AVOTurboworld after much testing with the WRX 2015+ vehicles concluded that the standard turbo and manifold setup was a major restriction when wanting to increase your horsepower and torque. Once boost was increased even with an upgraded exhaust system, the back pressure caused by the small manifold runners and small turbocharger increased to a point where it caused cylinder pressures and then detonation issues. The detonation issues then led to engine failure. So we thought to do this properly that a whole turbo kit which included manifold, turbocharger, oil and water plumbing, inlet hose from airbox to turbocharger entry and intercooler hose from turbocharger compressor outlet to hot side intercooler entry would be necessary.
While designing the kit, another aim was to make the boxer sound more prominent compared to its non-existence in standard trim. This would mean designing the manifold slightly unequal 4 into 1, it was not easy to do within the confines of space that was available but it was achieved and with the standard position exhaust system still being able to be fitted. We opted for a billet turbocharger that was going to max out at about 400hp at the engine with standard compression so that it was responsive down low and also could rev to redline. We think it is a good compromise.
The other reason for the turbocharger choice was that due to probably a large proportion of the vehicles being fitted with a CVT, we did not want a laggy turbo that all of a sudden increases torque and power over 1000rpm like some and then puts major pressure on the CVT. Our billet turbocharger is very linear and delivers smoothly across the rpm range.
To make the whole package work we have come up a good ECU MAP that incorporates all the usual changes required to be modified in the standard ECU plus MAP switching with 3 different boost control set points and some nice changes to the CVT to aid in smoother and faster gear changes. This is all been achieved via ECUTEK and the expertise of AVOTurboworld’s Ross Wilson. This MAP will be available with every turbo kit at a small additional charge if you are using ECUTEK. Where the ECUTEK is purchased through AVOTurboworld the MAP will be free of charge. When using the AVO MAP and ECUTEK, you must use our 3 Port Boost Solenoid to work in connection with the standard boost valve setup.
To ensure reliability we pre-assemble the kit. It is put together with Inconel Studs and 309 Stainless Nuts to ensure heat will not affect the tightness and therefore avoid possible exhaust leaks. We also use a stainless perforated layered turbo base gasket and turbo outlet gasket. We supply and fit a short turbo outlet adaptor that goes on the back of the turbocharger. The reason for this was to allow for the fitment of the standard setup factory or aftermarket exhaust system. We understood that emission conscious places like California and Japan require the standard cat to be run in the OEM position. There were also many customers that might already have an aftermarket exhaust system and that it would be a sore point if you had to spend more money on the exhaust system.
The turbocharger is fitted with the water banjos for the factory water lines to fit straight on to. We also supply the restricted oil supply fitting for the braided oil supply line in the kit. To finish it off there is an oil drain assembly to oil reservoir tank setup to hold the excess oil before it is scavenged back into the engine via the factory oil pump at the rear of the engine.
The power and torque figures for the manual transmission and CVT were very impressive to say the least. It transforms the vehicle into a seriously fast street drivable weapon. It has been tested in Japan at Mobara Race Circuit by Subaru’s world renowned rally driver Toshi Arai. His comments getting out of the car were - “This is the way the car should be as the power is very linear all the way from down low to the rev limit.
Notes: Turbocharger Compressor Housing uses a clamp-on inlet and outlet (not 2-bolt flanges like the stock turbocharger) and removes the factory plastic housing with BOV recirculation hose port and boost solenoid. Standard and Aftermarket intake hoses and charge-pipes will require modification for fitment. Aftermarket charge-pipes that use a clamp-to-flange adaptor (Process West, Perrin, Grimmspeed etc.) can simply remove the adaptor and clamp straight to the AVO turbo outlet, however BOV may need an extension made to reconnect. This Stage 1 Turbo-Kit includes a compatible inlet-hose and charge-pipe for bolt-on fitment with stock air box.
Base Turbo Kit:
Stage 1 Additions: