SKU: K721-EAP
Clutch Masters Engine Adapter Plate for Honda K-Series (2002-2011) to Subaru STI 6-Speed Transmission (2004-2021)
This adapter plate mates Honda K20 and K24 engines to Subaru STI 6-speed transmissions for smooth power delivery in performance swaps. Built with a 1-inch thick precision-machined plate, it supports single and twin-disc clutches in Subaru Impreza WRX STI and compatible models. Ideal for street and track builds demanding durability and precise alignment.
Key Features
- 1-Inch Thick Adapter Plate: Ensures rigid alignment between Honda K-Series engine and Subaru STI transmission, handling high torque without flex.
- High-Horsepower Compatibility: Works with single-disc flywheels (FW-K721-SF) and twin-disc (FW-K915-SF) for power levels from stock to extreme.
- Bolt-On Precision: Designed for K20/K24 engines and TY856-series STI 6-speed, includes all hardware for direct fitment.
- Starter Cover Plate Included: Allows factory Honda starter use with RWD K-Series harness, simplifying wiring on Subaru chassis.
- Hi-Leverage Design: Boosts clamping force while keeping pedal effort low, protecting thrust bearings in demanding applications.
Product Notes
- Angles Honda K engine at factory 11-degree tilt for correct Subaru alignment.
- Verify STI transmission is TY856 series using model year and VIN.
- Ships in protective packaging to prevent damage during transit.
Installation Notes
- Professional installation recommended.
- Requires compatible Subaru STI 6-speed transmission and Honda K-Series bellhousing pattern.
- Includes full hardware kit with bolts for secure mounting. no additional parts needed.
This Part Fits
| Year | Make | Model | Submodel |
|---|---|---|---|
| 2004-2021 | Subaru | Impreza | WRX STI |
| 2004-2007 | Subaru | Forester | XT (STI 6-speed swap) |
| 2004-2008 | Subaru | Legacy | GT (STI 6-speed swap) |
| 2002-2011 | Honda | Civic Si | K20 (engine donor) |
| 2002-2006 | Acura | RSX | K20 (engine donor) |
| 2004-2008 | Acura | TSX | K20/K24 (engine donor) |
| 2002-2008 | Honda | CR-V | K24 (engine donor) |
| 2003-2011 | Honda | Accord | K24 (engine donor) |
| 2003-2007 | Honda | Element | K24 (engine donor) |
Why Choose Clutch Masters?
- Decades of experience in performance clutch systems for motorsport applications.
- Premium materials and machining for long-term reliability under high stress.
- Proven designs used by professional builders for K-Series to Subaru swaps.
Frequently Asked Questions
- Q: Does this fit all Subaru STI 6-speed transmissions?
A: Compatible with TY856 series from 2004-2021 Impreza WRX STI. confirm with your transmission code and VIN. - Q: What clutch kits work with this adapter?
A: Supports OE Subaru STI clutches with FW-K721-SF flywheel, or Clutch Masters FX/850 Series with FW-K915-SF twin-disc. - Q: Is custom fabrication needed for installation?
A: No, bolt-on design includes all hardware, starter cover, and uses factory Honda starter for plug-and-play setup.
Shipping & Handling
- Method: UPS Ground or FedEx
- Availability: In stock – ships same or next business day
- Packaging: Securely boxed, dimensions 14in x 14in x 4in
- Weight: 10.5 lbs
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