Class Acts, Part 1: The Triumph 2000 and 2.5 PI Mk 1


Standard-Triumph had dropped out of rally competition in 1966, but planned to return for the 1967 RAC Rally with a 2000 powered by the new 2,498 cc (152 cu. in.) six from the TR5 PI. As we discussed in our article on the TR5 and TR6, the big six was a development of the 1,998 cc (122 cu. in.) engine with a redesigned block that allowed the stroke to be increased from 76 to 95 mm (2.99 to 3.74 in.). Adding to this the new Lucas Mk 2 mechanical fuel injection system gave 142 net horsepower (106 kW) and a very healthy infusion of torque. The RAC Rally was canceled at the last minute, but Triumph allowed the press to drive the rally car, which was enthusiastically received.

1969 Triumph 2.5 PI engine © 2012 Akela NDE CC BYSA 2.0 France
The 2.5 PI engine is immediately distinguishable by the long intake runners of the Lucas Mk 2 injection system. The Mk 2 was a multiport mechanical system with a separate injector for each cylinder and a complex vacuum-controlled metering unit. (The Mk 1 system used for years in racing had a simpler metering system with fuel delivery controlled by a cam operated by the throttle linkage.) Although the version of the injected engine used in sedans and estates had a milder cam profile than the engines of the TR5 PI and early TR6 PI sports cars, the idle was still rortier than some owners liked, so later Mk 2 2.5 PIs substituted an even milder cam. (Photo: “Triumph 2.5 PI Mk1 1969 in Morges 2012 – Engine” © 2012 Akela NDE; resized 2012 by Aaron Severson and used under a Creative Commons Attribution-ShareAlike 2.0 France license)

That reaction convinced Standard-Triumph to offer a production version of the injected car, which bowed in the fall of 1968, dubbed 2.5 PI (although the badges read “2500 Injection”). For the sedan, the injected engine received a new camshaft that trimmed peak power to 132 net horsepower (98 kW), but provided 153 lb-ft (207 N-m) of torque at only 2,000 rpm. To take advantage of the engine’s torque characteristics, the 2.5 PI also borrowed the taller 3.45 axle from the TR5. Wider 185SR-13 radial tires were specified, albeit on the standard 4.5×13 rims, and an alternator replaced the generator to better cope with the requirements of the injection system’s high-pressure fuel pump. Because there was still no tachometer, injected cars were fitted with a 5,800-rpm ignition cutout to prevent over-revving.

The 2.5 PI was expensive, starting at £1,133 (£1,487 19s 9d with tax, around $3,570) without overdrive — over £200 ($480) more than the still-available 2000 — but provided much stronger performance. Despite a taller axle ratio, a four-speed 2.5 PI sedan was capable of 0-60 mph (0-97 km/h) in a fraction over 10 seconds, while top speed approached 110 mph (176 km/h). That was almost as quick (albeit not as fast all out) as the new and significantly more expensive Rover 3500 and decidedly quicker than a Rover 2000TC, which actually cost a bit more than a 2.5 PI with overdrive.

1969 Triumph 2.5 PI front 3q © 2014 Andy Reeve-Smith (used with permission)
The Lucas-injected Triumph 2.5 PI was a good deal more expensive than a 2000, but the extra power was enough to trim about 4 seconds off 0-60 mph (0-97 km/h) acceleration times and added at least 15 mph (24 km/h) to top speed at little penalty in fuel consumption. (Photo: “Triumph 2500PI – PKV 390G” © 2014 Andy Reeve-Smith; used with permission)

The news wasn’t all good. The 2.5 PI engine was noisy when pressed and the injection system had various unhappy quirks, including the constant drone of the pump and a tendency to stall in turns if the fuel level fell too low. The fuel pump was prone to overheating, which would cause vapor lock, and the system needed regular fuel filter changes for good health. It was also important to remember that the fuel pump was running any time the ignition was switched on and if you weren’t careful you could flood the engine or create an engine compartment fire hazard. Moreover, if you had trouble with the metering unit, you were probably looking at an expensive replacement. The factory service manual sternly warned against tampering with the unit’s diaphragm springs, which required very fine tolerances beyond the skill level of most technicians.

