Open main menu

Opel cam-in-head engine

  (Redirected from Opel Cam-in-head engine)

The Opel cam-in-head engine (CIH) is a family of automobile engines built by former General Motors subsidiary Opel from 1965 until 1998. Both four- and six-cylinder inline configurations were produced. The name derives from the location of the camshaft, which was neither cam-in-block nor a true overhead camshaft. In the CIH engine the camshaft is located in the cylinder head but sits alongside the valves rather than above them. The overhead valves are actuated through very short tappets and rocker arms. The four-cylinder CIH was largely supplanted by the Family II unit as Opel/Vauxhall's core mid-size engine in the 1980s. A four-cylinder version of the CIH remained in limited production until 1998, and six-cylinder versions of the CIH until 1995.

Opel Logo 1987.svg Cam-in-head engine
Opel cih engine without valve cover.jpg
Production1965 - 1998
ConfigurationInline-4, Inline-6
  • Four-cylinders:
  • 1.5 L; 91.0 cu in (1,492 cc)
  • 1.6 L; 96.7 cu in (1,584 cc)
  • 1.7 L; 103.6 cu in (1,698 cc)
  • 1.9 L; 115.8 cu in (1,897 cc)
  • 2.0 L; 120.8 cu in (1,979 cc)
  • 2.2 L; 134.1 cu in (2,197 cc)
  • 2.4 L; 147.1 cu in (2,410 cc)
  • Six-cylinders:
  • 2.2 L; 136.6 cu in (2,239 cc)
  • 2.5 L; 151.9 cu in (2,490 cc)
  • 2.6 L; 158.3 cu in (2,594 cc)
  • 2.8 L; 169.9 cu in (2,784 cc)
  • 3.0 L; 181.1 cu in (2,968 cc)
  • 3.6 L; 220.6 cu in (3,615 cc)
Cylinder bore
  • 82.5 mm (3.25 in)
  • 85 mm (3.35 in)
  • 87 mm (3.43 in)
  • 88 mm (3.46 in)
  • 88.8 mm (3.50 in)
  • 92 mm (3.62 in)
  • 93 mm (3.66 in)
  • 95 mm (3.74 in)
Piston stroke
  • 69.8 mm (2.75 in)
  • 77.5 mm (3.05 in)
  • 85 mm (3.35 in)
Block materialCast iron
Head materialCast iron
Compression ratio9.0:1, 9.5:1, 8.2:1
TurbochargerGarrett T25 Twin-turbos (Lotus Carlton-Omega)
Fuel systemCarburettor, Fuel injection
ManagementBosch L-Jetronic, LE-Jetronic or Motronic
Fuel typePetrol
Oil systemWet sump
Cooling systemWater-cooled
Power output58–382 PS (43–281 kW; 57–377 hp)
Torque output174–568 N⋅m (128–419 lb⋅ft)

A diesel version of the CIH was also developed and appeared in the Opel Rekord D in 1972.


Although the camshaft is in the cylinder head, the CIH is not a true overhead camshaft design. Rather it can be thought of as a cam-in-block engine with a greatly shortened valve drivetrain. The camshaft is driven by a roller chain. Later versions used hydraulic tappets, which Opel pioneered for mass market production. The cylinder head is a non-crossflow layout. This led to lowered fuel economy but was considerably cheaper to manufacture. The head and block are both made from cast iron. The CIH engine was oversquare, with the original three versions having a stroke of only 69.8 mm (2.75 in). Later engines of over 2000 cc received longer strokes; up to 77.5 mm (3.05 in) for the 2.2 and 85 mm (3.35 in) for the 2.4 (also used for the 3.6 litre inline-six version).

