2015 Subaru WRX, Turbosmart blow off valve and other goodies

2015 Subaru WRX 2015 Subaru WRX at PREracing

2015 Subaru WRX Turbo - 2.0L DIT

Today we will be:

  • Fitting Turbosmart Kompact Dual Port blow off valve
  • Fitting LED low beam conversion
  • Fitting Nameless rear muffler delete pipes

First impression:

We haven’t seen a whole lot of these cars through the shop to this point but expect to see many in the months to come. That being said it was a great opportunity to see what fits and get ideas for future product development through our partner company RalliTEK.

Fitting the Turbosmart Kompact Dual Port blow off (bypass) valve

The installation of this valve is pretty straight forward. The factory bypass connects the hotside (pre-intercooler) charge pipe to the intake before the turbo in order to relieve excess boost pressure when you let off the throttle. The valve in the factory diverter is about the width of a pencil and frankly won’t do much but relive a small amount of pressure leaving a considerable amount inside the pipe to potentially shorten the life of the turbocharger and intercooler end tanks. Replacing this diverter with an upgraded valve from a reputable company like Turbosmart seems like a really good idea to us.

There are basically three different types of diverter valves to choose from:

  1. Full recirculation release - All the boost pressure is relieved back into the intake
  2. Full atmospheric release - All the boost pressure is relieved into the atmosphere
  3. Hybrid release - Part of the boost pressure is relieved back into the intake system and the remainder pressure is relieved into the atmosphere

For our demonstration today we chose the Hybrid release valve specifically the Turbosmart Kompact dual port valve.

Now on the 2015 WRX we have two different hose sizes connecting the diverter valve to the vehicles charge pipe and intake. The charge pipe size is 34mm while the intake connection is a much smaller 25mm. Previously this would have required an entire redesign of a valve to accommodate the two sizes or some kind of coupler to step one of the ports to the proper size. Fortunately the fine folks over at Turbosmart engineered their Kompact valves to accept a variety of hose connections allowing us to use a 34mm for the boost side and 25mm for the relief side. This is not a standard configuration and will require you to purchase the 34mm valve then buy the 25mm port separately, at least until Turbosmart reads this and packages them together.

The only other part we needed to complete this installation was a short length of high quality silicon vacuum line as the stock line was about a half inch too short for the new valve. After cutting the new line to length we were ready to install.

2015 WRX BOV Vac LineTurbosmart Dual Port Kompact Blow Off Valve

2015 WRX Stock Diverter Valve
The installation was pretty straight forward and starts with removing the factory plastic under tray from the vehicle. This is easy to accomplish with a 12mm ratchet and a pair of nice body clip pliers. Note we did not need to remove the secondary metal tray from the vehicle. Once the tray was removed we removed the softer plastic intake pipe that connects the intake system to the turbocharger. We then removed the two 10mm bolts that connect the turbo inlet from the turbocharger. This piece features a rubber ‘O’ ring seal so there is no need to replace any gaskets after re-installation. We removed the spring clamp that connects the inlet to the valve as well as the connector for the wastegate control solenoid and two other breather hoses from the inlet and removed it from the car. The next step was to remove the worm clamp and vacuum line from the factory bypass valve and remove it from the car. The bottom hose connection is a very snug fit so some wiggling was required to get the valve out.

Once out we confirmed the port sizes with our Turbosmart valve and everything looked good. Again, the boost port connection was a very tight fit, even more so on the Turbosmart valve due to the nice rib they machine into the port to keep it from slipping off under boost. A little silicon spray and some elbow grease and the valve was installed into the boost pipe. Now we replaced the factory vacuum line with our longer silicon line and began re-assembly in reverse order. All-in-all a very straight forward install that took about 30 min on a lift but would probably take a little longer in your driveway.

Stock 2015 WRX BOV vs Turbosmart Kompact2015 WRX Turbosmart BOV Install 2015 WRX Turbosmart BOV Install 2015 WRX Turbosmart BOV Install 2015 WRX Turbosmart BOV Install

Fitting LED conversion headlamp

LED conversion headlamps are a fairly new addition to the automotive marketplace. The customer supplied this conversion kit and unfortunately we did not catch the brand but these were the type that feature a driver box as well as a cooling fan. The issue with LED headlamps is the heat they produce in order to illuminate to the required brightness of automotive headlamps generates a very large amount of heat. LED’s being a diode are fairly heat sensitive so elaborate heat management solutions were required to make them work long term. Some kits we’ve seen (demonstrated at the 2014 SEMA show) had large heat syncs while others had a fan setup like these. The ones with the fan usually featured a driver box which likely just separates the current to power both the LED and the fan properly.

For probably the first time ever Subaru gave us room to work around the headlights. Go Subaru! This made the installation of these lights a breeze. For sake of ease we loosened the bolts around the intake air box and the batter tie down which gave even more access to the backs of the low beam projectors. After that these lights were as easy to install as any other bulb, just remove, replace, plug in and go. The driver box we mounted to the back of the headlight housing using some 3m adhesive tape and alcohol wipes to prep the surface.

As you can see light output is significantly more in the white spectrum. Passenger side is LED, driver is factory halogen.

2015 WRX LED Headlamp Installation 2015 WRX LED Headlamp Comparison

Fitting Nameless rear muffler delete pipes
As always, Nameless Performance has brought to the market a set of very nice muffler delete pipes. Installation was extremely straight forward, just unbolt the old mufflers, remove from hangers, and install new pipes with supplied gaskets. Done!

2015 WRX Nameless Muffler Deletes

Final Thoughts

What we have is minor improvements to an already great platform. Better vision with LED lightning, better sound with muffler deletes, and a diverter valve that actually diverts! Can’t wait to hopefully get this customer in for some custom dyno tuning in the future.

Established in 1998, PREracing specializes in forced induction systems and operates with the goal to provide extreme performance at a reasonable price. PREracing features a service shop, showroom, AWD dyno with full tuning capabilities, and a warehouse packed with inventory.


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