Despite these flaws and the relatively high price, the 2.5 PI was very well-received. It was the first British production sedan with petrol injection (although not the first British production car, that honor having gone to the TR5 a year earlier) and provided performance comparable to quite a few contemporary sports cars. As a result, the 2.5 PI sold quite well, accounting for more than 9,000 units in its first year. The large majority of these were sedans; although the injected engine was also available on the estate, the added cost of the latter was probably prohibitive for many buyers. The 2.5 PI brought total Mk 1 production to 113,157 units, a very respectable figure for a manufacturer Standard-Triumph’s size.

In part two of this story, we’ll look at the later history of these cars, including the Mk 2 and the 2000’s planned and actual successors.



Our sources on the development of the big Triumph sedans and their Rover P6 rival included “A Brilliant Triumph,” Wheels July 1964, reprinted in Triumph 2000 – 2.5 – 2500 1963-1977, ed. R.M. Clarke (Cobham, England: Brooklands Books, 1984): 16–19; Keith Adams, “The cars; Triumph 2000/2500 development history” and “The cars: Rover SD1 development history,” AROnline, 11 September 2011, www.aronline., accessed 19 June 2013; “Autotest: Rover 2600,” Autocar 22 October 1977: 54–58; “Autotest: Triumph 2000 Mk 2 (1,998 c.c.),” Autocar 16 October 1969: 132–135; “Autotest: Triumph 2.5 PI Mk 2,” Autocar 17 February 1972: 8–12; “Autotest: Triumph 2500S 2,498 c.c.,” Autocar 5 July 1975: 25–29; “Autocar Road Test No. 1944: Rover 2000,” Autocar 11 October 1963, reprinted in Rover 2000/2200, ed. R.M. Clarke (Cobham, England: Brooklands Books Ltd., ca. 1983): 10–15; “Autocar Road Test No. 1956: Triumph 2000 1,998 c.c.,” Autocar 10 January 1964: 66–70; “Autocar Road Test No. 2045: Triumph Vitesse Convertible 1,596 c.c.,” Autocar 17 September 1965: 535–540; “Autocar Road Test No. 2106: Triumph Estate Car 1,998 c.c.,” Autocar 18 November 1966, reprinted in Triumph 2000 – 2.5 – 2500 1963-1977: 28–33; “Autotest No. 2224: Triumph 2.5 PI (2,489 c.c.) [sic],” Autocar 6 February 1969, reprinted in ibid: 44–49; “Beefy commuter with few faults (12,000 mile staff car report),” Motor 14 November 1970, reprinted in ibid: 60–64; John Bolster, “Britain’s best medium-sized car,” Autosport 8 January 1970, reprinted in ibid: 58–59; Paul Bridger, “The Rover SD1 Story,” n.d., homepage.ntlworld. com/ william.whittaker1 /cache_sd1_story/ sd1story.htm, accessed 22 June 2013, and “The Rover Six Cylinder SD1 Story,” n.d., homepage.ntlworld. com/ william.whittaker1/ cache_sd1_story/ 2300_2600story.htm, 22 June 2013; Charles Bulmer, “Rover v. Triumph,” Motor 18 December 1965: 26–27; “Buying Secondhand: Triumph 2000,” Autocar 24 August 1974, reprinted in Triumph 2000 – 2.5 – 2500 1963-1977: 88–90; Wayne Cantell, “Triumph 2500 TC — injection beater?” Modern Motor June 1973, reprinted in ibid: 74–78; Michael Cook, Triumph Cars in America (St. Paul, MN: MBI Publishing Co., 2001); Barry Cooke, “Two-Pedal Triumph,” Modern Motor March 1965, reprinted in Triumph 2000 – 2.5 – 2500 1963-1977: 20–21; Mike Covello, Standard Catalog of Imported Cars 1946-2002, Second edition (Iola, WI: Krause Publications, 2001); C.R., “The New Rover 3500,” Motor Sport July 1976; Edward Eves, “Four Wheels for Snow,” Autocar 1 March 1973, reprinted in Triumph 2000 – 2.5 – 2500 1963-1977: 72–73, and “Taking Stock No. 22: What it means to own a Triumph 2.5 PI Estate car,” Autocar 13 July 1972, reprinted in ibid: 70–71; “Giant Test,” CAR April 1971, reprinted in ibid: 66–69, 79; “Giant Test: Consul 2500 Estate, Triumph 2000 Estate, Vauxhall Ventora Estate,” CAR January 1974: 58–65; “Giant Test: Triumph 2.5PI v. Rover 2000TC: The Battle Hots Up,” CAR January 1969: 42–59, reprinted in Rover 2000/2200: 68–73; “Giant Test: Triumph 2000 