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Triumph TR5 @ 50

Triumph TR5 @ 50 Published: 16th Feb 2017 - 0 Comments - Be the first, contribute now!

Triumph TR5 @ 50
Triumph TR5 @ 50
Triumph TR5 @ 50
Triumph TR5 @ 50
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The TR5 was supposed to be a triumph for affordable fuel injection that would elevate this rustic sports car to new heights and become heir apparent to the Big Healey. It was the first of numerous blind alleys for Triumph…

As stop gaps go, Triumph’s TR5 was legendary. Born out of necessity to appease the influential US market, slotting a bigger engine in the TR4A looked like a fast fix in many ways, staying in production for less than two years before it was replaced by the TR6. And yet half a century on, it’s the most revered of the illustrious TR line.

Hardly what you call cutting edge when launched in ’61, the TR4 was showing its age by the mid 1960s. Critics said that despite its bigger 2.2-litre engine, this model was no faster than the original post war TR2 and what with toughening US emission regulations and in-house rival MG readying it’s six-cylinder MGC, a new engine that didn’t belong on the farm was needed fast.

Triumph’s 1998cc six-cylinder engine found in the 2000 range seemed a natural solution and in the Spitfire-based GT6 proved swift and smooth enough.

However, in the heavier TR4, this smaller 95bhp unit offered scant gains over that lusty ‘tractor’ engine, but, in line with Triumph engineering tradition, there was plenty of potential for enlarging the six pot – in this case to 2.5-litres, which was a far cry from a basic engine block which first saw the light of day in the sub 1-litre Standard 8 saloon!

Standard Triumph’s engineering head Harry Webster was a genius. He progressively stretched that primitive little four-cylinder engine from 803cc to 1493cc by ingeniously staggering the cylinder bores, thus allowing much more metal between them for safe ‘overboring’. The six-cylinder off-shoot simply came about by tagging on two extra pots!

However, the stretch from 2-litres to 2.5 (this time achieved by stroking the engine’s crankshaft), in itself was only partly successful and the engine required further tuning to give the TR similar performance to the legendary Austin-Healey 3000 that bowed out around the time the MGC and TR5PI were launched.

Fuel for thought

Ambitiously, Triumph wanted to raise the 2.5 engine’s power to around 150bhp, 50 per cent more than the old trusty four pot that served Triumph and Ferguson tractors (and Morgan) so well. The problem was that to achieve this Healey-like output, from a smaller unit, demanded a ‘racier’ camshaft which meant poor low-rev performance when fuelled by normal carburettors.

The answer lay in the new-fangled idea of fuel injection which was steadily filtering down from the race tracks into certain upmarket production cars. PI enabled more precise metering of the petrol to the engine’s individual cylinders and helped to reduce the loss of low-speed torque plus quell the lumpy idling caused by racier camshaft timing.

Half a century ago, the Midlands was an engineering hotbed and just down the road from Triumph’s Canley base was Joe Lucas who had been developing a cost effective-mechanical fuel injection system that Triumph had already tried out on the TR4. Another benefit of this superior fuelling was lower exhaust emissions – a vital sale point for the North American market which was desperately trying to cut down pollution. In theory at least, because Triumph never got around to find this out…

The TR5 PI (the PI initials were also a useful marketing ploy) looked pretty much like the older TR4A – save for some weedy Ro-Style wheel trims that also adorned the GT6 and Herald-based Vitesse – and under-the-skin changes were surprisingly moderate as well, even the chassis frame and suspension required little modification, while the TR4 gearbox was still employed, as was its bonnet complete with a now redundant power bulge due to the compact PI system.

But as it looked purposeful you couldn’t have the muscle-bound TR5 looking less macho than the TR4 could you! Also carried over from the TR4A was the excellent Surrey top option which sadly wasn’t transferred to the TR6 but the interior was made posher as befitting a car wearing a PI badge.

While the beefy six pack engine gave the TR the desired performance, you have to question Triumph’s main motive for ditching the old Ferguson favourite. In a re-released book from Veloce ( on the Triumph TR range, author Bill Piggott quite rightly points out that, as tuners have shown, there’s still plenty of life in the old unit.

Triumph stretched it out to 2.5-litres quite easily due to its ‘wet liner’ design, but while quick enough, was deemed to be too rough and ready. Author Piggott wonders whether better balancing of the engine would have reduced this roughness as independent tuners have shown over the decades. Indeed, as much as 2.7-litres have been extracted from this unit in Triumph and Morgan racers with no ill effects.

With suitable uprating, a reliable and usable 135bhp is on the cards, enough to keep up with any TR5 PI in sight, despite its claimed 150bhp. Also that lighter, smaller ‘four’ always resulted in better weight distribution. And was that 150bhp a genuine figure?

