M52 Engine - The heard of my 323i
M52/M52TU Straight 6 DOHC 24V with Single VANOS/Straight 6 DOHC 24V with Double VANOS. 1996-1999.
Iron Block in US, Alloy Block in Europe . 118kg 260lbs (alloy) 140kg 308lbs Used in E39 520i/523i/528i, E36 323i/328i, E38 728i, Variation of this was used in late US E36 M3. 2.0 (150bhp), 2.5 (170bhp), 2.8 (193bhp), 3.2 (240bhp) Sometimes referred to as S52US.
Engine shares more common parts with M52 than Euro S52, but is a motorsport engine.
reference from: http://www.bimmerforums.com/engine_faq/