II/Vauxhall VX 4/90,” CAR January 1970: 68–73; Harold Hastings, “A new kind of Roving,” Motor 20 April 1968: ii–iv, 69–70; “The Triumph 2000 automatic: 24,000 mile staff report,” Motor 5 August 1967, reprinted in Triumph 2000 – 2.5 – 2500 1963-1977: 34–37; Geoffrey Howard, Dave Thomas, “2-Car Test: Rover 3500S, Triumph 2.5 PI,” Autocar 5 October 1972: 36–41; “It’s the little things that make it Truly a Triumph,” Wheels September 1968, reprinted in Triumph 2000 – 2.5 – 2500 1963-1977: 40–43; David Knowles, MG: The Untold Story (Osceola, WI: Motorbooks International, 1997); Egil Kvaleberg, “Lucas Petrol Injection,” 2000, t2000.kvaleberg. org/ t_pi.html, accessed 7 June 2013; Jonathan Lewis, “The Triumph 2000 Story – Conquest and Consolidation 1963-1969,” “The Triumph 2000 Story – Gilding the Lily: The Mk 2 Models, 1969-1974,” “The Triumph 2000 Story — Joining the Power Elite: The 2.5PI,” “The Triumph 2000 Story – Origins and Development,” “The Triumph 2000 Story – The Big Triumphs in ‘Works’ Competition: 1964-1976,” and “The Triumph 2000 Story – The Final Years: ‘TC’ and ‘S’ Models, 1974-1977,” Triumph 2000 Register, 2010, triumph2000register., accessed 10 June 2013; Annamaria Lösch, ed., World Cars 1979 (Rome: L’Editrice dell’Automobile LEA/New York: Herald Books, 1979); Raymond Mays, “Rover makes good,” Motoring Life #19 (1968), reprinted in Rover 2000/2200: 67+; F. Wilson McComb, MG by McComb, Second edition (Colchester, Essex: Osprey Publishing Ltd., 1978);, Book of Automobile Production and Sales Figures, 1945-2005 (N.p.: 2006); “Road Research Report: Triumph 2000,” Car and Driver Vol. 11, No. 5 (November 1965): 54–58, 114; “Road Test: Triumph 2500TC,” Motor 8 June 1974, reprinted in Triumph 2000 – 2.5 – 2500 1963-1977: 82–87; Graham Robson, The Rover Story, Fourth edition (Wellingborough, Northamptonshire: Patrick Stephens Limited, 1988), and The Triumph TRs: A Collector’s Guide, Second edition (London: Motor Racing Publications Ltd., 1981); Graham Robson and Richard Langworth, Triumph Cars: The Complete Story, Second edition (Pitlake, Croydon: Motor Racing Publications Ltd., 1988); “Room for Two?” CAR February 1967, reprinted in Rover 2000/2200: 56–57; “Rover 2000,” Autocar 11 October 1963, reprinted ibid: 5–10; “Rover 2000TC versus Triumph 2.5 PI,” Motoring Life August 1969, reprinted in Triumph 2000 – 2.5 – 2500 1963-1977: 50, 65; “Seven Years Apart (Giant Test: Triumph Vitesse Mk 2/Ford Capri 1600GT),” CAR May 1969: 56–61; “Shaping up well (Motor Road Test No. 51/69: Triumph 2.5 PI Mk. II),” Motor 25 October 1969: 27–32; “So similar, but so different (What Car? Compares Vauxhall, Triumph, Chrysler: Big four-door saloons for around £2,800),” What Car? December 1975, reprinted in Triumph 2000 – 2.5 – 2500 1963-1977: 91–96; James Taylor, “High Hopes,” Thoroughbred & Classic Car February 1992: 74–80, and The Classic Rovers 1934-1977: A Collector’s Guide, 2nd printing (Pitlake, Croydon: Motor Racing Publications Ltd., 1989); Mike Taylor, “Stag at Bay: Part two — the making of a classic,” Sporting Cars June-July 1984: 51–55; “Technical Specifications,” Triumph 2000 Register, n.d., triumph2000register., accessed 10 June 2013; “Triumph 2000,” Autocar 18 October 1963, reprinted in Triumph 2000 – 2.5 – 2500 1963-1977: 5–9; “Triumph 2000,” Road & Track Vol. 17, No. 2 (October 1965), reprinted in ibid: 22–25; “Triumph 2000 Extended Test,” Motor 14 March 1964, reprinted in ibid: 11–15, 57; “Triumph 2000 — Further Details,” Autocar 25 October 1963, reprinted in ibid: 10; “Used Car Test 275: Triumph 2000 (overdrive),” Autocar 28 December 1967, reprinted in ibid: 38–39; John Williams, “Practical Classics Buying Feature: Triumph 2000,” Practical Classics March 1982, reprinted in ibid: 97–100; and Rene Winters, “The World of the Rover SD1,” Dutch Rover Archives, June 2003, www.roversd1. nl/ sd1web/, last accessed 19 June 2013.

