Complex sentence: An interesting variant of the 2.7-liter M20 engine was Alpina's C2, introduced in February 1986 in uncatalyzed C2/1 form.
Split into simpler sentences: An interesting variant of the M20 engine was Alpina's C2. The larger yet 2.7 liter unit was introduced in February 1986 in uncatalyzed C2/1 form.