sure a car have changed to a degree that scarcely could have been imagined two decades ago.

A 247-hp normally-aspirated engine

Power output is always the first criteria and the Carrera 4 offers 33 more horses than the present 911 Carrera. Increased acceleration, which we suspect is much faster than Porsche’s conservative claim of zero to 60 mph in 5.7 seconds, is coupled with a top speed of 162 mph. The new air-cooled, light alloy, twin ignition, 3.6- liter engine produces 247 horsepower (SAE net) at 6100 rpm, with maximum torque 228 foot-pounds at 4800 rpm. It’s a bigger motor than anyone ever expected to find in the engine bay of a 911; while the crankcase is the same, the spacing between cylinder head bolts has been altered to permit the displacement increase achieved by enlarging bore and stroke to 100.0 x 76.4 mm. Owing to the twin ignition, a compact combustion chamber and knock control, the compression ratio is extremely high at 11.3:1.

Additional features inthe new engine include ceramic port liners, a lighter crankshaft, newly-designed two- stage resonance intake manifold managed by a yet further-evolved Bosch Motronic system and a metal matrix catalytic converter. The exhaust system and heat exchangers are also completely new and are part of the

PORSCHE PANORAMA

solution to good interior heat which has until now been a nagging 911 problem. Engine noise is reduced through a partial engine capsule, a further developed cooling fan and 50 percent more exhaust muffler volume.

Low drag coefficient and zero lift

Aerodynamic improvement of the 911 was a basic design criteria for the Carrera 4. Compared to the 0.395 of the present 911 Carrera, the Carrera 4’s drag coefficient is 0.32 and the important Cd.F value (drag coefficient times frontal area) is 0.573 square meters compared to 0.686. At the same time, lift has been reduced virtually to zero. The new smooth underbody, adapted to the space needs of the four-wheel-drive system, with its diffuser shape at the rear plays an important part. Additionally, cool air intakes in the nose of the car reduce air resistance and, according to Professor Bott, this is the first car which is slower with closed openings in the nose than with open.

The Carrera 4 uses an extendible rear spoiler to reduce lift and improve engine compartment ventilation. Nearly invisible in its closed position, the spoiler is automatically raised by electric motors at 50mph and is retracted at about 6mph. This guarantees that the spoiler

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Transaxle tube connects engine, four-wheel-drive components and front and rear axles. Center differential with multi-plate clutch is ahead of the gearbox.