Porsche Air-Cooled Turbos 1974-1996 E-Book

Johnny Tipler

• Herausgeber: Crowood
• Kategorie: Lebensstil
• Sprache: Englisch

Veröffentlichungsjahr: 2019

Beschreibung

Porsche applied turbocharging to its racing cars in 1972 and, within a year, this technology had crossed over into its production cars: the first road-going 911 Turbo was unveiled at the Frankfurt Motor Show in 1973. Johnny Tipler tells the story of the air-cooled turbocharged 911s, starting with the 934 and 935 race cars that fostered the Type 930 in 1974. The 930 accounted for over 21,000 vehicle sales before being replaced by the 964 Turbo in 1990, followed by the 993 Turbo in 1995. With 300 colour photographs, many taken specially by renowned photographer Antony Fraser this book also presents exclusive interviews with Klaus Ludwig, Jochen Mass and Nick Heidfeld, as well as including full specification tables for each key model type. Foreword is by Alois Ruf.

Leseprobe

TITLES IN THE CROWOOD AUTOCLASSICS SERIES

Alfa Romeo 916 GTV and Spider

Alfa Romeo Spider

Aston Martin DB4, DB5 & DB6

Aston Martin DB7

Aston Martin V8

Audi quattro

Austin Healey 100 & 3000 Series

BMW M3

BMW M5

BMW Classic Coupés 1965–1989

BMW Z3 and Z4

Citroen DS Series

Classic Jaguar XK: The 6-Cylinder Cars 1948–1970

Classic Mini Specials and Moke

Ferrari 308, 328 & 348

Ford Consul, Zephyr and Zodiac

Ford Transit: Fifty Years

Frogeye Sprite

Ginetta Road and Track Cars

Jaguar E-Type

Jaguar Mks 1 and 2, S-Type and 420

Jaguar XJ-S

Jaguar XK8

Jensen V8

Jowett Javelin and Jupiter

Lamborghini Countach

Land Rover Defender

Land Rover Discovery: 25 Years of the Family 4×4

Land Rover Freelander

Lotus Elan

MGA

MGB

MGF and TF

MG T-Series

Mazda MX-5

Mercedes-Benz Cars of the 1990s

Mercedes-Benz ‘Fintail’ Models

Mercedes-Benz S-Class

Mercedes-Benz W113

Mercedes-Benz W123

Mercedes-Benz W124

Mercedes-Benz W126

Mercedes SL Series

Mercedes SL & SLC 107 Series 1971–2013

Morgan 4/4: The First 75 Years

Peugeot 205

Porsche 924/928/944/968

Porsche Boxster and Cayman

Porsche Carrera: The Air-Cooled Era

Porsche Carrera: The Water-Cooled Era

Range Rover: The First Generation

Range Rover: The Second Generation

Reliant Three-Wheelers

Riley: The Legendary RMs

Rover 75 and MG ZT

Rover 800

Rover P4

Rover P5 & P5B

Rover SD1

Saab 99 & 900

Shelby and AC Cobra

Subaru Impreza WRX and WRX STI

Sunbeam Alpine & Tiger

Toyota MR2

Triumph Spitfire & GT6

Triumph TR6

Triumph TR7

VW Karmann Ghias and Cabriolets

Volvo 1800

Volvo Amazon

First published in 2019 by The Crowood Press Ltd Ramsbury, Marlborough Wiltshire SN8 2HR

[email protected]

www.crowood.com

This e-book first published in 2019

© Johnny Tipler 2019

All rights reserved. This e-book is copyright material and must not be copied, reproduced, transferred, distributed, leased, licensed or publicly performed or used in any way except as specifically permitted in writing by the publishers, as allowed under the terms and conditions under which it was purchased or as strictly permitted by applicable copyright law. Any unauthorised distribution or use of this text may be a direct infringement of the author’s and publisher’s rights, and those responsible may be liable in law accordingly.

British Library Cataloguing-in-Publication Data

A catalogue record for this book is available from the British Library.

ISBN 978 1 78500 670 8

Title page: Watercolour of a 930, painted specially for the book by French artist Laurence B. Henry (http://laurencehenry.hautetfort.com).

LAURENCE B. HENRY

CONTENTS

Acknowledgements

Foreword by Alois Ruf

Turbo Timeline

Introduction

CHAPTER 1

ANTECEDENTS: THE CARRERA RSR TURBO, 934 AND 935

CHAPTER 2

THE 930 TURBO

CHAPTER 3

THE 959 SUPERCAR

CHAPTER 4

THE 964 TURBO

CHAPTER 5

THE 993 TURBO

Index

ACKNOWLEDGEMENTS

This is my fourth book about Porsches, all written for Crowood, and like its predecessors, Porsche Air-Cooled Turbos is prolifically illustrated with photographs by Antony Fraser, who is my regular colleague on assignments mostly commissioned by editor Steve Bennett at 911 & Porsche World and Keith Seume at Classic Porsche magazines. So, I’m indebted to him for providing shots taken on our forays into the countryside when we visit specialists in Britain and Europe, travelling in press cars provided by Porsche GB as well as our own cars.

