When it comes to BMW’s modern engines, the N55 and S55 are two of the most talked-about powerplants in the lineup. Both are turbocharged inline-six engines and while they share some similarities, they cater to different types of drivers and vehicles. At Miami Engines, where we specialize in BMW service and repair, including advanced Dynojet tuning, we often get questions about the differences between these two engines. Let’s break it down.

The Basics: N55 and S55

N55 Engine

• Introduced: 2009
• Configuration: 3.0-liter inline-six, single twin-scroll turbocharger
• Found In: BMW models like the 335i, 435i, M235i, and certain X-series vehicles.
• Power Output: Typically ranges from 300 to 320 horsepower and around 300 lb-ft of torque.

S55 Engine

• Introduced: 2014
• Configuration: 3.0-liter inline-six, twin-turbochargers
• Found In: High-performance M models, including the M3, M4, and certain special editions like the M2 Competition.
• Power Output: Starts at around 425 horsepower and 406 lb-ft of torque, with higher outputs in special models.

Performance and Power Delivery

N55: The N55 engine is known for its smooth power delivery and linear torque curve. With a single twin-scroll turbo, it provides strong low-end torque, making it great for daily driving and providing ample power across the rev range. It's an ideal engine for those who want a blend of performance and comfort.

S55: The S55, on the other hand, is built for performance. With twin-turbos, it delivers more power and a more aggressive torque curve. The S55 engine is designed for track use, with a focus on high-speed stability and responsiveness. It’s an engine that shines when pushed hard, making it the heart of BMW’s modern M cars.

Reliability and Maintenance

N55: Generally considered reliable, the N55 does have some known issues, including potential problems with the electric water pump, high-pressure fuel pump (HPFP), and charge pipe. Regular maintenance and addressing these issues proactively can help keep the N55 running smoothly for a long time.

S55: The S55 engine is more complex, and while it shares some components with the N55, it’s built to handle more stress. It has reinforced internals and upgraded cooling systems to manage the additional power. However, it’s not without its quirks—issues with the crank hub are well-documented, and the cost of maintenance can be higher due to the engine’s complexity.

Tuning Potential

N55: The N55 engine offers good tuning potential, especially with bolt-on modifications and a proper dyno tune. You can see significant gains in horsepower and torque, making it a favorite among enthusiasts who want more performance without compromising daily drivability.

S55: The S55 is a tuner’s dream. With its stronger internals and twin-turbo setup, the S55 engine can handle much higher power levels. Tuners can extract significant gains from the S55 with modifications like upgraded turbos, exhaust systems, and, of course, a custom dyno tune. It’s not uncommon to see S55-powered cars pushing well over 600 horsepower with the right setup.

Our Verdict: Which One is Right for You?

Choosing between the N55 and S55 comes down to what you’re looking for in your BMW experience.

• Choose the N55 if: You want a reliable, smooth, and powerful engine that offers a great balance between performance and everyday usability. It’s perfect for those who enjoy spirited driving but don’t necessarily need track-ready performance.
• Choose the S55 if: You’re after raw power and track-ready performance. The S55 is the choice for M enthusiasts who crave the thrill of high-speed driving and want an engine that can take extensive modifications.

At Miami Engines, we’re equipped to service and tune both the N55 and S55 engines. Whether you’re looking for a BMW engine rebuild specialist near you or need BMW engine replacement service, we’ve got the expertise to make it happen. Our services include remanufactured BMW engines and high-quality options.

Contact Miami Engines Today!

Miami Engines: Your trusted partner for BMW service, repair, and tuning. Specializing in Dynojet services to optimize performance for N55 and S55 engines. Contact us today to learn more about how we can help you get the most out of your BMW, including the best BMW repair options in the area!