Hello EVOM members,
I'm finally taking my car to get tuned.. My question is when should i replace the stock diverer valve? How much boost can it hold? I've had mixed responces.. some say it's fine and I don't need to wast my money .. some say i should replace it right away.. I have all bolt ons.. no turbo upgrades. someone even said to "crush" the stock one to hold more boost???? any input would be greatly appreciated..

Thanks

 

i have this same question as well. I heard crushing the stock valve was just a band-aid solution. I will be pushing around 26 psi or so and want to do it correctly the first time around as a re-tune will be required once a new bov is installed.

Anyways I was looking at the Cobb BPV but not sure if it'll mount up with the AEM CAI.

 

stock will leak around 24-26 psi.

Many people switch to aftermarket just to be safe.

 

I've seen them leak right around 24/25 psi on even on a stock turbo car. Its a good idea to replace it because if you leak boost the turbo will have to work harder to try to make the target boost.

 

If you will be tuned higher than 26 PSI then replaced the stock diverter valve if not keep the stock valve because it has the best drivibility out of all VALVE except it doesn't hold more than 26 PSI. Normal safe tune usually is under 26 PSI so there is no need to switch, unless you like AGGRESSIVE tune and squeeze all power from your parts then you must buy a BOV.

 

You're thinking of final PSI, not peak. Even then, there are many reported incidents of stock dv's leaking around 24 psi. On my tune (and many other bolt-on tunes) boost tapers off to 24 psi, however it peaks at 25-27. And this is a conservative, safe tune.

If bolt-ons, you'll probably want to replace with an aftermarket dv, but just talk to your tuner.

 

I've tested crushing the stock BOV 50% and it does add about 2 psi extra boost holding capability according to before and after tests. Stock is usually good for 25-26 psi and crushed usually 27-28 psi, but there is always a chance you have a BOV that was built on Friday afternoon.

They all have a certain leakdown over time that is a pretty slow leak, and then a point where they just blow open losing all pressure.

 

We recently had a customer in our shop who was pushing 26 peak psi which would tapper down to 24 psi. After doing about 2-3 pulls with the car, it would start to leak and taper all the way down to 19-20 psi. After switching to the synapse dv, his car was spiking to 29 psi and we had to turn down the boost with the boost controller.

 

Thanks guys I went ahead and purchased a synapse synchronic BOV..