While an improvement over a cam-in-block engine, the advantages over an OHC design were limited. For one, the lower head allowed for a correspondingly lower bonnet line. The CIH engine was also lighter (negated somewhat by the use of a cast iron head) and was expected to require less maintenance than an OHC design.[1]

Four-cylinder versionsEdit

1.5 litre I4Edit

This is the smallest of the three original CIH engines introduced simultaneously. A 82.5 mm × 69.8 mm (3.25 in × 2.75 in) bore and stroke gives a 1.5 L (1,492 cc) displacement. As with most of Opel's engines of the 1960s and 1970s, versions optimized for low and high octane fuel were offered, with the 15N for normal and the 15S for super. Power ranged from 58 to 60 PS (43 to 44 kW) for the 15N while the rare 15S in the export-only Kadett B 1.5 has 65 PS (48 kW).

This engine was imported by Daewoo's predecessor companies GM Korea and Saehan Motors and went on to be built in South Korea by Daewoo beginning around 1983. The automobile taxation system of South Korea greatly favours engines of less than 1.5 litres displacement. It was installed in the Saehan Camina, the Saehan Gemini/Daewoo Maepsy series, and in the Saehan/Daewoo Royale (until 1987). 1.9 and 2.0 litre versions were also built in Korea.


1.6 litre I4Edit

The 1.6 L (1,584 cc) version has a 85 mm (3.35 in) bore and the same 69.8 mm (2.75 in) stroke as most CIH fours. It was introduced in September 1970 with the all new Opel Manta A and then, seven weeks later, in the Opel Ascona A. As with the 1.5 litre, a 16N for lower octane fuel and a more powerful 16S for higher octane fuel were offered. Power outputs were 68 and 80 PS (50 and 59 kW) at the time of introduction, but dropped to 60 and 75 PS (44 and 55 kW) respectively in early 1975 when tighter pollution controls were introduced. From 1975 there was also a still-cleaner A16S version with 69 PS for some markets.


1.7 litre I4Edit

The 1.7 L (1,698 cc) CIH was another of the original three introduced. Bore is 88 mm (3.46 in) while stroke remains 69.8 mm (2.75 in). The 1700 was only ever available in carburetted form, for either normal or super petrol with corresponding power outputs. Power outputs are 60 and 75 PS (44 and 55 kW) for the original 17N and 17S versions. The output of the 17N went up to 66 PS (49 kW) in 1969, and then back down to the original 60 after the compression was lowered in 1975. The 17S received a new carburettor setup in 1972 when the Rekord D was introduced, and power rose to 83 PS (61 kW). The 17S was popular in export markets like Italy and Greece where owners' costs were directly linked to engine displacement.


1.9 litre I4Edit

A 19S engine in a 1970 Opel GT

The 1.9 L (1,897 cc) CIH was the largest of the original three introduced. Bore is 93 mm (3.66 in) while the stroke remains 69.8 mm (2.75 in). The 1900 was available in carburetted or fuel injected forms, for either normal or super petrol with a variety of power outputs. An N version was a later addition. Output is 90 PS (66 kW) for the original 19S. There was also the 19HL (Hochleistung, or "high power"), introduced in 1967 for the sporty Opel Rekord Sprint and Kadett Rallye Sprint models. This version has 106 PS (78 kW), compared to 97 PS (71 kW) for the slightly more powerful 19SH only fitted to the Rekord. The 19SH lost some power in 1975, down to 90 PS (66 kW) and the new 19N was introduced to replace the discontinued 17S; like the 17S it offered 75 PS (55 kW) but used cheaper gasoline and more relaxed driving characteristics. The 1900 is the most common version in the CIH family, available in the most versions and with the longest production time.

The 19E was the first of the CIH four-cylinders to receive fuel injection. It first appeared in the Manta GT/E in March 1974, with 105 PS (77 kW). There is also a low-powered version of the 19N (the A19N) with 69 PS (51 kW) which was mostly fitted to the Opel Rekord E, and a special low emission version for the Swedish and Swiss markets called the S19S which develops 88 PS (65 kW).


