BMW 733i

Introduction

The BMW 733i, top of the 7 series, was also top of the BMW range as a whole. This popularity was probably due to the way BMW managed to combine an aura of solid respectability and luxury with an excellent sporting pedigree to provide a mixture guaranteed to appeal.

The 733i used the well known 3.3-litre straight-six engine which featured a cast-iron cylinder block and aluminium head with virtually hemispherical combustion chambers. This apart, the single-overhead-cam engine was a relatively simple design, but nonetheless it developed a very healthy 197 bhp at 5500 rpm, and 200 lb ft of torque at 4300rpm.

As the 'i' suggested, the 733i used fuel-injection, and perhaps it was this touch which helped give the car very good performance, comparable to bigger-engined cars such as the Jaguar XJ 5.3. The top speed was 127 mph, and the 0-60 mph acceleration time of 8.3 seconds was more in keeping with a more overtly sporting coupe than a large sedan.

The easy and precise four-speed gearbox of the manual version helped the driver to make use of the performance more easily than in the automatic version, and despite the fact that this BMW was a large car, it felt smaller from the driving seat thanks to good positioning of the seat and controls.

The well-weighted power steering and the generally neutral handling all combined to give a feeling of confidence in the car. The suspension was by MacPherson struts and lower transverse arms, with anti-roll bar, at the front, and by semi-trailing arms at the rear. It was set up to favour the luxury car side of the BMW 733i's character, being somewhat soft and, despite the anti-dive geometry of the front and the anti-lift of the rear, the car could still be said to wallow slightly - a penalty paid for an otherwise comfortable ride.

One of the strong points of the recent BMWs was the excellent instrumentation which was laid out in a particularly clear manner, with features that were to become a BMW hallmark, such as red instrument lighting; red being chosen as it detracts from night vision less than other colours such as the more usual yellow of cars from the era.

The automatic BMWs had an array of lights running across the dash to provide a constant reminder which gear you were in. The 733i fell into the category of those cars which did almost everything well, even if nothing about it was exceptional. It did, however, have a definite appeal as a prestigious long distance tourer which could also be fun to drive. In top gear at high speed the big six-cylinder engine was not working very hard, managing 21.3 mph per 1000 rpm, and thus the engine was running at less than 5000 rpm when the car is travelling around the 100 mph mark, making for relaxed travel.

BMW 733i Quick Specifications:

Engine: Front mounted, in-line, six-cylinder. 89mm (3. 504 in) bore x 86mm (3. 386 in) stroke - 3210cc (195.9cu in). Maximum power (DIN) 197 bhp at 5500 rpm; maximum torque (DIN) 206 lb ft at 4300rpm, cast-iron cylinder block and aluminium head. Compression ratio 9:1. 7 main bearings. 2 valves per cylinder operated via rockers by one overhead camshaft. Bosch L-Jetronic fuel injection.
Transmission: Single dry-plate clutch and four speed manual gearbox. Ratios 1st 3.851, 2nd 2.20, 3rd 1.40, 4th 1.0, rev 4.3:1. Hypoid bevel final drive, ratio 3.45:1.
Suspension: Front-independent by MacPherson struts, lower transverse arms, drag links, and anti-roll bar, rear-independent by semi-trailing arms.
Steering: lE recirculating ball.
Brakes: Discs front and rear. Serve-assisted Dual hydraulic circuit.
Wheels: 6.5in x 14in. Tyres 205/70VR x 14in
Dimensions and weight: Wheelbase 110in; track - front 54.94in, rear - 59. 84 in; length 191.3in; width 70.9in; height 56.3in; ground clearance 5.5 in; dry weight 35281b; turning circle 37.4 ft; fuel tank capacity 18.7 gal. Bocfj;,!chassis 4 door, 4 seats. Integral.
Performance: Maximum speed 127 mph; acceleration 0-60mph 8.3 seconds; fuel consumption approximately 17 mpg.