The Triumph TR7 Sprint version of the Triumph TR7 sports car was produced in 1977 by the Triumph Motor Company, then part of British Leyland. However, it was produced in only very limited numbers: Probably a maximum of 61 in total were manufactured. It used the 127 bhp, 16-valve, 2-litre version of the Triumph slant-four engine from the Triumph Dolomite Sprint, a highly tuned version of which, "rated at 225 bhp at 8000 rpm" by 1977, was used in the Group 4 TR7 cars of the BL works rally team, from 1976 until 1978. This was instead of the TR7 base model's 105 bhp, 8-valve, 2-litre version of the same basic slant-4 engine. The 16-valve version was originally specified in the Dolomite Sprint at 135 bhp, and "Spencer King relates how he went away on holiday and came back to find an engine running on the bed giving 150 bhp at the first build."
The reasons why so few TR7 Sprints were produced has been a matter of some debate, since it was never a catalogued model. It is widely assumed that the TR7 Sprints were built with the intention of it being produced for sale, but cancelled after only a few had been made. The suggestions are that it was either cancelled as a result of industrial action, and the consequent loss of BL's market share, or because the sales and marketing department did not want it, as it was not a sufficient improvement over the TR7 base model or because it could not meet the 1976 changes to emissions legislation requirements for the US market - at which the TR7 and later TR8 were primarily aimed. It has also been noted that none of the suggested reasons for cancellation are a good match for when the main production ceased about the end of June 1977. Neither do they explain why a 16-valve model would have started production with the TR8 so near, why no proper records for the model have been found, nor why the cars that were built would have been sold off, rather than scrapped or returned to normal specification - as happened to the 25 or so O-series engined TR7 version development cars when that programme was cancelled a few years later.
There is, however, some evidence that the 16-valve TR7 model was cancelled in favour of the TR8 in 1975 or 1976, but BL had still needed some 16-valve engined TR7s in 1977 as homologation specials. The cancellation was with that of the proposed Dolomite replacement Triumph SD2, which was also to use the 16-valve version of the slant-four engine and an electronic fuel injection system that should have met US emissions requirements. These were cancelled after British Leyland went bankrupt in late 1974 and was essentially nationalized under the almost £3 billion plan in the 1975 Ryder Report (British Leyland), which was still in force well into 1977. And several sources note that the 16-valve TR7 model was cancelled at the same time as or before this injection system. The need for homologation, and some production 16-valve TR7s that had to be "meant for the normal sale" and needed some supporting documentation, was to continue rallying the 16-valve Group-4 TR7 into 1978. This followed a change to the FIA's rules disallowing approval on 100 kits of parts (the 100-off rule), and a ban on some components including optional multi-valve cylinder heads, which applied to the TR7 and several other rally cars from the end of 1977. Several pictures in the British Motor Museum archives, titled "TR7 Sprint Homologation" and dated 1 Nov. 1977, show one of the TR7 Sprints. A second approval for the use of the 16-valve head on the Group 4 TR7 rally car was granted by the FIA in February 1978 in time for its use in the Mintex rally of that year.
Technical specification
Engine: Triumph Slant Four 1,998cc 16 valve
Capacity: 1998 cc
Valves: 16
Compression ratio: 9.5:1
Fuel system: Twin 1¾" choke SU HS6 carburettors
Maximum Power: 127 bhp @ 5200 rpm (estimated)
Maximum Torque: 122 lb ft @ 4500 rpm (estimated)
Performance Data
0–60 mph: 8.5 seconds (estimated)
Max speed: 120 mph (estimated)
The improvements in the 0–60 time and top speed over the TR7's 9.6 seconds and 111 mph are not huge. However, the figures for the 16 valve version of the TR7 are almost identical to those for the US specification carburettor version of the 3.5 litre 135 bhp Rover V8 powered Triumph TR8, which are 120 mph and 8.4 seconds. Also, one of the then Triumph engine development engineers is quoted as saying "The real test was the 30–50, 50–70 [mph] times and here the Sprint was significantly superior to the 2V [2 valves per cylinder] engine and even challenged the TR8's abilities. Certainly, if we were going 'off site' the preferred vehicle to 'borrow' was a Sprint TR7 over all others and that includes the TR8."
Also, The Sprint not only had more torque and power than the TR7, but peak values significantly higher in the rev range - presumably leading to a significant improved driver experience and the preference for this vehicle mentioned above. However, the production TR7 Sprints retained the gearbox and 3.9:1 final drive ratios of the TR7; where a number of converters of TR7s to TR7 Sprints suggests it benefits significantly from the use of the 6-cylinder SD1's 3.45:1 final drive or, with tuned engines, even the SD1 3500 or TR8 3.09:1 ratio (which all fit the 5-speed TR7 axle). Hence, given a change in ratio, even to an available alternative value, the resulting figures might have been an even bigger improvement over the TR7's.
