When you are talking about the inline-six engines of BMW, the B58 and S58 are the stars of the show. They are both known far and wide for being powerful, efficient, and versatile engines. Their exhausts also follow their lead and are designed to fit in with the car’s personality.
The B58 exhaust is focused in a smooth and refined tone for daily usage. On the other hand, the S58 exhaust is aggressive and loud on the tracks. Are you curious to know what sets these beasts apart? Let’s find out in detail!
Engine Background
Both the B58 and S58 engines belong to the BMW’s turbocharged inline-six lineup. However, they have completely different roles and goals in real-world applications. Looking at their foundations, you will be able to grasp the initial differences.
B58 Engine
- Introduced in 2015, the B58 engine is a part of BMW’s modular engine family. It serves as the powerhouse of many mainstream BMW models.
- It is used in cars like the 3 series (M340i), 5 series (540i), and Z4 M40i. You will also find it in some selected SUVs like the X5 xDeive40i.
- The target of the B58 engine is to provide a smooth, linear power delivery and fuel efficiency with everyday drivability.
- Depending on the tuning, it can produce from 322 to 382 horsepower.
S58 Engine
- Featured in 2019, it is the high-performance sibling of the B58 engine. Commonly found in the M models of BMW, like G82/G83 M4. It is also used in performance SUVs, like the F98 X4M.
- The S58 heavily customized to provide a high performance. It has upgraded internals, a stronger block, and a twin turbocharger.
- This mighty beast can produce from 473 to 503 horsepower in the stock setup. Of course, the horsepower depends on the model and car profile.
- With a high-performance build and track-focused design, the S58 is made to rock in the most demanding driving conditions.
Exhaust System Design
The exhaust systems of B58 and S58 are designed to complement the engine’s separate purposes. Here is an informative breakdown:
Material and Construction
The B58 exhaust focuses on cost-efficiency and durability. Therefore, they use materials that can hold onto everyday driving conditions. They are simple and don’t have any unnecessary weight or complexity.
- Simple Pipework with smaller diameters.
- Designed to meet strict noise and emissions regulations to cover a wide range of markets.
On the other hand, the S58 exhaust is built for high-performance demands, using more robust materials. These are capable of handling higher temperatures coming from the increased engine output.
- Larger diameter piping for better airflow. To boost the performance further, you can upgrade to a performance BMW S58 downpipe.
- Dual exhaust setups are common for this engine to optimize performance and sporty look.
Exhaust Flow Characteristics
The B58 exhaust flow is optimized for a balanced performance with fuel efficiency and emissions. The design focused on a smooth flow of exhaust for quicker operation. It makes this type of exhaust ideal for luxurious models. There is a slight backpressure kept intentionally to ensure drivability and lower torque.
But, the S58 gives more priority to high exhaust flow to maintain minimal back pressure. It is essential to harvest more power from the engine in high RPMs. It also supports aggressive tuning by using free-flowing components.
Mufflers and Resonators
The B58 exhaust is equipped with larger mufflers and resonators, keeping a quieter and more refined cabin experience. Overall, it is designed to attract a broad range of audiences who are looking for balanced comfort and sportiness.
The S58 mufflers are smaller to apply less restriction and amplify the engine’s sound profile. It is designed to deliver an aggressive exhaust note with pops and crackles. Especially in sport or track mode, you can feel the aggressiveness of the exhaust sound.
What are the Differences Between the B58 and S58 Exhaust?
The following table will give you an idea of the key difference between these two powerhouse engines.
| Feature | B58 Exhaust | S58 Exhaust |
| Focus | Efficiency, smoothness, and comfort | High airflow and peak performance |
| Sound Profile | Subdued, refined, and sporty | Aggressive and loud with pops and crackles |
| Material | Durable and cost-efficient | High-grade materials |
| Exhaust Flow | Slight intentional backpressure | Reduced back pressure |
| Mufflers/ Resonators | Larger and quieter | Smaller and louder |
| Tailpipe Design | Luxury style and can be single or dual | Quad pipes with bold and aggressive design |
| Applications | BMW 3 series and 5 series | BMW M series and selected SUVs |
Conclusion
In a nutshell, although they belong to the same modular engine family, they are quite different. Their usage, target, performance, build, and sound profile are focused on two very different usages. The S58 engine is for performance-hungry situations like on the track. But, the B58 is designed to be used in daily life for comfort and luxury.
