While the earliest engines use mechanical lifters, later versions use hydraulic tappets, which Opel pioneered for mass market production in the Family II unit which ultimately replaced the CIH.

The CIH engine was expected to require less maintenance than an OHC design and was also lighter, albeit negated somewhat by the use of a cast iron head.

Opel developed their own crossflow head for the CIH block, and tested it in the experimental GT-2 of 1975 with the intent of installing it in the production model.

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.

The automobile taxation system of South Korea greatly favours engines of less than 1.5 litres displacement.

From 1975 there was also a still-cleaner A16S version with 69 PS for some markets, this specific model also had a forged crank with 8 crankweights.

In the larger Rekord, the 17S was popular in export markets like Italy and Greece where owners' costs were directly linked to engine displacement.

The 1900 was available in carburetted or fuel injected forms, for either normal or super petrol with a variety of power outputs.

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.

Applications: In the early 1970s Opel announced a new DOHC engine project intended to be used in Formula 2 (F2).

Air and fuel were fed by twin 48DCOE Weber carburettors, and the engine received a dry sump.

Cosworth also consulted on the fuel injection system that replaced the carburettors on the road-going version.

Some later six-cylinder family members received true DOHC multivalve cylinder heads.

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.

With 9.2:1 compression and Bosch D-Jetronic (Commodore A & B), later L&LE-Jetronic, injection produced 150 PS (110 kW) and 186 N⋅m (137 lb⋅ft).

This engine was also fitted to southeast Asian export market versions of the Holden VP, VR, and VS Commodores between around 1992 and 1997.

The carburetted 30S version had 150 PS (110 kW; 148 hp), while the more popular fuel injected 30E 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.

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).

[10] Crossflow and multi-valve cylinder heads for the CIH block were developed by a number of well-known German tuning companies such as Irmscher, Mantzel, Risse, and Steinmetz.

[11] These heads and other parts were used for rallying, and the changes were later copied by Opel for factory backed cars.

[3][11] 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).

Diesel derivatives of the CIH engine family first appeared in September 1972, 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.

They received a stiffened block, longer strokes, and a single overhead cam head, the latter two making this engine considerably taller than the petrol CIH units.

[12] Most installations required a noticeable bump in the bonnet to fit the taller diesel engines.

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.

Compared to the previous version, the turbocharger was changed from a KKK K24 to a K14 from the same manufacturer and added air-to-air intercooler.

It won the 1966 European Rally Championship, with Swedish driver Lillebror Nasenius at the wheel of an Opel Rekord B.

In 1969 Virgilio Conrero became the official director of Opel's rally team, with responsibility for preparing the cars and selecting drivers.

[16][17] The car was a custom-bodied single-seat Opel GT with a turbocharged version of the 2.1 L OHC diesel engine developing 95 PS (70 kW).