Triumph TR250K

The TR250K was Kas Kastner's and Peter Brock's. Kastner ran Triumph's competition department in the United States, at Gardena in California, and Brock was the designer of the Daytona Cobra coupés. Kastner told Mandel how it began:

The importer's newsletter called it the Triumph 250-K, Car and Driver the TR-250K, and Brock, recalling it in 2020, the K-car.

On the TR4A frame Brock put a long, low open body, panelled in aluminium, and the TR250's six, moved back. The newsletter's preview listed what else it had: the standard suspension units modified with metal bushes and anti-roll bars, Firestone tyres on magnesium wheels, square Cibié headlamps, a roll bar built into the styling, foam-filled fuel tanks and a boot (trunk) a fifth bigger than a TR250's. Its first track tests, the newsletter said, pointed to a potential of nearly 250 km/h (155 mph) and 0–60 mph in under 6 seconds. Car and Driver added that it was "all ready and waiting for a 3.5 liter V-8".

How it was paid for is told three ways, and the three fit together. Kastner, in 1968: "we were trying to figure out how to do it on his few bucks and my few bucks". Aaron Severson writes that Bruce McWilliams, Leyland's marketing chief in America, authorised the single prototype. And Peter Brock recalled in 2020 that Kastner obtained a few thousand pounds from British Leyland.⁠source 2​source 1​source 3​source 5

Jim Dittemore and Bob Tullius drove it at Sebring, and its race lasted 49 laps; its entry is in the result below. The importer's newsletter reported the next month that in practice the car had been "easily faster than the MGC and a number of the more exotic entries", and that in the race a fuel line broke after 55 minutes and was repaired. Of the end it wrote:

The wheels were of a type, the newsletter said, used "on Chapparals" for several years. Peter Brock, writing 52 years later, remembered that a magnesium wheel failed, "ripping away part of the car's braking system"; the race report of the time, and the results, give the suspension. Had it finished, the newsletter thought, the TR250K would have been in the top ten, and it quoted Kastner: "If they'd re-start this race in two weeks we'd win!" Brock recalled that in the first couple of hours it lapped faster than "most of the works-backed Porsche team cars".

Car and Driver called the TR250K "the biggest gamble Kas Kastner, Leyland Triumph's U.S. competitions director, and Peter Brock, the last of the real car designers, have ever taken", and Kastner offered Mandel a forfeit if it failed:

It was meant as the basis of a production TR. Severson writes that Kastner pressed George Turnbull, Standard-Triumph's chairman, to adopt it, in vain, Kastner believing that the factory dismissed it because it was not its own idea, and McWilliams holding that it could not have been built "without being hopelessly watered down". Brock later believed, Severson reports, that the TR7 "owed a lot to the TR250K".

The car survives: it was with a private owner in the United States when Brock wrote in 2020, and its later outings are set out below.⁠source 1​source 3​source 5