The BMW N55 Engine

The BMW N55 engine is one of BMW’s most revered inline-six engines, known for blending performance, efficiency, and smooth driving dynamics. Launched in 2009, the N55 succeeded the popular N54 engine, introducing several advancements in technology. This engine was produced until 2019 and used in a variety of BMW models, including the 3 Series, 4 Series, 5 Series, X3, X5, X6, and even the M2.

Characteristics of the BMW N55 Engine

• Configuration: 3.0L inline-6
• Turbocharger: Single twin-scroll turbocharger (as opposed to the twin-turbo setup of the N54)
• Fuel Injection: Direct fuel injection system
• Valvetronic: BMW’s variable valve timing technology
• Double VANOS: Variable camshaft timing on both the intake and exhaust sides
• Output: Power ranges from 300 to 370 hp (depending on model and year)
• Torque: Up to 369 lb-ft (500 Nm) in the M2 Competition and X4 M40i models
• Transmission: Compatible with automatic, manual, and dual-clutch transmissions

Modifications and Variants

1. Standard N55:
   • Found in models such as the BMW 335i, 535i, X3 xDrive35i, and X5 xDrive35i.
   • Power output around 300 hp and 300 lb-ft of torque.
2. BMW M Performance Models:
   • The N55B30T0 variant, used in vehicles like the BMW M235i and M2, offers a more performance-oriented setup.
   • Output boosted to around 365 hp and 343 lb-ft of torque.
3. Hybrid Versions:
   • The BMW ActiveHybrid 3 and 5 models paired the N55 with electric motors, providing additional performance and efficiency benefits.

Pros of the BMW N55 Engine

• Strong and Reliable Power: The single twin-scroll turbocharger offers linear and predictable power delivery, unlike the sudden surge of power in twin-turbo setups.
• Fuel Efficiency: The N55 is more fuel-efficient compared to the N54, thanks to improvements like Valvetronic and the twin-scroll turbo.
• Smooth Driving Experience: The inline-six design ensures that the engine runs smoothly, with minimal vibration, offering a refined driving experience.
• Longevity: With proper maintenance, the N55 can easily surpass 200,000 miles.
• Wide Application: Found in many models, the N55 has a vast aftermarket ecosystem for tuning and performance parts.

Cons of the BMW N55 Engine

• Common Mechanical Issues: Like any engine, the N55 has its known weaknesses:
  • Chargepipe failure: The plastic chargepipe is prone to cracking, especially under high boost levels.
  • Water pump failure: Electric water pumps can fail prematurely, requiring frequent replacements.
  • Oil leaks: Valve cover gaskets and oil filter housing gaskets are known to leak over time.
  • High-pressure fuel pump (HPFP) issues: While less common than with the N54, HPFP failures can still occur.
• Tuning Limitations: The single turbo configuration provides less top-end power potential than the twin-turbo N54.

Proper Maintenance for the BMW N55 Engine

1. Regular Oil Changes: High-performance engines like the N55 rely on fresh oil. Use high-quality synthetic oil and change it every 5,000-7,000 miles.
2. Check for Oil Leaks: Inspect gaskets regularly, especially the valve cover and oil filter housing gaskets. These components are prone to leaks.
3. Cooling System Upkeep: Pay attention to the water pump and thermostat, as cooling system failures are common. Consider replacing them every 60,000-80,000 miles.
4. Fuel System Maintenance: Keep an eye on the fuel injectors, HPFP, and low-pressure fuel pump, especially if you plan on increasing performance.
5. Turbocharger Inspection: Ensure the turbo is running efficiently. Address any signs of oil leaks or excessive play in the turbo to avoid damage.

Ways to Upgrade and Tune the BMW N55 Engine

1. Aftermarket Chargepipe: Replacing the stock plastic chargepipe with a stronger aluminum version is a must for anyone considering tuning. The stock pipe is known to crack under high boost.
2. Upgraded Intercooler: A larger intercooler can help reduce intake temperatures, making the engine more efficient, especially after performance tuning.
3. Exhaust System: Swapping the stock exhaust for an aftermarket cat-back or downpipe can increase power and improve sound.
4. ECU Tuning: An ECU tune can unlock significant power from the N55, with Stage 1 tunes pushing the engine to 350-400 hp with just software. Further tuning with bolt-on modifications can see this number climb higher.
5. Turbo Upgrade: For enthusiasts seeking even more power, upgrading to a larger turbo or a hybrid turbo can push the N55 to well over 500 hp.
6. Fueling Modifications: If you’re looking to reach high horsepower, upgrading the fuel system, including injectors and fuel pumps, is critical.

Conclusion

The BMW N55 engine is a powerful and reliable workhorse that offers excellent performance and tuning potential. Whether you’re looking for a daily driver or a weekend warrior, the N55 provides a perfect balance of power and efficiency. With proper maintenance and smart upgrades, it’s possible to take this engine to new heights.

At GDO Automotive, we offer a wide range of parts and services for BMW enthusiasts, including N55 owners. From performance upgrades to maintenance advice, our expert team is here to help keep your BMW running at its best. Reach out to us for any assistance with your N55 or to discuss the best tuning options for your goals!