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1977 Porsche 934.5 Coupe

  • Chassis Number: 930 770 0951
The Porsche 934 was the FIA-homologated Group 4 racing version of the turbocharged 930 road car and was developed during the mid-1970s under Wolfgang Berger and Norbert Singer. Porsche submitted the 934 prototype for inspection by IMSA's (International Motorsports Association) John Bishop for inclusion into the Camel GT series in late 1975 but due to fears that the 934 would follow in the footsteps of its 917/30 Can-Am sibling and dominate the series, Bishop rejected the 934 in 1976. The SCCA, however, welcomed it in Trans Am. Perhaps Bishop's fears were realized when the 934 was virtually invincible, winning the 1976 European GT Championship and the 1976 and 1977 SCCA Trans Am titles. George Follmer handily won the season title in what was really a lightly modified production car that was fitted with a full aluminum-alloy roll cage, yet it still retained the 930's electric window lifts.

With interest waning in its series, IMSA finally allowed turbocharging for 1977, along with large rear wings and wider fenders. Since the U.S. market was important to Porsche, and they wanted to platform to showcase their technology, they agreed to build a series of cars to contest the series. Since John Bishop would not allow the 935-77 to race, and following many negotiations between IMSA and Joe Hoppen (Porsche's U.S. racing director), the 934.5 was born. Wearing a wide 935-style rear wing, wider wheel arches concealing wide tires, and fitted with mechanical fuel injection, the updated 934 was alternatively called the 934/5 (moniker used by the Porsche factory) or 934 1/2 and built in a ten car batch in 1977. Only one example (chassis 930 770 0956) was sold new to Europe, and most European teams did not want them since they were less competitive against a 935-77. The example sold to Europe was acquired by an Italian team to run in Italian races.

The Porsche 934½ continued the pedigree of the normally aspirated RSRs and was one of two racing versions of the Type 930, or Turbo Carrera, Porsche's first production-based turbocharged automobile. The first was the 934 configured for FIA Group 4 competition while the other was the 935 built for Group 5 and would eventually dominate GT racing during the 1980s.

The 2,993cc air-cooled flat 6-cylinder engine used Bosch Mechanical fuel injection, a single KKK turbocharger with intercooler, and developed an estimated 600 horsepower at 7,000 RPm. They were backed by a four-speed manual transaxle and stopping power was by ventilated disc brakes. The front suspension was independent with coil-over shock absorbers, torsion bars, control arms, and anti-roll bars. The rear suspension also had an independent setup with transverse torsion bars, coil-over shock absorbers, and an anti-roll bar.


The car's initial Achille's Heel was its late arrival in the U.S., with the first examples not arriving until Sebring. Although they qualified 1st and 2nd, they had issues during the race. The car driven by Gregg and Busby had its wheel fall off during the race and following repairs, they were able to place third behind a pair of RSRs.
Politics intervened at the next race - Atlanta, and Peter Gregg's new car was banned on the spot. The remainder of Porsches racing in IMSA had mixed results throughout the season. For a second year in a row, Al Holbert would win the IMSA title in a Chevrolet Monza.

After Gregg's car had been banned, Porsche immediately went back to Trans-Am, and the interim 'point-five' captured all but two of the season's eight contests. After another team, who was racing with a standard 934, protested the new car as illegal at Canada's Mosport round, the SCCA agreed and took away Greeg's championship. Gregg had won eight races, and perhaps in spiteful protest, Porsche produced a commemorative poster claiming the title.

Following the 1977 IMSA season, the 934/5 was obsolete, as IMSA had approved the 935 customer cars to race during the 1978 season. Thus, many owners of the 934/5 began upgrading their cars to 935 specifications, which required new engines, bodywork, wheels, and various other modifications. Several of these updated cars competed in IMSA for many seasons.

Chassis number 930 770 0951
This Porsche was the first example built and was sent, along with 930 770 0952, to Peter Gregg and the Brumos Racing team in Jacksonville, Florida. Along with co-driver Jim Busby, it was driven at the 12 Hours of Sebring race in 1977. It had arrived late and little preparation work had been performed to properly ensure it was ready for the endurance race. The original white hood, however, had been replaced with another that already had Brumos' iconic red and blue stripes on it. The car qualified on the pole and eventually finished in 3rd place, despite some issues during the race. It wore race number 61.

