Road Test -- Caterham Super 7 HPC
Vim and vigour
Since 1957 the Lotus 7 and its 1973 licensed successor, Caterham Super 7, have attracted hardened Britons and an increasing export market to purchases that many see as the equivalent of buying a Morgan.This is not quite the truth: traditional the Seven may be, but it has been developed to the last detail within its traditional format, and we can think of many mass manufacturers who have not been so successful as Caterham cars in sympathetically developing an existing concept.
Last year, some 800 Caterham Super Sevens were made by the 52 staff employed at their Crayford, Kent, factory. The site opened in 1987, which was also the first year that the company offered a five-speed gearbox.
This year the British recession will bite back overall numbers, but the future has never looked so secure with important new engine options from Vauxhall and Rover entering production alongside the faithful Ford crossflows that will eventually disappear.
The chassis construction formula of tubular steel space frame and stark alloy panels looks much the same as ever. A Computer-Aided Design (CAD) session, courtesy of London University, analysed many weak points in the eighties; extra triangulations are visible, along with a far higher standard of construction than Lotus could ever have aspired to in 1957-73.
The Seven is now better made and developed than it has ever been, but its price does show signs of running wild. Our demonstrator would have cost more than £20,000 to duplicate, and that takes this flyweight into cost conflict with the aero-bodied generation of sporting cars.
Despite some verbal opposition from the PR consultants, we managed to test an example of the fastest (over 120 mph, 0-60 mph in less than 5.5 seconds) Seven derivative that is now entering production. When the 2-litre Vauxhall 16v is implanted the Super Seven bears the suffix “HPC.” This may mean High Performance Caterham to the originators, but also stands for High Performance Course — as administered by the severe John Lyon to all buyers of the 1986 Cosworth BDR-powered Seven HPC.
The UK Range
Caterham company owner and MD Graham Nearn has never lost sight of the fact that the Seven started life as a cheap sports car for home construction. The machine is still not available to British residents in any other form than carefully separated components.
You can buy a starter kit at £3948 with a live axle, or spend £4747 for a de Dion example, but major items (such as an engine) will be required at additional expense. More realistic is the £12,057.32 demanded for a complete Ford 1600 GT crossflow-propelled kit, which can become £14,468.28 if you opt for the most expensive component Caterham Ford in 1700 Super Sprint trim.
The new Seven with Rover K-series motivation comes at £13,883 and is further discussed in our driving impressions, whilst the Vauxhall 16v series (all with engines uprated to 175 bhp rather than the standard 150 bhp) are priced from £17,860.75. This cost includes VAT and Car Tax, but options like the leather trim of the demonstrator put you on the path to a £20,000 Seven, even supplying your own assembly labour.
Technical Analysis
As for the apparently simple tube chassis, it is easy to assume the constructional details of the Seven remain largely as they have always been. The principles — light weight, low centre of gravity, high power to weight ratio — remain at the heart of any Seven’s startling performance-to-bhp abilities, but the details have altered radically during the late ’80s and early ’90s. The product is now undoubtedly much improved, far beyond the mass-produced wares offered under “new, improved” slogans.
The chassis of the test HPC model is a prime example. It utilises the traditional double wishbone front end, but its non-parallel arms offer a 40mm reduction in roll centre and radically reduced camber changes. It is easily adjustable in respect of camber and castor, now featuring a forged upright that replaces the old Triumph Herald hardware that has become dangerously dated to meet modern chassis loads.
Front roll bar stiffness was boosted by nearly four times over its predecessors and the bar has a girth of 18mm. Spring rates, front and rear, are stiffish (bearing in mind vehicle weight) at 170 lb in. Jarring impacts are absorbed by exceptional suspension travel lengths (a philosophical and practical legacy from Colin Chapman) and Bilstein low gas pressure damping, the latter incorporated after four years development.
The rear remains on the de Dion principles that have been offered since 1985, but for this variant relocation of the de Dion A-frame, to a position within the chassis, has again altered the handling and responses. In association with Bilsteins and a slightly lighter roll bar, a feeling of supple grip contrasts with the Seven’s image of a stark and harsh character. The front bar is actually a 5/8ths UK item, but is referred to as a 16mm for convenience. Because of the adjustments possible in radius arm location (up to a full race setting) and roll bar action, it is relevant to note that the press car was set up deliberately to oversteer.
