The Ford Sigma is a small straight fourautomobileengine introduced in 1995 by Ford Motor Company. Its first evolution was sold as the Zetec-S (not to be confused with the trim level), then Zetec-SE and finally, in later years, renamed Duratec.[3] The last upgrade of the engine is named Duratec Ti-VCT. Conceived for Ford's smaller models, the motor was intended to replace the older HCS (a derivative of the even older Kent unit) and smaller capacity CVH units.
Introduction and production
As with the SHO V6 engine, development of the Zetec-S was a collaborative effort between Ford, Mazda and Yamaha.[1][2] The engine's sound profile was refined in Ford's acoustics center in Cologne-Merkenich, Germany.[1] Production of the Zetec-SE was carried out in the Ford Valencia Engine Plant, with Yamaha building the 1.7 L engine blocks in Japan.[1][2]
When the Zetec-SE debuted in 1995, it included many firsts, including 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 metalconnecting rods, which were quite exotic at the time. This feature makes the engine more challenging to rebuild at the end of its working life, since it is not possible to re-machine the bearing ladder as is done with a conventional cylinder block — the entire assembly has to be renewed. Despite this, engine tuners have found novel ways to increase the power of the unit through use of different valves and increasing the compression ratio of the engine through skimming of the cylinder head.
The engine first appeared in the Mk4 Ford Fiesta and the virtually identical Mazda 121 in 1.2 L (1,242 cc) capacity, with 1.4 L (1,388 cc), 1.6 litres (1,596 cc) and 1.7 L (1,679 cc) derivatives coming later.
Difference between Zetec-SE/Zetec-S/Duratec/Duratec Ti-VCT
1.6-litre Duratec engine with TI-VCT in a 2012 Ford Focus
The Sigma engine was introduced under the Zetec-S name; after the upgrade it was renamed to Zetec-SE, Duratec and Duratec Ti-VCT. The latest upgrade of Sigma is called Ecoboost 1.6 engine (Not to be confused with the smaller 1.0 or larger 2.0/2.3 engines)
The 1.7 L; 102.5 cu in (1,679 cc) engines uses a heavily modified 1.4 L engine block and features Variable Cam Timing on the inlet camshaft. This displacement has only been used in the Ford Puma. A 155 PS (114 kW; 153 hp) version of this engine was developed for the Ford Racing Puma with only 500 units built.
Zetec RoCam
In 2000, Ford of Brazil developed a cheaper version of the Zetec-SE engine, to compete with the classic Volkswagen EA827 engine series known locally as Volkswagen AP [pt] (from Alta Performance, "High Performance" in English) engine in Brazil. It is 8v SOHC instead of 16v DOHC and its block is made of cast 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 (Rollifinger 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 95 PS (70 kW; 94 hp) version was released for the Ford Fiesta, to compete with the 1.0 Turbo 16v 112 PS (82 kW; 110 hp) version of the Volkswagen Gol.
In 2001 the Zetec RoCam engine was introduced in Europe, but labeled as Duratec 8v, for the Ka and Fiesta. Later a 1.6-litre version was also released for the SportKa and StreetKa. The European versions of the engine are produced in the South Africa plant.
In October/2004 a newer bi-fuel version was introduced labeled "1.6 L Flex", capable of running on both petrol and ethanol, even mixed at any proportion. This version also featured a high compression ratio of 12.3:1 and "Compound High Turbulence" chambers, as used on the CHT engine. The 1.0 L Flex runs with a compression of 12.8:1.
