BMW has long been revered as the Ultimate Driving Machine, and these engines live up to that expectation. The N54 and N55 offer both flexibility (BMW provides factory-backed tuning upgrades) and reliability as long as oil changes are performed regularly and no overheating occurs.
The main difference between BMW N54 and N55 lies in their turbochargers: while the former boasts twin units, while its successor uses only a single twin-scroll unit. Here are some significant difference between BMW N54 and N55:
Engines are the key issue for BMW N54 vs N55. The N54 was BMW’s first mass-produced turbocharged engine in over three decades. Producing 365hp and 343lb-ft of torque between 1,500rpm and 6,500rpm, this turbo charged motor powered the car up to 60mph in under four seconds.
Although the N54 did have some reliability issues with regards to fuel injectors and HPFP (high-pressure fuel pump), most were addressed through recalls or extended warranties by BMW. Even so, you should remain wary if purchasing an N54 BMW. Here are a few common issues you should look out for before purchasing one:
One such issue is with an oil filter housing gasket that leaks, mixing oil and coolant together and potentially damaging your engine if it drips onto the drive belt. VANOS systems also can become damaged over time due to dirty solenoids; so when searching for N54 cars make sure their VANOS bolts have been changed out as this may indicate quality maintenance work has taken place on them.
The N55 engine is more reliable and cost-effective than its N54 counterpart, yet there are still some potential drawbacks that should be taken into consideration before purchasing one. Plastic inlet pipe may break down over time; replacing this part and the intercooler may help prolong their lifespan.
Secondly, having only a single twin-scroll turbo instead of bi-turbo technology limits air flow into the combustion chamber compared with what can be accomplished with bi-turbo systems like on the N54; larger turbos and supporting mods could potentially increase performance but reduce engine’s potential output potential. It can be claimed that engines are not so different for BMW N54 vs N55.
The N54 and N55 engines can be found in BMW sedans and sportscars, both have won International Engine of the Year awards, but differ primarily in that the former features twin turbos while its successor features only one twin-scroll turbo. Furthermore, Valvetronic gives more power to this latter option than with its counterpart.
The N55 has identical cylinder heads with an identical compression ratio of 10.2:1, but differs by increasing valve adjustment range on its intake camshaft and decreasing that on its exhaust camshaft; additionally it uses an ECU called MEVD17.2 with an improved oiling system.
Other modifications included the implementation of a Bosch solenoid valve fuel injector as opposed to its piezo counterpart used on the N54 due to cost and reliability considerations outweighing any potential lean-burn benefits of piezo style injectors. Furthermore, electronic diverter valves were switched out in place of pneumatic ones as well as switching from dual exhaust turbos with twin scroll setup.
Even with its advancements, however, the N55 still falls short in some respects. Oil leaks from either its filter or head gasket may lead to unfiltered engine oil reaching the oil pump, damaging internals and leading to poor performance and power. Furthermore, its diverter valve may malfunction, rendering it nonfunctional.
BMW designed their N55 turbo engine as their inaugural production turbo engine with integrated VANOS and Valvetronic systems, hoping that this would resolve some of their previous inline-six reliability issues (the N54). While BMW did their work here, there are a few things you can do yourself to extend its longevity and improve reliability even more than stock.
An upgrade that’s frequently recommended for a BMW N55 is a high-performance exhaust. This upgrade covers everything behind the catalytic converter, giving an increase in both power and an aggressive sound.
An essential upgrade for turbocharged engines, efficient cooling is crucial. While OE coolers tend to do an adequate job at stock levels, more power or intense use (such as track days) can strain them to their limits and may require replacement with aftermarket oil coolers such as those made by CSF, who produce some of the finest fluid cooling gear available today.
Consider getting a new charge pipe; plastic ones on both N54 and N55 models can be very flimsy and will begin to give way under standard boost pressure, while an upgraded charge pipe will withstand much greater strain and outlive its plastic predecessor much sooner – an upgrade is essential to getting the most out of an N55! It can be said that for BMW N54 vs N55, both models offer safety.
The N54 and N55 engines both feature aluminum engine blocks with variable construction materials; their main differences lie in their turbochargers and valvetrain. The N55 features twin-scroll turbos with direct injection using Valvetronic for the first time to reduce power loss while offering a more linear torque curve. Furthermore, its innovative new valvetrain is controlled by actuators instead of solenoids to maintain performance efficiency under all conditions.
BMW’s N54 engine has long been plagued with problems. These vehicles often need expensive repairs long after their warranty period has ended, leading many buyers to opt instead for the more reliable N55.
The N55 has seen some improvements to its reliability, such as adding a water pump with larger capacity and revising the thermostat to help with carbon issues. Furthermore, it features a recirculating blow-off valve to reduce excessive oil consumption.
Unfortunately, however, there remain a few common failure points with this car that can be costly to repair, such as its HPFP which may result in long crank times or loss of power; fuel injectors which fail unexpectedly leading to misfires and stuttering; as well as fuel injectors failing misfires and stuttering caused by misfires occurring while engaging its fuel injectors that causes misfires stutterings as well.
To emphasize BMW N54 vs N55, it can be said shortly that both models have developed technology in comparison to other models in the car market.