Blown beast

Even if the stillborn twin-turbo Commodore ZB Supercar had hit the track, it wouldn’t have claimed the honour of being the rst forced-induction six-cylinder factory racing Holden. The early ’70s rallycross boom attracted the interest of Harry Firth, who reckoned a warmed-over LC Torana would be a pretty good thing – just as they were proving in rallying generally. The rallycross technical rules were fairly free and easy, so the HDT boss started with a stock LC GTR and then went to town: he tted a Wade K200 supercharger with twin 2-inch SUs to the side of a 186 he had beefed up with a steel crankshaft and better pistons, gudgeon pins and conrod bolts. It ran the stock GTR camshaft, so it wasn’t a high-revving engine, but with some careful work on the head, the use of nimonic exhaust valves, and twin SUs feeding a belt-driven supercharger geared so it would scream its way to 10,000rpm, it was not lacking in the grunt department.

Though it never went on the dyno, Firth estimated it would have had around 300 horsepower at about 5000rpm. Regardless of the actual numbers, though, as Harry once outlined, the power was ‘adequate’.