Tomioka Racing TD05-20G Ball Bearing Billet Turbocharger — 2002-2007 Subaru WRX / 2004-2021 STI
The Tomioka Racing TD05-20G Dual Ceramic Ball Bearing Billet for the 2002-2007 Subaru WRX and 2004-2021 STI transforms the most popular EJ turbo upgrade with dual ceramic ball bearings and a billet compressor wheel. The result is factory-like spool time with 480 HP capacity — this TD05-20G spools close to a factory turbo with the right tune while providing the daily-drivable character the TD05 frame is known for.
DETAILS
- Platform: 2002-2007 Subaru WRX EJ20/EJ255 and 2004-2021 STI EJ207/EJ257
- Dual ceramic ball bearing CHRA — significantly faster spool than journal bearing
- Billet compressor wheel
- Compressor: 52.5 mm inlet / 68 mm exducer (billet)
- Turbine: 56 mm inlet / 49.2 mm exducer
- Turbine housing: 8 cm²
- Actuator: 1.1 bar / 16 psi (optional 1.3 bar)
- Max. power: 480 HP
- Same seamless bolt-on fitment as TD05-20G predecessor
| Bearing Type | Dual ceramic ball bearing |
|---|---|
| Flange Type | Standard Subaru 5-bolt |
| Compressor Inlet | 52.5 mm (billet) |
| Compressor Exducer | 68 mm |
| Turbine Inlet | 56 mm |
| Turbine Exducer | 49.2 mm |
| Turbine Housing | 8 cm² |
| Actuator / Gate Pressure | 1.1 bar / 16 psi (optional 1.3 bar) |
| Max. Power | 480 HP |
Turbocharger Design and Specifications
A ball bearing turbocharger replaces oil-film journal bearings with angular contact ceramic ball bearings. Ceramic ball bearings operate with significantly less friction — reduced friction is the mechanism behind faster spool time. With less energy required to spin the shaft from zero speed, boost builds sooner in the RPM range. Dual Ceramic Ball Bearing (DCBB) designs use two separate bearing assemblies for additional support and reduced deflection under high load. Ball bearing turbos also require less oil flow than journal bearing units, reducing heat input to the oil and the risk of oil coking during hot shutdowns.
Installation, Kit Contents, and Wastegate Spring Guide
Each Tomioka Racing turbocharger kit includes all hardware needed for the installation: the turbocharger unit, wastegate actuator, oil feed and return pipes, water cooling connections, all gaskets, and the hardware kit. All current production TR turbos include a billet wastegate actuator. Professional installation is recommended for turbocharger swaps — the oil feed and return line routing, water cooling connections, and boost line setup all require attention to detail for correct long-term function. For DCBB turbos, a Turbosmart TS-0811-0012 OPR V2 Turbo Oil Pressure Regulator is recommended to ensure correct oil pressure at the bearing unless otherwise noted.
Wastegate Spring Selection: 1.1 bar vs 1.3 bar
The actuator spring sets the gate pressure — the minimum boost the turbocharger will produce. You cannot run boost lower than the spring rating regardless of ECU or boost controller settings.
Choose 1.1 bar (16 psi) if your boost targets include values below approximately 22 psi, or if you run multiple boost maps including a low-boost street mode. The 1.1 bar spring provides good boost controller authority across a wide operating range.
Choose 1.3 bar (19 psi) if your minimum target boost is 19 psi or higher and your normal target is in the 22-28 psi range. The 1.3 bar spring provides better control stability at higher boost targets and better resistance to premature wastegate opening under high exhaust backpressure conditions.
As a general guideline, peak target boost should not exceed approximately 2x the gate pressure for stable boost control authority from the solenoid.
What’s in the Box
- Turbocharger
- Gaskets
- Hardware kit
Why Choose Tomioka Racing (TR)
Tomioka Racing has been building direct-fit turbocharger upgrades for Subaru performance vehicles since the early 2000s. Every TR turbocharger is engineered around the factory connection points — oil feed, water cooling, mounting flange, and charge pipe inlet all match OEM positions — so installation is genuine bolt-on without custom fabrication. TR covers the full span of EJ-series and FA-series Subaru platforms, from the GC8 through the current VB WRX, and their turbochargers are proven in both street and motorsport use including rally racing. Each kit ships complete with turbocharger, actuator, oil pipe, water pipe, gaskets, and hardware — everything needed for the swap in one box. RallySport Direct stocks the full TR turbocharger catalog because their engineering quality and fitment accuracy are what our customers expect.
The RallySport Take
The TR TD05-20G DCBB breaks the slow-spooling TD05-20G reputation entirely. Dual ceramic ball bearings provide genuine fast spool while the billet compressor wheel provides the efficiency for 480 HP — with the TD05-20G’s daily-drivable street character intact. For GD WRX and STI owners who want the TD05-20G’s character with ball bearing spool speed, this is the definitive version.
Fitment
| Year | Make | Model | Notes |
|---|---|---|---|
| 2002-2007 | Subaru | WRX | EJ20/EJ255 MT |
| 2004-2021 | Subaru | WRX STI | EJ207/EJ257 MT |
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