X25XE

The C20XE Engine with 'Vauxhall' spark plug cover

The C20XE is a DOHC, inline 4 cylinder Family II, General Motors engine. It has a capacity of 1998 cc (2.0L) and develops 110 kW (150 PS; 148 bhp).

The C20XE came into production as an evolution of the 20XE engine. Incidentally, the 20XE engine was a further development of the 1987 model 8v 20NE engine. The 20XE(Bosh Motronic ML 4.1) first saw the light of day in 1987 with the launch of the Opel Kadett GSI 16v, introducing 16 valve technology and Knock Sensors to Opel/Vauxhall lineup. In 1988 the C20XE was introduced, with a 150 hp (110 kW) output compared to the earlier 20XE's 157 hp (117 kW). This was due to new emission standards, which forced manufacturers to specify their cars with a catalytic converter and a lambda sensor - this requirement permitted the fitment of a new generation of Engine Management Systems(Bosch Motronic 2.5).

The C20XE engine featured in many General Motors vehicles including some models of the Vauxhall/Opel Astra/Kadett E and the Vauxhall/Opel Calibra/Cavalier/Vectra. Enthusiasts commonly refer to this engine as the 'Red Top' (or just 'XE') because of the appearance of the red L-shaped spark plug cover.(This was red, but black colours are available, and the rocker cover was only available in silver). At the time of its launch, this engine was something of a milestone unit in Europe and was widely used in motorsport in many specialist race versions. It is still revered and sought after by enthusiasts today nearly two decades later. A version of the engine also appeared in Lada cars in the late 1990s.

The C20XE served as the base for the turbocharged C20LET, which appeared in versions of the Vauxhall Cavalier/Opel Vectra and the Vauxhall/Opel Calibra. The C20LET was identical on the surface, apart from a black plastic plenum/'top hat' shroud with a 'turbo' script. This version features forged, lower compression Mahle pistons, and offers a 34% increase of power (204 PS) over the C20XE.

Some versions of the engine implemented switchable Traction Control (commonly included in the early Astra GSi models). The inlet had a secondary throttle valve sandwiched underneath the primary throttle body. This is closed by a motor/arm assembly when the traction control ECU senses loss of grip/spin at the wheels. The engine was also equipped with a different Throttle Position Sensor (six pin, as opposed to three), and a different Coolant Temperature Sensor (which was black, as opposed to the normal light blue colour).

In its last version before production ended, the C20XE came with a new engine management system which included a distributorless ignition system, namely Bosch Motronic 2.8. The last version was called C20LN (Low Noise) and has a stronger engine block. The engines that appeared in the early 90's also swapped the cast metal spark plug cover for a cheaper (and less regarded) plastic version.

The C20XE evolved into the X20XEV(1994) with 136 hp (101 kW) and taking on the GM Ecotec name and finally it evolved into the X20XER(1999).

The 20XE has now evolved into a large family of GM 16v engines, one of which is a 2.2L 16v chain driven engine found in many GM brands, including Saab, Pontiac, Saturn, Chevrolet, Oldsmobile. It was borrowed to Fiat and Alfa Romeo, for the Croma and the 159 respectively.

All of the 2 litre engine of this era share the same cast iron engine block with the exception of the oil return for the turbo on the C20LET.

Origin

The engine was designed by Dr Fritz Indra, who was head of Advanced Engine Development for Opel in Germany from 1985 to 1989. The engine was originally intended for race application, hence Cosworth's involvement.

'COSCAST' (Early) and GM (Later) head differences

The C20XE engine's heads came in two notable forms. The original versions that appeared for a number of years in the Astra GTE, Calibra and Vauxhall Cavalier/Opel Vectra from 1988 to 1991 were cast by Cosworth. These are usually more sought after, due to their superior casting qualities, over the GM version which was introduced some time in 1991 (appearing with the Astra GSi). One of the alleged qualities of the 'COSCAST' head is its inherent resistance to porosity; this was achieved by eliminating the presence of tiny air bubbles during the casting process. The Coscast head can be identified by a 'Coscast' logo which is stamped under the 3rd exhaust port. The GM head was manufactured by Kolben-Schmidt and featured different oil/water galleries, which required a pair of welsch plugs to be pressed in at either end. Incidentally, the presence of welsch plugs proved to be the sole means of identification for a GM manufactured head. A reinforced version of the GM head became available in the later years of the C20XE; however, these reinforcements meant that it had smaller inlet/exhaust canals than the other two.

