The Mk1 Golf 1.8T swap is a popular conversion for enthusiasts seeking a significant performance boost. This guide provides a detailed overview of the process, covering key components and considerations for a successful engine transplant. While this swap requires mechanical knowledge and specialized tools, understanding the fundamentals will help you navigate the project with confidence.
Engine Selection and Preparation
The most common engine choice for a Mk1 1.8T swap is the transversely mounted AGU code engine found in the Audi A3 and Mk4 Golf. This simplifies the conversion process significantly compared to using a longitudinally mounted engine. Aim for a low-mileage engine with documented service history for reliability. The stock AGU features a K03 turbocharger, producing 150bhp in its factory configuration.
Gearbox and Drivetrain
Utilizing the standard 020 gearbox from the Mk1 GTI simplifies the drivetrain setup. Source a complete clutch and flywheel assembly from any 020 equipped 5-speed vehicle, ensuring compatibility with the gearbox input shaft splines. Replace the dual-mass flywheel from the 1.8T with the single-mass 020 unit. You can typically retain the stock driveshafts, with both 90mm and 100mm options being viable.
Engine Mounts and Placement
The gearbox side engine mount can be retained from the GTI, but upgrading to a polyurethane rear mount is recommended for improved stability. The cambelt side mount requires a custom fabricated or adapted solution available from various suppliers specializing in VW conversions. You’ll also need a 16v cambelt tensioner and an 8mm spacer to ensure proper belt alignment. This is an ideal time to replace the water pump and timing belt.
Fuel System Modifications
Minor adjustments to the fuel lines are necessary. Carefully bend the existing fuel lines towards the driver’s side and trim them to the appropriate length. Select a compatible fuel filter for integration into the modified fuel system.
Auxiliary Components
The power steering pump can be eliminated for this conversion. A shorter alternator belt is required (specific part number can be researched). The standard Mk1 GTI starter motor is sufficient for cranking the 1.8T engine.
Gear Linkage Adjustment
The shift linkage may interfere with the turbo actuator. Bend the linkage downwards to provide clearance, a task often easier performed with the linkage removed from the vehicle.
Cooling System Considerations
Install a Mk2 16v radiator and fan assembly due to its smaller dimensions, positioning it on the left side. A Renault Laguna upper radiator hose and a Mk2 Golf lower hose are often suitable replacements. Heater hoses may require trimming for optimal fitment without interfering with the turbocharger or other components.
Intercooler Installation
A custom intercooler sourced online is a common solution. Ensure it fits between the grille and radiator, with the outlet and inlet positioned for easy connection of piping. Use high-quality clamps to secure boost hoses and prevent leaks.
Engine Management
Various aftermarket engine management systems are available to control the 1.8T engine in the Mk1 chassis. Popular options include Megasquirt, Emerald, and DTA. Select a system that aligns with your budget and technical capabilities. Most systems include detailed wiring instructions for integration with the Mk1 wiring harness.
Exhaust System
Aftermarket downpipes designed for this swap are available, often requiring a sleeve to adapt to the Mk1 exhaust system.
Conclusion
The Mk1 1.8T swap is a challenging yet rewarding project, transforming the driving experience of this classic hatchback. Careful planning, research, and attention to detail are crucial for success. Consult online forums and communities dedicated to VW modifications for additional support and guidance. This guide provides a solid foundation for embarking on your Mk1 1.8T conversion.
