Cobb Tuning - Mazdaspeed 3 & 6 / Subaru WRX/STi XLE BPV

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1 - Cobb Tuning - Mazdaspeed 3 & 6 / Subaru WRX/STi XLE BPV

With the introduction to Cobb Tuning making a comeback to producing hard parts, their anticipated release of a bypass valve is welcomed. Many of us have been waiting for a valve that is easy to adjust, sounds great and works 100% without any surging on the turbo compressor.

Question: So what exactly is a BPV and what is the difference between a BOV ( Blow off valve ) and a BPV (Bypass Valve)?

Answer: Its simple.. It all boils down to whether or not your car runs on speed density or mass air. If you have a car that is speed density, you will not have a mass air meter. So, effectively, you can run a Blow Off Valve which give off a very loud WHOOSH sound as you shift gears when in boost. A Bypass Valve takes that boosted air its venting, and recirculates it back into the intake. The importance of this on a mass air car is, that air was already metered and counted, therefore, venting that air to the atmosphere will cause your can to go rich. You are effectively removing air once counted and letting it blow in the air, so the car is going to add more fuel thinking that air is still incoming. Many enthusiast prefer the sound of a BOV, but generally they end up doing damage to their catalytic converters because of the rich conditions incorporated into running a VTA ( Vent To Atmosphere ) system on a MAF equipped car.

Question: Whats the purpose of these valves anyways?


Answer:

1) Boosted cars produce tremendous amounts of pressurized air that is pumped very quickly throughout the intake system. When the throttle body is open, this air can move very quickly into the engine. Once the throttle body closes, that fast moving air has no place to go. You have an abundance of air trapped in a small place ( charge pipes ) which can burst, causing significant damage to your intake system and even your cars hood. On turbocharged cars especially, its main function as a Bypass Valve (BPV)/Blow Off Valve (BOV), is to release this boost pressure to prevent this pressurized air from being diverted back toward the turbo impellers. If this pressurized air is not released, the diverted air can cause the turbine wheels to slow and possibly even stall, causing wear and damage to the turbocharger. A turbochargers impeller wheels can spin in excess of over 60,000 RPM, so if the impeller was to fail, you would see a lot of damage.

2) Its second function is being able to hold peak boost during gear change without a significant loss of boost during this event. A good BPV/BOV can hold a high amount of boost, for the needed time of shifting gears, without degrading performance.

3) One important thing to remember on a Mazda, the stock BPV leaks, even at as low as 8 psi of boost. That is almost half of the rated 15 psi a speed can produce stock!

Cobb Tuning has an answer for those looking for that loud blow off sound but with a safety margin, the Cobb Tuning XLE BPV. It can be setup to run in 3 modes, one of them being a hybrid mode that allows a minute amount of VTA without placing the car in a lean condition. You get that loud WHOOSH but you also get that important counted air, recirculated back into the system.

Even though this valve comes in at a steep price of $299, its not any more expensive then the most over-rated BPV on the market, the HKS SSBOV... The Cobb XLE doesn't require any type of flange adapter. The HKS requires an adapter to be fitted to it before it can be mounted on a Mazdaspeed 3 or 6. Installing the adapter is a pain since it uses a snap ring... The most troubling part of the HKS is how much plastic is found inside the valve, but more daunting, its inability to be adjustable. $300? Really? There are numerous reports on our forum about the HKS falling apart... The plastic inside is breaking... This is definitely not the type of valve i want inside my car. Step aside, we have a new BPV on the market thats going out be worth the $299.

The Cobb Tuning XLE BPV is one unit that can be adapted to several cars. First off, if you plan to replace your Mazda with a scoobie, this can be done with a simple part change without having to buy a new valve. Below are the specs on the Cobb XLE:

YouTube - Cobb Tuning XLE Bypass Valve (BPV) Part 2

YouTube - Cobb Tuning XLE Bypass Valve (BPV) Part 2

YouTube - Cobb Tuning XLE Bypass Valve (BPV)

YouTube - Cobb Tuning XLE Bypass Valve (BPV)

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