I’ve received support from Porsche GB in respect of access to state-of-the-art 911 Turbos, for which many thanks indeed to Nick Perry, Rob Durrant and Rob Puncheon. At the Porsche Museum in Zuffenhausen, Jessica Fritzsch ensured photoshoots happened, while other helpful individuals at the factory have included Katja Leinweber, Conny von Buehler, Tobias Hütter, Tony Hatter and Dieter Landenberger. I’ve also much appreciated assistance from Porsche photographic archivists Jens Torner and Tobias Mauler, who have unstintingly presented legions of pictures from their library, and I’ve tried to use photos that have never been seen before, at least by me. Other photographers who’ve supplied images include Peter Meißner of Moment-fotodesign with 9ff material, Sarah Hall, Alex Denham and Peter Robain.

In the course of my job as a freelance journo I visit a lot of Porsche specialists in Britain and Europe as well as interviewing racing drivers and personalities associated with the marque, and I visit establishments such as the Porsche Museum at Zuffenhausen and attend race meetings and historic rallies where there tends to be a preponderance of Porsches. In this context I’m particularly fond of the Nürburgring 24-Hours, Spa Six-Hours and Monte Carlo Rallye Historique. The point is, I meet a great many Porsche enthusiasts who’ve become friends and have been helpful one way or another in the compilation of this book. So, here they are, in no particular order: Johan Dirickx, Mike Van Dingenen, Hans Deckers and Joe Pinter at 911Motorsport; John and Tanya Hawkins at Specialist Cars of Malton; Ian Heward at Porscheshop; Sarah Li at Fazedpictures; Paul and Rebecca Stephens; Adrian Crawford, Richard Williams and Louise Tope at Williams Crawford; Andy Moss and Stuart Manvell at SCS Porsche; Andrew Mearns at Gmund Cars; Rick Findlow of 911Retro; Ollie Preston at RPM Technic; Simon Cockram at Cameron Cars; Mark Sumpter at Paragon Porsche; Martin Pearse at MCP Motorsport; Jonny Royle at Cambridge Motor Company; Jonathan Sturgess at Autostore; Joff Ward at Finlay Gorham; Phil Hindley at Tech9 Motorsport; Russ Rosenthal at JZM; Josh Sadler, Steve Woods and Mikey Wastie at Autofarm; Colin Belton at Ninemeister; Karl Chopra at Design911; Mike at Ashgood Porsche; James Turner of Sports Purpose.

Then I must mention my continental friends, beginning with tuner and builder extraordinaire Alois Ruf and his team, including Estonia (Mrs Ruf), Claudia Müller, Marcel Groos, Marc-André Pfeifer, Michaela Stapfer, Anja Bäurle and Anja Schropp, who have always made our trips to Bavaria a real pleasure. Next up, the genial Willy Brombacher and his FVD operation, including his son and daughter, Max and Franziska; Thomas Schnarr at Cargraphic, whose silencer adorns my Boxster; my colleague and I have also been entertained by Ande Votteler, Manon Borrius Broek, Tobias Sokoll at TechArt, Björn Striening at speedART, Oliver Eigner at Gemballa, Thomas Schmitz at TJS German Sportscars, Michael Roock at Roock Racing, Jan Fatthauer at 9ff, Dirk Sadlowski at PS Automobile, Eberhard Baunach at Kremer Racing, and Manfred Hering at Early911S. My thanks go to Kobus Cantraine for providing 911s to have fun in; likewise, to Mark Wegh at Porsche Center Gelderland.

Constructive observations and encouragement from my PA, Emma Stuart, are much appreciated, and I want to mention a swathe of aficionados, colleagues and commissionaires with whom I spoke or drove, including Brent Jones, Mauritz Lange, Peter Bergqvist, Jürgen Barth, Hans-Joachim Stuck, Jacky Ickx, Vic Elford, Mike Wilds, Mario Andretti, Ron Simons, Steve Bennett (editor of 911 & Porsche World magazine), Mark Mullen, Lee Maxted-Page, James Lipman, Simon Jackson (editor of GT Porsche magazine), Alastair Iles, Mike Roberts, Lee Sibley (editor of Total 911), Timo Bernhard, Peter Dumbreck, Wolf Henzler, Olaf Manthey, Brendon Hartley, Angelica Grey, Walter Röhrl, Andrea Kerr, Steve Hall, Tim Havermans, Wayne Collins, Peter Offord, Alex Denham, Fran Newman, Joachim von Beust, Kenny Schachter, Ash Soan, Nick Bailey and Els van der Meer at Elan PR, Angie Voluti at AV PR, Sarah Bennett-Baggs, Mike Lane, Sarah Hall, Angelica Fuentes and Keith Mainland, Keith Seume (editor of Classic Porsche magazine), Andy Prill and Bert Vanderbruggen – to name but a few.

