The BMW M52 is a straight-6 DOHC petrol engine which was produced from 1994 to 2000. It was released in the E36 320i, to replace the M50. The BMW S52 engine is a high performance variant of the M52 which powered the American and Canadian market E36 M3 from 1996 to 1999. In 1998, the "technical update" (M52TU) upgrades included adding variable valve timing to the exhaust camshaft. The M52 was replaced by the M54 in the year 2000. The M52 and S52 engines were on the Ward's 10 Best Engines list from 1997 to 2000. Design In most markets, the M52 switched from the M50's cast iron engine block to a lightweight aluminium engine block. However, most 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, while other 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 M52TU ("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 version was introduced in 1994. Bore is and stroke is . The compression ratio is 11.0:1. Applications: 1994-1998 E36 320i 1995-1998 E39 520i M52TUB20 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 M52TUB24 2.4 L. For Thai market only. The bore is and the stroke is . M52B25 A version introduced in 1995. It produces . Bore is and stroke . The compression ratio is 10.5:1. Applications: 1995-1998 E36 323i 1995-2000 E36/5 323ti 1995-1998 E39 523i M52TUB25 The "technical update" in 1998 included double VANOS, which improved low rpm