Radical rethinking

Claimed to be 87% new, believed that or not, the type 964 Carrera 4 was definitely the most radically re-engineered 911 up to then. It had new front and rear suspensions, modern aerodynamics, an advanced electronic 4-wheel drive system and a heavily revised engine. Compare with the previous Carrera 3.2, the 964 seemed like a revolution rather than evolution.

The monocoque chassis was basically unaltered, so was the general body shape that characterised 911 for a quarter of a century. However, the smooth, body-integrated and body-coloured front and rear bumpers indicated the great effort spent to aerodynamics. Instead of the predecessor's 0.42, the 964 achieved a remarkable drag coefficient of 0.32 while generating virtually no lift at high speed. Apart from bumpers, the flat undertrays which sealed front suspension, engine and transmission tunnel also played an important role to reduce drag and lift, so did the automatically raised rear spoiler which replaced a fixed wing. The little spoiler normally acted as ventilation for the engine and recessed smoothly on the engine lid. It raised at above 50 mph and dropped down (for the benefit of engine cooling) at under 6 mph. The movement was quite spectacular to look at.

The flat-six engine received so much modifications that it was given a new name, M64 series. Its major mission was to comply with stricter emission regulations, cope with the considerable weight increase of the 964 without compromising performance. Moreover, it was designed to be a "world engine" - suitable for all markets without any modifications. To achieve 250 hp and 228 lbft output (up from Carrera 3.2's 231 hp and 210 lbft) even in the presence of catalytic converter, it was bored and stroked to 3.6 litres and employed a very high compression ratio of 11.3:1 which was made possible by twin-spark per cylinder and knock sensor. Advancer Motronic program worked in associate with ignition and sequential fuel injection. A 2-stage resonance intake manifold was introduced to improve mid to high speed power.

That enabled the Carrera 4 to sprint to 60 mph in 5.2 sec, slightly quicker than its predecessor. That was very respectable, considering the car weighed an astonishing 250 kg more. It topped 161 mph, which actually matched the contemporary 911 Turbo 3.3, thanks to superior aerodynamics.

For the first time, the 911 received a proper MacPherson strut suspension with concentric coil spring instead of torsion bar. As earlier we have mentioned, the original 911 chose torsion bar in order to give more luggage room at the front. However, as Carrera 4 had the 4WD system already engaged a lot of space, there was no reason to maintain the torsion bar setup. At the rear, a revision of geometry to the semi-trailing arms, plus addition of rubber bushing to pivot joints, enabled a passive rear-wheel steer (inspired by 928's Weissach axle) to counter the oversteering. The new trailing arm was also made in cast aluminium instead of iron.

However, the biggest technology breakthrough must be the intelligent 4-wheel drive, which was simplified from 959. It normally transferred 69% torque to the rear axle, but in case of slide, the electronic control could send more to the wheels which had most traction. Active rear LSD also keep oversteer tightly in check. It was so effective that, accompany with the changes in suspension geometry, many 911 traditionalists criticised it as an understeerer ! In fact, not every motor journalists were convinced that the new-found traction and security of handling justified the lost of involvement. Many regarded it as the most boring 911 after the SC.

The launch of rear-wheel drive version Carrera 2 relieved some pressure from Porsche, but there was still something to be desired. Like the Carrera 4, it rode quite hard and was not all that beautiful. The RS and RS 3.8 were even harsher to live with.

So, what made it one of "the most memorable 911s" ? Radical rethinking. Without a reform like this, the 911 would have never kept alive and popular in its last 10 years, and its successor 993 would have been either unsuccessful or non-existent.

Model

964 Carrera 4

964 Carrera 2

Year

1989

1990

Layout

Rear-engined, 4wd.

Rear-engined, Rwd.

Flat-6, sohc, 2v/cyl,

Flat-6, sohc, 2v/cyl,

Engine

Motronic, twin-spark,

Motronic, twin-spark,

2-stage resonance intake

2-stage resonance intake

Engine Capacity

3600 c.c.

3600 c.c.

Bore x stroke

100 x 76.4 mm

100 x 76.4 mm

Power

250 hp

250 hp

Torque

228 lbft

228 lbft

Gearbox

5M

5M

Top speed

161 mph**

164 mph**

0-60 (0-62.5) mph

5.2 sec*

5.1 sec*

0-100 (0-99.5) mph

( 13.2 sec** )

( 12.9 sec**

Weight

1460 kg

1380 kg

* Tested by Autocar ** Tested by Auto, Motor und Sport

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