2.0 litre I4Edit

The 2.0 L (1,979 cc) CIH was based on the 1.9 litre version, with the bore expanded to 95 mm (3.74 in) while the stroke remained 69.8 mm (2.75 in). Unlike the earlier 1.9, the 2.0 received hydraulic tappets. Developed to counteract the diminishing outputs which resulted from stricter emissions rules, the 2.0 was available in carburetted or fuel injected forms, for either normal or super petrol with a variety of power outputs. Output of the original 20S, presented in September 1975, is 100 PS (74 kW) at 5200 - 5400 rpm. This was soon followed by the fuel injected 20E version, with 110 PS (81 kW), and the slightly more powerful 115 PS (85 kW) 20EH fitted to the Kadett 2.0 GT/E. This received the Bosch L-Jetronic system, until it was replaced by the updated LE-Jetronic towards the end of 1981. A 90 PS (66 kW) 20N version appeared in August 1977. There are also two special low-emission versions for the Swedish and Swiss markets, called the S20S and S20E, with slightly less power than their dirtier counterparts.


2.2 litre I4Edit

The 2.2 CIH engine was fuel injected or carbureted and was produced from 1984 through 1987. It was used in the Opel Rekord E, Opel Monza A2 and Opel Senator A2.

2.4 litre I4Edit

The 2.4 L was the final four-cylinder CIH version. It was first used in the Omega A in the German market, while the 2.0 L Family II unit was the top spec four-cylinder engine option for the Omega in most markets outside of Germany. Its final application was in the Frontera SUV.


400 I4 / Cosworth KAAEdit

Opel Manta 400 engine

In the early 1970s Opel announced a new DOHC engine project intended to be used in Formula 2 (F2).[2] The engine was designed in-house, and was unveiled in 1975.[3] Homologated in Group 4 rallying, the engine suffered a series of failures, which prompted Opel to contact Cosworth engineering.

With the basic design of the engine already frozen, Cosworth's work included revising the port and camshaft shapes and extensive development work with a focus on reliability. Based on a diesel CIH block with bore and stroke of 95.2 mm × 85 mm (3.7 in × 3.3 in), the engine displaced 2,420 cc (147.7 cu in).[4] Compression was 11.5:1. Power and torque outputs were 190.2 kW (255 bhp) at 7200 rpm and 28 kg⋅m (202.5 lb⋅ft) at 5000 rpm. Air and fuel were fed by twin 48DCOE Weber carburettors, and the engine received a dry sump.

As a result of their successful work on the racing version of the engine, Cosworth was awarded the contract to build the 400 copies of the engine required to homologate the Opel Ascona 400, and later another 400 copies to homologate the Opel Manta 400. Cosworth also consulted on the fuel injection system that replaced the carburettors on the road-going version. The detuned 16 valve engine was rated at 107.4 kW (144 bhp) at 5200 rpm and 21.4 kg⋅m (155 lb⋅ft) at 3800 rpm.

Six-cylinder versionsEdit

The straight-six CIH was used in the largest Opel and Vauxhall cars from 1968 to 1993. It was succeeded by the Opel-designed 54° V6 in the mid-1990s.

Most of these engines were single cam-in-head engines with chain-driven camshafts. In the 1960s and 1970s, all came with carburetors, but were later fitted with Bosch fuel injection in the early 1980s. Some later six-cylinder family members received true DOHC multivalve cylinder heads.

2.2 litre I6Edit

This is the rarest of the inline-sixes. At only 2.2 L (2,239 cc), it shares its 82.5 mm (3.25 in) bore and 69.8 mm (2.75 in) stroke with the 1.5 litre "four". It debuted in December 1966. With 95 PS (70 kW) it had only marginally more power than the 1900S, at a substantial weight and cost penalty. It was dropped from the Rekord C following the introduction of the six-cylinder Commodore line in February 1967, and was discontinued entirely towards the end of 1968, when the 1969 models were introduced.


2.5 litre I6Edit

A 1980 25S engine in a Commodore C

The modern Opel straight-six line began in 1968 with the 2.5 L (2,490 cc) 25S unit used in the Opel Commodore. Still a 12-valve engine, it had a very oversquare 87 mm × 69.8 mm (3.43 in × 2.75 in) bore and stroke. 9.5:1 compression and a single carburettor produced 117 PS (86 kW) and 174 N⋅m (128 lb⋅ft), while 9.0:1 compression and dual carbs produced 132 PS (97 kW) and 186 N⋅m (137 lb⋅ft).