Since an engine's oil pressure is much higher than its coolant pressure, oil in a porus head has a tendency to gradually seep into the cooling galleries. A typical symptom of a porous head is usually a 'mayonnaise'-like substance in the coolant (residing on the cap). However, symptoms of a porous head have a tendency to vary, depending on the degree of porosity. Many C20XE operators have described the symptom as a curry-like residue or in more severe cases, a thick brown sludge. During the porous head debarcle, GM faced bankruptcy - therefore dealers failed to recall affected models. However, as a result, many businesses now specialise in the repair of porous GM C20XE/LET heads - by either sleeving the affected gallery or by injecting a polymer based substance into the porous region. Typically, the amount of cylinder heads that were reportedly porous remained relatively low.

The early engines used round tooth cambelts, the later used square (with a plastic pre-tensioner). There are also subtle differences between the crankshaft, and visible difference in the pattern of the SFi airbox.

Motorsport

The C20XE has seen extensive use in motorsport. Typical uses for the engine have ranged from hillclimb events, to open wheel racing categories. Despite its age, it remains the powerplant of choice for many Formula 3 teams and has most recently found acclaim in the Australian F3 scene where Tim Macrow, the 2007 Australian F3 champion, drove an Opel-Spiess powered car to claim victory. Tuned by Spiess, an F3 grade C20XE is easily capable of producing 250 bhp (190 kW) in its naturally aspirated form. Many aftermarket tuners have further developed the C20XE for racing purposes. Recently, SBD Motorsport, an aftermarket tuning company based in the UK, developed a C20XE unit with a power output in excess of 290BHP. Typically, the SBD built engines have seen use in Westfield and Caterham vehicles competing in various hillclimb events. The C20XE is currently used by the Chevrolet WTCC (World Touring Car Championship) team and the new Lada WTCC team. The engine is an option in Westfield kitcars.

Technical information

The breakdown of the engine name is as follows:

• C - Exhaust Emissions Level: ECE R 83 A
• 20 - Displacement: 2 litre
• X - Compression Ratio Threshold: X = 10.0-11.5:1
• E - Mixture System: Electronic Fuel Injection

The engine produces 150 bhp (112 kW; 152 PS) at 6,000 rpm, with a low optimum specific fuel consumption of 232 g/kWh which is equivalent to a maximum efficiency of 37 per cent; a better efficiency than some of the diesel engines that were available at the time of its release. The valves are set at 46 degrees and are accompanied by pistons with shallow valve pockets - thereby eliminating the need for a shorter con rod hence, allowing a suitable compression ratio to be achieved. Long spark plugs are used and positioned concentric to the cylinder. Incidentally, the engine has a square bore/stroke and shares piston dimensions with the Bugatti Veyron (86mm x 86mm).

Engine	C20XE
No Of Cylinders	4
Configuration	Inline/Straight
Displacement	1998 cc (121.88 cu in)
Bore (mm)	86.0
Stroke (mm)	86.0
Power	150 bhp (111.9 kW; 152.1 PS)/6000 rpm
Torque	196 N·m (145 lb·ft)/4800 rpm
Compression ratio	10.8:1
Engine management	Bosch Motronic 2.5/Bosch Motronic 2.8
Idle speed rpm	800-900
Max rpm	6800
Firing order	1-3-4-2

List of cars fitted with C20XE

Model	Years	Market
Opel Calibra 16V	1989-1994	Europe, Australia
Opel Kadett E, GSI/GTE	1988-1992	Europe - Germany, Ireland
Opel Vectra A, GTE	1988-1995	Europe, New Zealand
Opel Astra F	1991 - 1996	Europe, Australia
Vauxhall Calibra 16V	1989-1994	UK
Vauxhall Astra Mk 2, GTE	1988-1992	UK
Vauxhall Cavalier Mk 3, GSi, SRi	1988-1995	UK
Vauxhall Astra Mk 3, GSi	1991 - 1994	UK
Lada 110	1996 -	Europe, Russia
Chevrolet Vectra GSi	1993 - 1996	Brazil
Holden Commodore	1988-1991	Australian export to New Zealand, Singapore, sold strictly as the Holden Berlina in those markets

References

el:C20xe nl:C20XE