Unlocking 1030WHP From An EJ25 | Subaru STI Drag/Street Build [TECH TOUR] - Featured Image

Running 1030WHP at 42 PSI via an Extreme Turbo Systems prepared Precision Turbo & Engine 7675 turbocharger, IAG Performance Stage 4 block, GSC Power-Division cams, and valve springs, Headgames Motorworks ported head just to name a few things, the English Racing built 2013 STI of Brandon Huntley (@scrappysti_115 on Instagram) is one very well setup Subaru WRX.

The Manley rod, pistons and crank fitted EJ25 head cylinder sealing is done via an MLS gasket with stainless steel o-rings to give greater clamping force along with oversized 14mm ARP head studs to seal the deal and a Boomba Racing 74mm DBW throttle body and Process West machined intake manifold sits on the top. A Magnus Engineering dry sump kit with Peterson pump has been fitted to make sure bearing life is not an issue.

M1 Racing Methanol fuel is fed to the EJ via 8 Injector Dynamics ID2000 injectors and all of this is controlled via a Motec Systems USA M1 with a John Reed Racing package that allows the car to retain all the factory dash and steering wheel button functions including cruise control, as well as monitoring fuel, oil, and coolant pressures to adjust to the conditions the car is running in and maintain reliability.

One of the last pieces of the puzzle is getting power to the ground, and this is done with a PPG dog engagement gear set that sees 1st to 4th replaced but retained the factory 5th and 6th gear for street use. The H pattern box is fitted with a strain gauge for clutchless shifting, Exedy triple plate clutch, and Driveshaft Shop axles and shafts along with Torque solution engine transmission and suspension components have been fitted to handle the increased output.

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Comments
  • 's profile image
    I have a stock 1993 2.2L Subaru EJ22T (Turbo motor) that I am trying to convert to DBW for an Engine swap.

    The factory throttle body is about 62mm ID.

    After doing some preliminary calculations, it seems like a 44-46mm Bosch DBW Throttle Body ought to be plenty big to support the factory 165HP. Why does the factory use such a large throttle body (2.5"/62mm)? That seems huge for the lowly 165HP that the engine puts out. Do I really need a 62mm DBW Throttle Body?

    I am upgrading everything because the factory ECU won't work with my engine swap. My engine is almost totally stock at this point. I am using a Haltech R5 ECM. I am running the factory turbo. I have added AEM smart coils, Iridium spark plugs, and MSD plug wires to be driven by the Haltech R5 ECM. I want to stay under 200HP. Nothing wild.

    I really need help calculating the correct size DBW Throttle Body for this swap and ECM conversion. I am just not confident with all the different calculations and formulas I have seen online. Any help with formulas and calculations, with references/links, would be very much appreciated.
    - Climer97007 USA
    10 months ago