M52

Upgrades

Intake

For most Stage 0.5-1.5 M52, an upgraded drop-in filter is usually perfectly fine and offers a similar power gain to a full intake system. At higher power levels, upgrading the intake system will be more worthwhile.

Exhaust

The stock exhaust manifold is relatively good for OE. Upgrading this component is still a worthwhile investment, and can reduce weight, temperatures, and increase overall engine efficiency.

A cat-back exhaust offers the least gains in comparison to intake and exhaust manifold. 57-76 mm (2.25-3 inch) diameters are ideal, though there is minimal difference beyond 65 mm (2.5 in) diameter at lower modification levels. Please consider the weight difference to power gain and decide what works best for you.

Head

Camshaft

Read the camshaft page for more information.

Valvetrain

+1 mm oversized valves are a worthwhile upgrade. If you plan to rev high, the most important upgrades are valve springs and rockers.

Block

Generally the cylinders can be oversized by 0.5 to 1.0 mm without causing much concern.

Forced Induction

You can expect between 6-10 Hp per pound of positive pressure added for most forced induction setups. The M44B19 is able to handle 6-8 PSI relatively well without any internal modifications. With just ARP head studs and a quality head gasket, an otherwise stock engine can handle 12-15 PSI relatively well.

B20

A 1,991 cc (121 cu in) version was introduced in 1994. Bore is 80 mm (3.1 in) and stroke is 66 mm (2.6 in).[7] The compression ratio is 11.0:1.

Applications:

1994-1998 E36 320i 1995-1998 E39 520i

TU

The "technical update" in 1998 included double VANOS, which improved low rpm torque.

Applications:

1998-2000 E46 320i, 320Ci, 1998-2000 E39 520i 1999-2000 E36/7 Z3 2.0i

B24

2.4 L. For Thai market only. The bore is 84 mm (3.3 in) and the stroke is 72 mm (2.8 in).

B25

A 2,494 cc (152 cu in) version introduced in 1995.[8] It produces 125 kW (168 hp). Bore is 84 mm (3.3 in) and stroke 75 mm (3.0 in). The compression ratio is 10.5:1.

Applications:

1995-1998 E36 323i, 1995-2000 E36/5 323ti 1995-2000 E39 523i

TU

The "technical update" in 1998 included double VANOS, which improved low rpm torque.

Applications:

1998-2000 E46 323i, 323Ci 1998-2000 E39 523i 1998-2000 E36/7 Z3 2.3i

B28

The 2,793 cc (170 cu in) version of the M52 debuted in 1995. It has a bore of 84 mm (3.3 in), a stroke of 84 mm (3.3 in) and produces 142 kW (190 hp).[9] The compression ratio is 10.2:1.

Applications:

1995-1999 E36 328i, 328is 1995-1998 E39 528i 1995-1998 E38 728i, 728iL 1997-1998 E36/7 Z3 2.8 1997-2000 Land Rover Defender (South Africa only)

TU

The "technical update" in 1998 included double VANOS, which improved low rpm torque.

Applications:

1998-2000 E46 328i, 328Ci 1998-2000 E36/7/8 Z3 2.8 1998-2000 E39 528i 1998-2000 E38 728i

Notes

The aluminum M52 engine received criticism in some markets with high levels of sulfur in the petrol during the late 1990s. Sulfur has a corrosive effect on Nikasil and led to many early M52 and M60 engines having premature bore-liner wear. Countries with high sulfur fuel (such as the United States) received an iron block version of the M52 (except for the M52B28 in the Z3 which was an aluminium block), so the Nikasil problem does not apply to most M52 engines in these countries.

Once the Nikasil coating was determined to be the cause of the problem, steel cylinder liners were used instead of the Nikasil coating. Therefore, the M52TU engine was not affected by the Nikasil problem.

In 1998, the M52TU ("Technical Update") was released, adding variable valve timing to the exhaust camshaft (called "double VANOS"). Other upgrades included electronic throttle control (which uses a throttle cable as backup), a dual length intake manifold (called "DISA") and revised cylinder liners.