BMW M52

Design

In most markets, the M52 switched from the M50's cast iron engine block to a lightweight aluminium engine block. Prior to 1999, M52 engines produced for the United States and Canadian markets (except for those used by the BMW Z3 roadster) retained the M50's cast iron engine block. Beginning with the E46 in 1999, US cars used the new aluminum M52 block with iron sleeves.

The largest version of the M52 is 2.8 litres, compared with 2.5 litres for the M50. As per the later versions of the M50, the M52 uses variable valve timing on the intake camshaft (called "single-VANOS"). The redline remained at 6,500 rpm.

Technical Update versions

In 1998, the M52TÜ ("Technical Update") was released, adding variable valve timing to the exhaust camshaft (called "double VANOS"). Other upgrades included a new design throttle body with the ASC (traction control) motor built in and throttle cable override, revised coolant passages with an additional drain back passage and a new cooling system with push fit hoses and a separate expansion tank plus a dual length intake manifold (called "DISA") and steel cylinder liners (in the aluminum block) carried over from the previous M52, these replacing Nikasil in March 1998.

Models

M52B20

A 1991 cc version was introduced in 1994. Bore is 80 mm and stroke is 66 mm. The compression ratio is 11.0:1.

Applications:

• 1994–1998 E36 320i
• 1995–1998 E39 520i

{{anchor|M52TUB20|TUB20|TÜB20|M52TÜB20}} M52TÜB20

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

{{anchor|M52TUB24|TUB24|TÜB24|M52TÜB24}} M52TÜB24

2.4 L. For Thai market only. The bore is 84 mm and the stroke is 72 mm.

M52B25

A 2494 cc version introduced in 1995. It produces 125 kW. Bore is 84 mm and stroke 75 mm. The compression ratio is 10.5:1.

Applications:

• 1995–1998 E36 323i
• 1995–2000 E36/5 323ti
• 1995–1998 E39 523i

{{anchor|M52TUB25|TUB25|TÜB25|M52TÜB25}} M52TÜB25

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

M52B28

The 2793 cc version of the M52 debuted in 1995. It has a bore of 84 mm, a stroke of 84 mm and produces 142 kW. 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)

{{anchor|M52TUB28|TUB28|TÜB28|M52TÜB28}} M52TÜB28

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

Nikasil problems with high sulfur fuels

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.

{{anchor|S52|S52B32}} S52

The S52 is a higher performance version of the M52, which replaced the S50B30US in the post-facelift (1996-1999) North American E36 M3.

Compared to the European-spec S50, the S52 is less powerful. The S52 also shares more in common with the regular M52 engine than the S50 did with the M50, for example sharing the engine block (cast iron, as per North American M52 engines) and cylinder head. Unique to the S52 is a bore of 86.4 mm and stroke of 89.6 mm for a total displacement of 3,152 cc. Compression ratio is 10.5:1. Other upgrades over the M52 include lighter camshafts (with increased lift and duration), valve springs and the exhaust system.

The S52 produces 240 hp at 6,000 rpm and 236 lbft of torque at 3,800 rpm. The S52 has a redline of 7,000 rpm while the M52 has a 6,500 rpm redline.

Applications:

• 1996–1999 E36 M3 (Canada and United States only)
• 1998–2000 E36/7/8 Z3M (Canada and United States only)

References

References

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