The car was constructed by the McKee Corporation of Bob McKee. He designed the closed cockpit car with the pilot seated to the left of the car with the entrance of the cockpit through two butterfly doors. Oil radiators were placed in the sides with a Naca air duct front of it.
The Turbine engine was the Continental TS 325-1 Turbine with a possible 330 bhp. At the front of the engine, there is an axial compressor and a centrifugal compressor. Air is drawn in by a box located at the top of the roof and compressed to 6 bar before being sent at a very high flow rate into the combustion chamber via two connecting tubes. At this point there is kerosene aviation fuel injected. The mixtures ignites, the gas expands and drives two turbine wheels, which drive the compressor and two other turbine wheels, on which the power is recovered. This goes through a reduction gearbox ( from 55000 to 6000 rpm) and drives the axle directly via the driveshaft.
So this technique avoids the use of a gearbox and clutch. The throttle controls fuel flow and when pushed deeper it closes the wastegate, throwing more flaming gases at the power turbine and hence the wheels. A big fire extinguisher was needed in the cockpit and the engine produced lots of noise.
Heppenstall thought the car was Ideal for the Le Mans circuit. It was very easy to change the gear ratio, it was less easy to find one that allowed for comfort everywhere, both in terms of top speed and acceleration. It was also necessary to have a reverse gear. Howmet used an auxiliary electric motor.
The Howmet TX (Turbine Experimental) did his first laps on the Daytona Speedway in 1967. The real debut was during the 24 hours. After a promising start, Heppenstall-Lowther were eliminated by an accident when the blow-off valve jammed shut in a corner. The potential of the car was obvious at Sebring. With a third time in qualifying ( only 1’’2 seconds behind the Porsche 907 from Siffert), they had a miserable race with different issues that made them retire.
In Europe, Hugh Dibley and Dick Thompson have again to retire in the Brands Hatch event when they were off track by again a valve problem. One week later, Dibley was present at Oulton Park and the car would not start.
Heppenstall then did some races for the SCCA and won the race at Huntsville. The first race where a turbine engine was the winner! The next win came at the Marlboro 300. In the euphoria, two cars are entered in the 6h Watkins Glenn. This time, both cars crossed the finish line. Dibley-Tullius on P12 and Heppenstall-Thompson (chassis 02) on P3 behind the Ford/Gulf.
The 24 Hours of Le Mans: Challenges and Setbacks
After a third place at Donnybrooke, it was time for the race at Le Mans. Unfortunately, they were not capable to live up to the promises. With their weight, 811 and 803 kg, they were a match for the Porsche and Alpine 3L. In the training sessions it was already clear: 3’55’9 for Thompson was 20 seconds slower than the 908 Porsche and 12 seconds slower than Bianchi in his Alpine. Even the 2l Alfa did better.
In the race, they were quickly left behind. The #22 of Thompson- Heppenstall had a turbine that was not giving full power and #23 Dibley-Tullius had troubles with a wheel bearing. When they also got chassis troubles, they lost 3h in the pits and were disqualified in hour 9 for insufficient laps covered. The other car was running P29 in hour 7, when Thompson ran off track at Indianapolis corner. He flew over the sandbank and by miracle landed on his four wheels.
Conversion and restauration of the Howmet TX
After the race, the firm decided to stop the project. Heppenstall transformed chassis 02 into a spyder configuration in an attempt to attack some world records. The Howmet was now called the MK2. And indeed on the Talladega circuit, he did six new records.
After that Howmet gave the cars to Heppenstall for one dollar, but the turbine engines went back to continental.
In 1996 Heppenstall asked McKee to restore the car (GTP3 chassis) in his original configuration and that car was bought by Frenchman Xavier Micheron, who entered the car in the Le Mans Classic. The car used a smaller engine, an Allison Turbine.
