2 weeks ago we took some time to do a quick test on a 2015 Subaru STi that client brought to us wanting to extract more power from it. We were very curious to have first hand information regarding the new 2015 STi as we have seen a lot of stuff posted online but it is much easier to validate directly. Having driven a few 2015’s the car feels significantly faster out of the box then any previous generation STi that I have driven from 2004-2014. With that in mind we spent our own time to do this testing so that we could provide this information to all of you. We first put the car on the dyno 100% stock and did 3-4 pulls to check for consistency. After the first pull we were pretty floored by the numbers, the car made 269 Peak HP and 272 Peak Torque. This is about 40 HP more then we saw previously on a stock 2010 STi that we dyno’d. The peak numbers were quite good but as you can see in the plot the power is not smooth and the boost was very wavy as well. This can be felt while driving the vehicle and is something we’ve become accustom to with stock Subaru tunes. The most likely reason for the power increase is a slightly larger turbo and/or the tuning strategy used.
We then reflashed the car with the latest COBB APV3 stage 1 91 octane map. The reason it was done on the 91 octane map was to confirm safety and the owner of the vehicle was flying and we could not get confirmation if he had filled the car with the 94 octane we had requested. When the customer arrived we did find out that the car was filled with 94 octane so we may have gotten a bit more HP from the stage 1 dyno but we were mainly looking to see the differences between the different setups. With the stage 1 map loaded we did multiple pulls and ended up with around 317 Peak Torque and 255 Peak Horsepower. So we gained a huge chunk of torque but the COBB map is actually more conservative up top and makes less horsepower. You can also see that the low end power band has been smoothed out over the stock map.
Once we completed the above testing we were quite curious to see how much power could be safely extracted from this 2015 STi with the upgrades planned. We rolled the car over to our lift and proceeded to change out parts. We installed an Invidia Catted Downpipe, Invidia Q300 Cat-Back, AEM Intake and Grimmspeed 3-Port EBCS. This is essentially a Stage 2+ Setup with the addition of the EBCS for precise boost control. Once complete we rolled the car back and let Sasha at OnPoint do his thing for a few hours tuning the car. As always Sasha did a phenomial job tuning the car and the graph speaks for itself. Target boost was set to 18.5-19PSI and when it was all said and done the car made 310WHP and about 345WTQ. There’s probably a bit more power left on the table but when we started getting to 350WTQ we decided to call it a day since the car only has around 5000KM on the clock. For comparisons sake, we did a 2013 STi earlier this year with an SF Intake, turbo-back and 3-port BCS and it made 295 Peak HP and 330 Peak Torque. Something else to note is how much lower the boost threshold is with the turbo-back and intake installed. It looks like it takes about 300rpm less to reach the same amount of boost compared to stock. Overall we’re very impressed by the new 2015 STi, out of the box it is a great car but there’s still power left on the table while maintaining a good margin of safety as well.
Event: Dyno
Location: Touge Tuning, Mississauga Ontario
Ambient Temp:
Elevation: 249 ft.
Weather:
Car: 2015 Subaru STi
Tuner: Sasha from OnPoint Dyno
Dyno Info: Dynapack
Transmission: Stock 6 speed
Gear: 4th
Peak HP at RPM: 310@ 5350RPM – SAE J1349 (2004) Corrected
Peak Torque at RPM: 345 @ 3700RPM – SAE J1349 (2004) Corrected
Baseline HP/TQ for Stock 2015 STi on same dyno: 269WHP/272WTQ
Target Boost: 18.5PSI Tapering
Fuel: 94 Octane – Petro
Mod List
-Invidia Catted Downpipe
-Invidia Q300 Cat-Back
-AEM Cold Air Intake
-Grimmspeed 3-Port EBCS