Other benefactors who in no small way enabled the composition of the book include Chris Jones at Brittany Ferries, Frances Amissah at Stena Line, Michelle Ulyatt at DFDS Ferries, Natalie Benville at Eurotunnel, Charlotte Wright at Rooster PR, Natalie Hall at P&O Ferries, Simon and Jon Young at Phoenix Exhausts, Vredestein Tyres, Falken Tyres and Continental Tyres. Many thanks to all concerned, and hopefully I haven’t left too many people out.

FOREWORD

ALOIS RUF

CEO and owner of Ruf Automobile GmbH, Porsche concessionaire and doyen of turbocharging methodology

When we began to build our first turbo engines, we were inspired by the movement in motor sport, particularly by Porsche’s enormous success with the turbocharged 917/10 and 917/30 Spyders in Can-Am and Interserie racing in 1972 and 1973.

One of the world’s leading authorities on turbocharging, Alois Ruf has been applying the methodology to his own range of 911-derived models since 1977. ANTONY FRASER

In a road-going context, the Swiss engineer Michael May pioneered the way when he installed a turbo in the Ford Capri, and it was still a street-worthy car. We began our first experiments at Ruf Automobile in 1974, turbocharging a 2.7-litre 911 engine, and in 1977 we presented our first Ruf Turbo, developing 303bhp. The first car to bear a Ruf chassis number was the BTR of 1983, running a 3.4-litre Ruf turbo engine producing 374bhp, and our ‘Yellowbird’ CTR achieved international acclaim when it beat the world’s fastest supercars in a media shootout at Ehra-Lessien test track in 1987, going at 340km/h (211mph).

The fact that you can utilize the velocity of the exhaust flow to drive a turbo compressor to pre-charge the intake air is fascinating, conceptually as well as in a practical sense, because it is free power that would otherwise go to waste.

The traditional ways of increasing the performance of an engine are enlarging the displacement of the engine, raising the rpm or raising the combustion pressure.

The latter option works with turbocharging as the most efficient and elegant solution. When the boost ‘sneaks up’ on you, I call it the ‘quiet storm’ – like a ghost that suddenly pops up behind you. You check your speedometer, and the needle shows 50km/h (30mph) more than you expected – achieved in a split second.

Instead of squeezing out the horsepower from a naturally aspirated engine, the turbocharger effortlessly elicits the horsepower from a turbo engine, giving it a light-footed feel. All the years spent developing turbocharged engines bore fruit, and the infamous turbo flat spot was banished by balancing the plumbing of the intake and the exhaust side, as well as identifying the ideal initial compression ratio for the engine. Digital engine management perfected everything, protecting the engine and enabling economical fuel consumption. Turbo is the future of our combustion engines.

So, I hope all readers and petrolheads thoroughly enjoy reading Johnny Tipler’s book on Porsche – and Ruf – Turbos.

TURBO TIMELINE

1973 A 911 Turbo show car is displayed at the Paris Salon.

1974 The first road-going 911 Turbo, Type 930, is unveiled at the Frankfurt Motor Show, boasting a 3.0-litre engine producing 260bhp.

1977 Porsche announces the revised 930 version with bigger 3.3-litre engine and a single intercooler, lifting power output to 300bhp.

1989 Production of the 930 comes to an end, with over 21,000 examples sold, including LE and SE variants.

1990 The 964 Turbo is launched with 3.3-litre flat-six, with a capacity increase to 3.6 litres with a new engine in 1992.

1995 The 993 Turbo is introduced with four-wheel drive and twin turbochargers.

2001 The 996 Turbo is the first of the water-cooled Turbo models, offering 420bhp and 4 × 4 transmission.

2006 The 997 Turbo is announced, with 480bhp. Subsequent Gen 2 models hit 500bhp.

2013 The 991 Turbo is launched, producing 513bhp, with all-wheel drive and four-wheel steering.

First shown at the 1973 Paris Salon, the 911 Turbo was presented in a silver-grey hue, with bulging wheel arches and wide-rim Fuchs wheels. The ensemble was set off with Porsche side stripes and turbo graphics, plus striping down the sides from front to rear. PORSCHE PHOTO ARCHIVE

In the 1980s, Turbo was the new catchword, and materialism was rife. Yuppies were the 30-something baby-boomers of the expanding economy. And the car that exemplified the decade? The 930 Turbo. ANTONY FRASER

A Porsche publicity shot from when the 964 Turbo 3.6 came out; the model is Andrea Röscheisen, wife of a Porsche employee, whom the photographer simply asked to be in the shot. PORSCHE PHOTO ARCHIVE

INTRODUCTION

The works Porsche 935 #002, helmed by Rolf Stommelen and Manfred Schurti, rounds the Kleine Karussell during the 1976 Nürburgring 1,000km. They started from pole but a distributor drive belt subsequently failed. PORSCHE PHOTO ARCHIVE

Racing improves the breed, goes the saying: no marque has been as steadfastly diligent in that pursuit than Porsche. Sure, a few others like Ferrari and Lotus, possibly also BMW, have used racing as a way of projecting their images, and those niche specialists have even sold road cars to fund their racing activities: ‘Win on Sunday, sell on Monday.’ But Porsche has consistently applied its race technology directly to its road-going models, fine-tuning and innovating, putting its products on the line with one-model race championships like the global SuperCup and Carrera Cup series. So, from 1973, when Porsche first applied forced induction to its 917 Spyders for use in the North American Can-Am series and the European Interserie championships, it was inevitable that the technology would transfer onto the 911 street car.