A Caterham employee told me this was to meet the needs of the press who entertain their readers with opposite-lock cornering shots of the ‘look at me, Mum, what a hero’ variety. Our Caterham source added, “you will find it is a bit too easy to tail-slide the car away from roundabouts and it would be hopeless on a race track, just for the sheer lack of grip.” All that he said was true. I felt ashamed of my job and ignored the inefficient characteristic, which had not been present on an earlier HPC that I drove with a development engineer for the SMM&T test day last June.
Other technical features that merit comment are the five-speed Ford gearbox and Ford rear axle (their whines on part throttle over-run are pronounced and judged “typical”), a quartet of disc brakes (first seen in 1988) and the motor conversion. This sees complete Vauxhall 16v “square” (86 x 86mm) units delivered, minus electronic injection and exhaust manifolding.
Caterham now have expanded into the engine building business for the Ford units and they have also developed a range of carburation, lubrication and exhausts to suit their needs on Vauxhall units. For racing use they supply their famous side exhaust, a simple dry-sump system that cuts out some of the nightmare plumbing of yore, and 48mm side draught carburettors.
Our test car stuck with wet sump lubrication, but the sump is a cast aluminium unit that is heavily finned to avoid the need for a separate oil cooler, temperatures proving well within Mobil recommendations. Carburation for “our” Caterham was confined to Weber 45mm sidedraught units and the exhaust top manifolding was notably smaller than that used in racing (but a lot larger than an Astra 16v GTE unit). Yet the result was an entirely credible 175 bhp claim, supported by a near-standard 155 lb ft of torque.
The official rpm limit is 7600, but we used little over 7000 to establish our figures, thanks to a lack of instruction or tachometer encouragement to go much beyond this point.
At The Wheel
This simple two-seater has always majored upon acceleration and handling abilities which leave mere mortal motors gasping. The advent of a 175 bhp Vauxhall engine has emphasised its seductive slingshot ability to memorable degree.
The GM engine has a lot more torque than did Cosworth BDA variants of the HPC (still supplied to the Japanese, at their insistence), and the result is the kind of crushing acceleration advantage that the Seven has always traditionally inflicted on more mundane motor cars.
A modest 3500 rpm was enough to leave some of the oversize Goodyears behind on the surface of our Bedfordshire test track. Less than two seconds later, “Blue Seven” had leapt to 30 mph, the kind of breathless launch that only a powerful Audi quattro 4-WD machine, or the more accelerative Porsche 911s deliver. When you consider how much such machinery costs, and that the Seven still sticks to a simple (bar the de Dion) rear drive, such a figure is doubly remarkable.
Barely three seconds are required to punch up 40 mph, and the much quoted 0-60 mph standard was achieved in an average of 5.42 seconds, again right in current Porsche 911 territory. Yet that was not enough for Caterham Cars. “Oh,” said an engineer in miffed tones, “AutoFastSpeedCarGTIWorld & Motor managed 0-60mph in 4.9 seconds.”
Quite honestly we were lucky to get two runs to average that 0-60 tally in, for the synchromesh had obviously taken a very considerable beating in achieving such sensational statistics. Not so sensational are the figures beyond 90 mph, and you feel the 0.6 + aerodynamic Cd as a forceful air wall beyond the elapsed quarter mile at 89 mph. The 0-100 mph figure lags behind an aerodynamic modern saloon like the BMW 325i tested last month.
Overall fuel consumption was disappointing at less than 20 unleaded mpg, but the BDR Seven (rated at 175 bhp) was independently tested at 17 to 18 mpg.
The demonstrator cockpit was an uneasy alliance of useless tradition (the shin-biting under-fascia hand brake), beige leather that was bound to suffer during the aerobics required to enter and leave a door-less two-seater, and an assortment of switches to baffle all but the afficionado. For example, the winkers work from a fragile toggle, and there is one illustration of a flying Walrus that translates as the windscreen washer prompt. Equally baffling are toggle switches for headlamp dip and headlamp flash that are separate, but identical. Perhaps some race-style labelling would not go amiss?
