Buyers looking for an engine that combines power, comfort, and great performance are likely to seek an inline-six motor such as the mighty 2JZGTE from Toyota and the RB26DETT used in Nissan’s Skyline R32, R33, and R34 GTR. While these are great choices, similarly high-performance options can be found in BMW’s N55 and B58 engines – two of the most reliable engines out there.
In this post, we’ll compare the N55 and B58 engines and discuss their distinct features so that potential buyers can better choose the one that’s right for them.
Table of Contents
Overview of the N55 and B58 engines
N55 engine
B58 engine
N55 vs B58 comparison
1. Engine architecture and design
2. Cooling systems
3. Fuel efficiency and emissions
4. Performance comparison
5. N55 vs. B58 reliability
Which engine is the right one for you?
Conclusion
Overview of the N55 and B58 engines
N55 engine
BMW introduced the N55 engine to the market in 2009 to replace the already discontinued N54. The N55 brought many changes compared to the former engine, with one of the biggest being its single twin-scroll turbo setup, with BMW ditching the twin-turbocharged configuration of its predecessor. This new design was named TwinPower Turbo, and can be found in the F30 335i, F22 M235i, F10 535i, and F87 M2.
Other features of the N55 engine are the Valvetronic and Double-VANOS, both of which are designed to boost performance and throttle response.
B58 engine
The B58, developed in 2015 as part of BMW’s modular engine range, replaced the N55. Like its predecessor, the B58 is a 3.0-liter inline-six engine but with several improvements, namely, a closed-deck chassis, a higher compression ratio, and an integrated water-to-air intercooler. These led to better cooling, reliability, and power output.
The engine drives newer BMWs like the G20 M340i, G29 Z4, and G05 X5, as well as the Toyota Supra (A90), showcasing its versatility and efficiency. The B58’s modular architecture is also suitable for hybrid setups, including the BMW 745e plug-in hybrid.
N55 vs. B58 comparison
1. Engine architecture and design
The N55 and B58 engines use the same inline-six, which is a hallmark of BMW’s engineering expertise. But they differ in the manner in which they are built.
For example, the N55 engine is built around an open deck aluminum block, making it easy to manufacture and cool. Stylish for the era, the open-deck design was not as strong under extreme driving conditions, with the N55 turbocharger being separate and requiring larger piping, meaning it may suffer from turbo lag in comparison with more advanced units.
The B58, meanwhile, is made from a closed deck aluminum block that provides greater rigidity and more resistance to higher cylinder pressures. This configuration makes the B58 especially robust and ideal for high-end use cases.
Additionally, the B58’s engine uses a modular design, which enabled BMW to simplify production and customize it for various displacements. The engine also has harder forged internals (including its crank and connecting rods), enabling the engine to perform better at higher power levels.
Another notable upgrade to the B58 is the addition of the exhaust manifold to the cylinder head. This configuration minimizes heat and turbo lag by narrowing the distance between the exhaust ports and the turbocharger and speeds up engine start-up for improved emissions and fuel efficiency.
2. Cooling systems
Airflow is essential for turbocharged engines, and the B58’s abilities go far beyond the norm here. While the N55 utilizes a classic air-to-air intercooler, which is effective but can be sluggish and encounter intake temperature problems (like hot soaking) during long-range driving, the B58 includes a water-to-air intercooler mounted in the intake plenum. This arrangement shortens the distance the air must travel, thus minimizing turbo lag and increasing efficiency. Its water-to-air intercooler also better stabilizes intake temperatures during high loads, making it great for track use and extreme driving conditions. In addition, the B58 features multiple heat exchangers to precisely control the engine’s temperature.
3. Fuel efficiency and emissions
BMW developed the B58 in response to the ever-increasing emissions standards and enhanced fuel economy. As dependable as the N55 was, its technology is now dated, offering decent fuel economy but none of the B58’s cutting-edge emissions management systems. For example, it does not use particulate filters that modern engines employ.
Improved combustion technology means that the B58 burns less fuel and produces fewer emissions. Details such as the integrated manifold, better thermal control, and a gasoline particulate filter (GPF) allow the B58 to meet stringent global emissions regulations at a competitive price. It also benefits from start/stop technology and quick warm-up times.
4. Performance comparison
- Power output: The N55 produces 300-322 hp and 295-332 lb-ft of torque, depending on model and year. It is extremely smooth to drive and ideal for both high-performance and everyday driving.
The B58, meanwhile, goes above and beyond in terms of performance. In stock configuration, it generates between 322 and 382 horsepower and up to 369 lb-ft of torque, depending on the version. The B58’s superior power handling and well-thought-out cooling system mean that it runs at full strength for hours at a time. - Tuning potential: The N55 has been a favorite with tuners due to its moderate upgrade support. Add bolt-ons, a tune, and other tweaks, and it should be able to achieve 450-500 horsepower. However, its open-deck configuration limits its capability to handle larger power levels without internal enhancements.
The closed deck of the B58 makes it better suited for power builds. Some have achieved more than 600 horsepower with fairly simple tweaks. The B58’s increased power and upgraded cooling systems offer it a clear tuning advantage.
5. N55 vs. B58 reliability
In terms of reliability, both N55 and B58 are fairly reliable, although they differ in terms of design and frequent problems encountered.
N55 reliability
The N55 is generally more secure than its predecessor, the N54, but some problems remain. Common issues include:
- Leaks: These typically include the valve cover gasket leak and oil filter housing gasket leak
- Charge pipe failure: The plastic charge pipe can crack under high boost pressure
- High-pressure fuel pump (HPFP): More durable than the N54’s HPFP but known to fail occasionally
- Water pump: The electric water pump sometimes stops working after 60,000 to 100,000 miles
- Ignition coils and spark plugs: Misfiring happens all the time, and these parts should be replaced every 40,000-50,000 miles
Read more: 7 most common BMW N55 faults
Despite these concerns, preventive maintenance and repairs can keep the N55 running smoothly for well over 150,000 miles.
B58 reliability
The B58 takes the N55’s strengths and addresses some of its flaws. Common problems include:
- Coolant leaks: Problems in the coolant expansion tank or lines may leave drivers stranded
- Oil filter housing gasket: Similarly to the N55, this gasket can leak over time
- PCV valve: PCV valve failures are found in a few early B58 engines, but not as many as the N55
- Carbon build-up: Indirect injection engines such as the B58 tend to accumulate carbon deposits on the intake valves, requiring periodic walnut blasting
Overall, the B58 is one of BMW’s most stable modern engines. It features a stronger construction and better parts than the N55, which reduces the chance of any major catastrophic failures.
Which engine is the right one for you?
Whether you opt for the N55 or B58 will most likely be up to the user’s preference:
- N55: A perfect option for anyone looking for a solid and somewhat economical BMW inline-six. Perfect for daily driver and light tweaker users.
- B58: Excellent for drivers who need the most modern technology, more tuning options, and more durability. Maintenance might cost a bit more, but the B58’s power alone is likely to be considered worth the cost among enthusiasts.
Conclusion
There’s no winner in the N55 vs. B58 – who’s better debate mostly because each engine has its own upsides. The N55 defined BMW’s inline-six technology, while the B58 pushed on from there. Whether buyers are searching for a reliable daily driver or a platform for high-powered tuning, knowing the differences between engines will make the decision much easier.
After all, both the N55 and B58 are a testament to BMW’s engineering prowess, which should help keep them at the forefront of enthusiasts’ wishlists for years to come.
