Description

Forged turbo

The BP-4W engine is a well-known engine among enthusiasts, particularly for those who are into the Mazda MX-5 (Miata). It’s a 1.8-liter DOHC inline-four engine that was used in various Mazda models, including the NB-series MX-5 Miata (1999-2000). The “BP-4W” specifically refers to the engine with a revised head design, known for its improved airflow compared to earlier versions.

Forged Turbo Build for BP-4W Engine

1. Forged Internal Components:

• Pistons: Upgrading to forged pistons is crucial when increasing boost levels. Forged pistons are stronger and better at handling the higher pressures and temperatures that come with turbocharging.
• Connecting Rods: Along with pistons, forged rods are recommended to prevent bending or breaking under increased power.
• Crankshaft: The stock crankshaft is usually robust enough, but if you’re aiming for very high power, a forged crankshaft might be worth considering.

2. Turbocharger Setup:

• Turbo Selection: Choosing the right turbo is critical. Common choices include Garrett GT series, BorgWarner, or Precision turbos, depending on the desired power output and response characteristics.
• Exhaust Manifold: A custom or aftermarket exhaust manifold designed for turbo applications will be necessary. It needs to be matched with the turbo for optimal performance.
• Intercooler: A front-mount intercooler (FMIC) is typically used to cool the intake charge, which is essential for a turbocharged engine to avoid knocking.

3. Fuel System Upgrades:

• Injectors: Larger fuel injectors are necessary to provide the increased fuel demand.
• Fuel Pump: An upgraded fuel pump is also required to ensure consistent fuel delivery under high boost.
• Fuel Pressure Regulator: An adjustable fuel pressure regulator might be needed to fine-tune the fuel delivery.

4. Engine Management:

• ECU Tuning: Proper tuning is critical for a turbocharged engine. An aftermarket or standalone ECU (like Megasquirt or Haltech) allows for precise control of fuel, ignition timing, and boost levels.
• Boost Control: An electronic boost controller allows for more precise management of boost levels, potentially offering different boost settings for various driving conditions.

5. Cooling Upgrades:

• Radiator: A high-performance radiator helps keep engine temperatures in check.
• Oil Cooler: An oil cooler is often recommended to help manage the increased heat generated by a turbocharged engine.

6. Exhaust System:

• Downpipe: A custom downpipe that matches the turbo setup is necessary. A larger diameter is typically recommended for better exhaust flow.
• Exhaust: A free-flowing exhaust system with a larger diameter (e.g., 2.5″ or 3″) helps reduce backpressure and allows the turbo to spool faster.

7. Drivetrain Upgrades:

• Clutch: An upgraded clutch that can handle the increased torque is essential.
• Transmission: Depending on power goals, the stock transmission may need reinforcement or replacement.

8. Safety and Monitoring:

• Boost Gauge: A boost gauge allows you to monitor the turbo’s boost pressure.
• Wideband O2 Sensor: Monitoring air-fuel ratios (AFRs) is critical to ensure the engine is running safely.
• Knock Sensor: Helps detect detonation (knock) early, protecting the engine.

This is a general overview of what’s involved in building a forged turbo BP-4W.