The most important feature of a recirculating bypass valve (Recirc Valve, BPV, BOV) on your Subaru is to evacuate the pressure out of the charge circuit when the throttle is closed. This prevents a surge of boost from hitting the throttle and then reflecting back toward the compressor wheel where it can slow or even stop the movement of the compressor wheel and corresponding turbine wheel. Ideally, the function of a bypass valve is to open this circuit and dump that pressure and drag on the turbocharger compressor wheel out to the unpressurized intake downstream of the Mass Airflow Sensor. This ensures that the vehicle still has the air accounted for to avoid afterfire and extreme rich running conditions on transition from one gear to the next. The faster the valve can open and the more the valve can flow, the better it is at evacuating that drag on the turbocharger. Unfortunately, with most diaphragm based designs, that comes at a trade off. You either have a valve that acts slowly (opening too slow resulting in some really interesting sounds as it opens) or a valve that can open quickly but has a small cross-sectional area of flow in order to allow it to act quickly but to hold boost when you want it to remain closed. Unfortunately the factory is a perfect example of the latter valve. It opens reasonably quickly, but the valve itself is the size of the head of a 16 penny nail, measuring roughly 5/16" across. That's right, it's just a hair over 1/4" in diameter.
The Nameless Performance FA20DIT Wave Spring Bypass Valve ensures that your charge circuit purges quickly, without restriction, and holds boost better than even the factory restrictive valve.
We have run these successfully with and without tuning, but the behavior of the valve is identical to factory, so the only need for a re-tune is if you've got the vehicle tuned with an already leaking valve and are replacing it with one that does not leak.
Posted by Adam SS on
This part is the best replacement for the OEM DV on the SJG.
It has much quicker recovery of boost & smoother transition during on/off pedal mashing. Very good for zipping through traffic.
The OEM part was a serious lag unit. It was difficult to pounce from one spot to the next.
The price is right & best of all made in America. Not everything needs to be JDM.
Posted by Steven Arant on
The beauty of this part is there's no guesswork. Its designed for the FA20DIT so you can be sure it will work. You want a quality bypass valve then look no further. This is the one!
Posted by Roman on
Best replacement for the stock BOV. Cool turbo sound. No boost leaks. Performance more than on stock.
Posted by Pat Hicks on
This is one of the best additions to my stage 2 wrx. It holds boost at 22 psi strong with no bouncing boost needle. I have mishimoto intake with box, invidia catless downpipe, nameless midpipe and axle back with 3" muffler deletes, Cobb stage 2 tune
I also have a video review on youtube...blacrsx
Posted by Jordan on
Yet another great Nameless product! Happy with it easy to install and gives a nice little sound with the stock intake. Can't wait for more products from them!
All prices are in USD