Further, despite being specified at 127 bhp, Spen King related "how he went away on holiday and came back to find an engine running on the bed giving 150 bhp at the first build." This would be very close to the 153 PS DIN (±5%) that was given by the Rover V8 engine in the UK Specification TR8 (and higher in the rev range). Hence, it is possible that had Triumph produced the TR7 Sprint and TR8 to UK specification, as was apparently planned at one time, there likely would have been significant debate of their relative merits.
Production details
According to the British Motor Industry Heritage Trust (BMIHT) archives at the British Motor Museum, Gaydon, there are production records for chassis numbers ACH/4 to ACH/25, and ACH/00501 to ACH/00535 and ACH/00700: 58 cars. Also, ACH 1 is identified by the TR Drivers Club, as UK registration WAC 274S, and that ACH 2 and ACH 3 existed might have been inferred from this: "One [unattributed] source states that there were three batches of Sprints, ACH 1 to ACH 25, ACH 501 to ACH 536 and ACH 700 on its own, a total of 62 vehicles." However, following a requested search of the BMIHT records it was discovered that "the build records we have for ACH/000535 cover 4 separate sheets and there is no record or build card for chassis number 536 as the next vehicle is chassis number 700." What production records there are at the BMIHT do not provide registration details from which cars might be traced; however, some further details of the cars known to have been produced are provided by the TR Drivers Club.()
While the 'A' in the ACH prefix to the commissioning numbers indicate that the factory TR7 Sprints were built at Speke, a Triumph engine development engineer is quoted as saying "Some if not all of these cars were definitely converted at Canley from 8-valve to 16-valve". The reason given for this is that "the Speke unions wanted added bonuses for dealing with 'non-standard' cars." However, there were at least some built on the production line at Speke: another Triumph employee, responsible for engineering liaison between Speke and Canley, is quoted as saying that "At the changeover in July 1977 (to the new common underframe) we built a batch of thirty TR7 Sprints."
The TR Drivers Club website gives details for only two of the first group of 25 chassis numbers: what was presumably the first prototype, WAC 274S, and one other, WAC 253S. Both known cars from this group were registered in Coventry in September 1977. It is suggested that most of the other cars in this batch were LHD and sold abroad. According to an inspection of the BMIHT archives, of the cars in this batch of 25 chassis numbers, at least were 11 LHD (some records have been lost) and 3 were UK specification - the remaining 11 are 'unknown' but assumed to be LHD.
The first two cars of the second group of chassis numbers were both white, and registered in Coventry as VVC 696S and VVC 697S in August 1977. These were, according to an owner written article in the TR Driver's Club Magazine from 1991,() used for reliability testing. While there are no reliable details for BL's use of these actual cars, according to one source the procedure used with the TR7 and TR8 was to run a test car on the Belgian pavé track at MIRA for 1000 miles, "effectively providing wear harder than a vehicle might experience in a lifetime of normal use". The same source also states that "A related assessment exercise for the TR7 was the '90 day corrosion test', for which a prototype was built without the usual zinc primer or anti-corrosion treatments and the body painted white, the best colour to show up any rust streaks." A Triumph engineer is quoted as saying, "this prototype was run around a variety of road surfaces under wet conditions and then the damp areas were checked. The vehicle was then fitted with a series of nozzles which sprayed salt solution into these same areas".
Thirty cars from this second group of chassis numbers were sequentially registered SJW 521S to SJW 550S (see Figure 4) in Birmingham in three groups in November 1977, and it is repeatedly claimed that they went to the BL press garage at the Canley site, Coventry; presumably for publicity purposes. It is also claimed that these cars were stripped and re-trimmed, and possibly also re-sprayed. However, the only evidence for this is that production record trace certificates for many of these SJW cars from the BMIHT state they were for a press release, and such cars would normally have gone to the Press garage. This statement is itself based only on most of the cars having "UK PRESS VEHICLE" handwritten in felt-tip pen on their build cards. Also, the TR7 Sprint Homologation pictures show no evidence of the work it is suggested would have been done to a press car, even though the pictures were taken only days before its disposal by Sales and Marketing Dept. and months after its production and departure from Speke in July 1977.
Another car of this second group of chassis numbers was registered in Coventry as ARW 181S in July 1978. According to a letter from the then archivist, reporting the research of the BMIHT records, "This car was originally intended for display at the 1977 [ Daily Express ] Motorfair in Earls Court, London. We can not verify whether it was in fact displayed here." This car was factory fitted with engine CH 2 HE which it still has as of September 2017.
It seems that the last car built in October 1977, ACH/00700, was intended for a motorshow in Scotland. However, again, it is not known if it was actually used for that.
The addition of two leading zeros to this second group of chassis numbers to make them five digits, the same length as production TR7's chassis numbers, may indicate these were pre-production cars, not prototypes. However, the differences in where and by which division of BL they were registered (from their (V55) registration documents), indicates that they may still not have been manufactured as a single batch. Hence, it is possible that the press garage (SJW) cars were the "batch of thirty TR7 Sprints" built at "the changeover in July 1977", and the cars in the first group, and possibly some of the second, may have been those built as 8-valve cars at Speke, and converted to 16-valve at Canley.
Distinguishing features