Page 1 of 3 Next >> During the 1968 racing season the reign of the piston engine was briefly challenged by the gas-turbine. Well known innovators Lotus impressed at Indy with their turbine engined single seater and the grid of the 24 Hours of Le Mans that year featured a two turbine engined machines entered by the Howmet Corporation. Dubbed the Howmet TX (Turbine Experimental), the unusual car was the brainchild of Philadelphia born sports-racer Ray Heppenstall.
He convinced one of his racing friends, Tom Fleming, that a lightweight turbine engine mounted in a conventional chassis could be a winning combination. At the time Fleming was the vice-president of the Howmet Corporation. Among the metal company's many products were the precision aluminium parts used in many turbine engines. A successful Howmet labelled racing car would be a very effective marketing tool.
The first order of business for Heppenstall was to find a gas-turbine engine that was suitable for use in a car. The standard turbine engines were not designed to slow down for corners and suffered from considerable lag during acceleration. Eventually Heppenstall picked the Continental TS325-1, which had originally been developed for use in military helicopters. This engine featured a two-stage set-up; a gas-generating turbine fed a second turbine that was connected to an output shaft.
The lag problem was solved by fitting two waste-gates between the two turbines. At 1/3 throttle all the gasses were fed through the waste-gates and out the centre exhaust. This way the blades kept spinning but the engine generated no power. As more throttle was applied the waste-gates closed gradually, feeding more and more gasses to the second turbine. At full throttle the engine produced around 325 bhp, which was very impressive considering it only weighed 77 kg.
A further advantage of the turbine engine was its completely flat power curve, so it did not require a conventional gearbox. It was instead mated to a Continental gearbox that featured just one forward gear. A separate electric-motor was used if reverse was required. A quick-change differential was used so the final drive ratio could be adapted to each track's characteristics. Page 1 of 3 Next >>
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During the 1968 racing season the reign of the piston engine was briefly challenged by the gas-turbine. Well known innovators Lotus impressed at Indy with their turbine engined single seater and the grid of the 24 Hours of Le Mans that year featured a two turbine engined machines entered by the Howmet Corporation. Dubbed the Howmet TX (Turbine Experimental), the unusual car was the brainchild of Philadelphia born sports-racer Ray Heppenstall.