Turbocharging was nothing new, even in 1973. Forced induction was first applied to aircraft in World War I to enable planes to gain greater altitude and a height advantage over rivals. By the mid 1920s, turbocharged diesel engines also started appearing on ships and locomotives. Supercharging was commonplace in competition cars during the 1930s, exemplified at its most extreme in the Silver Arrows, the Auto Union and Mercedes-Benz Grand Prix teams that reigned supreme in the latter part of that decade. Use of supercharging declined in the 1950s in favour of normally aspirated engines, though commercial vehicles employed turbocharged diesel engines. Even that wasn’t novel: the patent for the first turbocharger was awarded in 1905 for a compressor driven by exhaust gases in order to force air into an internal combustion engine.

The first road cars to be turbocharged were the Chevrolet Corvair Monza and the Oldsmobile JetFire, launched in 1962, though both suffered from reliability issues and were quickly withdrawn. Porsche applied turbocharging to its racing cars in 1972 with the 917/10 in the European Interserie races and the North American Can-Am series and, as we’ll see in Chapter 1, the first racing 911s to receive turbochargers were the factory’s Carrera RSR Turbo race cars, one of which finished second at Le Mans in 1974, driven by Gijs van Lennep and Herbert Müller. Porsche’s racing 911s evolved into the 934, hugely successful as a Group 4 car in the GT category of the World Sportscar Championship (Le Mans and so on) and the US-based IMSA (International Motor Sports Association) series. By 1976 the turbocharged Porsche of choice for international GT racing was the more extreme Group 5 935, which was good enough to win Le Mans outright in 1979. Both 934 and 935 featured twin turbos as well as single units, depending on which category or race series they participated in.

Porsche’s first turbocharged racing car was the 850bhp 917/10 spyder, campaigned successfully in the North American Can-Am series in 1972: George Follmer was champion in the Penske Racing car. Here, Gijs Van Lennep demonstrates the 1,500bhp 5.3-litre twin-turbo 917/30 (in which Mark Donohue was 1973 Can-Am champ) at the 2017 Zandvoort Historic grand Prix. JOHNNY TIPLER

Porsche’s first foray into endurance racing with a turbocharged 911: Herbert Müller and Gijs van Lennep brought the 911 Carrera RSR Turbo 2.1 home in second place in the 1974 Le Mans 24-Hours. They averaged 118.64km/h (117.21mph) and covered 4,527.45km (2,813.23 miles). PORSCHE PHOTO ARCHIVE

In 1976, Porsche’s racing 911 was the 934, hugely successful as a Group 4 car – special grand touring cars with minimum production of 500 units in one year – running in the GT category of the World Sportscar Championship and US-based IMSA series. ANTONY FRASER

Porsche’s first road-going application, the 930, or 911 Turbo as it was originally known, appeared in 1974, pipped by BMW’s short-lived 2002 Turbo. Saab joined the turbo club in 1977 with its 900 Turbo, just ahead of the widespread adoption of turbocharging in Formula 1. The following year, Mercedes-Benz and Buick offered turbocharged petrol-fuelled four-door saloon cars, and the phenomenon was here to stay. It’s fair to say that, in racing and rallying terms, turbocharging peaked in 1986 with F1 turbo engines releasing 1,500bhp in qualifying trim, and the WRC Group B’s extreme ‘silhouette’ rally cars, in play from 1982 to 1985, banned as being too dangerous. At the time, Porsche’s contribution to the world rally stage was the 444bhp twin-turbo 959 supercar, built to comply with Group B rules, but also a showcase for the company’s engineering expertise.

