We delved into BMW technical handbooks and discussed with Stephan Papadakis what sets this 3.0-liter, single-turbo inline-six apart from others.
I was quite doubtful initially when I heard about it.
MkV Toyota Supra
Would opt for a BMW inline-six. Clearly, BMW maintained the torch for the inline-six configuration as many manufacturers shifted towards V-6 engines; however, providing this powerplant to Toyota meant their turbocharged ‘six had considerable legend to uphold. The renowned reliability of the MkIV Supra’s 2JZ twin-turbo motor has earned its place, often achieving over 1,000 horsepower through tuning efforts.
However, over time, I grasped a crucial lesson—not to dismiss anything prematurely.
Bayerische Motoren Werke
When it comes to issues regarding, um, motors, the B58 3.0-liter single-turbo inline-six found in the Supra and numerous other BMW models stands as a legendary engine for its era. It’s an exceptionally capable heir to the 2JZ lineage and ranks among the finest engines currently available.
Engine builders can achieve more than 700 horsepower using standard components, possibly adding camshafts, a turbo upgrade, a custom tune, and additional modifications, all while keeping the original connecting rods and pistons,” explains Stephan Papadakis, the founder of Papadakis Racing, which constructs 1,000-hp B58 engines for Formula Drift competitions. “There’s no doubt they designed this engine to handle far beyond typical expectations.
The situation with the 2JZ is similar. It emerged during Japan’s economic boom period when car manufacturers such as Toyota had ample funds available for research and development. Keep in mind, we’re talking about Toyota—a brand renowned globally for exceptional dependability both then and now.
In essence, the 2JZ’s iron block can be described as robust, capable of withstanding virtually unlimited boost levels. The engine features an exceptionally durable three-part head gasket, along with a forged steel crankshaft for added strength. Additionally, a reinforcement girdle is attached to the block to enhance overall stiffness. This design closely mirrors those found in diesel trucks rather than conventional gasoline engines.
In contrast to the 2JZ’s robust build, the B58’s aluminum engine block appears quite delicate, yet appearances may mislead. “It has an elegant design,” remarks Papadakis. The disparity at the base of a 2JZ versus a B58 underscores significant advancements within the automotive sector over time. Toyota engineered the 2JZ back in the ’80s when computer-aided design (CAD) technology was still nascent.
Papadakis notes that CAD technology has become highly sophisticated today, complemented by tools such as finite element analysis (FEA) and improved metallurgy techniques. This enables the creation of parts that are extremely lightweight without compromising their robustness. Consequently, compared to the 2JZ engine block, which seems relatively bulkier, the B58 appears nearly streamlined; however, it remains capable of handling power outputs up to an impressive 1,000 horsepower.
Similar to numerous car manufacturers, BMW incorporated substantial modularity into the design of the B58 engine. This engine shares close ties with the B38 three-cylinder and the B48 four-cylinder engines commonly found across various models from BMW and Mini. Additionally, it bears resemblance to the B57 diesel six-cylinder engine, which can handle high compression ratios of up to 16.5:1. Both the B57 and B58 have identical basic casting designs for their blocks; they both feature “closed-deck” architecture, meaning that most of the cylinder area’s cooling jacket ports remain enclosed.
In a technical training manual for the B58, BMW states that “a closed-deck design is primarily utilized in BMW diesel engines.” This is due to the significant combustion pressures within diesel engines necessitating higher stiffness so these forces can be effectively managed. Despite this being typical for diesels, since the base structure of the B58 mirrors that of the B57, it still enjoys the advantages provided by the closed-deck configuration. Similarly, the 2JZ employs a closed-deck design for enhanced structural integrity. It’s worth noting both the B57 and B58 feature comparable forged-steel crankshafts; however, an additional advantage of the B58 lies in its usage of forged connecting rods as well.
Utilizing shared parts between diesel and gasoline engines offers a triple advantage for BMW: cost savings, decreased manufacturing intricacy, and enhanced performance of the gasoline engine. This is similar to what we’ve seen with modifications on the 2JZ; tuners are achieving impressive power levels from B58 engines as well.
The B58 also boasts a smart design. Similar to many contemporary BMW engines, the B58 incorporates Valvetronic, which is BMW’s proprietary continuously adjustable intake valve lift mechanism, along with Double VANOS for variable camshaft control.
Valvetronic employs an electric motor to turn an eccentric shaft, which through rocker arms adjusts the lift of the intake valves. The ingenious aspect—not exclusive to the B58—is that this setup offers significant variability in lift, enabling the intake valves themselves to act as the engine’s throttle mechanism. In BMW models equipped with Valvetronic, although they still feature a conventional throttle body, it usually remains fully open. When you press the gas pedal, you’re essentially managing the Valvetronic system instead.
Initially, Papadakis had doubts about the system due to what seemed like delicate components. He recalled thinking, “‘Man, this seems like it will have a low rev limit.’ We even considered finding ways to take it out.” However, he found that it performed well in practice. Indeed, according to Papadakis, Valvetronic turned out to be “incredibly dependable” up to an impressive 9,000 rpm.
For his Formula Drift engines, Papadakis opts for billet camshafts sourced from Kelford Cams along with more robust valve springs and retainers provided by Supertech. This combination ensures a sturdy engine head capable of handling builds pushing as much as 1,000 horsepower on a B58 platform.
The engineer emphasises the factory oiling setup as well. This conventional wet-sump design includes a variable-displacement pump, providing oil flow only when needed. According to Papadakis, this stock element can handle up to 9,000 rpm drifting events over an entire season without issues. However, he modifies several parts for improved durability under high-horsepower demands typical in Formula D racing. These modifications include upgraded camshafts and valve springs, along with different pistons, a bigger turbocharger, and a bespoke exhaust manifold. Additionally, they switch from the standard direct fuel injection to port injection and implement new engine control software.
Over ten years of production, BMW has made several improvements to the B58 engine. In 2018, they implemented a “Technical Update” which included enhancements such as refined fueling and cooling systems, along with an integrated exhaust manifold within the cylinder head, and a more straightforward timing mechanism. These changes were designed to increase power output while simultaneously lowering emission levels.
The second update, which came in 2022, went even further. BMW adopted a dual-fuel injection system with both direct and port injection, and implemented a new electric actuation for the VANOS system. The Valvetronic system also got major updates, and BMW standardized a 48-volt mild-hybrid system. I recently had a chance to drive this engine in the X3 M50, and performance improvements are immediately noticeable. And it delivered much better fuel economy than its predecessor.
BMW told
Motor1
In the most recent B58 update, the aim was to satisfy a wide range of international standards using minimal technical variations. However, upcoming improvements in engine performance are still anticipated. Keep an eye out for further developments.
Papadakis thinks of the B58 as a genuine heir to the 2JZ legacy. This comparison highlights just how far engine technology has advanced over roughly three decades. While maintaining similar capabilities to what the 2JZ offered, the B58 achieves this with reduced size, weight, and improved efficiency. Additionally, it adheres to stringent global regulatory standards that didn’t previously exist.
The lesson here? Never write off BMW. Especially not when discussing their inline-six engines.