Ford Sigma engine

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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 the virtually identical Mazda 121 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)
- Ford Fiesta
1.4 L (1388 cc) (76x76.5 mm), 55 kW (74 hp) at 5000 rpm and 123 Nm (90 ft.lbf) at 3500 rpm
1.6 L (1595 cc) (79x81.4 mm), 74 kW (99 hp) at 6000 rpm and 142 Nm (104 ft.lbf) at 4000 rpm

For the second generation Focus, launched in late 2004, the engine was known as the Duratec with the 1.4 L and 1.6 L units unchanged from before, but a new 1.6 L version with variable valve timing, known as Ti-VCT (Twin independent Variable Camshaft Timing), generating 115bhp was introduced - to replace the 1.8 Zetec-E unit as used in the original Focus.

Rather confusingly, this engine has been renamed "Duratec" for use in the Mk II Ford Focus for Europe, being available in 1.4 L and 1.6 L versions. This incarnation also spawned a 1.6 L derivative with variable valve timing, known by Ford as Ti-VCT (Twin Independent Variable Camshaft Timing).

Applications (all in the Ford Focus II (C307)):

1.4 L (80bhp)
1.6 L (100bhp)
1.6 L Ti-VCT (115bhp)

[edit] Zetec-Rocam

In 2000, Ford of Brazil developed a cheaper version of the Zetec-SE engine, to compete with the classic VW AP engines. It is 8v SOHC instead of 16v DOHC and its body is made of iron instead of aluminum. Also, its camshaft is driven by a chain instead of a belt. As a result this engine exhibits rougher behaviour, producing more vibration and noise.

On the other hand, it has a superb torque output thanks to the addition of the Rocam (Rollerfinger Camshaft) feature. It's also a much smaller engine than the SE version, which allowed it to be installed on the Ford Ka, replacing the Endura-E engine which by that time was considered underpowered and outdated.

The engine also featured a new patented process for the aluminum head production, which resulted in a better alloy than those produced in Spain and UK, and at a lower production cost.

In 2002 a supercharged 1.0 litre (95hp) version was released for the Ford Fiesta, to compete with the 1.0 turbo 16v (110hp) version of the VW Gol.

In 2003 the Zetec-Rocam engine was introduced in Europe, but labeled as Duratec 8v, for the SportKa, StreetKa and Fiesta. Later a 1.3 litre version was also released as an option for the standard model, but the European versions of the engine are produced in the South Africa plant.

In October/2004 a newer bi-fuel version was introduced labeled "1.6L Flex", capable of running on both petrol and alcohol, even mixed at any proportion. This version also featured "Compound High Turbulence" chambers, as used on the CHT engine.

Currently, this engine powers nearly all Brazilian Ford models - except those with 2.0 litre engines - in many different variants:

65hp 1.0L (Ford Ka)
95hp 1.6L (Ka Action, Ka XR)
66hp 1.0L (Ford Fiesta)
95hp 1.0L Supercharged (Ford Fiesta, Ford Ecosport)
98hp 1.6L (Ford Fiesta, Ford Ecosport)
103hp 1.6L (Ford Focus)
111hp 1.6L Flex (Ford Fiesta Sedan)

1.3 L Endura(1299 cc/79 in³) applications:

–present Ford Ka 1.3, 59 PS (58 hp/43 kW) and 77 ft·lbf (104 N·m)

1.6 L (1596 or 1597 cc/97 in³) applications:

–present Ford Ka 1.6, 94 PS (93 hp/69 kW) and 100 ft·lbf (136 N·m)
–present Ford StreetKa 1.6, 94 PS (93 hp/69 kW) and 100 ft·lbf (136 N·m)
–present Ford Fiesta 1.6, 99 PS (98 hp/73 kW) and 108 ft·lbf (146 N·m)
–present Ford Fusion (European) 1.6, 100 PS (99 hp/74 kW) and 108 ft·lbf (146 N·m)
–present Ford Focus 1.6/1.6 100, 99 PS (98 hp/73 kW) and 111 ft·lbf (150 N·m)
–present Ford Focus C-MAX 1.6 100, 99 PS (98 hp/73 kW) and 111 ft·lbf (150 N·m)
–present Ford Focus 1.6 115, 113 PS (111 hp/83 kW) and 114 ft·lbf (155 N·m)
–present Ford Focus C-MAX 1.6 115, 113 PS (111 hp/83 kW) and 114 ft·lbf (155 N·m)