The slant-nose 935 of Jacky Ickx and Jochen Mass fuels up during the 1977 Nürburgring 500km, a round of the World Sportscar Championship endurance series. Fuel consumption was 2.8mpg. PORSCHE PHOTO ARCHIVE

The 911 Turbo 3.0 coupé was presented as a design study at the Paris Salon in 1973, and officially launched at the 1974 Frankfurt Motor Show. PORSCHE PHOTO ARCHIVE

Porsche expertise in turbocharging road and race cars extended to F1: this is the 1983 McLaren MP4/2 TAG-Porsche 1.5 V6 Turbo in development testing at Weissach, observed by one Alain Prost, who joined Niki Lauda for the 1984 season. The pair were indomitable, recording four 1–2 finishes en route to winning the Constructors’ title. PORSCHE PHOTO ARCHIVE

The twin turbos serving this 936 are located below the rear of its tubular spaceframe chassis. PORSCHE PHOTO ARCHIVE

Cutaway KKK turbocharger, with slices of casing removed to reveal the inner workings, including turbine spinner and compressor.JOHNNY TIPLER

TURBOCHARGING

Most enthusiasts will know what a turbo does, but as this is a book about cars that specifically use them and are designated as such, it would be remiss not to provide a basic definition of how a turbocharger functions. The turbo is basically an air pump that takes air at ambient atmospheric pressure and compresses it to a higher pressure, feeding the compressed air into the engine’s cylinders via the inlet valves. Engines are dependent on air and fuel, and an increase in either will increase power output. To augment airflow, compressed air is blown into the engine, mixing with the injected fuel and enabling the fuel to burn more efficiently, thereby increasing power output. The turbocharger harnesses the engine’s exhaust gases to drive a turbine wheel that is connected by a shaft to a compressor wheel. Instead of discharging down the exhaust pipe, hot gases produced during combustion flow to the turbocharger. The exhaust gases spin the turbine blades up to a mind-boggling 150,000rpm. The compressor sucks air in through the air filters and passes it into the engine. As the exhaust gases are expelled from the engine via the exhaust valves, they are passed to the turbine fan within the turbo, and so the cycle continues. The additional oxygen consumed enables a turbocharged engine to generate around 30 per cent more power than a non-turbo unit of the same cubic capacity.

The turbo engine ideally needs an intercooler to moderate the temperature of the incoming air. That’s because, in passing through the turbo blades and being thus boosted, it gets exceedingly hot, and this is not good news for the engine. Most turbocharged engines, certainly in a competition context, employ an intercooler. This is basically an air-to-air radiator, and is usually mounted prominently in the car’s airstream – for example, at the front of the engine bay in the case of the 924 Carrera GT and in the rear wing of the 930. Hot air from the turbo goes in at one end and is cooled as it passes through the intercooler, just like a water-cooled car’s radiator, before entering the engine at a much lower temperature; it is also denser than hotter air.

The turbocharger installation housed within the exhaust system of a 934 race car. The KKK K33 turbo is made by Kühnle, Kopp and Kausch at Frankenthal in the Pfalz region of western Germany. In a road car installation, the turbo fits in between the heat exchangers and the silencer. ANTONY FRASER

Up on a hoist, the rear end of the 935 racing car engine compartment is dominated by the pair of K36 turbochargers and ancillaries. PORSCHE PHOTO ARCHIVE

The alternative means of forced induction is supercharging, which was more widely employed to boost engine performance in the 1930s. The difference between the two units, supercharger and turbocharger, is that the supercharger derives its power from the crankshaft, from whence it’s driven by a belt (in the same way as the water pump and alternator), whereas the turbo draws power from the engine’s exhaust gases. Superchargers spin at up to 50,000rpm while the turbocharger can spin much faster. Emissions-wise, the supercharger doesn’t have a wastegate, whereas turbos have catalytic converters to lower carbon emissions. Turbochargers run extremely hot and need to be well insulated. Superchargers deliver boost at lower revs then a turbocharger whereas the turbo works best at high engine speeds. In practical terms, the supercharger is easier to install, though it takes a small portion of the engine’s power in its operation. Turbochargers are quieter in operation, and fuel economy is affected less adversely with a turbo’d engine, while superchargers are more reliable and easier to maintain than the more complex turbocharger. The turbo mutes the exhaust note, so if, like me, you derive a certain pleasure from the raw rasp of a Porsche flat-six, air- or water-cooled, you’ll know that the gruff boom emitted by a turbocharged car is slightly anticlimactic by comparison. There are fairly clear advantages and disadvantages to both forms of forced induction, but since turbos work better with high-performance applications and, at the same time, are more efficient in dealing with emissions, Porsche took the turbo option.

Supercharging is an alternative means of employing forced induction to obtain more power and acceleration. This TPC device was fitted by Colin Belton of Ninemeister in a 993 RS, in the care of specialist Martin Pearse of MCP Motorsport, lifting power output from 296bhp to 353bhp. ANTONY FRASER

Whereas the turbocharger uses the engine’s exhaust gases to force-feed the induction process, the supercharger – such as this TPC unit fitted on a 993 RS – is belt-driven off the crankshaft. In both examples, the enclosed spinner pressurizes the induction system by blowing in compressed air at a faster rate than normal, thereby speeding up the combustion process. ANTONY FRASER

The turbocharger installation in this 934 race car comprises the compressor spinner and exhaust gas turbine fan, coupled together by a solid shaft and boosting the intake pressure. There are two tailpipes; the smaller secondary pipe emerges from the wastegate outlet, which joins up further downstream in the main exhaust. ANTONY FRASER

