History of turbocharging: the force awakens

In 1939, Rolls-Royce’s Ernest Hives explained the rationale: “The benefits from a system of this type have been found by experience to be twofold, since not only is the machine speed increased due to the exhaust momentum effect, but also the backward ejection of gases at high velocity smooths out the airflow over the body, suppressing turbulence and eliminating the interference set up when the exhaust gas is discharged at right angles to the slipstream.”

French engineer Auguste Rateau was an early turbocharging pioneer who came to the nascent aviation party equipped with well-developed forced-induction ideas

During the First World War, experts at Farnborough had tested turbos of their own design, along with those from French expert Auguste Rateau, but had not been convinced.

According to one observer, speaking at a time when most aircraft were largely wood, string and fabric: “The festoons of red-hot exhaust pipe from each cylinder were considered too alarming to the pilot.”

The arrival of creative engineer Jimmy Ellor, first at Farnborough and then at Rolls-Royce, soon put things right.

Across the Atlantic, in the meantime, the experts at General Electric were making turbo-supercharging advances under the guidance of the entirely committed Sanford Moss.

This view of an experimental, shaft-driven, centrifugal blower taking up space in an RAF aeroplane shows why early turbos were viewed with wary scepticism

With the 14,115-foot altitude of Pikes Peak as his proving ground, he evolved convincing turbochargers that culminated in Lt John Arthur Macready reaching a record altitude of 40,800ft on 16 October 1921 in a Le Père biplane powered by a GE-turbocharged Liberty V12.

This left no doubt about the potential for aviation in general, and exhaust turbocharging in particular, but the arrival of peacetime put America’s aviation experts to sleep.

Save the record-setting exploits of Wiley Post and Charles Lindbergh, little note was taken of what General Electric had wrought.

Post-Pearl Harbor, however, both GE and the users of its steadily improving turbochargers were again seen for what they were: war winners that could command the highest altitudes.

American Sanford Moss brought the might of General Electric to turbo-supercharging, saying that it: “Kidded the piston engine to think it was at sea level”

Coming up to and including the Second World War, the rise of the diesel truck engine was an encouragement to the developers of turbos to tackle this market.

Swiss engineer Alfred Büchi’s patents played a role in creating robust yet compact turbochargers that were a boon to the performance of heavy diesel engines.

For the first time, the topic of ‘turbo lag’ entered the lexicon, but it could be tolerated given the sluggish demands of these diesels.

While Europe was ablaze with its wartime conflict, both active and passive participants suffered from a shared problem: a paucity of petrol.

War became the ruling consumer of this valuable fuel, leaving less worthy users in the lurch.

Sanford Moss and his team drove this impressive machine up Pikes Peak in 1918 to test turbocharging at altitude. They brought along propellers of both 8ft and 10ft in length

However, a tolerable compromise was available to all parties. Its fuel could be brown coal, coke, peat, charcoal or wood, the latter usually in chip form.

Simmering in an oxygen-deprived atmosphere at up to 1400°C, dedicated equipment generated what was known variously as producer, wood or generator gas.

This contained enough energy to operate an internal-combustion engine – and it would do so surprisingly well.

In Germany, the use of generator gas was encouraged by tax measures, and more than a dozen companies produced systems.

Pilot Lt John Macready (on left) next to Sandford Moss with their V12 Liberty and GE-turbo-powered Packard-Le Père. They set a new world altitude record of 40,800ft in September 1921

By far the largest was Imbert Generatoren GmbH, based in Cologne and credited with manufacturing the majority of Germany’s 300,000 gasogene generators. These commonly used Roots blowers to maintain their combustion.

Observing the situation in 1944 from his eyrie at the Luftwaffe’s Adlershof research centre, where he was in charge of supercharger development, Werner Theodor von der Nüll saw an opportunity to make a step-change in turbocharger design.

There was a desperate need for a means of enhancing the output of German gasogene-fuelled vehicles. Von der Nüll had in mind a radial-inlet or centripetal turbine.

Any suggestion on his part hitherto, he recalled, that a turbine could function radially, like a compressor working backwards, “was greeted by pitying smiles”.

A GM-Opel ‘six’ was the test bench for the ultra-novel small turbocharger developed in 1944 by Werner von der Nüll to run on solid fuels by gasogene

His vision, though, was that the turbine would receive the hot gases at the periphery of its rotating blades and exhaust them at the centre.

