Four doors. Five seats. 150 mph

Tuning topics

There are several ways of buying 150 m.p.h. performance and shattering acceleration for over £7,000, but the only purchaseable package I am aware of which achieves this and at the same time makes available luxury accommodation for five people, four doors, copious luggage space while out-accelerating a Lamborghini Miura to 60 m.p.h. is the BMW Alpina 3.0 Si. A maximum speed of 146 m.p.h. and a 0-60 time of 6.1 sec. must surely make this the fastest four-door saloon obtainable for road use in Europe.

The 3.0 Si tested recently had basically the same modifications, including the 260-b.h.p. DIN engine, from the Bavarian Alpina tuning firm as that company's own 3.0 CSL which I tested on the Continent for the February issue. However, I make no apologies for what appears to be a duplicate test, for the four-door saloon so modified represents a different philosophy to the lightweight coupé. This Si belonged to BMW Concessionaires GB, who on the day of writing increased their prices to compensate for the de-valuation of the £ against the Dm., the standard 3.0 Si rising by £600 to £4,899 and the Alpina car by a similar amount to £7,595, £700 more than the standard 3.0 CSL. Orders for similar cars can be placed through any BMW dealer, who should make arrangements through John Markey or Mike Heath-Wise at the Concessionaires.

For those readers who don't have the February issue to hand a re-cap is necessary on the Alpina specification, which varies slightly on this saloon, particularly in respect of the gearbox which was the standard four-speed Getrag unit with ratios of 3.855:1, 2.202:1, 1.401:1 and 1.0:1 with a final-drive ratio of 3.25:1 in place of the five-speed ZF gearbox and 3.89:1 final drive fitted to the Alpina CSL. Most of the cost goes into the engine, which the Concessionaires continue to claim 250 b.h.p. DIN for, although Aipina told me that 260 to 265 b.h.p. is nearer the mark. The increase from 200 h.p. DIN of the production car comes from a comprehensive rebuild, including increasing capacity from 2,985 c.c. to 3,020 c.c., fitting forged pistons, polished the conrods, increasing the compression ratio to 10.5:1, converting the combustion chambers from triple-hemisphere to fully-hemispherical, polishing the ports and valves, fitting an Alpina sports camshaft and replacing the Bosch electronic fuel injection by a Kugelfischer mechanical pump and Alpina's own design of injection system, fed by a special air-cleaner and cold air box. The exhaust system is of a larger diameter, though the standard manifold is retained. A larger diameter Fichtel and Sachs clutch (240 mm. instead of 228 mm.) with alloy pressure plate is attached to the lightweight flywheel assembly and the complete crankshaft assembly is balanced. Aids to efficiency are a thermostatically controlled oil cooler and an electric cooling fan.

Suspension improvements on the saloon included Bilstein struts and rear dampers, increased rate progressive coil springs all round, negative camber on all four wheels and adjustable front and rear anti-roll bars. While the CSL had alterations only to the front discs of the four-wheel ventilated disc-brake system, involving increasing their width from 22 mm. to 28 mm., this saloon had 28 mm. discs all round.

A limited slip differential had been added to the saloon as well as 7J x 14 in. Alpina alloy wheels shod with 195/70 x 14 in. Michelin XWX tyres, items which are standard equipment on the CSL. The wheel arches had not been modified to accept the wider wheels, for which the CSL receives shiny wheel arch extensions, though they appeared not to protrude illegally. An Alpina front spoiler was included as a very necessary aid to streamlining and high-speed stability, making the car's aesthetics rather more distinctive.

The beauty of this saloon was that performance was achieved without sacrificing comfort or having to endure vastly increased noise level. The Alpina CSL had proved much noisier than this car and had a choppier ride, because of the reduction in sound insulation and the lighter shell. The standard Si makes no concessions to lightness, occupants being well-protected from mechanical and road noises and surrounded by solid, heavy steel. Indeed though the distant engine note sounded rather more urgent in this modified car, it was certainly not painfully obtrusive, and what could be heard aided one's appreciation of the finesse put into the engine.

