With the arrival of the new APS SS42 and SS45 turbo, we knew it was a matter of time until we put one on the 2008 STi we have here to see what this turbo could do.
The APS SS45 turbo is a 45lb wheel in a TD06 20G 8cm^3 housing. It is pretty much the largest 20G. Now, on to the car,
2008 STi 17000 Miles
APS Bypass Valve
Invidia V3 Catless Down Pipe
HKS Legamax Jasma Legal cat back (65mm, 2.55″).
HKS Racing Suction intake
Samco IC hose kit
HOA Boost control Solenoid
Cobb Tuning Access Port
Cobb Tuning Pro-Tune. Thanks John
Temps: mid 50’s
Fuel: Utah winter 91 Octane (10% alcohol). Worst gas EVER!
The comparison you see is of a Stage 2 2008 STi (new calibration of the Mustang Dyno at Cobb tuning is ruthless. Putting a Stage 2 2008 STi’s at 250WHP), talk about a heart breaker . But we all know, it’s not about the HP numbers, it’s about the before and after comparison.
First and foremost, this turbo needs AIR! We tried to see what the car could do with a stock air intake box and a drop-in filter. The numbers were a bit disappointing to say the least. It was apparent that we needed to free up the flow going in and out so we decided to put on a HKS Racing Intake and the results were impressive!
After doing the re-tune for the intake, we ran into another problem. The 65mm cat-back on the car started backing up the motor in the higher RPM (past 6K), not allowing us to run more than 18 degrees of timing. The boost is set at 22PSI tapering to 17psi by redline. This gives it a safe and conservative tune as well as make the car easier to drive at the road course. So next up will be a 3″ cat back and the power should jump up another 15-20WHP! Then add a larger TMIC and another 10WHP or so will be had
As you can see, the turbo is spooling up relativity fast compared to other 20G turbo chargers. The power delivery is very smooth, and the car drives similar to stock around town. The biggest difference was noticed after 4000RPM, the car now pulls ALL the way to redline, which is something the stock VF48 could never do. If you noticed, the power and torque is up from stock everywhere past 3600RPM.
Overall impression: This is a great turbo for anyone looking to get more power out of their car without stressing out the motor. The powerband is very smooth and consistent, giving you solid power from 3500RPM all the way to redline.
To sum this all up, the power jumped 50WHP and 50WTQ by just bolting on the turbo, and injectors on top of a Stage 2 car. Not bad.