Caterham have suffered the inputs of too many journalists and customers to form a coherent policy on the black and white VDO dials. I did not like them much, even though Caterham bought the most expensive set, many of which are also seen (and criticised) on the Lotus Esprit. Personally the VDO information reminded me of what we could have, and that which I think is correct for this car: old Smiths-style black and white with proper graduations. The nearest in concept I have seen are from Raceparts, but they could be allied with a larger Stack rev-counter on the HPC model as well. It is genuinely hard to change gear fast enough to keep up with the startling acceleration and rpm peaks.
A little more time and one begins to appreciate the practicalities of Seven accommodation once again. That winker toggle switch is less than an extended finger’s length from the diminutive steering wheel. The heater may be uncomfortably on all the time, but it always ensures the enveloping welcome of the cockpit is accompanied by real warmth. The problem was overcome on a K-series example we briefly experienced.
We have described the suspension modification made in some detail. Here we can say that all that detail work has been thoroughly worthwhile. The Seven HPC rides better than 80 per cent of sports hatchbacks, yet has grip and agility to make even the best of that bunch feel like the mass-production conversions they really are.
Sensibly rapid steering (under 3 turns from lock to lock) is communicative without excess wriggling. The ability to change direction suddenly remains without equal amongst production cars in my experience.
That “swerve-ability” has always been part of Seven appeal, a simple product of low weight and overall height. Now the Seven has true grip, the de Dion hanging on where the live axle used to skip and kill any ride-quality pretensions at birth. Those plump Goodyears deserve equal credit for a gain in cornering forces, now reported to hit 1.05g in harsh cornering and 1.15g in emergency brake testing.
There is no purer form of driving pleasure than that offered by this HPC Seven in dry conditions. We did not have any seriously slippy surfaces to contend with last August, but I am told the Seven now has a measure of wet weather adhesion that is only confounded by its tremendous power to weight ratio (307 bhp per ton!).
Another by-product of low weight is excellent braking from one of the few performance car systems (like that of the steering gear) that lacks power assistance. The precision and capacity of both systems was almost as memorable as the searing acceleration rates.
Dynamic snags? Nothing to remotely impinge on overall driving enjoyment, but I could have done without the crack of the open air-filtered carburation and the hiccups when the 45DCOE Webers were asked to cope with anything other than the most modest acceleration in the 1500 to 2250 rpm range. We re-learned driving around that problem (shades of ’60s tuned cars), but it does seem a bit contrary to take off an effective Bosch-managed electronic injection system and not quite get the carburation right for the lower speed running that all of us have to do these days.
Underlining this flexibility point was a brief ride with Caterham development engineer Reg Price in the newly announced K-series Seven. This does have multipoint electronic fuel injection and drives with an ease and charm that has seriously worried some Caterham insiders; they feel the customers will stay away on the basis that it is “not rorty enough.”
In fact the Seven K-series still has 200 bhp per ton from the 103 bhp Rover 1397cc, so one could expect 0-60 mph to remain in the six second region (as per Cosworth Sierra RS). Caterham are claiming a 112 mph maximum and 40.9 mpg at 75 mph and are outwardly confident that this green machine (a catalytic convertor is a £490 option upon a CKD kit price of £13,883) will replace the Ford crossflow generation. That will occur first in racing — there is a series for Seven-K in 1992 — and then as the affordable road machine. The car tested here with Vauxhall power will remain the higher performance option for the forseeable future.
Verdict
If the Good Lord has a “grin machine” for recreational purposes, it must be a Caterham 7 HPC. The vehicle has been excellently developed in its present guise, and a short ride in the Rover K-series-powered alternative proves that it can be a quietly docile and economical tourer, if required.
The writer would like to see the same recipe enclosed in a more aerodynamic outline (shades of Lotus 11?), so that we could enjoy even higher levels of performance with less fuss. Surely that is what Colin Chapman originally progressed toward? It would give Caterham owners a further level to aspire toward, and justify Caterham pricing beyond £20,000.
