911 SC (G-series (impact bumper))

Rationalisation, 1977 For the 1978 model year Porsche collapsed a sprawling 911 range into two cars. The 2.7-litre 911 and 911 Lux and the 3.0-litre Carrera all disappeared; what remained was the 911 SC and the 911 Turbo. Porsche's own account of the G-series describes the SC as adopting the Carrera's widened rear wings along with its three litres of displacement, and Motor Sport's May 1978 test framed the change plainly: the SC replaced a 165 bhp 2.7 Lux and a 200 bhp Carrera 3.0 with a single 180 bhp car that gave away peak power to the Carrera but beat it on flexibility and driveability. That trade - less headline output, more usable engine - is the whole argument for the SC, and it has not changed in fifty years.

The Aluminium Three-Litre The engine is where the SC earns its reputation. Displacement is 2,994 cc from a 95 mm bore and 70.4 mm stroke, with a single overhead camshaft per bank, two valves per cylinder, Nikasil-lined barrels, dry-sump lubrication and Bosch K-Jetronic continuous injection. The significant change was the crankcase: pressure-cast aluminium in place of the magnesium used since 1968. Magnesium cases were light but soft, and the head studs passing through them had a habit of pulling their threads out, which is the defining structural weakness of the 2.7. Aluminium did not eliminate head-stud trouble; specialist accounts note that it moved the failure from the case threads to the studs themselves. It did produce an engine that tolerates mileage and heat in a way the 2.7 does not, and that is the single reason the SC is the cheapest air-cooled 911 an owner can reasonably use hard.

Three Power Steps, and a Market Split Output rose twice. Porsche Classic gives 180 PS for the 1978 and 1979 model years, 188 PS for 1980 and 204 PS from 1981 to the end, while Porsche's G-series press kit dates the same two increases to late 1979 and 1980 - the same sequence expressed as production timing rather than model years. The 188 PS engine brought a compression rise to 8.6:1, revised valves and cam timing, a new oil cooler and a revised timing-chain tensioner idler arm; the 204 PS engine went to 9.8:1. Cars for the United States and Japan did not follow. What American engines actually produced is not agreed: Wikipedia states they kept the lower-compression 180 PS unit throughout, an RM Sotheby's catalogue for a 1983 United States cabriolet quotes 180 bhp, and the Porsche Club of America states that emissions equipment and a restricted intake manifold cut output to 172 hp from 1980. A buyer comparing a European 204 PS car with a federal one is comparing two quite different machines.

The Model That Was Meant to Be the Last Under Ernst Fuhrmann the SC was intended as the 911's closing chapter, with the front-engined 928 taking over as flagship. It did not work out that way. The SC outsold the 928 heavily - Supercar Nostalgia puts the ratio at roughly twenty to one - and in 1981 Peter Schutz arrived as chief executive and reversed the decision, by the widely repeated account extending the 911's production line on Helmuth Bott's wall chart out past the edge of the paper. Porsche's own retrospective is drier, noting only that some of the press read the two-model range as the end of the sports car and were wrong. Either way, the SC is the car that was still selling while the argument was being had.

Open Air, and the Handover The last act was a roof, or the removal of one. A cabriolet prototype on the wide Turbo body, with four-wheel drive, appeared at the 1981 Frankfurt show; the production car was shown at Geneva in March 1982 and built from that October at DM 64,500, the first fully open 911 and the first Porsche convertible in nearly two decades. Its three-bow hood used panel elements covering about half the roof area rather than narrow steel bows, and Porsche rated the structure to 245 km/h. It sold immediately. For 1984 the 3.2-litre Carrera replaced the SC and brought with it the pressure-fed chain tensioners that were the fix for the SC's most quoted mechanical anxiety.

The airbox is the fault the SC is known for. A backfire through the Bosch K-Jetronic intake raises pressure inside the plastic airbox and splits it or tears out its self-tapping screws; the resulting vacuum leak stops the engine starting, and a dealer replacement can pass 1,000 dollars before labour. The standard remedy is a spring-loaded pop-off valve fitted to the box to vent the pressure, and cars from 1980 to 1983 with the internal metal manifold are more awkward to modify. Head studs are the second recurring theme. Porsche adopted Dilavar studs from 1977 and issued a technical bulletin covering their fitment; on the SC's aluminium case the failure mode moved from thread pull-out to outright stud breakage, and the symptom is persistent oil weeping at the head joint. Timing-chain tensioners are not oil-pressure fed. The idler arms were revised for 1983 and the problem was only fully resolved by the Carrera-style pressure-fed units of 1984, which are routinely retrofitted. Early rubber-centred clutches fail around 45,000 miles and can take other parts with them. The 915 gearbox baulks when worn, with rebuilds quoted at 4,000 to 10,000 pounds. Beyond that: heat exchangers rot, the auxiliary air valve and the K-Jetronic metering head suffer from ethanol in modern fuel, fuel-pump relays fail, and the ceramic fuses corrode.

Structure first. SC shells are galvanised but less thoroughly than the later Carrera 3.2, and the areas that matter are the sills, the bottom rear corners of the door apertures, the A-pillars and windscreen surround, the jacking points, the front wing tops, the rear torsion-bar housing and the so-called kidney bowls behind the B-pillars. A leaking windscreen seal drains into the pedal box, so lift the carpet. UK guidance puts serious corrosion work at 7,000 to 10,000 pounds. Then establish which car it is. European 204 PS cars, 188 PS 1980 cars and federal cars are three different propositions, and 1981-on cars carry the 17-digit VIN that makes identification straightforward. Ask which timing-chain tensioners are fitted and whether the Carrera pressure-fed conversion has been done, since the answer sets the maintenance horizon. Ask for head-stud history: most cars have either broken studs or receipts for fixing them, and the receipts are worth money. Look for a pop-off valve on the airbox, and check the airbox self-tapping screws are seated rather than standing proud, which indicates a past backfire. Drive it for the gearbox. A 915 that baulks into second when warm, or refuses lower gears, is telling you about linkage, oil and synchros; a properly rebuilt one shifts cleanly, but rebuilds run to four or five figures. Check the clutch has been converted from the rubber-centred original. On a cabriolet, work the hood through its full travel and inspect the frame and rear window.

As of August 2026, classic.com's Porsche 911 SC market benchmark stands at $63,732, with the coupe at $64,811, the Targa at $55,375 and the cabriolet at $49,927. That ordering is worth noting: the cabriolet is the rarest of the three bodies and the cheapest to buy. The recorded spread is very wide. As of August 2026 classic.com's high for the SC market is $515,000 for a 1982 car sold in November 2025, an outlier it does not characterise, against a low of $2,016 for a 1981 Targa in October 2024. Auction evidence sits in a far narrower band. RM Sotheby's sold a 9,230-mile United States cabriolet from the Taj Ma Garaj collection for $52,640, and Gooding sold a European-specification 204 bhp cabriolet at Amelia Island in 2025 for $62,720. Published guidance runs 30,000 to 70,000 pounds in the United Kingdom and roughly 35,000 to 90,000 euros in Europe as of 2024, with condition mattering more than body style and a project car and a sorted one separated by the price of a full restoration. For position, as of August 2026 the Carrera 3.2 coupe benchmark is $83,205 and the 930 Turbo averages $171,008 across 740 recorded sales, so the SC remains the cheapest way into the impact-bumper era.