With their decision to put the V8 platform on the bottom pole, despite several car manufacturers gradually switching to V6 engine layouts, BMW and their iconic six-inline engines once again continue to rock the under-the-hood powerplant that served them for a long time since their emergence in 1912.
No doubt that BMW creates insanely powerful engines- their B58s were kick-in-the-back kind of fast, but we still cannot stop our human tendencies from becoming competitive even in discourse. And that is when comparisons are made.
Today, we will talk about BMW’s S55 and B58 engines. We will run a side-by-side on how they perform, characteristics, special features, and reliability.
First, let us talk about the engine’s specifications; let’s get right to it.
First is BMW’s S55. The S55 engine is the high-performance version of the N55 and is used for F82 M4 and F80 M3, replacing the BMW S65 naturally aspirated V8 engine used in the prior generation M3.
S55 is an inline-6, high-rev, turbocharged petrol engine. It is equipped with the new BMW’s M TwinPower Technology: two mono-scroll turbochargers that can develop up to 7500RPM, high precision direct-injection, and Valvetronic VVT, and double VANOS variable camshaft timing that provides complete control on intake valve lift.
It also allows the engine to deliver its power resulting in lower fuel consumption efficiently. These high-rev machines are responsive, insanely instantaneous to provide linear control over a wide range of varying engine speeds.
The second is the award-winning B58 engine. B58 is a phenomenal machine; it is powerful and has a smooth running feel at the same time. It holds the BMW’s highest horsepower record to date, making it a real contender as one of the best engines out in the market.
B58 is a 3.0-Liter, 328 horsepower, 369 lb-ft, straight-six petrol engine. Its engine is comprised of a closed-deck aluminum block, aluminum head, DOHC Valvetronic, and Double VANOS. BMW began B58’s production in 2015 and was launched in the 2016 340i as a replacement for the N55.
B58s also appear in Z4 M40i, X5, M240i, M340i, and Toyota Supras.
How do B58s and S55s Differ?
B58s and S55s differ in many ways. But they share the same materials, such as aluminum head and closed-deck aluminum block. Note that B58 is a replacement for N55, while S55 is the high-performance version of the N55 engine. So, S55s are more relative to N55 than B58 to N55.
B58 is a single twin-scroll turbocharger, while S55 uses two mono-scroll turbochargers. B58s weigh less as much as 25% as BMW integrated turbos into a compact steel exhaust manifold and impellers for faster response and power.
Before, the exhaust manifold and turbo were two separate components. Those reductions result in rapid boost pressure producing instantaneous power. B58s are also part of BMW’s new modular engine family, and it has a new crankcase design that imitated the diesel version of B57 that is engineered for gasoline and diesel.
S55s, however, were made for performance cars, even beating some V8 models. Its bores, instead of liners, a twin-wire arc-spray coating making it lighter. S55s are lighter than B58s. S55s weigh 132 kilograms, B58s weigh 139 kilograms.
B58s has an improved cooling system; BMW did a great job of addressing temperature management in B58s.
The B58 engine uses a liquid-to-gas intercooler incorporated into the intake plenum, reducing air volume between the turbocharger and the cylinders; an engine-mounted heat encapsulation system that allows the engine to retain some heat up to 36 hours to minimize wear and harmful emissions during start-up.
For S55’s cooling system and engine fuel supply, BMW modified it to fit a track-like environment for outstanding performance.
It also has additional radiators apart from the main for high and low-temperature circuits, turbochargers, and transmission; and a temperature-stabilizing electric water pump to ensure maximum and efficient performance.
Problems surrounding B58s and S55s
BMW S55 Issues
S55 problems revolved around a complaint that besieged the S55 engines, that some engines produced before 2016 were HPFP failure bound that resulted in a spun crank hub.
However, the S55 hub is the same design used for N54 and N55. It turns out that the company TPG Tuning, which sells aftermarket crank hubs, made fraudulent claims to sell more of their products.
BMW answered, and they solved it, and they also improved it. This is not alarming as it is more of an isolated case than a common one.
Also, not only S55’s, but most of BMW’s valve cover and rubber gasket are the components that are more susceptible to deterioration – such as cracking and leakage that comes with years and mileage.
We all know the environment that these elements undergo, and it is undeniably harsh – high temperatures, varying pressures, and non-stop cycles. This extreme condition will eventually destroy the gaskets and result in oil leaks.
BMW B58 Issues
This issue must be tackled and draw some emphasis as the engine grows old after years of usage. Though it is less common, some B58 owners reported that their coolant in the main tank and its secondary tank – for the intercooler, is always at a low level.
Without noticeable leaks on the engine, your coolant might be going somewhere, or there could be a potential leakage.
As we already know, turbo BMW engine valve cover gaskets are rubber-made. And mind you, these gaskets have been under extreme conditions ever since they are made, such as constant heating and cooling cycles that may lead to oil leakage.
These leaks, however, are not premature as they show signs at around 80,000- 110,000 miles. Valves that are made of plastic are also more susceptible to leaking and cracking than rubbers.
Burning oil smell, smoke from the valve cover, or light indicators for low engine oil, might be a symptom of an oil leak.
The B58 oil filter does not have much resistance to shear stress. When subjected to shear, its bottom part leaves a portion of the oil filter and remains in the housing. This issue can be solved with your simple hand tools such as pliers, though.
If you are still under warranty, you might want to replace it with a new one.
Also, BMW’s VANOS system, since it arrived in 1992, has been a regular visitor in the maintenance component room so far. Though cases are isolated, problems on VAMOS happens heavily on solenoids.
Though they are relatively cheap, replacing solenoids might be a pain for some because of B58’s timing chain location being on the rear of the engine, hard to reach area. That requires some tools. That might be a challenge, but you don’t have to lift the engine; find the right tools for that.
B58s and S55s are highly reliable engines. Some say that these engines are redemption engines, but those claims are not true for BMW in the time, work, and effort for these innovations and technology to integrate into their engines.
So, if you are looking for a track-like ready urban performance car, consider checking S55s. But, if you are curious about how far six inlines can do, considering its iterations, go ahead and try B58s to experience it firsthand. Sharp, powerful, and undeniably fast.