1. Design
     1998 Technical Update  

2. Models
    M52B20  M52TUB20  M52TUB24  M52B25  M52TUB25  M52B28  M52TUB28 

3. Nikasil problems with high sulfur fuels

4. {{anchor|S52|S52B32}} S52

5. See also

6. References

The BMW M52 is a straight-6 DOHC petrol engine which was produced from 1994–2000. It was released in the E36 320i,^[1] to replace the M50.

In 1998, the "technical update" (M52TU) upgrades included adding variable valve timing to the exhaust camshaft.

The M52 was replaced by the M54 in 2000.

The 1996–1999 E36 M3 in the United States and Canada is powered by the S52 engine, a higher performance version of the M52.

The M52 and S52 engines were on the Ward's 10 Best Engines list from 1997 to 2000.^[2]

Design

In most markets, the M52 switched from the M50's cast iron engine block to a lightweight aluminium engine block.

In the United States and Canada, some cars (not including the Z3) retained the M50's cast iron engine block,^[3][4] while other cars used the new aluminum M52 block with iron sleeves.^[3] 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 by BMW). The redline remained at 6,500 rpm.

1998 Technical Update

In 1998, the M52TU ("Technical Update") was released, adding variable valve timing to the exhaust camshaft (called dual VANOS by BMW). Other upgrades included electronic throttle control (which uses a throttle cable as backup),^[5] a dual length intake manifold (called "DISA" by BMW) and revised cylinder liners.^[6]

Models

M52B20

A {{convert|1991|cc|cuin|abbr=on|0}} version was introduced in 1994. Bore is {{convert|80|mm|in|abbr=on}} and stroke is {{convert|66|mm|in|abbr=on}}.^[7] The compression ratio is 11.0:1.

Applications:

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

M52TUB20

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

Applications:

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

M52TUB24

2.4 L. For Thai market only. The bore is {{convert|84|mm|in|abbr=on}} and the stroke is {{convert|72|mm|in|abbr=on}}.

M52B25

A {{convert|2494|cc|cuin|0|abbr=on}} version introduced in 1995.^[8] It produces {{convert|125|kW|hp|abbr=on}}. Bore is {{convert|84|mm|in|abbr=on}} and stroke {{convert|75|mm|in|abbr=on}}. The compression ratio is 10.5:1.

Applications:

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

M52TUB25

The "technical update" in 1998 included dual 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 {{convert|2793|cc|cuin|0|abbr=on}} version of the M52 debuted in 1995. It has a bore of {{convert|84|mm |in|abbr=on}}, a stroke of {{convert|84|mm |in|abbr=on}} and produces {{convert|142|kW|hp|abbr=on}}.^[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)

M52TUB28

The "technical update" in 1998 included dual 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.^[10][11][12] 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.^[13]

Once the Nikasil coating was determined to be the cause of the problem, steel cylinder liners were used instead of the Nikasil coating.^[14] Therefore, the M52TU engine was not affected by the Nikasil problem.^[15]

{{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), cylinder head and single VANOS. Unique to the S52 is a bore of {{Convert|86.4|mm|in|1|abbr=on}} and stroke of {{Convert|89.6|mm|in|1|abbr=on}} 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.^[16][17]

The S52 produces {{Convert|240|hp|kW|0|abbr=on}} at 6,000 rpm and {{Convert|236|lbft|Nm|abbr=on}} of torque at 3,800 rpm.^[18] 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)

See also

• BMW engines
• BMW M50
• BMW M54

References

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