Currently, this engine powers nearly all Brazilian Ford models – except those with 2.0 litre engines – in many different variants:
155 PS (114 kW; 153 hp) at 7000, 162 N⋅m (119 lb⋅ft) at 4500
1999–2000 Ford Racing Puma 1.7
Current use
The Ford Sigma engine was produced at Bridgend Ford in Wales, U.K. until September 2020 and at Taubate Engine and Transmission Plant, Taubate, São Paulo, Brazil. Today the Sigma engine is used as the basis for the four cylinder Ford Ecoboost 1.5 litre and 1.6 litre engines. A 110 bhp (82 kW; 112 PS) version was used by Morgan for their 4/4 Roadster coupled to a Mazda transmission from 2009 until the model was discontinued in 2018.[4]
1.25/1.4/1.6 L Sigma
These engines in the first generation Focus produced 75 and 100 brake horsepower (75 kW; 101 PS) respectively, but for MkII Focus the 1.4 variant was slightly modified and produced 80 brake horsepower (60 kW; 81 PS). Both engines have belt driven camshafts and Electronic Fuel Injection systems. They weigh 90 kilograms (198 lb).[5][6] The 1.6 Ti-VCT was introduced in 2004, it features Variable Cam Timing; this 115 brake horsepower (86 kW; 117 PS) version is used in MkII Focus. A new 105 brake horsepower (78 kW; 106 PS) or 125 brake horsepower (93 kW; 127 PS) EU5 version is used in the MkIII Focus, also a 1.6 L 120 horsepower (89 kW; 122 PS) version is used in Ford Fiesta Zetec-S. The Sigma is usually coupled to the Ford IB5 five-speed manual transmission.
Brazil
Recently the Sigma engine was present in modern Brazilian versions of the Fiesta, Focus and Ecosport (1.6 L TI-VCT version) and a 1.5 version was used by Ka. This engine was able to use the flex technology.
Power with ethanol:
1.5 L Sigma (non TI-VCT) — IB5+ manual transmission
In 2018 the Sigma engine was replaced in all Ford compact/subcompact cars to the newer and stronger "Dragon" engine, displacing 1.5 L with a 3-Cylinder layout and with a power output of 136HP.
Caterham usage
Some Caterham Cars use modified Ford Sigma engines[7] such as the Caterham Seven 270, which uses a tuned Sigma engine producing 135 horsepower (101 kW; 137 PS) at 6,800 rpm as a modern equivalent to the original Ford Kent Crossflow engine used in the Lotus 7 from 1957 to 1972.
Ford Sigma 1.6-litre overview Technical features:
a high level of running refinement and low emission levels
aluminium alloy cylinder block and head
cross flow cylinder head
structural aluminium oil-pan for increased engine stiffness
individual throttle bodies in place of the standard intake manifold
twin overhead camshafts each with five bearings
sequential multi-port fuel injection system
long life, glass fibre reinforced camshaft drive belt with automatic tensioner
state-of-the-art Twin Independent Variable Camshaft Timing (on Ti-VCT variant)
Code
Displacement
Bore x stroke
Power at rpm
torque at rpm
Compression
Ford Sigma 1.6
1.6 L; 97.3 cu in (1,595 cc)
79 mm × 81.4 mm (3.11 in × 3.20 in)?
125 PS (92 kW; 123 hp) at 6100
162 N⋅m (119 lb⋅ft) at 5350
11.0:1
150 PS (110 kW; 148 hp) at 6900
162 N⋅m (119 lb⋅ft) at 5600
Caterham Sigma 1.6 Ti-VCT EU4
115 PS (85 kW; 113 hp) at 6000
155 N⋅m (114 lb⋅ft) at 4150
SCCA Spec Racer
The third generation of the SCCASpec Racer, commonly known as the Gen3 was introduced in 2015,[8] and uses the 1.6 L Sigma engine. The engine is sold by SCCA Enterprises as a sealed unit.
Zetec-E comparison
The Zetec-SE has no common parts or design with the larger Zetec-E engines apart from the name. This gives rise to some confusion since it suggests that they are members of the same family when they are, in fact, completely different. Zetec-E units are mounted transversely with the inlet manifold at the rear, whereas the Zetec-SE units are mounted with the inlet manifold at the front.
Replacement
In 2012 Ford replaced the Sigma engine with a brand new 3-cylinder 1.0-litre EcoBoost engine for some markets and models. The new engine provides more power and torque with less fuel consumption and lower CO2 emissions.[9]
