Triumph TR5, Triumph TR250 and Triumph TR6 Sports Cars

Triumph sports cars benefited in the mid-sixties when Lucas develop a cheap and efficient fuel injection system which allowed better fuel metering. This allowed Triumph to take its six-cylinder Triumph 2000 engine and add a long-stroke crank to take it to 2500, stick on the Lucas fuel injection and a hotter camshaft and get 150bhp. Significantly up from the 100bhp of the Triumph TR4s without any loss in driveability apart from a slightly lumpy idle. The 'six' slotted in to the TR4s body quite nicely without any weight penalty, just a few inches extra in engine length which the car could easily accept.

Unfortunately things didn't quite go as Triumph hoped and many Triumph sports car customers found themselves doing the final development work on getting the fuel injection system to work properly. One of the markets that never saw the TR5 was America.

America got the TR250 which was the TR5 fitted with carburettors to meet newly emerging emission legislation which the basic Lucas fuel injection system would struggle to meet without further modification. The downside was a power figure no better than the TR4, but fortunately with restrictive speed limits in America at the time that was less of a problem than it might have been. Top speed for the TR250 was around 110mph with 0-60mph in 10.5 seconds. The UK spec TR5 did 120mph with 0-60mph in 8.8 seconds and 0-100mph in 28 seconds with fuel consumption of near 25mpg according to Autosport magazine.

Despite the performance shortcoming the TR250 sold nearly 8,500 in its 14 month production life. There were even fewer TR5s with less than 3,000 in total, most in left-hand drive for European markets. It is this scarcity value and the fact it was also the fastest of the TRs that leads the TR5 to be one of the most valuable to collectors.

The TR5/TR250 had always being a holding model while Triumph got the new Karmann styled TR6 body in to production. Which is actually just a new front and rear section for the car with the centre section still being the old TR4/5. The TR6 was released in 1968. America still got it with the TR250 carburettor engine rather than fuel injection, and even in the UK and Europe the injection engine was detuned to 125bhp (by substituting a milder camshaft) to overcome customer complaints about the problems with keeping the 150bhp version running smoothly.

With less power the TR6 was slower than the TR5. It could only manage just over 110mph and 0-60mph fell to around 10 seconds, hardly any better than the early Triumph TR3s. The US spec carburettor engine was even slower. But Triumph still built almost 78,000 of them with under 14,000 of the injection versions built for the rest-of-the-world.

The Triumph sports car engine could be persuaded to give more power as the American RW 'Kas' Kastner proved.He eventually got the engine up to 250bhp at 7,500rpm, winning the Category C championship in the process in 1969.

With over 30 years of extra development it is possible today to get the 150bhp engines to run smoothly and a lot of 125bhp TR6s have been upgraded. But non of this affects the American market who had to struggle along with the old carburettor version and 105bhp to the end. But the demand was still there and the car continued to sell until production ceased in July 1976.