Ride was firm, again not to the discomfort of passengers, the frequency of pitch being low, but feeding an exceptional feel of tautness to the driver—even more so than the standard Si, itself almost beyond criticism. Roll was well subdued, if rather more noticeable than on the CSL because of the heavier superstructure, and handling was equally neutral. Roadholding was such that it was virtually impossible to get the tyres so much as to drift in the dry, however hard the car was pushed and in the wet the XWX tyres showed supreme adhesion, though there was an ultimate and fairly sudden breakaway point from which the big car could be recovered easily. In fact the wet weather road manners were better than the Alpina CSL's, largely because the latter had 205 section tyres on the rear, prone to aquaplane very easily in heavy rain and making breakaway even more sudden and recovery less smooth.

The Concessionaires had chosen to retain the power steering with its standard 18.9:1 ratio, effective ratio to the driver slightly reduced by fitting a smaller diameter Alpina leather-rimmed steering wheel. I praised Alpina at the time of the other test for fitting a manual steering box to their car, but now I'm not so sure: for one thing I've driven several power-steered big BMWs since then so have grown accustomed to the system and for another the suspension modifications on this Si had undoubtedly helped the feel and response. Certainly after my experience with this car, which had steering superior to the standard CSL, I would choose power-steering should I be lucky enough to afford an Alpina car. It was not overlight, yet it made traffic conditions, parking and tight cornering into supremely easy exercises.

Of course the one thing which really made this car stand out was its performance, which bears comparison with the best of the world's performance cars, even if its gearing and extra weight made it slower than the Alpina CSL, 3.9 sec. quicker from 0-100. The gear ratios, though somewhat wide, were perfectly adequate for main road driving, the torque of this engine being considerable, although I missed the sheer pleasure of screaming through the close-ratios of the Alpina CSL's five-speed box. Speeds in the gears were lower than might have been expected, showing the rather poor ratios of the standard box: 1st, 36 m.p.h.; 2nd, 65 m.p.h.; 3rd. 103 m.p.h. Accelerating through the gears showed these ratios to be just about adequate having regard to engine characteristics: where this inappropriate selection was inadequate was when driving hard round winding roads when the right ratio was never available for the right corner and when changing down for braking effect.

While acceleration was really electrifying, made all the more so by the knowledge that it was a big, heavy motor car which was achieving it, an even more remarkable fact was that this Si was remarkably tractable and flexible, quite happy pottering through London traffic at 1,200 r.p.m. or burbling along at 30 to 40 m.p.h. in third gear in a for-once sensible and consistent convoy in 50 or 60 miles of motorway fog. The plugs never fouled and the engine never coughed. One slight problem early in the test was that the throttle pedal was sticky and insensitive at small openings. This disappeared after the performance tests during which the vertical link to the throttle butterflies continually fell apart at one of the plastic knuckle joints, because of the peculiar angle at which it worked on full-throttle. The problem of stickiness must have been that knuckle joint because the feeling subsequently disappeared. Apparently the linkage will be modified for future cars.

The rev-counter needle fairly flew round the gauge in every gear including top, which makes the fitting of an ignition cut-out at 7,200 r.p.m. (the standard Si cut-out operates at 6,300 to 6,400 r.p.m.) extremely sensible and necessary to avoid a blow-up which could run into four sterling figures. Right up to the cut-out figure the engine was superbly smooth and crisp, a tremendously satisfying unit.

Performance needs no more qualification other than perusal of the accompanying performance figures, which speak for themselves, but this type of mechanical vigour in a heavy motor car must be paid for, the penalty in this case being an overall thirst of 16 m.p.g. of five-star, yet considerably less than an XJ12 and not likely to worry the man who can afford £7,000. The range is reasonable on a 15-1/2-gallon tank, including 1-3/4-gallon reserve, operated automatically, at which point a warning light comes into operation.

The comfort and spaciousness of these big BMWs has been written about in this journal before, so requires no further comment. Suffice to say it is difficult to better and combined with the Alpina modifications makes this an extremely desirable motor-car, particularly for the businessman who makes frequent continental journeys on which he can utilise its performance to the full.

Performance

0-30 m.p.h. ..... 2.2 sec.

0-40 m.p.h. ..... 3.7 sec.

0-50 m.p.h. ..... 4.7 sec.

0-60 m.p.h. ..... 6.1 sec.

0-70 m.p.h. ..... 9.3 sec.

0-80 m.p.h. ..... 11.5 sec.

0-90 m.p.h. ..... 14.4 sec.

0-100 m.p.h. ..... 17.8 sec.

Maximum speed: 146 m.p.h.

Standing 1/4-mile: 14.95 sec. (terminal speed 94 m.p.h.)

Consumption overall: 16 m.p.g.