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

With the introduction of Cobb Tuning, hard parts manufacturing is back and the expected release of bypass valves is welcomed. Many of us have been waiting for a valve that is easy to adjust, sounds good, and works 100% without spikes in the turbo compressor.

Question: So what exactly is BPV and what is the difference between BOV (blow-off valve) and BPV (bypass valve)?

Answer: Its simplicity .. It’s all summarized in speed density or whether your car runs in large amounts of air. If you have a car with high speed density, there is no mass air meter. Therefore, you can effectively perform a blow-off valve that produces a very loud WHOOSH sound when you shift gears when boosting. The bypass valve takes the boosted air into the vent and recirculates it to the air intake. The importance of this in mass air cars is that the air has already been weighed and counted. Therefore, releasing that air into the atmosphere enriches the can. When you count it, it effectively removes the air and blows it in, so the car thinks it’s still in the air and adds fuel. Many enthusiasts like the sound of BOV, but due to the abundant conditions built in to run the VTA (Vent To Atmosphere) system in cars equipped with MAF, they generally end up damaging the catalytic converter. Become.

Question: What is the purpose of these valves anyway?

Answer:

1) The boosted car produces a large amount of compressed air that is delivered very quickly throughout the intake system. When the throttle body is open, this air can move very quickly to the engine. When the throttle body closes, the fast-moving air has nowhere to go. A large amount of air can be trapped in a small area (charge pipe) and explode, causing serious damage to the intake system and the hood of the car. Especially in turbocharged vehicles, the main function as a bypass valve (BPV) / blow-off valve (BOV) is to release this boost pressure and prevent this pressurized air from flowing back into the turbo impeller. If this compressed air is not released, the diverted air can slow down the turbine wheels and even stall, causing wear and damage to the turbocharger. Turbocharged impeller wheels can rotate in excess of 60,000 RPM, resulting in a lot of damage if the impeller fails.

2) The second feature is that you can keep the peak boost during gear changes without losing significant boost during this event. A good BPV / BOV can hold a lot of boost for the time needed to shift gears without compromising performance.

3) One of the important things to keep in mind at Mazda is that even with an 8 psi boost, the stock BPV leaks. This is almost half the speed rating of 15psi that can produce inventory.

Cobb Tuning provides the answer to anyone looking for that big blow-off sound, but looking for a Cobb Tuning XLE BPV with a safety margin. It can be set to run in three modes. One of them is a hybrid mode that allows a small amount of VTA without leaving the car lean. You yell that loud, but you also get that important counted air and recirculate it into the system.

This valve sells for as high as $ 299, but it’s not as expensive as the HKSSSBOV, the most overrated BPV on the market … The Cobb XLE doesn’t require a flange adapter. HKS must be fitted with an adapter before it can be mounted on a Mazdaspeed 3 or 6. Installing the adapter is a hassle because it uses a snap ring … The most annoying part of HKS is the amount of plastic. It’s inside the valve, but it’s more daunting and unadjustable. $ 300? Really? There are a lot of reports on our forums that HKS is broken … the plastic inside is broken … this is definitely not the type of valve I want in my car. As an aside, a new BPV worth $ 299 is on the market.

The Cobb Tuning XLE BPV is a unit that can be adapted to multiple vehicles. First of all, if you want to replace Mazda with a scooby, you can do this with a simple replacement without having to buy a new valve. The following are the specifications of CobbXLE.

Features

body

* Body, mounting flange, and secondary outlet cover are made of 6061 T6 aluminum.

* The body is hard anodized for additional strength.

* The primary outlet has a rectangular shape and provides the maximum cross-sectional area for expelling pressurized air as quickly as possible.

* The secondary outlet cover can be removed to enable partial atmospheric vent mode or full atmospheric vent mode.

* The height of the unit is only 3.5 inches from the base of the flange to the preload adjuster at the top, which fits in the narrowest space.

* The interface between the body and the mounting flange is sealed with an O-ring, allowing flanges of various shapes to be used in multiple applications.

piston

* Lightweight aluminum pistons allow faster reaction times than heavy pistons.

* Aluminum pistons are hard anodized and Teflon impregnated to provide smooth movement, reduce surface wear and minimize maintenance.

* The rounded piston profile smoothes the flow of air as it passes through the cylinder.

* The rounded piston profile combines with the rounded piston seat for excellent sealing when the BPV is closed.

* Tight tolerance O-rings are used to properly seal the piston to the cylinder bore at normal engine operating temperatures without sacrificing piston speed.

Preload adjuster and spring

* The adjuster allows you to adjust the spring preload to fine-tune the release pressure.

* Spring and spring seat are made of 303 stainless steel.

* The spring preload adjustment mechanism and fasteners are made of stainless steel.

operation

* Due to its lightweight components, port shape and low sliding friction, the valve expels pressurized air very quickly.

* Unique exhaust noise due to the speed of air release.

* Construction materials are compatible with XLEBPV with alcohol / water injection due to their inherent corrosion resistance. * Lighter than most aftermarket BPV and BOV.

Operating mode

Complete recirculation-Outlets are piped to the intake pipe before the turbo. This configuration provides the best drivability in a stock-based MAF system. This configuration minimizes noise generation.