2.6 litre I6Edit

At the introduction of the 24v DOHC engine in the Senator/Carlton/Omega, the 2.5 was enlarged to 2.6 litres. With a reworked 12-valve cylinder head and RAM induction it now produced 150 PS (110 kW; 148 hp). This engine was also fitted to southeast Asian export market versions of the Holden VP, VR, and VS Commodores between around 1992 and 1997. These cars were usually labelled "Opel Calais".

2.8 litre I6Edit

The 2.8 was introduced in the first Commodore model. The carburetted version can also be found in the Monza and Senator, while the second Commodore was also available with a fuel-injected version producing 150 PS (110 kW; 148 hp).

3.0 litre I6Edit

The 3.0 L (2,969 cc) version was introduced in 1977 alongside the fuel-injected 2.5. The carburetted version had 150 PS (110 kW; 148 hp), while the more popular fuel injected 3.0 version produced 180 PS (132 kW; 178 hp) and 248 N⋅m (183 lb⋅ft) in the Opel Monza GSE and Opel Senator 3.0E, as well as their Vauxhall-badged equivalents, the Royale and later Senator. Bore was increased to 95 mm (3.74 in), but the stroke remained at a very short 69.8 mm (2.75 in).

The 1986 Opel Omega 3000 / Vauxhall Carlton GSi introduced the latest version of the 3.0. The injected engine produced 180 PS (132 kW; 178 hp) and 240 N⋅m (177 lb⋅ft). Amongst the changes were larger valves and a switch in engine management to Bosch Motronic. This engine later found its way into the Senator and Omega 3.0i.

In 1989, a DOHC 24-valve version with a variable length intake manifold was introduced, with power increasing to 204 PS (150 kW; 201 hp) and 270 N⋅m (199 lb⋅ft).

The Omega Evo had a special Irmscher version of the 24-valve engine with an uprated head and forged internals producing 230 PS (169 kW; 227 hp).

3.6i I6Edit

Irmscher made a 3.6i 12v engine and fitted this 36E coded engine into the Monza E and Monza GSE models. In the UK some of these engines, originally designated for Opel Monzas, found their way into Vauxhall Senator Bs instead.

In late 1987 newer, more environmentally friendly versions of this engine with tuning by Irmscher were installed in versions of the Omega A/Mk3 Carlton and Senator B models. These later units, with engine codes 36NE, C36NE, and C36NEI, produced (200 PS (147 kW; 197 hp)), less than the first 207 bhp (154 kW) engines that were used to power the earlier Opel Monzas. 24-valve versions of the 3.6 were also developed.

4.0i I6Edit

4.0i 24v DOHC versions were made by two well-known German tuning companies, Irmscher and Mantzel. The 4.0 L (3,983 cc) Irmscher engine had a C40SE code and was the only one of these two engines to use a specially cast engine block as part of this increased capacity engine conversion. Mantzel's 4.0 L (4,032 cc) engine used an M4024V code number and modified standard 30NE/C30NE/C30LE/C30SE coded Opel engine blocks for its 4.0 litre conversions. The Irmscher version, producing 272 PS (200 kW; 268 hp), was an option in the Opel Omega Evolution 500 models.

Lotus 3.6 Twin-turbo I6Edit

The Lotus Carlton-Omega introduced a 3.6 L; 220.6 cu in (3,615 cc) version of the engine achieved by increasing the stroke to 85 mm (3.35 in) while keeping the bore at 95 mm (3.74 in). Lotus added Garrett AiResearch T25 twin-turbochargers and an air-to-water intercooler along with a compression ratio of 8.2:1 and custom fuel injection. The turbos were arranged in parallel, each fed by and feeding three cylinders. The company reportedly experimented with a variety of forced induction schemes, including paired supercharging and turbocharging and sequential turbos, before settling on two small turbos for quick spool-up. The Lotus engine produced 382 PS (377 bhp; 281 kW) at 5,200 rpm and 568 N⋅m (419 lb⋅ft) at 4,200 rpm.[5]

Diesel versionsEdit

Diesel versions of the CIH engine family began to appear in the early 1970s, and progressively became more popular in the following two decades. These compression-ignition engines were used in Opel's medium or high range cars and were designed for maximum fuel economy and long life, with performance a secondary consideration. All CIH Diesels were inline four-cylinder engines. They were offered in three displacements, listed below.