It’s 1977, and Porsche technicians fettle a couple of 3.3 Turbos in the Weissach workshops. PORSCHE PHOTO ARCHIVE

SPECIFICATION OF THE 930 ENGINE

The 930 Turbo engine contained a number of internal differences to the contemporary normally aspirated unit. There were fundamental similarities: Reynolds Aluminum in the USA supplied the crankcase material for the 3.0-litre Carrera 3 and the original 930 models, in the guise of aluminium silicone – or AluSil – which provided an appropriate correlation of light weight and rigidity. In construction terms, the two-piece crankcase was split vertically and united by eleven bolts, while the 70.4mm forged crankshaft was treated with a Tenifer case-hardening process (AKA ferritic nitrocarburizing) and ran in eight main bearings of 56.9mm diameter and big-end journals of 51.9mm diameter. The con rods were of forged steel, with aluminium pistons of 95mm diameter, giving a capacity of 2994cc. While the normally aspirated Carrera 3 engine used cast pistons with raised crowns to produce a compression ratio of 8.5:1, the Turbo pistons were forged and flat-topped, giving a 6.5:1 compression ratio. This was a necessary measure because the additional volume of mixture created by the forced-induction system had the effect of raising combustion pressures.

This crankcase endured for some time, but the 3.0-litre crankshaft was replaced in 1978 with the bigger-capacity 3.3-litre unit, which had a heavier crankshaft, with dimensions of 74.0mm stroke and 59.9mm mains and 54.9mm big ends, with the additional capacity of the turbo engine produced by its 97mm pistons. The barrels were of the same Nikasil as the 2.7 Carrera RS, and for the turbo unit, the shrouding around the barrels was modified to improve engine cooling. Subsequently, the fins on the top of each barrel were omitted on the 3.3-litre engine in order to promote stiffness. Located in spigots in the crankcase halves, the barrels were retained by four studs, and there was no gasket between the head and cylinder barrel, a departure from previous practice, the engine relying instead on the chamfered face of the head sealing against the flat barrel top as the retaining studs were torqued up. The original 930 engine employed Dilavar steel-alloy head studs, which were prone to corrosion caused by a reaction to the casing material, but by 1984 plastic-coated stud shanks solved the problem. The stud issue was finally resolved in 1994 with the 993 model’s M64 engine, which employed fully threaded treated studs.

The turbo engines had specifically designated alloy cylinder head dimensions: the diameter was the same as in normally aspirated engines, at 49mm inlet, 41.5mm exhaust valves, but both inlet and exhaust ports were smaller, with 32mm inlet and 36mm exhaust valves in the 3.0-litre engine, and smaller 34mm exhaust ports in the 3.3-litre unit. The combustion chamber shape was also specific to turbo engines, with each pair of valves set at a shallower angle in sintered steel seats, with the exhaust valves sodium-filled to aid cooling.

The early 911 Turbo of 1974–8 was powered by a completely reworked 3.0-litre flat-six derived from the Carrera RS model, producing 260bhp at 5,500rpm. Its KKK 3LDZ turbocharger operated at a maximum speed of 100,000rpm, delivering maximum boost of 0.8bar. ANTONY FRASER

The 930’s camshaft layout was the same as on previous flat-sixes, though Porsche developed a specific camshaft for the turbo unit. The single camshaft superimposed over each bank of three cylinders was driven by duplex chains via the crankshaft-driven intermediate shaft housed in the crankcase. From 1984, Turbo units benefitted from improved hydraulic chain tensioners, while different chain-ramp designs were incorporated to apply pressure to the lengthy chain. Each camshaft had four bearings of 49mm diameter, rising from the 47mm of earlier three-bearing cams. The valves were actuated by cast steel rockers, with manual tappet adjustment. There were further sophistications, one of which was a small pump, belt-driven from the back of the left-hand camshaft, which injected air into the exhaust ports. This ensured that gases were burned off once they left the combustion chamber and thereby reduced emissions, and it also improved engine pick-up by increasing turbo speed at mid-range velocities. As for lubrication, the dry sump system was the same as used in earlier flat-sixes. The 3.0-litre 930 used the same pump as the 2.7 Carrera RS, with a larger unit fitted on the 3.3-litre engine.

