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