BMW M52B20 Engine (Design, Issues & Tuning)

The M52B20 is a 2L inline-6 engine producing 148hp and 190nm. It was made between 1994-1998, the M52TUB20 was an updated version of the same engine produced between 1998-2000.


It's an M52 series engine, along with the M52B24, M52B25, M52B28, and S52B32. This engine seems to have replaced the M50B20 at the time.


The M52B20 was used in the following cars:

  • 1994-1998 E36 320i

  • 1995-1998 E39 520i


The updated M52TUB20 was used in the following cars:

  • 1998-2000 E46 320i, 320Ci,

  • 1998-2000 E39 520i

  • 1999-2000 E36/7 Z3 2.0i


BMW M52B20 Engine

Design

The bore-liners of the cylinder block, which is fully comprised of an aluminium alloy, have a Nikasil coating.


New connecting rods and pistons were installed in the engine (the length is 145mm). The M52B20 cylinder head is a DOHC 32-valve aluminium cylinder head, often referred to as the M50B20TU cylinder head.


A simple plastic intake manifold and a variable timing system (VANOS) that solely affects the intake camshaft are present in the engine. 154 cc fuel nozzles are used in the engine.


In 2000, the M52B20 engine was replaced by the 2.2-liter M54B22 engine from the M54-series.


M52TUB20 - M52 Technical Update

When the M52TU ("Technical Update"), featuring variable valve timing to the exhaust camshaft (referred to as "double VANOS"), was produced in 1998, the engine was named the M52TUB20.


Additional improvements included:

  • dual VANOS (variable valve timing system for both camshafts)

  • variable geometry intake manifold (DISA)

  • cast iron sleeves within the block

  • new connecting rods, pistons

  • an electronic throttle body


The M52TUB20's camshaft specs are as follows:

  • Valve lift: 9.0/9.0 mm

  • Duration: 244/228 degrees


Specs

  • Manufacturer: Munich Plant

  • Production years: 1995-2000

  • Cylinder block material: Aluminium

  • Cylinder head material: Aluminium

  • Fuel type: Gasoline

  • Fuel system: Fuel injection

  • Configuration: Inline

  • Number of cylinders: 6

  • Valves per cylinder: 4

  • Valvetrain layout: DOHC

  • Bore: 84.0 mm

  • Stroke: 84.0 mm

  • Displacement: 2793 cc

  • Type of internal combustion engine: Four-stroke, naturally aspirated

  • Compression Ratio: 10.2:1

  • Power: 193 hp at 5,300 rpm, 193 hp at 5,500 rpm (TU)

  • Torque: 210 lb-ft (280 Nm) at 3,950 rpm, 210 lb-ft (280 Nm) at 3,500 rpm (TU)

  • Firing order: 1-5-3-6-2-4

  • Engine oil weight: SAE 0W-30, 0W-40, 5W-30, 5W-40

  • Engine oil capacity: 6.5 litres

  • Oil change interval: 6,000 miles (10,000 km) or 12 months

  • Applications: BMW 328i E36, BMW 328i E46, BMW 528i E39, BMW 728i E38, BMW Z3, Land Rover Defender


Problems & Reliability

There are only issues that afflict the M52-series as a whole, as described below; this engine does not have any particular issues.


  • Overheating: The M52B20 engine has an issue with overheating. A cylinder head might soon become obsolete if it overheats.

  • Oil usage: The engine's oil rings are unreliable, and if they break, a lot of oil is lost as a result.

  • Ignition: Blocked hydraulic tappets or lifters may be the cause of ignition problems. When a valve is partially closed in a cylinder, the ECU will shut off the ignition.


Issues exist in all M52 engines. Depending on the engine's age, mileage, and variations, different issues may arise.


Tuning

Other than remapping, which is frequently how most people tune their cars, there are a variety of other ways to modify your M52B20.


  • Stage 1 improvements include fast road camshafts, sports exhaust manifolds, panel air filters, drilled and smoothed air boxes, intake headers, and remaps/piggyback ECUs.

  • Stage 2 upgrades include the induction kit, sports catalyst and performance exhaust, ported and polished heads, modified fuel pumps, and high flow fuel injectors.

  • Stage 3 modifications include adding or improving forced induction (turbo/supercharger), twin charging conversions, engine balancing and blueprinting, internal engine improvements (head flowing porting/bigger valves), competition cam, crank, and piston changes to adjust compression.


Intake

Depending on their design and flow characteristics, the air intake manifolds of the M52B20 might significantly affect fuel atomisation. Although some manufacturers provide air intake manifolds that flow reasonably well, the majority require motorsport modifications.


Power can be improved by using larger intake pipes, smoother piping, a cold air feed, or ram air feed.


Camshafts

Fast road cams are one of the most significant mechanical modifications, but they must be installed by a trained mechanic and are not always simple to find.


The majority of the time, these modifications won't increase power on their own, but by eliminating the restriction, they could help increase power following other changes.


Forced Induction

The best method for increasing airflow is forced induction, which enables you to burn more fuel and produce more power. Even though it's one of the most expensive upgrades, it offers the most significant gains.


Headwork

The main goals of porting and flowing the head are to increase airflow while minimizing flow restrictions and turbulence.


To increase power, the M52B20 valve may be made larger, some port matching added, and have a better flowing cylinder head. You'll also be able to gain additional performance from other tuning changes.


Mapping

Use ECU mapping to optimise the performance of all the installed components on your M52B20.


An aftermarket ECU can be the best choice in some cases because the original ECU is locked. Many of them will perform better than the original ECUs; nevertheless, you must ensure that they are fitted properly and have knock protection.


The final result will depend on the hardware you've installed and the health of your engine, but it will normally give you approximately 30% more power on turbocharged cars and 15% more power on vehicles with naturally aspirated engines.


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