In 1978, the 911 Turbo engine capacity rose to 3.3 litres when bigger pistons and barrels were fitted. Visually, the main difference was the installation of an air-to-air intercooler, which sat on top of the engine and beneath the slats in the engine lid, reducing air-charge temperature by 50–60 degrees.ANTONY FRASER

In 1978, the 930’s capacity rose to 3.3 litres with the fitment of a new crankshaft with longer 74.4mm stroke, together with an air-to-air intercooler mounted atop the engine, raising power to 300bhp. ANTONY FRASER

TAKING IT TO THE STREETS

As we shall see, chapter by chapter, in the unfolding chronology of Porsche sports turbos, the application of race-bred technology gleaned from the 911 RSR 2.1 Turbo was applied to the road-going 911 – commonly referred to by its Porsche type number 930 in 1974. In order to proceed with racing derivatives, it needed to build 400 production cars so the model could be homologated for racing; to put this in some kind of context, the 1,000th 930 was built in May 1976. With its single KKK turbo, the 930 road car gained a larger-capacity engine in 1977, rising from 3.0 litres to 3.3 litres. However, shifting emissions legislation led Porsche to cease sales of the 930 in Japan and the USA, though it was reintroduced in these markets in 1986, having been available all the while in the rest of the world. The 930 was discontinued in 1989, having just received the fìve-speed G50 gearbox. Special editions included the Cabriolet and Speedster drop-tops, and the ‘slant-nose’ cars that emulated the 935 race cars.

Almost as scarce, and arguably the most exotic version of the 911 Turbo, was the 959: certainly, when it was unveiled it was like no other Porsche. Conceived in response to 1982 Group B rally regulations, this flagship model showcased the company’s high-tech resources and capabilities during the 1980s supercar boom. The 959 debuted as a design exercise at the 1983 Frankfurt Show, a white car dubbed the ‘Gruppe B’ study. It was Richard Soderberg’s futuristic design exercise under the aegis of Porsche styling boss Tony Lapine. Porsche had gone out of its way to create a masterpiece. Mechanically it was the brainchild of chief engineer Helmuth Bott and incoming managing director Peter Schutz, who were convinced that the company’s future lay with the tried and tested 911, provided it could continue to evolve.

The 3.3 Turbo is an aesthetic masterpiece, especially when finished in a luscious Tobacco Brown metallic (colour code: X5X5) like this 1980 model. ANTONY FRASER

This gorgeous 1980 3.3 Turbo is finished in Metallic Tobacco Brown, a hue from the contemporary 911 SC palette. ANTONY FRASER

As if the 930 turbo is not sufficiently dramatic in its own right, Porsche offered the targa variant in slant-nose format in 1986. Cooling louvres atop the front wings and slatted air ducts in the leading edges of the rear wings (fenders) endorsed the spectacle in a nod to the 935 race cars. ANTONY FRASER

Back in 1980, the FIA’s impending regulations for the hyperquick Group B category provided Porsche with the focus to build a supercar that would showcase its engineering expertise on road and track. The rules called for a minimum of 200 units, which suited the company’s aspirations, and it was clear that successful international rally cars needed to be all-wheel drive, so that was another element of the 959’s spec. The roof, front and rear wings, integral sills, rear bodywork and aerofoil wing are all in Kevlar, a medium not so well known in the early 1980s. The 959 is powered by a 2848cc flat-six, derived from the racing unit that powered the 935-inspired ‘Moby Dick’ Group 5 Le Mans car, with air-cooled block and water-cooled cylinder heads, 4 valves per cylinder, and twin sequential KKK turbochargers with intercoolers, developing 450bhp.

René Metge and Dominique Lemoyne won the supremely arduous Paris–Dakar Rallye for the second time in 1986 in their works Porsche 959. Jacky Ickx and Claude Brasseur came second in a 959 sister car. PORSCHE PHOTO ARCHIVE

The 959 is very special, with 292 cars assembled by Baur between 1986 and 1988, and eight cars made in 1993 from leftover spare parts. ANTONY FRASER

In the early 1980s, Porsche management was convinced that the company’s future lay with the tried and tested 911, and the 959 supercar was the result: its cutting-edge specification was unprecedented. ANTONY FRASER

The 959 is a rare beast in the Zuffenhausen hagiography, with 292 cars assembled by Baur between 1986 and 1988, and eight cars made fìve years later from leftover spare parts. There were fìve works rally cars – the Rothmans-liveried Paris–Dakar machines – and one racing car, the 961. I spoke with racer Nick Heidfeld at the Pininfarina factory where he is retained as test driver of their electric hypercar, as he owns a 959.

The 964 Turbo was introduced in 1991, two years into the 964 life-story. It had significantly more flared wheel arches than its normally aspirated siblings, and was powered initially by a follow-on version of the 930’s 3.3-litre engine, until fitted subsequently with the turbocharged 3.6-litre flat-six in 1993. ANTONY FRASER

Launched in 1991, the 964 Turbo was a latecomer in the 964 range. It had a wider body with significantly more-flared wheel housings compared to the 964 Carrera models. At the rear, the rear wing largely adopted from the Turbo 3.3 of the G-model 930, as well as two oval tailpipes, emphasized the vehicle’s uniqueness. Exhaust gases only escaped through the left pipe when the boost-pressure control valve of the turbocharger was open. In model years 1991–2, the 964 Turbo was powered by a turbocharged 3.3-litre engine with 320bhp. Then, in model year 1993, a 3.6-litre flat-six with a power output of 360bhp was installed. One of the distinguishing features of this version were the red brake calipers. The 964 Turbo was – with the exception of a limited production run cabriolet – only available as a coupé. There were also a small number of Turbo S lightweight and slant-nose versions. Altogether more rarefied was the 911 GT1, essentially a WSC racing car but also produced as a road car in small numbers in 1996 for homologation purposes (twenty-three in total).