For his first such design, he employed an impeller as his model, including its set of axial induction blades, which produced an extra impulse on exiting the system.

“In 1944,” von der Nüll would recall, “I and fellow workers started the development of a very small exhaust turbo-supercharger for Otto cycle engines of the Chevrolet and Ford class, basing our work on other studies.”

The new development in their unit was the turbine, which was of a radial type.

By the end of the Second World War, and following lengthy laboratory and road testing, the development was close to completion.

While reminiscent of the work of Auguste Rateau, this superbly machined turbo wheel was created by aerospace engineer Jimmy Ellor, later of Rolls-Royce

The engine used was the 3.6-litre straight-six unit that powered Opel’s Blitz lorries and Admiral cars.

Derived from a Chevrolet design, it had served the Wehrmacht nobly during the war.

Increasing the Opel’s power from 32bhp to 50bhp on generator gas, the experiment was a success.

Germany collapsed before von der Nüll’s concept could be commercialised, although many of his countrymen had to struggle on with their generator-gas devices in their straitened post-war world.

Corralled at Bad Kissingen in the American Zone, engineers and scientists nominated by the US Air Force were transported to the United States in due course.

The Oldsmobile Jetfire was an early adopter of turbo technology

Given his credentials, Werner von der Nüll was a no-brainer for the USAF Wilbur Wright Field technical base in Ohio.

There he rubbed elbows with Hans von Ohain, the physicist whose work led to Germany’s first turbojet engine.

In October 1947, these were two of the Wright Field engineers consulted on a gas-turbine project by Homer Wood, assistant chief engineer of Garrett AiResearch in Los Angeles, California.

For Wood, who had been with Garrett since 1943, the experience was fascinating.

In the design of his turbine, he had consulted some of von der Nüll’s wartime reports in which the German had pointed out the merits of the radial-inflow turbine.

Oldsmobile used turbocharging to make its all-aluminium V8 more powerful without increasing the capacity

Under von der Nüll’s influence, he had used the technique in his gas-turbine design.

It was the breakthrough in the creation of a turbocharger that was small and efficient enough to live anywhere in an automobile.

The US Air Force loaned ‘Ted’ von der Nüll to Garrett late in 1947 to assist with the company’s projects; in 1948 he became an AiResearch employee as a senior development engineer. 

In this capacity, he oversaw the production launch of the compact turbo of his dreams. 

AiResearch started series production in 1955 and by 1959 had made 22,000 turbochargers. 

The Chevrolet Corvair Turbo was more popular than the Oldsmobile Jetfire, but both failed to excite the public’s imagination as expected

At this juncture the company was contacted by Harold Metzel, chief engineer of General Motors’ Oldsmobile division, which had been experimenting with turbochargers since 1950.

Pizzazz was not new to Oldsmobile.

Indeed, it had the reputation of being the GM division with the most adventurous technology.

In 1939 it was the first marque to offer the four-speed Hydra-Matic automatic transmission, which would set an industry standard.

In 1949, it matched prestigious Cadillac in bringing high-compression V8 engines to the masses – the first Olds ‘Rocket’ motors.

Turbocharging was a perfect fit for this forward-looking image.

The Chevrolet Corvair Turbo’s air-cooled flat-six was boosted with a Thompson Ramo Wooldridge turbo © Max Edleston/Classic & Sports Car

Its Cutlass F-85 model had an all-aluminium V8 of 3.5 litres, which would be difficult to enlarge; a turbocharger would suit it well.

Cleveland’s Thompson Ramo Wooldridge Inc was the source for a turbo to suit the offspring of another GM division, Chevrolet.

Here, too, forced induction promised more power: for a sporty version of the rear-engined Corvair, with a 2.7-litre, air-cooled flat-six.

TRW assisted in an installation that was much simpler, with a form of throttling to keep the turbocharger from reaching excessive outputs.

Swiss engineer Michael May opened the door to compact and efficient turbos in Europe. His designs were widely sold and inspired many to follow suit

Although Chevrolet started about a year after Olds, it caught up with its rival for the 1962 model year.

While Oldsmobile sold 9607 Jetfires in two years, it took Chevy only four to deliver almost 50,000 Corvair Turbos.

Forecasters had prophesied a big future for turbos, but the American sales disappointed. 

