The 2.0-litre 16-valve Twin Spark engine of the 2.0 TS model was based on the Fiat SuperFIRE-family block, featuring an Alfa Romeo-developed cylinder head with two spark plugs per cylinder. Variable inlet cam timing, which allowed for 25 degrees of variation, was designed to improve torque and give a more linear power delivery. In addition, this engine has two belt driven balance shafts rotating at twice the engine speed, to eliminate engine vibrations. The base 1.8-litre engine did not feature balance shafts. The TS was the best-selling version of the GTV and Spider. CF2 and CF3 engines have plastic valve cover and variable-length intake manifold.