The 993 Turbo 4 came out in April 1995, twelve months after 964 Turbo production finished, and it remained in production until July 1998, two years after the inception of water-cooled 911s. The overlap is quite interesting: you might have expected a clean cut-off separating old and new model lines. The 993 body shape was the fruit of Porsche’s virile in-house Zuffenhausen styling department, overseen by Harm Lagaaij and rendered by Tony Hatter and Richard Soderberg. It was mostly available as a coupé, although a further fourteen factory-made 993 Turbos were configured as cabriolets in 1995, albeit with single turbo and rear-wheel drive only. The 993 shell was 80 per cent new, and tauter than the 964, with bonded front and rear screens, and the Turbo is also 60mm (2.36in) broader in the beam than the standard 993 in the tradition of 911 Turbos. Front and rear valances are squared off to the ground and merge with the side sills. The frontal air intake consists of a large central opening flanked by a pair of side openings, while the fixed rear wing is a fresh take on the traditional Turbo tea tray, with drooping sides that look as if they’ve melted like cheese slices from the heat of the engine.

A rare visitor to the Goodwood Festival of speed, the 536bhp 911 GT1 was powered by a 3.2-litre twin-turbo flat-six. It was built to contest the GT1 class in the WEC, winning Le mans in 1998. the FIA’s BPR Global series rules required twenty-five examples of a road-going version to be produced, and this is one of the twenty-three actually created. JOHNNY TIPLER

Last of the air-cooled ‘Mezger’ units, the 3.6-litre engine has a compression ratio of 8.0:1 and employs a pair of KKK K-16 turbochargers, each with integrated wastegates and two charge air intercoolers, allied with Bosch M5.2 Motronic engine management, with a single plug per cylinder, developing 408bhp at 5,750rpm, with 398lb ft torque at a low 2,500rpm.

I should clarify the ‘Mezger’ appellation here: it refers to Porsche’s long-term race engineer, Hans Mezger, who worked for the company from 1956 to 1994. His career highlights include the 718 Carrera engine, 917 flat-twelve and its turbocharged 917/10 and 917/30 evolutions, and the McLaren TAG turbo F1 engine; he was also responsible for developing the air-cooled flat-six engine into a virtually bomb-proof powerplant. The Mezger flat-six endured as the basis for the water-cooled turbo engines fitted in the 996 and 997 as well.

The 993 Turbo’s transmission is the same 4 × 4 transmission as the normal Carrera 4, making it the first 911 Turbo to feature four-wheel drive. End-of-the-line 993 Turbos have stronger driveshafts too. The 993 Turbo’s running gear includes the multi-link LSA (lightweight, stable, agile) ‘Weissach’ rear axle suspension, larger ‘Big Red’ brakes with ventilated, cross-drilled brakes and four-pot calipers, and star-shaped hollow-spoke 18in (45cm)-diameter, 8in (20cm)- and 10in (25cm)-rimmed ‘Technologie-Rad’ alloy wheels that fill out the bulging arches.

During my career as a car journalist, I’ve driven a fair crosssection of turbocharged 911s, ranging from press cars to the products of Porsche specialists, as well as offerings from specialist dealers and private owners, and I’ve been privileged to have driven them on road trips to some stunning locations in the quest for feature articles too. There’s simply no substitute for being behind the wheel and making a journey in order to fully gauge and comprehend what a car is capable of, and what defines its character, and that’s what a large part of this book comprises: my on-the-road experiences in 911 Turbos, illustrated by a plethora of superb photos provided mostly by my regular colleague Antony Fraser, with contributions from Peter Meissner and Peter Robain, together with my own contributions and some stunning shots from the Porsche Photographic Archives, expertly collated by Jens Torner and Tobias Mauler. The illustrative material is augmented by a few super artworks by talented automotive painters Caroline Llong, Laurence B. Henry, Tanja Stadnic, Alina Knott and Sonja Verducci.

The 993 Turbo featured a twin-turbo 3.6-litre flat-six and four-wheel drive, with power split 20/80 with rearward bias, rendering it easier to handle than its immediate predecessor. Introduced in 1995, a year after the regular 993 launch, the Turbo also had a six-speed gearbox, and apart from the 959, it was the first turbocharged 911 model to offer all-wheel drive.ANTONY FRASER

A key figure in Porsche hagiography, Hans Mezger worked for the company from 1956 to 1994, during which time he was responsible for designing the 718 Carrera engine, the 917 flat-12 and its turbocharged 917/10 and 917/30 evolutions, and developing the 930’s air-cooled flat-six into a bomb-proof powerplant.PORSCHE PHOTO ARCHIVE