Hybrid Mode-The outlet is piped to the intake pipe in front of the turbo and the auxiliary port cover is removed. If the piston is more than 30% open, the auxiliary port will open to ventilate the atmosphere. If the open is less than 30%, it will completely recirculate and improve drivability.

Complete Atmosphere-Exit and auxiliary ports are open to the atmosphere. Recommended only for MAP-based air metering. This configuration produces the highest sound level.

Adjustment

Spring Preload-Spring preload determines the pressure difference across the BPV piston required before the BPV opens and releases the pressurized intake charge. COBB XLE BPV can be adjusted by loosening the locknut and turning the Allen head shaft clockwise to increase preload or counterclockwise to decrease preload. When the preload is set, the locknut is retightened to ensure the adjustment.

Installation:

Parts list:

* Bypass valve

* O-ring (Mazdaspeed 3 application only)

* Paper gasket (Mazdaspeed3 or LGT / 08 + WRX application only)

Required tools:

* 3/8 “Ratchet

* 10mm & 12mm socket

* 10mm & 12mm open end wrench

* Pliers

Tools required for maintenance:

* 3mm Allen key

* 4mm Allen key

* 13mm open end wrench

* Molly-based grease

Installing this piece is as easy as it gets. The stock bpv is black, made of plastic and can be found at Stock Mazda, which is very close to the stock TMIC cold pipe.

1) Take the pliers and remove the recirculation hose (large 23mm hose) on the back of the valve. Guide the pliers to the butterfly clamp, compress the pliers to release tension, and slide the clamp 3 inches from the lip. Pull the hose to remove it from the valve.

2) Remove the pliers and remove the small vacuum line in the same way as the recirculation hose above.

3) Remove the 10mm bolt that secures the BPV to the pipe, remove it sideways, and reuse it.

Now you need to decide whether to run in full recirculation mode or hybrid mode. If you choose to run a larger hybrid mode, you will need to use a 3mm Allen key / bit to remove the valve trap door. It’s really easy because only four of these hold it.

Once you have decided which route to choose, remove the paper gasket from the box and place it on the valve, using both bolts to hold it in place. Return the valve to the BPV flange and retighten. You need to be careful here. If you are using alumni TMIC, it is highly recommended that you use a ratchet extension with a 10mm deep well socket and tighten both bolts evenly by hand. After tightening by hand, attach one 1/4 inch crank to both bolts. That’s it. They require very little torque and continue to hear that Heracles breaks cold pipe bolts and unscrews.

After reducing the torque, connect both hoses and remove them for driving. I seriously suspect that the valve needs to be adjusted, but keep reading if you do.

Adjustment:

Adjusting this valve is easy. Simply place a 13mm open-end wrench on the jam nut at the top where the vacuum line is connected, take the 4mm Allen / bit and turn it clockwise to increase the tension of the spring (compressor surge / vent). (Increase the possibility of) or reduce the spring pressure counterclockwise (reduce the possibility of compressor surge / vent).

Here, increasing the tension of the spring does not increase the amount of boost that this valve can hold. If you want to keep more boost, you need to install another spring on this valve.

maintenance:

It is advisable to inspect the COBB tuning bypass valve each time you change the oil to make sure the piston is still free to move. To do this, remove the BPV from the vehicle mounting flange and push the piston. If you feel resistance, it is recommended that you remove the piston from the body, clean the piston and re-grease it. ARPUltra-TorqueFastener Assembly Lubricant, P / N 100-9911 is recommended, but Molly-based grease works well. I like the red molly on the red line that I used during the installation of both CobbSTS and TWM Performance STS.

Disassemble the COBB tuning BPV

To remove the piston, use a 3mm Allen key to unbolt the base flange from the body. Depending on your BPV model, there are 5 to 6 socket head cap screws. When removing the piston, be careful not to cut the O-ring. If the O-ring is damaged, you can contact COBB Tuning to replace it.

Reassemble the COBB tuning BPV

To reassemble the BPV, push the piston back into the body and prevent the piston from sticking out of the body. You can hold the piston at that point by placing your finger on the vacuum connection.

Place the base flange on the body and clock the flange again. Depending on the model, use a 3mm Allen key to secure the flange with 5-6 socket head cap screws.

Conclusion:

Not only does it look and sound cool, but it’s also fully functional, adjustable, and not awkward right out of the box, and I’m very happy to see such a simple valve on the market. For years I was running a forge valve with a blue spring and two shims. It gave me a shimless problem, which also gave me a red shim problem. It was a 75% mark with 2 shims.

With Cobb XLE, you keep all the boosts during the shift and at its loud volume. In other words, people know that they are boosting. Also, it doesn’t sound like a couple of ninjas fighting a sword under the hood like Forge.

Note the valves that require grease. Be especially careful if you are running hybrid mode or if your car is in a damp place such as rain or snow. This will decompose the grease in the piston.

Also, keep in mind that both Scooby and Mazda need paper gaskets. I’ve seen geniuses trying to make straight O-rings, but unless the flanges are 100% horizontal, boosts can leak without gaskets. So use the gasket person … it is reusable and is necessary for our application to prevent this valve from leaking.

Thanks to Gary Sheehan for accidentally putting this in the box when we delivered Cobb FMIC V2.0 to us.