The Porsche Carrera 2.7, which in Europe features a 200-bhp engine with Bosch mechanical fuel injection and hotter cams than the K-Jetronic U.S. version, is now part of the normal Porsche production program. But the RS 3.0 version, like the 2.7-liter RS that preceded today's production Carrera, is a limited edition whose origin is in the CSI racing rules. By making 100 units of the model Porsche was able to homologate the RS 3.0 as an “evolution” of the 1973 lightweight Carrera RS model and incorporate into its design several modifications that had proved worthwhile in last year's Carrera prototypes run by the Martini Racing Team. Otherwise these couldn't have been used in GT racing this year.
Most important among these changes are a larger rear spoiler, wider wheels and tires, a die-cast aluminum crankcase and slightly different inner pivot points for the rear suspension. The wider wheels and tires have required wider fenders, which for racing can be extended laterally a further 2 inches each to cover 11-in.-wide front and 14-in.-wide rear wheels. As delivered, the car has 8-in. forged alloy wheels at the front and similar 9-in.ones at the rear, shod with 215/60VR-15 and 235/60VR-15 Pirelli CN36 tires front and rear. It also comes with two rear engine covers: one carrying a larger-than last year’s horizontal spoiler with a rubber surround that makes it acceptable for road use in Germany without the special permit required for the 1973 model, and another even larger one without rubber for racing. That the car is delivered with both makes the second one eligible for the GT group. Clever, isn't it?
This story originally appeared in the October 1974 issue of Road & Track.
Having set themselves a target of only 100 cars, the pundits in Stuttgart-Zuffenhausen could assume most of them would be bought by people intending to race them, presumably with Group 4 modifications as races for Group 3 cars are almost nonexistent. Consequently they decided to offer as standard as much of a full racing specification as possible, to save the owner the expense of throwing away perfectly good units to replace them with the racing parts. Thus the car comes with the die-cast crankcase, 95-mm Nikasil-plated alloy cylinders, the big oil cooler for racing, a transmission oil cooler with the necessary pump built into the gearbox end cover, and the immensely expensive drilled disc brakes developed for the 917 turbocharged Can-Am car! All this makes the car about twice as expensive as the production Carrera, but then Group 4 preparation is correspondingly cheaper—about $6000.
The RS 3.0 is built around a perfectly standard 911 bodyshell, but the integrated “bumpers" are plastic and so are the front and rear lids; the door panels are of light-gauge steel. Further weight has been saved by much simplified interior trim, deletion of the rear seats and other interior equipment, the use of expensive but light Gleverbel safety glass and the replacement of the standard seats by plastic rally bucket seats. We were curious enough to put the car on a scale and found it to weigh just over 2400 lb; this is slightly heavier than last year’s car, but the wheels and tires are heavier and there are two oil coolers with their plumbing. Also, the aluminum crankcase weighs about 22 lb more than the magnesium one of the standard 911 models, which may seem a retrograde step; but with the 95-mm bores there isn’t enough metal left between the cylinders for safety in a 330-bhp engine.
Despite the capacity increase, port and valve sizes as well as the camshafts have remained the same as for the European 2.7 Carrera, so the 3-liter engine is remarkably flexible and has fabulous mid-range torque. But at least 20 additional horsepower had to be found to compensate for the increased drag created by the wider wheel arches and extra weight, and this could not be achieved by displacement alone. Porsche thus deviated from normal policy of tuning engines for regular fuel and raised the compression ratio from 8.5 to 9.8:1 to achieve 230 bhp DIN (about 220 by the SAE net method or just the required 20-bhp increase). Even this proved not quite sufficient to reach the 150 mph we timed for the Carrera 2.7 last year: the current car was just 1 mph slower, though its acceleration has remained much the same. Still, this is one of the fastest road cars we have ever timed: 60 mph is reached in a staggering 5.2 sec with the help of superlative rear-wheel grip and the 1/4-mile mark comes in 14 seconds.
Since last year’s lightweight Carrera RS closely matches this car’s performance, the driver interested in fast road work rather than racing is surely better off with that model, considering things on a value-for-money basis. Even for the fastest road use the normal production brakes of the 2.7-liter car were fully adequate, and road-holding was as good as anyone could wish for along with a slightly better ride. At a higher level, which usually can be reached only on a track, handling and roadholding are of course better but basically like that of all other Porsches. The car understeers, though lifting off at the limit of adhesion will swing the tail out rather sharply. On hairpins there is an increased tendency to push the front end straight, because of the limited-slip differential, unless you enter the bend fast enough on a trailing throttle and swing the tail around under power. On the Casale track, near Torino, I found that fast bends must still be approached with some power on and that getting the car around fast and safely still calls for a certain amount of delicacy. From experience I know that even with stiffer springs and shocks, lower ride height and racing tires, a far lesser degree of this delicacy is required; but it is nevertheless required.
Back on the road one notices that the wide tires and stiff anti-roll bars tend to increase the usual. Porsche sensitivity to road irregularities, and the car feels rather lively if the road isn’t perfectly smooth. On the other hand, the stiff suspension and wide tracks reduce body roll to an amount that passes unnoticed by passengers, contributing as much to passenger confidence as the precise handling. Obviously they entail a comfort penalty on rough roads, and some clatter can be heard from the Unibal-jointed stabilizers. But I drove the car over long distances on main roads and motorways without feeling any more fatigue than in my own 911S, probably thanks to the good shape of the (admittedly hard) rally seats. Otherwise, despite its fierce looks and racing orientation, the RS 3.0 is a surprisingly civilized car. Engine noise reaching the occupants is in no way objectionable and wind noise seemed less than in my own car. Nor is road noise any more obtrusive than in other Porsches. But quite noticeable gearbox chatter is heard in all gears except at very high speeds. The clutch is light, helped by an over-center spring which cannot be detected by the feel of the pedal, and so is the steering.
In more than 1800 mi of very hard driving (we averaged 124 mph for the 78 mi of autostrada from Milano to Torino, despite being blocked behind a truck for 2 mi) we did 11.5 mpg overall and ranged between 10.7 and 12.7 mpg on various tankfuls. But perhaps the most endearing feature of the Carrera RS is its air of thoroughness, quality and perfect workmanship, even in this lightweight version. Probably no other car of comparable performance requires so little servicing: recommended service intervals are at 12,000 mi just as with the lesser Porsches. And there is no good reason why a Carrera RS should not, like the other Porsches, go on and on producing its staggering performance with utmost reliability without needing anything other than routine attention. One only wishes there were places in America where its performance could be used without fear of apprehension—and that one could get it in America for the purpose.