Ever wondered if the aftermarket Blow Off Valves “BOV” really work or what can they do for your car? Well we did some testing with our 2014 Subaru STI using Turbosmart’s Subaru Dual Port BOV. Info on the car: It’s a Stage 2 STI, only mods are turbo back exhaust, Turbosmart FPR-800, and a Cobb Tuning Accessport Protuned by Snail Performance. We strapped the car on the dyno, then got everything warmed up and ready to go. We started out with the Turbosmart Subaru Dual Port BOV installed and fully tuned the car running just under 19psi of boost. After getting the tune dialed in we swapped out the Turbosmart Subaru Dual Port BOV for the factory BOV the STI comes with stock from Subaru. Now with the stock BOV installed we did some dyno pulls with the same tune and what the graph showed is pretty crazy.
This dyno graph shows the boost curve. “Solid line is the Turbosmart Subaru Dual Port BOV / the Dotted line is the Stock BOV”. As you can see the stock valve is not able to hold the higher boost pressures that the Turbosmart BOV can in the early RPM range. Turbosmart BOV peak boost is 18.6psi and the Stock BOV is 17.8psi but that is just peak boost the graph shows the real gains. Check out how much quicker the boost comes on about 150rpms over the Stock BOV.
This dyno graph shows the horsepower, torque, and boost curve. So you can see the difference in power and torque. Not being able to hit the target boost pressure with the stock BOV the STI’s torque curve is lowered by 13 lbs. So the question “does a BOV add power?” has been answered why yes it can because boost pressures aren’t lost.
So next time you are looking at a BOV and thinking it only just adds sound think again. It can actually do more than the cool blow off sounds between shifts. For more information on the Turbosmart Subaru Dual Port BOV, check out this link.
Turbosmart Subaru Dual Port
Subaru of America invited a member of Snail Performance to attend a private test drive at Laguna Seca to try out the all-new 2015 Subaru WRX STI. Of course, I “Travis” couldn’t pass up this opportunity to try out the new STI on one of the top road courses in the United States.
Myself and a few others in the automotive industry arrived at Laguna Seca around 8:00am after a quick breakfast and an informative briefing about the improvements on the new STI. We headed down stairs to check out the STI for the first time. My first impressions of the STI were way different after seeing the car in person. I was unsure if I was going to like the new redesigned STI after seeing all the pictures of it, but after seeing it in person I was really impressed with the new look.
The chassis was completely reworked to provide greater handling over the previous models by greater use of high-tensile steel, stiffening the chassis in key locations and suspension-mounting locations. The STI engineers also made some changes to the suspension, by upping the front and rear spring rates, bigger sway bars “24mm Front and 20mm Rear” and added a quicker steering rack “13.0:1”. By doing this the STI now has 16% less body roll and 67% faster steering response; able of pushing up to 0.96g of lateral acceleration.
Yes, I know a lot of you were not happy about Subaru not giving us a new engine but the EJ is still a great engine. They did however do some remapping in the ECU compared to the previous years. The throttle mapping is better than before, with a more responsive pedal in the different SI-DRIVE modes. It has a smoother, more low-end power unlike the previous year STI’s. The engine is still connected to a 6 speed manual transmission with Multi-Mode Driver Controlled Center Differential (DCCD), a helical-type limited-slip front differential and a TORSEN® torque-sensing limited-slip. The biggest add on for this year’s STI is Active Torque Vectoring. This system helps by applying brake pressure to the inside front wheel to help with cornering. Subaru also stepped it up by totally redesigning the cabin. I would have to say my favorite part of the cabin would be the new seats. When I first sat down in the new seats first thing that came to mind was “It’s about time”. The seats are very comfortable to sit in and the side bolsters really help hold you in place while driving the car on track. Next on the list of favorites would have to be the D-Shape Racing Style Steering Wheel. It fits in your hands very nicely and provides exceptional grip over other STI steering wheels. Other key items on the inside are: the new Multi-Function display with 4.3-in. LCD screen provides rear camera display, boost gauge display, audio, Bluetooth and climate control settings, VDC screen showing traction control operation and a vehicle self-check and maintenance reminder, you can get Keyless Access and Start, and new for the STI a Harman/Kardon 440-watt, 9-speaker system.
Well enough of the over view I’m sure you want to know “How did it perform on track?” Well I could just sum it up in one word for you “AWESOME!” The car is a night and day difference over the prior year STI’s. As most of you know I currently own a 2012 STI so that gave me a great base line to start from when comparing new STI. On track you can really feel the many the changes the engineers made in the chassis. It only took one turn at Laguna Seca to feel the difference. Coming down the front straight at Laguna Seca cresting over the hill in 4th gear throttle pinned to the floor doing 100+ MPH. I stepped into the brakes at the #2 brake marker; first thing I noticed is the back end of the car felt way more stable under hard braking. Down shifting into 3 gear turning into turn 2 I was waiting for the car to understeer like the STI’s in the past have always done. As I was about half way into the turn, the new STI was not understeering so I rolled back into the power to see if the STI would allow it and to my amazement I was able to apply power with no understeer. Finally an STI will turn without you wonder if you will end up off track. After a few more laps I started to push the car harder on track. The STI was very well balanced and a pleasure to drive on track so much that I noticed that I was more focused on driving the track and not having to worry about the STI being unpredictable on track. The new Torque Vectoring system really helps the turn in under power; it also allows you to get back into the power way quicker. I did drive the STI with the Torque Vectoring system off and there was a noticeable difference in the handling of the car. Not to say the Torque Vectoring system needs to be on to make the STI perform at its peak even with the system off the STI can still perform outstanding on track.
Oh yes, the part you have been waiting for, “The Corkscrew” at Laguna Seca. STI managed it like a champ. When you come up the hill in 4th gear to turn 7, the car gets a little light as the suspension is unspun at this point as you come over the “Little Kink”. Just after the kink is where I got into the brakes hard and the ABS system got a little bit of a work out here but performed flawlessly. Downshifting into 3rd gear turning into The Corkscrew holding on for dear life but as soon as you see the bottom of The Corkscrew I can roll right back into the power and enjoy the ride down.
Overall impressions of the new 2015 Subaru WRX STI: I love it; the STI engineers did a great job. The Snail Performance family should have the new 2015 Subaru WRX STI in their hands very soon as we have already place an order for one. Big thanks to everyone at Subaru of America for the invite to test drive the new STI at Laguna Seca, it was a blast. Lastly, if you haven’t driven Laguna Seca you need to add it to your list of tracks to drive.