* Engine Code: The 2003 GS likely has the 2.4L 4G64 engine, while the 2006 GT has a 2.4L 4G69 engine. These engines, while similar in displacement, have different internal components, mounting points, and potentially different electronic control systems.
* Transmission Compatibility: The 2006 GT may have a different transmission than the 2003 GS. The engine and transmission need to be compatible for proper operation.
* Wiring and Electronics: The wiring harnesses, sensors, and ECU (engine control unit) may be incompatible between the two years and engine types.
* Exhaust System: The exhaust manifolds and the rest of the exhaust system could be different, requiring modifications or a complete replacement.
The Challenge of Swapping Engines:
While not impossible, swapping engines is a major project that involves:
* Extensive Modifications: You'll likely need to modify the engine mounts, exhaust system, wiring harness, and potentially the transmission to make the new engine fit.
* Specialized Knowledge: This project requires a deep understanding of engine mechanics, electrical systems, and fabrication techniques.
* Potential for Complications: Swapping engines can lead to unexpected problems, especially if you're not experienced with the process.
Alternatives to Swapping:
* Engine Rebuild: Consider rebuilding your existing 2.4L 4G64 engine. This could be a more cost-effective option, especially if the engine has minor issues.
* Used Engine Replacement: Find a used 2.4L 4G64 engine from a similar year Eclipse. This might be a better choice if the original engine is beyond repair.
* Performance Upgrades: Instead of swapping the entire engine, consider performance upgrades for your existing engine. These upgrades could give you the power you desire without the complexity of a swap.
Before making any decisions, it's crucial to consult with a qualified mechanic to assess your options and determine the best course of action.