2.0 litre Diesel I4Edit

The 2.0 litre saw wider use at the end of the 1970s, but in some markets, including Italy, it had appeared in 1974. This engine was created by reducing the earlier 2.1 litre diesel unit's bore from 88 mm (3.5 in) to 86.5 mm (3.4 in), resulting in a bore and stroke of 86.5 mm × 85 mm (3.4 in × 3.3 in), and a total displacement of 1,998 cc (121.9 cu in). It was built only in naturally aspirated form and in a single variant, the 20D, whose compression ratio was 22:1. Fuel supply was provided by Bosch injection. The maximum power supplied by this engine was 57 hp (42.5 kW) at 4400 rpm, while the maximum torque was 117 N⋅m (86.3 lb⋅ft) between 2000 and 2200 rpm. This engine was available in:

  • Opel Rekord D 2.0 D (1974-77 in select markets, including Italy)
  • Opel Rekord E 2.0 D (1977-81)
  • Opel Ascona B 2.0 D (1978-81)

2.1 litre Diesel I4Edit

The CIH 2.1 litre diesel engine appeared in 1972 as an engine option in the Opel Rekord D range. This engine has the distinction of marking the debut of the Rüsselsheim company in the production of diesel engines. The 2.1 litre had bore and stroke dimensions of 88 mm × 85 mm (3.5 in × 3.3 in), for a displacement of 2,068 cc (126.2 cu in). It was built only in naturally aspirated form and in only one variant; the 21D. The compression ratio and the fuel injection system were the same 22:1 and Bosch system used later in the 20D. Power and torque outputs were different, but only slightly: the 21D engine was capable of delivering a maximum power of 60 hp (44.7 kW) at 4400 rpm, with a maximum torque of 120 N⋅m (88.5 lb⋅ft) at 2500 rpm. It appeared in:

  • Opel Rekord D 2.1 D (1972-77)
  • Opel Rekord E 2.1 D (1977-81)

2.3 litre Diesel I4Edit

The CIH 2.3 litre diesel engine was introduced in 1979 and by the 1980s had become a staple of Opel's automotive production for high-end diesel models. This engine resulted from the reworking of the 2.1 litre diesel engine, which was also slated for replacement. The bore was enlarged from 88 mm (3.5 in) to 92 mm (3.6 in), while the stroke remained unchanged at 85 mm (3.3 in). As a result displacement rose to 2,260 cc (137.9 cu in). Unlike the other two CIH diesel versions, the 2.3 litre was offered in several variants, some of which used forced induction in either a turbocharged version or the very rare Comprex configuration. Variants of the 2.3 litre version are listed below.


With this code the debut variant of the 2.3 litre diesel engine is indicated. It is a naturally aspirated engine with a compression ratio of 22:1 and Bosch fuel injection. Some features were taken from the previous naturally aspirated 2.1 litre. Maximum power supplied by this engine was 65 hp (48.5 kW) at 4200 rpm, with maximum torque of 127 N⋅m (93.7 lb⋅ft) at 2500 rpm. This engine appeared in:

  • Opel Rekord E 2.3D (1979-1986)


This variant was produced for a short period of time; from 1984 to 1986. It is a supercharged variant, but instead of the classic turbocharger it used a device called a Comprex, which saw some sporadic use in the 1980s. The compression ratio was 23:1 and the fuel system was Bosch injection. Maximum power produced by this engine was 95 hp (70.8 kW) at 4200 rpm, with a peak torque 195 N⋅m (143.8 lb⋅ft) at 2200 rpm. It was used in:

  • Opel Senator A 2.3 Comprex D (1984-1986)


