THE SIX-CYLINDER engine in the VB-VK Commodores was designed in the 1960s and debuted in the EH Holden in 1963 (yeah, yeah, we know there might have been some in EJs…) so by the early 1980s, the all-iron, over-head valve engine was regarded as hoary old-tech. Holden’s update for the VC Commodore provided more efficient six-cylinder engines – officially XT5 but colloquially known as the Blue motors thanks to their colour – featuring hardware such as a counterweighted crank, better-breathing 12-port cylinder heads, two-barrel carburettor and two-branch exhaust systems. But even with the tweaks, the engine couldn’t operate on unleaded petrol (lead helps lubricate engine valves) so Holden – unable to afford to design its own new engine and with nothing available from other GM brands – had to find an unleaded-capable engine from another manufacturer. In early 1983 it signed a deal with Nissan in Japan for its forthcoming RB30E, an alloy-headed, overhead cam fuel injected 3.0-litre six with a turbo version, too. An RB20 2-litre was also available outside Australia. Despite being used in just one series for little more than two years, the VL Commodore and Calais became well-regarded, rather than considered parts-bin orphans.