I had a chance to finally tune one of our GT52 turbochargers on a 2006 STI. This turbocharger is very similar to many other 7cm TD06 20G framed bolt-ons but that’s where the comparison ends. In this particular turbocharger we are using a Garrett compressor and turbine wheels plus extensively ported housings. The compressor is a GT30R rated at 52 lbs utilizes an internal wastegate.
Engine is OEM 2006 STI
Element Hydra EMS
Element GT52 Bolt-on Turbocharger Internal WG
Element Fuel Surge Tank
Aeromotive A1000 fuel pump
TurboSmart E-Boost 2
TurboSmart Megasonic BOV
Clutch Master’s STG4 Clutch
1000cc Low Impedance Fuel injectors
BDL Fuel Rails
Ported TGV Housings
TBE (2.5” axle section)
The biggest hurdle I ran into was the silicone inlet pipe. It just kept collapsing but it was old and maybe past it’s prime. Pulling the air filter and various plugs on the intake didn’t help so I removed the intake system completely. Since we are using the Element Hydra EMS this didn’t present a problem. Once we had all the issues ironed out the first clean pull on pump gas with the Hydramist water/meth injection kit netted 400 whp. I turned up the boost more and more until we started to max out with the boost level. I was tired at this point and really didn’t want to try and preload the internal WG more on a hot turbocharger so boost would drop to 21 psi absolute. I could raise the torque by increasing boost but it would always drop down around peak power. I did what I could with fuel and spark tuning to net a peak power of 436 whp. Ideally I would have much preferred to up boost a couple more pounds which should have put this setup in the 450-460 whp range but this just wasn’t going to happen on the dyno. In the real world I had no problems holding 23 psi due to the higher loads generated.
All in all this is a pretty awesome setup for a bolt-on turbocharger with 20 psi peaking as early as 3600 rpm (on the dyno a little longer) without boost creep. No doubt an external wastegate setup would have allowed me to hold boost on the dyno but in the real world this just wasn’t an issue. The power delivery is fantastic for road racing as it allows great straight away power but more importantly you can short shift the car in technical sections and just let the torque pull you through where easily metered power is faster.