Their launches ran aground on a huge sweep towards much bigger, atmospherically fed V8s.

With triple carbs on a 7-litre V8, you didn’t need much more power.

This diagram of a BMW 2002’s turbo reveals the concept’s relative simplicity – exhaust gases enter from the top left and spin the turbine, which shares a shaft with a compressor that draws in fresh air from the right

But Europe saw things differently, and its bellwether was Michael May.

This Swiss engineer kept the flame burning for turbo-boosting of Otto cycle engines at a time when car makers and their suppliers – struggling with emissions issues – were otherwise preoccupied.

May went in his own direction by designing kits for installation in Ford V6s by dealers, and he sold some 500 of them.

Then, in 1968, he responded to a call for help from BMW that resulted in going “from 150bhp to 320bhp in two days”.

Michael May worked closely with BMW to introduce turbocharging in racing cars and on the road. The 2002 turbo’s reversed script, a Bob Lutz idea, annoyed higher-ups © Jayson Fong/Classic & Sports Car

Turbocharged BMW racers were successful, and a BMW Turbo concept car was also well appreciated.

Meanwhile, May helped others with tuning, including a formidable twin-turbocharged sports-racer for Toyota.

Porsche had been interested in turbocharging from the early 1970s, when the German marque swept the Can-Am Series so comprehensively that it was ruled out for the future.

Its new leader, Ernst Fuhrmann, wanted turbocharging for a possible roadgoing sports car: “I said to my people, ‘Why don’t we put this success into our cars?’

“They said, ‘Oh, this was tried already. There’s not enough room.’”

Installation of the first Porsche 911 turbo’s compressor confounded engineers who said it wouldn’t fit

“This was my contribution,” Fuhrmann recalled. “I looked in the engine bay and said, ‘There must be room!’”

This was the man who had found space in the back of a 356 for a four-cam engine with twin spark-plugs per cylinder.

Supervisory-board chairman Ferry Porsche was also convinced, not least by the economics of manufacturing: “If you have one engine in production and you want to use it in two kinds of cars, it’s the cheapest way. 

“On one line you can make two kinds of engine! We also saw the turbo was good for reducing air pollution. You get high power with low noise.”

The Porsche 911 turbo still stands as a performance benchmark © Max Edleston/Classic & Sports Car

A massive blow to the programme and others like it was the OPEC oil boycott at the end of 1973 and its dislocation of the automotive world.

Suddenly, in the eyes of many, it was no longer socially acceptable to buy, drive or even build motor vehicles of high performance and fuel consumption, but this negative atmosphere didn’t halt the rise of the 911 turbo.

When the production model was introduced at the Paris Salon in October 1974, it was lacking nothing and priced accordingly.

Half a century has passed since the launch of the 911 turbo, and a like-minded descendant is still available from Porsche.

Four turbochargers help the Bugatti EB110 Supersport’s V12 take the car to 218mph © Luc Lacey/Classic & Sports Car

In the meantime, producers of turbochargers have changed hands many times and new technologies have been implemented.

First to come forward was a system that could vary the angles of the blades at the fresh-air inlets of turbos in order to affect their operation favourably; far tougher was the creation of variable vanes for the turbo’s hot side, but this, too, was eventually achieved – and by Chrysler, of all brands.

Some turbocharged cars have made history.

Audi’s quattro was a five-cylinder rally legend; the Lotus Carlton set a high-speed benchmark at 169mph; the menacingly black GMC Syclone pick-up hit 60mph in 5.3 secs; Toyota’s Supra Turbo had ‘Two-Way Twin Turbo’ technology; the Supra-rivalling Nissan Skyline GT-R’s RB26-DETT ‘six’ set standards for ruggedness; and Romano Artioli revived dormant Bugatti with the EB110’s quad turbos and the stupendous engineering of Paolo Stanzani.

Today, the use of turbochargers is almost universal: what would we do without them?

Images: Karl Ludvigsen

Karl Ludvigsen’s three-volume masterwork on forced induction, Power Unleashed, is published by Evro and priced at £395; ISBN 9781910505373. Click here to find out more.

Enjoy more of the world’s best classic car content every month when you subscribe to C&SC – get our latest deals here

READ MORE

Maserati Biturbos: two’s a party

BMW 2002 turbo, E30 M3, Z3 M Coupé and 1M: small wonders

Porsche 911 turbo at 50: icons of the air-cooled era