The B58 is part of BMW's modular engine family, each engine using a displacement of 500 cc (30.5 cu in) per cylinder, following the B38 and B48 engine.[3]
The S58 engine, which was released in early 2019, is the high-performance version of the B58.[8][9] It was named to Ward's World's 10 Best Engines in 2023 (installed in the M2).[10]
Compared with its BMW N55 predecessor, the B58 features a 20% increase in boost pressure, a closed-deck engine block design, an increase in compression ratio to 11.0:1 and a slight increase in displacement from 2,979 to 2,998 cc (181.8 to 182.9 cu in) with added weight of 8 kg (18 lb).
The turbocharger is a twin-scroll design, for more efficient power delivery with less turbo lag and more power than a conventional single turbocharger, as well as for weight and space saving benefits.[11] The intercooler - a water-to-air design - is integrated into the intake plenum, to reduce the volume of air between the turbocharger and the cylinders.[12][13]
The B58 also features an engine-mounted heat encapsulation system to reduce engine wear and emissions during start-up.[16]
For durability and longevity, the rotating assembly has a forged steel crankshaft and forged connecting rods.[17][18]
As a part of BMW's new modular engine family, the crankcase is a completely new design identical to the B57 diesel version,[19] engineered as both a gasoline and diesel engine in one common part. The closed deck crankcase is equipped with a completely new structure which can be identified by a complex array of ribs on the exhaust and intake side and an additional reinforcement frame on the oil pump side.
The engine was revised in 2018, dubbed "B58TU", with notable changes and improvements. The fuel system was updated with 75% increased pressure with updated high pressure fuel pump and injectors, a new particulate filter in the catalytic converter, a new one-part timing chain as opposed to the earlier two-part, and new separate cooling circuits for the cylinder head and crankcase. For weight savings, the crankcase wall thickness and forged crankshaft were optimized, and the exhaust manifold was integrated into the cylinder head housing.[20]
Another engine revision in 2022 added port fuel injection to complement the existing direct injection system for better emissions and functionality.[21]
The S58 engine is the high-performance version of the B58 engine. It was introduced in the F97 X3 M and F98 X4 M, marking the first time a stand-alone M model was produced for the X3 and X4.[33]
The S58 features twin mono-scroll turbochargers, a compression ratio of 9.3:1, a redline at 7,200 rpm with the bore and the stroke at 84 mm × 90 mm (3.31 in × 3.54 in). It also features a forged chrome molybdenum heat-treated steel crankshaft, plus forged steel connecting rods and forged aluminum pistons. The pistons are forged by Mahle and feature their proprietary anti-friction coating.[34]
As opposed to the B58, the S58 features a slightly smaller displacement, increased bore, decreased stroke, and larger valves. Compression is decreased to 9.3:1 from 11.0:1. The S58 favors top-end power and has a higher redline of 7,200 RPM.[34]
