pull the tube off my diverter and plug the end to hear the pssssh sound each time i shifted my car would stumble and then my turbo would have to build boost back up. Autocrossers will tell you that recirculating that air is important to keep the turbo spinning.
Also anyone that says the air is heated again may have a little bit of a point because the air is run through the turbo and compressed but that air is also run through the intercooler again so the difference is probably little to none.
I would also like to point out another thing. There is a reason that the engineers that designed the system used a diverter valve instead of a bov. It does have to do with noise but if that was truly the case they could have vented into a muffler like aparatus.
In the Eagle Talon days it was general knowledge that you did not need a BOV unless you had a big turbo usually a 20g or larger. That being said there are ways to safely run a BOV on a car like these. Mach V who also makes products for Mini's has it on their website. It is called a Vein Pressure Converter made by HKS.
Diverter Valve can also be called Compressor bypass Valves.
Now I once again say that this information is based on my experience with an Eagle Talon and that unless the system is laid out in the same order this may not hold true but if the MAF is before the turbo then the same effects will most likely occur to those who choose to use a BOV on the R56

 

Unless I am reading what you said I do not agree....the purpose is exactly oppsite of what you said...by releasing the pressure when you let off the gas (or decrease boost) the ov helps keep the turbo spooled by releasing pressure from slowing down the charge when the engine is not in demand of boost!!!!

 

The unique sound caused by a blowoff valve (but not a compressor bypass valve) sometimes comes at a price. On a car where the blowoff valve is mounted after the mass airflow sensor, venting to atmosphere confuses the engine control unit (ECU) of the car. The ECU is told it has a specific amount of air in the intake system, and injects fuel accordingly. The amount of air released by the blowoff valve is not taken into consideration and the engine runs rich for a period of time. Engines with a manifold absolute pressure regulated ECU or where the blowoff is mounted upstream of the MAF sensor are not affected.

This is a direct quote from the wikipedia blowoff valve page.

Also I will add that the diverter valve should in no way be slowing down the turbo since all it is doing is creating a loop. Now like I said this is different for large turbos when more air is being compressed but with a small turbo like on the mini it is not slowing the turbo. The only difference is that instead of introducing new air through the MAF the diverter valve is using the same air to send back through the turbo.

 

As SccrMan13 has said, in a system with the BOV mounted after the MAF the car will dump fuel and end up running rich (possibly throwing a CEL as well). If you have full tuning capability (standalone?) this can be tuned out, but why bother when there is a mechanical solution already in place.

You want to keep the turbo spinning for a couple reasons: a) for back-on throttle response, and -more importantly- b) so the pressure doesn't attempt to go the wrong way through the turbo causing cavitation, or what's more commonly referred to as 'compressor surge'. This can severely damage your turbo.