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Triumph 2000 / 2.5Pi

Published: 15th Oct 2014 - 0 Comments - Be the first, contribute now!

Triumph 2000 / 2.5Pi
Triumph 2000 / 2.5Pi
Triumph 2000 / 2.5Pi
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Triumph 2000 / 2.5Pi

At first glance Triumph’s luxury 2000/2.5 saloon hardly has the makings of a performance car or motorsport foil even though it boasts a rich history. The Triumph 2.5PI was made for just one event, the 16,244 miles dash from London to Mexico City that was the 1970 World Cup Rally. It was an unlikely rally car certainly, but after 66 days of the toughest marathon ever second and fourth places, splitting the far fleeter Ford Escorts, will go down as one of the manufacturer’s greatest (pardon us) triumphs.

If you look at the 2000 and 2.5PI as a sort of ‘TR6 saloon’ then you’re on the right track as much the same rules apply – it even uses a derivative of the sports car’s independent rear suspension. So there’s some potential there…


Rot is endemic, and facelifted Mk2s (May 1974 on) seem most rot-prone of all. The front wings are double-skinned around the wheelarches, creating a water trap. The most common problem concerns rotten sills and footwells while rear suspension pick-up points also dissolve, as do the top spring mountings on the rear suspension.

Engines are durable, but can suffer from excess crank ‘endfloat’. Up to 12thou means a simple replacement of the thrust washers might effect a cure. Over about 50thou and the thrust washers fall out, and that’s very expensive as a rebuild and even a new block is required.

Oil pressure should be quite high; if it drops as low as 10psi at idle or the needle becomes erratic, the crank is probably worn. Gearboxes are long-lived; never lightning fast, but if it is noisy then a lack of oil may well have ruined the layshaft. Clonks on take-up may be UJs (cheap), worn driveshafts or cracked diff mounts.


Works rally cars ran in standard tune with high compression heads. With a modded head, cam and exhaust near 200bhp remains possible although around 175bhp is best for a useable road engine. Racers often ditch the PI for double or triple Webers; Rimmer Bros (http://www.rimmerbros. ) can supply most parts for converting or find a 2000 or 2500TC, the latter which uses larger SU Units.

The petrol injection experts are Wrexham-based Prestige Injection Developments ( and that infamous Lucas set up can be made reliable; a modified Bosch fuel pump and modern metering unit are two remedies; Revington TR markets modified throttle assemblies which takes out the wear and slack of the originals and allows proper throttle openings for an immediate power boost. Jigsaw (www. and Canley Classics ( also supply suitable tuning equipment.

There’s a bit of stretch in the 2.5 to 2.7-litres but it’s a dear option and a luxury for most. The 2000 engine can be taken to 2.5 using its crank etc, but needs TR6 head for best effect as fitted to late 1968 engines. The same tuning rules apply to the smaller engine but the hike to 2.5-litres is worth up to 20bhp alone according to Triumph so it has to be the best first step.

Talking of factory power figures, there’s always been a lot of rot about the early 2.5PI kicking out 150bhp in the TR6 before it was derated in 1973 to 125bhp yet the 2.5PI saloon and estate kicked out an in between claim of 132bhp.

Triumph specialists believe the original TR5s and early TR6s didn’t kick out a true 150bhp. In fact, by 1973, Triumph was quoting 120bhp for the PI and 125bhp for the TR6. In the real world a well-tuned TC engine of around 100-106bhp will match or beat an average PI, we reckon. Also factory 2500 TCs ran a milder camshaft because the TR6 one is too racey to work on carbs and will lead to lumpy running – it’s the reason why PI was originally installed! The 2000 (latterly 2000TC) was originally posted at 90bhp and certainly power crept up during 1974 right across the ranges care of revised breathing.

How about Stag power? It’s essentially a 2.5 beneath the skin so a doable if not straight swap. A handful of factory cars were made but nothing came of it. Instead an enterprising Ian Lines (who used to prepare Triumph’s works rally cars) made a batch of them and cracking cars they were.


With its modern strut suspension up front and telescopic damping at the rear, the 2000 range boasted a far superior design to the old TR one although they were too softly sprung for saloon and estate use.

Firming up the suspension with better damping and springs is the first step. Another mod tweak that’s recommended is fitting 2500S front anti-roll bar as it stops the dreaded 2000 ‘lean’ into corners – made much worse on the longer Mk2 cars. Poly bushing the suspension is now all that’s needed by most owners.

The brakes are okay; DBA disc and Mintex or Green Stuff pads being the first upgrade before looking to specialist conversions such as Wilwood.

While five-speeds (Ford Sierra, Toyota Supra or the Rover SD1 ’box) are available, don’t pension off the overdrive as provides six ratios. A Revington TR Logic Smart Activator makes it more responsive and useable; incidentally Stag ratios were standardised in 1974. Like the Stag, a BMW diff can be fitted using a special kit to mate with the hubs for a wider spread of ratios but typically costs the thick end of £2000 – there’s a wide range of Triumph ratios so they may suffice for most.

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