The signature rumble of the Subaru boxer engine, whether it has equal or unequal-length headers, is one of the most recognizable exhaust notes in the world. For some, it’s enough reason to buy their Subaru in the first place. For John Proulx, however, it wasn’t good enough. He yearned for that shrieking churn of double-digit cylinders, but he wasn’t ready to give up a coveted WRX STi Hatchback. We understand the sentiment.
Engine-swapped Subarus are not an entirely new endeavor for Proulx. Before he had this 2009 hatch, he 2JZ-swapped a previous WRX and made it rear-wheel drive. Looking for a bigger challenge than that, he soon after purchased the 2009 STi hatchback you see on these pages, and set it up with an all-wheel drive 2JZ setup. Looking once again to take it a step even further, Proulx proceeded to lose his mind, and acquire a 1GZ-FE V12 from a Toyota Century, and a BMW DCT on the same day. It was time to get creative.
With a pair of JZ Subarus under his belt, he had a basic idea of where to start - but with an engine twice the size, there would be some differences. He was going to need an ECU that could control 12 injectors, 12 coil packs, two drive-by-wire throttle bodies, sensors, and also manage the BMW 7-speed DCT he intended to mate to the Toyota V12. MaxxECU’s Pro standalone was the perfect fit. He was also starting to think about a twin-turbo version of the 1GZ.
Over the next eight months, he would dedicate time to making the complicated swap perfect. Custom engine mounts, transmission mounts, and hand made intake manifolds were made, and then Proulx spent time making his own harnesses and wiring to connect the MaxxECU Pro to the drivetrain, and then to the OEM Subaru cluster. He didn’t want this to be another hacked together engine swap with a gutted interior built for internet points - it had to be prim and proper down to every last detail.
Before he had even finished assembly, Proulx knew he wanted to turbocharge the V12 with a set of twin turbos. A pair of Pulsar’s 5855G turbos would be perfect for the job, and he would keep them pushing low boost - just 4 psi to keep the V12’s skinny stock rods in one piece. From there, he hand built two turbo manifolds as equal length as possible to preserve the V12 sound that brought him to this point in the first place, finished with chrome quad-tips and a fun little option in the form of electronic bypass valves for when he re- ally wants to sound like a ‘90s F1 car.
Once the engine and BMW DCT were tuned in harmony, the V12 was putting 450 horsepower and 455 lb-ft of torque to the rear wheels. Output from the V12 travels through BMW's DCT - a transmission known to hold considerable power in stock form - into the custom driveshaft, which rotates a Ford 8.8 IRS rear diff with 3.08 gearing and an Eaton TrueTrac, and custom axles. Due to the nature of the V12, and Proulx’s proclivity for burnouts, this Subaru would remain rear-wheel drive.
Continuing his efforts to keep this build clean and proper despite its wild nature, he turned his attention to the STi’s exterior. Bentley’s Eclipse Gray Metallic paint serves as the baseline for its simplified and sleek style, with blacked out headlight housings, a metallic black front grille, custom front lip and diffusers, and tinted tail lights adding some subtle yet aggressive flair. The black and gray Toyota badges in the front and rear are the icing on the cake.
At ground level, the wheel and tire package seemingly gives away the game. You can’t look at a set of 15-inch Weld wheels wrapped in 275-wide Mickey Thompson ET Street slicks in the rear and assume the car is all for show. Up front, the same wheels - finished in the same gloss black as the rear - appear in an 18-inch variant, wrapped in Zeknova tires. The meaty, tell-tale rear, as well as the front setup, meet the body of the car with good fitment thanks to custom X1 coilovers from Cygnus Performance.
For the time being, Proulx spends his days with the V12 STi cruising the streets of eastern Ontario, Canada. While it’s already one of the cleanest and most impressive swaps we’ve seen in a Subaru of any kind, he tells us he does have intentions to fully build the internals of the 1GZ and turn the boost up, with power aspirations in the four-digit range. In the meantime, he’s already got another weird engine- swapped Subaru in the works. He sold another 2JZ-swapped one and started a Coyote-swapped version during the time this was written!
Photography by Jag Imaging
Full photo gallery after spec list.
ESSENTIALS
LOCATION › Vankleek Hill, ON
ENGINE › Toyota 1GZ-FE 5.0L V12
HORSEPOWER › 450 whp
TORQUE › 455 lb-ft
SOCIAL MEDIA
IG: @1lowrx
ENGINE
Toyota 5.0L V12 engine swap
Pulsar 5855G turbos
MaxxECU Pro standalone
Fuelab fuel pressure regulator
Velocity turbo blankets
EXHAUST
Custom 3-inch 304 stainless steel dual exhaust
Dual resonators
Custom X-Pipe
Dual mufflers
Polished quad tips
Electronic by-pass valves
DRIVETRAIN
BMW DCT E9X 7-speed transmission w/ custom adapter
STI A-Line paddle shifters
Clutch-by-wire clutch pedal
Custom driveshaft
Ford 8.8 IRS rear differential w/ 3.08 gear
Eaton Trutrac LSD
Custom axles
WHEELS / TIRES / BRAKES
Welds S71 RTS wheels - 18x9 (f), 15x9 (r)
Zeknova front tires - 265/35/18
Mickey Thompson ET Street rear tires - 275/50/15
WRX rear calipers
STI Brembos
CHASSIS / SUSPENSION
Cygnus Performance custom X1 Coilovers
SPL outer tie rods
Whiteline braces
EXTERIOR
Toyota badge swap
Bentley Eclipse gray metallic paint
Tinted (windows, tail lights)
Custom (front lip, rear diffuser)
Blacked out HID headlights
LED fog lights
Metallic black front grille
SPONSORS
DNA Driftshop
LP Custom Fab
Weld Racing Wheels
Capital Auto Parts
Ottawa Driveshafts
A2B Distribution
Collins Performance Technologies
Cygnus Performance
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