Meanwhile, the Vauxhall engine has provided the most potent of arguments for fresh air speed and rear drive handling. — JW
***
MOTOR SPORT TEST RESULTS — CATERHAM SUPER 7 HPC
SPECIFICATION:
ENGINE: Water-cooled, light alloy head, iron block; inline four cylinders; DOHC, 4-valves per cylinder. Capacity: 1998cc (86 x 86mm). Baffled alloy wet sump, belt-driven overhead camshaft, electronic ignition, 10.5:1 cr. Max power: 175 bhp @ 6000 rpm. Peak torque: 155 lb ft @ 4800 rpm
TRANSMISSION: Front-mounted longitudinal engine, Ford Sierra rear drive differential via forward Sierra 5-speed manual; hydraulically operated single-plate (8 in/203mm) diaphragm spring clutch. Optional limited slip differential (£117.50)
GEAR RATIOS: 1st: 3.36; 2nd: 1.81; 3rd: 1.26; 4th: 1.00; 5th: 0.882…20.2 mph per 1000 rpm; Final drive: 3.92.
BODY: Tubular space frame, aluminium honey-comb cockpit stiffening offers extra side-intrusion protection; aluminium panels but glassfibre nose-cone and wings; strictly two-seater. Petrol tank of 45.4 litres/10 gallons. Aerodynamic drag factor “in excess of” 0.64 Cd.
DIMENSIONS: Wheelbase 88.5in/2250mm; front track 50in/1270mm; rear track 52.5in/1335mm; width 62in/1574mm; length 133in/3380mm; height (hood down) 39in/990mm; hood up 44in/1120mm. Kerb weight 1276 lb/580 kg (press demonstrator), circa 550 kg more typical; 520 kg, K-series.
FRONT SUSPENSION: Double wishbones, 18mm anti-roll bar; gas-pressurised Bilstein telescopic shock-absorbers, coaxial 170 lb in coil springs. Steering: Unassisted rack and pinion, 2.75 turns lock-to-lock.
REAR SUSPENSION: De Dion axle, diagonal links and radius arms, coil sprung (170 lb in) with gas pressurised Bilstein telescopic dampers. Multiple adjustment mounts for radius arms and 16mm anti-roll bar; test car deliberately biased to low speed oversteer.
BRAKES, WHEELS, TYRES: Non-assisted solid discs of 9in/229mm diameter. Light alloy 7 x 16 inch front and rear wheels; 205/45 ZR-16 Eagle GSD tyres.
PRICE: From £17,860.75 UK taxes paid in CKD form; £18,867.42 in British component build trim. As tested “just over £20,000.”
MANUFACTURER / IMPORTER: Orders to Caterham Cars Ltd., Seven House, Town End, Caterham Hill, Surrey CR3 5UG.
CLAIMED PERFORMANCE: Max speed 125 mph; 0-62 mph, under 5 seconds.
TEST RESULTS:
Conducted at Millbrook Proving ground using 1991 Correvit electronic measuring gear. Weather conditions: Sunny, dry tarmac.
ACCELERATION: 0-30 mph 1.85 seconds; 0-40 mph 3.06 seconds; 0-50 mph 4.15 seconds; 0-60 mph 5.42 seconds; 0-70 mph 8.16 seconds ; 0-80 mph 10.34 seconds; 0-90 mph 13.51 seconds; 0-100 mph 21.05 seconds.
FLEXIBILITY: Third gear 50-70 mph 3.94 seconds; Fourth gear 50-70 mph 5.44 seconds; Fifth gear 50-70 mph 9.35 seconds.
Standing 0.25 mile/400 metres: 14.62 seconds @ 89 mph.
Maximum speed: Millbrook 2.029 mile bowl, best 0.25*: 123.46 mph
Maximum gear speed @ 7000 rpm: First 31.8 mph; Second 63.8 mph; Third 93.1 mph;
Overall fuel consumption: Test Average 19.36 mpg.
Government mpg figures: Not released.