After Sebring, Gregg would turn his attention to 0952, selling 0951 to Busby who raced it in three more events in 1977, with a 2nd place at Laguna Seca, framed by two DNFs at Road Atlanta and Mid-America in Missouri. At the end of the 1977 season, the car was sold to Portland, Oregon-based racer and sports car dealer Monte Shelton. During his ownership, the car was converted to full 935 specifications and was campaigned extensively in IMSA and Trans Am competitions in the US and Canada. Among the accolades that Shelton earned with the Porsche was a victory at the Trans Am race in Mont-Tremblant, Québec, where he beat Ludwig Heimrath to the finish by over 29 seconds. Shelton raced the Porsche through the 1980 season, and subsequently sold it to Ted Anderson of Bend, Oregon.

In 1992, the car was advertised for sale in Excellence magazine by a dealer in Tulsa, Oklahoma. The next known owner was Karl Singer, who acquired it from a Florida auction in the 1990s and raced it a few times, but did not use it much before selling it to the current owner circa 2001.

The current owner has treated the car to a restoration. Since the work was completed, the car has been shown just once at the 2020 Amelia Island Concours d'Elegance. It is currently finished in its 1977 Sebring livery, wearing the iconic colors of Brumos Racing.

By Daniel Vaughan | Nov 2021
The 1977 IMSA season launched 'the year of the turbo'. The problem was that the new Porsches had failed to produce a winning result at Daytona. Three new 934 turbo Porsches showed up for the 1977 12 Hours of Sebring. The #61 wearing Brumos Porsche's famous white-red-blue livery arrived by air freight directly from the factory. It qualified on the pole and dominated the first eight hours of the race building a seemingly invincible five-lap lead for Peter Gregg and Jim Busby. During the eighth hour, following a routine pit stop, a wheel came off the leading #61 and Gregg nursed the wounded Turbo back to the pits. Damage to the suspension and an oil cooler required a lengthy repair. Gregg and Busby fought back. In their chase, they led 141 laps (from the pole) and Gregg set the race's fastest lap in the process of climbing back into second place. But a flat tire caused more mechanical mayhem during the ninth hour dropping the new #61 934 Turbo to third and promoting a normally aspirated Porsche Carrera RSR to the lead. And that's where they finished; five laps behind a pair of Carrera RSRs but the first of the new Porsche Turbos to finish in a ten-deep Porsche sweep of the 25th annual 12 Hours of Sebring.

2022 Gooding & Company : Amelia Island Auction

Pre-Auction Estimates :
USD $1,000,000-USD $1,300,000 
Sale Price :
USD $912,500

2021 Gooding & Company : Pebble Beach Concours Auction

Pre-Auction Estimates :
USD $1,300,000-USD $1,600,000 
Lot was not sold

1977 Porsche 934.5 Auction Sales

Recent Sales of the Porsche 934.5

(Data based on Model Year 1977 sales)
1977 PORSCHE 934/5
Chassis#: 930 770 0958
Sold for USD$885,000
  2022 Gooding & Company : Pebble Beach
1977 Porsche 934.5 image  1977 Porsche 934.5 image  
1977 PORSCHE 934/5
Chassis#: 930 770 0951
Sold for USD$912,500
  2022 Gooding & Company : Amelia Island Auction
1977 Porsche 934.5 image  1977 Porsche 934.5 image  
1977 Porsche 934/5
Chassis#: 930 770 0956
Sold for USD$1,187,500
  2019 Gooding & Company : Pebble Beach
1977 Porsche 934.5 image  1977 Porsche 934.5 image  
1977 Porsche 934/5
Chassis#: 930 770 0956
Sold for USD$1,375,000
  2017 Gooding & Company : Amelia Island
1977 Porsche 934.5 image  1977 Porsche 934.5 image  
1977 Porsche 934½ IMSA/Trans-Am
Chassis#: 930 770 0957
Sold for USD$550,000
  2013 RM Auctions - Monterey
1977 Porsche 934.5 image  

Porsche 934.5s That Failed To Sell At Auction

1977 Porsche 934.5's that have appeared at auction but did not sell.
VehicleChassisEventHigh BidEst. LowEst. High
1977 PORSCHE 934/5930 770 09602023 Gooding & Company : Amelia Island Auction $800,000$1,100,000
1977 Porsche 934/5930 770 09512021 Gooding & Company : Pebble Beach Concours Auction $1,300,000$1,600,000
1977 Porsche 934.5/935 IMSA Swap Shop470122017 Mecum : Monterey$750,000  
1977 Porsche 934.5/935 IMSA Swap Shop 2017 Mecum : Kissimmee$600,000  
1977 PORSCHE 934.5/935 IMSA SWAP SHOP471022014 Mecum Monterey$550,000$700,000$800,000
1977 Porsche 934 1/2 1 of 10 Factory Built Cars93077009572012 Mecum Monterey, CA$550,000  

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1977 Porsche 934.5

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