Figure it out

At most, it’s more likely 142bhp, as was quoted for the replacement TR6, but even this figure is now viewed optimistic because when that engine was detuned to 125bhp for 1973, to improve low speed running, performance didn’t suffer greatly. “Don’t get hung on this 150bhp thing”, one leading TR specialist told us. And to confuse matters further, when the same engine (and PI system) was slotted in the 2000 saloon and estate to create the fine 2.5PI ranges, its engine was rated at 132bhp!

Mind you, the Yanks would have killed for even 125bhp, because, despite investing in fuel injection, Triumph didn’t fit it to US cars, even though this market accounted for the bulk of sales. The reason, Tim Piggott believes, was a fear of garages, more used to fixing Mustangs, being flummoxed by the PI set up. And let’s face it, even our mechanics fumbled around in the dark for decades!

Instead, running on twin Stromberg carbs after further detuning, the TR250, as it was called in the US, kicked out a measly 104bhp which, given the engine’s added mass and weight coupled to higher gearing, all resulted in a sports car that was barely quicker than the one it replaced! This point was not lost on the acerbic Car & Driver magazine who sarcastically called the TR250 “something less than a Triumph” adding it was “a lot less fun than a TR4A.” As you might expect, countries enjoying the full fat ‘150bhp’ TR5s were far more enthusiastic about this beefy sports car!

The Veloce book throws up an interesting theory on why the TR6 was detuned – and it’s a marketing one. Was it acutely embarrassing for Triumph to have a cobbled together 2.5-litre TR6, produce more power than Canley’s advanced twin overhead camshaft 3-litre V8 fitted to the new Stag, and more reliably, too?

Hot and bothered

Reliable? Well, of sorts, that is… The euphoria felt by media road testers swanning around in specially prepared cars didn’t register with the many owners who finished Triumph’s development work for them. When it was good it was very good. But when it was bad…

“We were surprised at how well the Lucas fuel injection functioned and even the few minor noticeable shortcomings will be limited before full production starts,” said an optimistic Autocar in October 1967. Yeah, right!

Chief faults included diabolical hot starting, over rich mixtures and dicky fuel supply, the latter due to the PI’s electric pump becoming overheated in hot weather causing the TR to stutter to a halt.

Bags of frozen peas, stuffed around the ailing pump (the choice of frozen produce was limited back then-ed) was a well known ruse until a re-located aftermarket German Bosch instrument completely cured that particular foible. But the infamous prickly nature of ‘our’ PI was made ten times worse by owners and workshops tinkering with the unknown.

Fed up owners eventually threw in the technological towel and switched back to old fashioned carbs and without any detrimental reduction in performance – but a transformation in reliability so it was a good job Triumph kept the TR4’s bonnet… But as today’s specialists have highlighted, a well set up PI ploy is a joy.

Just under 3000 TR5s were built (1165 UK cars) as opposed to 94,619 TR6s so you can see why the earlier model is so exclusive as well as expensive; £45,000 is not unknown for a top TR. This short-lived model was really a test bed for the forthcoming 2.5PI range and the TR6 – both introduced for 1969 – who fared no better reliability-wise and, as a result, Triumph ditched the entire injection idea when the TR6 was killed off in 1975 reverting back to carbs to fall in line with the rest. The PI saga summed up the Canley company to a tee: Full of good ideas (Stag, Dolomite Sprint, TR7) but, sadly, poorly executed.

Remember when… 1967

It was the 60s at its very best with Flower Power and The Summer of Love, but it wasn’t all hugs and kisses with everyone as this snapshot reveals…

The race to the moon suffered its first official casualties; in January a launch pad fire claimed the lives of three legendary American Apollo astronauts, while that April the first Soyuz crashed to earth after the parachutes tangled, killing cosmonaut Komarov.

As trouble in the Middle East spreads in 2011, due to different reasons, mid ’67 saw the Six Day War which had been simmering from the start of the year in Sinai and culminated on 5th June, when war formally broke out between Israel and Egypt.

In the autumn the UK’s dock workers went on a long and painful strike in sympathy with their Merseyside colleagues over working practices. Jack Dash, the Corbyn of his day, was the trade union leader who gained notoriety during the late 60s and 70s.

The 1960s wasn’t always about good times… Strikes became more common and, like now, belt tightening became the norm. The then Chancellor, James Callaghan (right), devalued the pound that autumn plus announced we were going to decimalise in 1971. Goody…

In sport, Spurs beat Chelsea in the FA Cup 2-1, Scotland beat England 3-2 in the Home Internationals (and so became unofficial World Champions!) while Denny Hulme, in a Brabham, became the only Kiwi to win the driver’s F1 crown after a pretty nondescript Grand Prix season.

Entertainment-wise, BBC 2 became more widespread, The Prisoner started its long, mysterious cult following, top soaps were our Crossroads and America’s Peyton Place, and the UK Government finally killed off those naughty Pirate stations, and all for the sake of Radio 1 and 2!


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