* Engine Bay Compatibility: The V6 engine's dimensions and mounting points are significantly different from any 4-cylinder Toyota engine that would reasonably fit. You'd likely need to extensively modify the engine bay, firewall, and potentially even the frame.
* Transmission Compatibility: The V6 likely uses a transmission not designed for a 4-cylinder engine. You'd need a compatible transmission, driveshaft, and potentially even the rear differential depending on the gear ratios.
* Wiring Harness and Electronics: The wiring harness and computer system are specific to the V6 engine. Adapting it to a 4-cylinder engine would be incredibly difficult and require significant rewiring and potentially a new ECU (Engine Control Unit).
* Fuel System: The fuel system (fuel pump, lines, injectors) is designed for the V6. Adapting it to a 4-cylinder would require substantial modifications.
* Exhaust System: A completely new exhaust system would be needed.
* Cooling System: The cooling system might need modifications to accommodate the different engine size and heat output.
* Brakes and Suspension: While not directly related to the engine swap, the lighter 4-cylinder engine might require adjustments to the braking and suspension systems for optimal performance and handling.
* Cost and Labor: The cost of parts, labor, and specialized tools would likely exceed the value of the truck, especially considering the extensive fabrication involved.
In short: While theoretically possible, converting a Toyota V6 pickup to a 4-cylinder is a massive undertaking requiring significant mechanical expertise, specialized tools, and a substantial investment of time and money. It's far more practical and cost-effective to either keep the V6 or find a 4-cylinder Toyota pickup if fuel economy is a primary concern.
