In the early 1970s Opel announced a new DOHC engine project intended to be used in Formula 2 (F2).
The engine was designed in-house, and was unveiled in 1975.
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 2.0E 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).
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 Ascona 400, and later another 400 copies to homologate the 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.
In the early 1970s Opel announced a new DOHC engine project intended to be used in Formula 2 (F2). The engine was designed in-house, and was unveiled in 1975. 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 2.0E 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). 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 Ascona 400, and later another 400 copies to homologate the 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.
Opel cam-in-head engine