Additional information on the Triumph’s various rivals came from “Autocar Road Test No. 1870: Ford Zodiac Mark III 2,553cc,” Autocar 20 April 1962: 623–627; “Autocar Road Test No. 1874: Austin A.110 Westminster 2,912 c.c.,” Autocar 15 March 1963: 436–440; “Autocar Road Test No. 1917: Jaguar 3.8 Mark 2 Automatic 3,781 c.c.,” Autocar April 1963, reprinted in Jaguar Mk 2 1959-1969, ed. R.M. Clarke (Cobham, England: Brooklands Books Ltd., ca. 2000): 54–58; “Autocar Road Test No. 1982: Austin A.110 Westminster Mk. II 2,912 c.c.,” Autocar 10 July 1964: 72–76; “Autocar Road Test No. 2022: Ford Executive Zodiac 2,555 c.c.,” Autocar 9 April 1965: 713–718; “Autocar Road Test No. 2040: Ford Anglia 1200 Estate Car 1,198 c.c.,” Autocar 13 August 1965: 303–308; John Baker, “Austin A70 Hampshire,” “Austin A90,” “Austin A99 Westminster,” “Austin A105,” and “Austin A110/120 – 125/135,” Austin Memories, n.d., www.austinmemories. com, accessed 13 June 2013; William Boddy, “Jaguar 3.8 Mk. II: One of the Best Saloon Cars in the World,” Motor Sport September 1960, reprinted in Jaguar Mk 2 1959-1969: 30–31, and “The Latest Citroën DW,” Motor Sport March 1964, reprinted in Citroën DS & ID 1955-1975, ed. R.M. Clarke (Cobham, England: Brooklands Books Ltd., ca. 1988); “Executive’s bargain (Motor Road Test No. 11/67: Ford Corsair 2000E),” Motor 6 April 1967: 23–28; “Giant Test: Corsair 2000 E -v- Victor 2000,” CAR February 1968: 44–49; “Flexible five-seater (Motor Road Test No. 16/66: Ford Zodiac Mk. IV),” Motor 23 April 1966: 55–60; “Giant Test: Ford Zephyr V6/Vauxhall Cresta d/l,” CAR August 1966: 43–49; “Giant Test: 4 symbols of status,” CAR January 1967: 38–45; Peter Hall, “Charming Jaguar Cub,” Wheels March 1962, reprinted in Jaguar Mk 2 1959-1969: 48-51; Annamaria Lösch, ed., World Cars 1979 (Rome: L’Editrice dell’Automobile LEA/New York: Herald Books, 1979); “The Autocar Road Tests 1762: Jaguar 3.8 Mk 2 Overdrive,” The Autocar 26 February 1960, reprinted in ibid: 12–15; “The Jaguar 3.4-litre Mark 2,” The Motor 16 Aug. 1961, reprinted in ibid: 40–43; and “Z cars Mk IV,” Motor 23 April 1966: 47–54.

Some historical exchange rate data for the dollar and the British pound came from Lawrence H. Officer, “Exchange Rates Between the United States Dollar and Forty-one Currencies” (2011, MeasuringWorth,, used with permission). Exchange rate values cited in the text represent the approximate equivalency of British and U.S. currency at the time, not contemporary U.S. suggested retail prices. Please note that all equivalencies cited herein are approximate, provided for the reader’s general reference; this is an automotive history, not a treatise on currency trading or the value of money, and nothing in this article should be taken as financial advice of any kind!



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  1. That rev limiter on the injected engine can be negated without much trouble and without that a Rover V8 can be easily outrun

  2. Wow, I can detect traces of each and every one of the many styling themes one got on an American Ford of the era crammed onto that tiny little car. There’s the proto Galaxie (the show car Galaxie, that is) roof. The surprised double headlights. The horizontal fin. The stars in the grill. Hysterical.