This variant was also introduced in 1984 and was also supercharged, but unlike the 23DK unit, used a traditional turbocharger. The 23DT is Opel's first turbodiesel engine. As in the 20DK Comprex variant, the compression ratio is 23:1, and the injection system is by Bosch. The turbocharger used was a KKK K24. Maximum power was 85 hp (63.4 kW) at 4200 rpm, while maximum torque was 192 N⋅m (141.6 lb⋅ft) between 2200 and 2400 rpm. This engine found use in:

  • Opel Rekord E 2.3 TD (1984-86)
  • Opel Senator A 2.3 TD (1984-86)


This variant is a naturally aspirated model introduced in September 1986, a few months after the launch of the Opel Omega A which the engine was developed for. Compared to the earlier naturally aspirated 23D, the compression ratio was raised from 22:1 to 23:1, while the injection system has remained unchanged. Maximum output was increased from 65 to 73 hp (48.5 to 54.4 kW) at 4400 rpm, with maximum torque of 138 N⋅m (101.8 lb⋅ft) at 2400 rpm. From 1989 on the engine had a catalytic converter.

  • Opel Omega A 2.3 D (1986-93)


This model was a 2.3 litre turbodiesel that resulted from an update of the previous 23DT. The new engine did not include major changes, but provided more horsepower, reaching 90 bhp (67.1 kW) at 4200 rpm and reaching a maximum torque of 190 N⋅m (140.1 lb⋅ft) at 2200 rpm, just below that of the 23DT engine.

  • Opel Omega A 2.3 TD (1986-1988)


This model is the last CIH Four diesel engine produced by Opel. It is an update of the 23YDT unit which it replaced beginning in August 1988. Compared to the previous version, the turbocharger was changed from a KKK K24 to a K14 from the same manufacturer. This engine delivered a maximum power of 100 hp (74.6 kW) 4200 rpm and was installed in the following models:

  • Opel Omega A 2.3 TD (1988-93)
  • Opel Frontera A 2.3 TD (1991-95)

While in the first model above maximum torque was 218 N⋅m (160.8 lb⋅ft) between 2000 and 2200 rpm, in the second it was just below 215 N⋅m (158.6 lb⋅ft) at 2200 rpm.


The CIH engine had a long competition career in both four- and six-cylinder forms. It won the 1966 European Rally Championship, with Swedish driver Lillebror Nasenius at the wheel of an Opel Rekord B. Crossflow cylinder heads for the CIH block were developed by a number of tuners such as Steinmetz, Mantzel, and Irmscher.[6] Some models received four-valve heads, such as the Manta 400 and the later 24-valve sixes in the Omega A and Senator B. The most powerful iteration was the 380 PS (279 kW; 375 hp) twin-turbo 3.6 litre C36GET used in the Opel Lotus Omega/Lotus Carlton.

A 4.0 litre version (C40SE) was also developed by Irmscher, and installed in the Opel Omega A and Senator B. These engines have a bore and stroke of 98 mm (3.86 in) and 88 mm (3.46 in) respectively, for an overall displacement of 4.0 L; 243.1 cu in (3,983 cc). Power is 272 PS (200 kW; 268 hp).


  1. ^ Matt (2013-05-03). "Technical Curiosities: Opel's Cam-In-Head Engine". Spannerhead. Retrieved 2013-12-07.
  2. ^ Robson, Graham (15 May 2017). Cosworth: The Search for Power (6 ed.). Veloce Publishing. pp. 84, 85. ISBN 978-1845848958.
  3. ^ Burr, Norman (1 October 2014). First Principles: The Official Biography of Keith Duckworth OBE. Veloce Publishing. p. 206. ISBN 978-1845845285.
  4. ^ Jones, James (1 September 2013). "Opel Ascona 400 & Manta 400 History by James Jones".
  5. ^ Hughes, Mark (March 5, 2006). "Lotus Carlton".
  6. ^ "The history of the development of the Opel CIH engine, 1966-1993". Customs and Classics. Archived from the original on 2013-05-29. Retrieved 2013-12-07.

Further readingEdit