And in the early and middle 1980s, Alfa Romeo incorporated this technology into their road cars to enhance their performance and to comply with stricter emission controls.

So, similar design to the earlier and famous Alfa Romeo Twin Cam engines, but with narrower valve angle and double ignition on this model.

When new, these engines were notable for their high efficiency as demonstrated by the BMEP (brake mean effective pressures) exerted upon the piston crowns.

There is no room for a centrally positioned spark plug due to 2-valve design which uses rather large 44 mm diameter inlet valve on the 2.0 engine.

However the engine is able to idle smoothly in very lean conditions (up to 18:1 AFR), this suggests the addition plug is here to improve combustion efficiency under light loads.

The next generation Alfa fours, the JTS engines lost the second plugs gained direct injection and increased performance.

The engines also incorporate two other devices to enhance the performance under operation, the Camshaft Phase Variator and the Variable Intake Length Control (or Modular Inlet Manifold in Alfaspeak) on the later (plastic cam cover) 1.8- and 2.0-litre versions.

Where both these variable systems are deployed they are controlled in tandem by the Bosch Motronic Engine Management ECU in response to rpm, load, and throttle position.

At maximum torque speed the control unit sets the "open" phase: cam advanced by 25°, inlet casing long ducts (Only 1.8/2.0 TS).

At the maximum power speed the control unit sets the "closed" phase: cam in normal position, inlet box short ducts.

At idle speed the control unit sets the "closed" phase: cam in normal position and inlet box short ducts.

In the other engine operating conditions, the control unit selects the most suitable configuration to optimise performance - consumption - emissions.

The Alfa Romeo Modular Inlet Manifold is a variable intake system fitted to the later CF2 1.8 and 2.0 litre Twin Spark engines.

The rpm band over which the pressure wave arrives at the open inlet valves and is able to assist in the cylinder filling is set by the length of the runner and is a relatively narrow.

Symptoms are a slight loss of performance and a diesel type rattle from the top of the engine, which appears at startup and gradually lasts for longer.