    1. What works on 18 feet land yachts never quite translates to smaller platforms- eg the Vauxhall Victor.

      Another fine, enlightening article too. Thank you for your efforts.

    2. The Zebu wasn’t quite that OTT, but it had its own oddities, like a split scoop at the leading edge of the bonnet. Take a mid-50s Mercury, add a sloping hood between the headlight pods, graft on the roofline from a ’63 or ’64 Breezeway four-door hardtop, reduce it to about three-fifths scale and you get a rough approximation. I think if Standard-Triumph had produced it that way, by 1964 it would have looked painfully old-fashioned, especially next to the Rover 2000.

  3. Thanks for yet another fascinating article.
    I know this is nitpicking, but “occasional tendency of the sliding driveshaft splines to bind under power” Don’t you mean halfshafts? TR4A, 5, 250 & 6 had a reputation for halfshafts binding under hard cornering and considering that the 2000 uses a similar IRS setup, would probably exhibit like behavior. It seems to me there’s a good reason other makers used rotoflex or CV joints back there instead of U-joints & splines. Also, since the diff is mounted to the body / chassis structure in an IRS, the driveshaft splines shouldn’t see much movement anyway.

    1. Oops, that should have been halfshafts; I fixed it in the text. Yes, the IRS TRs and 2000 had basically the same rear suspension (the big difference being that the TRs had lever-action shocks in back because there wasn’t room for tubular shock absorbers) and the same issue with the driveshaft splines and their tendency to bind, which on the sedans tended to happen if you jumped on and off the throttle suddenly (e.g., to make a quick shift).

      The reason the sliding splines were used was that the rear suspension geometry would allow the track width to change as the wheels went from full jounce to full rebound; the splines accommodated those track changes. I assume STI decided CV joints were too expensive. Interestingly, when Ford went to semi-trailing arm independent suspension on the Mk IV Zephyr in 1966, they were determined not to use splines and so concocted an odd little arrangement wherein the inner bearing closest to the differential would actually move on a little swing shackle instead.

  4. We are dealing with vocabulary differences here. in the UK, what they call the propeller shaft, or ‘propshaft’ is what we Americans call the driveshaft. What we Americans call a halfshaft is what the Brits call a driveshaft.

  5. The availability (or not)of the various driveshaft / halfshaft techniques and their manufacturing technologies has been a strong influence on car design, a study of it’s own even.
    I expect Triumph would have used C.V. joints if they had been available in the right size at the right price. From about the same date, the first Porsche 911s used what now seems an odd arrangement of Hooke joint + double Hooke joint as another solution to the same problem. Then there were Rotoflex and other fabric/rubber joints. None of these techniques are in common car use today.

  6. Good, interesting article.

    One little point; the engine was tilted at 7 degrees to avoid the dynamo touching the battery.

  7. Surely Triumph could have uprated the 1.6 6-cylinder engine to increase its power and make it more suitable for a low level version of the Triumph 2000 (plus further use in the Triumph GT6, etc)?

    At minimum it should be possible to extract around 83 hp from the 1.6 6-cylinder (similar to Rover’s initial 80 hp 1.8 version of the 2-litre P6 Overhead Cam engine), while the TS and PI routes should equate to around 92+ hp and 96+ hp respectively, even if such an engine would likely be more suited to an earlier RWD Triumph 1300 (were it feasible of course).

    1. One would think! After all, the warmer “Mexico” version of Ford’s 1.6-liter Kent crossflow was good for 86 PS DIN, as was Toyota’s 2T-B four (the former with a single Weber two-throat, the latter with two Aisan dual-throat carburetors). The small six’s porting and combustion chamber design really sacrificed a lot for smoothness. Triumph found that even with the 1,998cc six, getting more power at the high end compromised low-end torque by a like degree and made the engine dreadfully thirsty to boot. (The PI approach did as well, since its original cam profile was really pretty radical for a street engine, but the 2500’s much longer stroke sort of balanced the ledger in terms of torque.) Since the 2000 was significantly heavier than the Vitesse, that would have been a significant problem and was the main reason there wasn’t a 1600 sedan.

      I know Triumph wrestled with the limited output of the small six and concluded there was no quick fix. I’m assuming “completely redesign the cylinder head” wasn’t in the cards for financial or organizational reasons, which is what I suspect it would have taken.

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