The Ford Sigma is a small straight-4 automobile engine sold by Ford Motor Company as the Zetec-SE and by Mazda as the MZI. The engine was introduced in the mid-1990s and production continues through the present. Like the SHO V6 and SHO V8, the Sigma was designed with help from Yamaha. Intended for Ford's smaller models, it was intended to replace the older HCS and smaller capacity CVH units.
The Sigma Zetec-SE has no common parts or design with the larger Zeta Zetec engines apart from the name. This gives rise to some confusion since it suggests that they are members of the same family, but are in fact, completely different. Like the Zeta, the Sigma was later sold under the Duratec name.
This engine included many firsts, such as a plastic inlet manifold, a "ladder" style main bearing and crankcase assembly, and big-end bearing caps which are forged in one piece and subsequently split. It also incorporates powder metal connecting rods, which were quite exotic and notable at the time.
Zetec-SE first appeared in 1995, in the fourth-generation Fiesta and Mazda2 in 1.25 L (1242 cc) capacity, it grew to 1.4 L (1388 cc), 1.6 L (1596 cc) and 1.7 L forms to power the Ford Focus and Ford Puma.
The Zetec-SE is also sold by Ford Power Products as a crate engine as the ZSG Range. It is available in 1.4 L or 1.6 L sizes. Dimensions:
1.25 L (1242 cc) (71.9x76.5 mm)
1.4 L (1388 cc) (76x76.5 mm), 55 kW (74 hp) at 5000 rpm and 123 Nm (90 ft-lb) at 3500 rpm
1.6 L (1595 cc) (79x81.4 mm), 74 kW (99 hp) at 6000 rpm and 142 Nm (104 ft-lb) at 4000 rpm