For a short period of time in the last century, turbine-driven cars were all the rage. Manufacturers hawked them, race engineers played with them, and the public drooled over them. 8W takes a glimpse into our kerosene-fueled past. —Ed.
Turbines: The Pros and Cons
To see why turbine engines caught on quickly during the sixties and moved over from road cars to racing cars, it is best to devote some paragraphs to explaining their internal workings.
First, let's start with the quick and dirty answer. The basis is formed by two turbines, the first of which is tasked with compressing air and forcing it into an ignition chamber (or "burner") with added fuel. The exploding mixture of fuel and air then rapidly expands into a second two-stage turbine, giving drive to the compressor turbine, which is rotating on the same shaft (first stage, using 10% of generated power) and a single-gear transmission that is powering the car (second stage, using 90% of power).
It's as simple as that. It's no miracle invention, as turbines have existed for centuries; water turbines drove mills alongside fast-streaming rivers as early as the middle ages, while steam turbines were among the most prominent power sources of the 19th century. So if "turbine" is the general denominator for a machine or motor driven by a wheel that is turned by the pressure of air, steam, water or gas, the innovation of the turbine car engine is in its application.
Let's get to the nitty-gritty: What are its strengths and weaknesses? First, the pluses: The turbine's simplicity is its main advantage. It is smaller than a piston engine. A 250-hp turbine engine has a power turbine that is four to five inches in diameter, usually with a compressor turbine seven to ten inches in diameter. It also weighs less, with 80 percent fewer parts, and is less susceptible to vibration due the rotary (instead of reciprocating) motion of its moving parts. It will run on any flammable liquid or gas, from alcohol to peanut oil, from perfume to Jack Daniels, as the fuel's detonation characteristics don't really matter. It is in full working order from start-up, as fuel is injected directly into the burner, with timing and vaporarization not critical at all. This in turn kills the need for a warm-up period — there is instantly available heat, instead of cylinder blocks and coolants that need to be warmed for efficiency. Antifreeze isn't needed either, as operating temperature is effectively controlled by the air flowing through the engine. Finally, the exhaust gases are cool and clean, with practically no carbon-monoxide emissions. The performance part? You can't kill a turbine engine by overrevving it, as the compressor rotates independently of the power turbine.
On the downside, there is surprisingly little tricky stuff. The turbine has just one drawback, but it's a relatively big one: It guzzles fuel, often up to eight times more than a piston engine of similar output. Early on, this problem was countered by using the first part of the two-stage turbine to not only drive the compressor turbine, but to also drive a pair of "regenerators." These honeycomb regenerators acted as a pair of clever heat exchangers, directing exhaust heat back into the system to lighten the burden of the burner, with fuel now only needed to raise the gas temperature up to the required level. As an added bonus, exhaust temperature was further cooled to safe levels. This resulted in the regenerative turbine engine (below) that was to form the basis of all turbine-powered road and racing cars.
Turbines: The Heritage
After a brief look-in by Opel in 1927, road-car turbines were separately pioneered by Rover and Chrysler, with GM and Fiat also examining their capabilities. Rover started work in 1939, shortly after war was declared between England and Germany. This was on commission from the British government that, amidst clouds of secrecy, approached Rover's Spencer Wilks to help out a company called Power Jets Limited, which had a brilliant jet engine design but lacked production facilities. Chrysler latched onto the concept in 1945, but let's look at the British effort first.
Rover: True Pioneers
The top-secret request to Rover came on the back of Rolls Royce's lack of interest for the project, as they were in the middle of Merlin V-12
production for their Spitfire fighter range. Indeed, the first application considered for the gas turbine developed by Power Jets' Frank Whittle (left) was aviation –- and it being wartime, military aviation came to mind first, although for Rover mum was the word. The car manufacturer being the backup choice and uninvolved in aeronautics, Wilks left his engineers in the dark over the project, claiming that it was a new "supercharger" development…
Rover and Power Jets co-developed and produced two versions of Wittle's original design, but they soon fell out as Rover made alterations -– erm, "improvements" –- to the W2 design, going another step further with the W2B, again without consulting Wittle. Rover had good reason, as the initial engines suffered from surging and turbine failure. Soon, with war now raging all over the continent, Rover managed to secure the government's commission to go it alone. The new B-26 turbine was almost drawn on a blank sheet, and when Rolls-Royce stepped into the turbine arena in 1942, the B-26 formed the basis of the Rolls-Royce Welland, the world's first production jet engine.
The designs may have been sold, but the knowledge did not go with them. As soon as a couple of months after the end of the war, the Wilks brothers began planning further turbine development for road-car applications. For this, Spencer Wilks made an approach to Leyland to help fund the project, while also luring away turbine engineers Frank Bell and Spencer King from Rolls-Royce.
Despite immediate post-war material shortages, a prototype engine called the JET 1 was up and running in February 1947. And although they had some steep hills to climb -– like working out how to link a 50,000-rpm turbine to the back axle of a road car! –- a working fifth incarnation of the JET 1 was finished in May 1948. This had the aforementioned two-stage turbine solution to the drive problem that was later followed by other manufacturers; it produced 100 hp at 55,000 compressor rpm while weighing less than a Rover piston engine. A more powerful version was successfully tested in a boat at the end of 1949 and subsequently mated to a Rover P4 road car. On March 14, 1950, this car made its first runs and, as the "JET 1" (above), saw its first public appearance soon after.
The rear-engine JET 1 lit up at 3000 rpm, with its compressor turbine's speed at 40,000 rpm and the power turbine maxing out at 26,000 rpm. The idling speed was an impressive 13,000 rpm! With 100 hp, it could hit 85 mph while returning 6 mpg. In 1952, an uprated JET 1 appeared with a whopping 230 hp on tap, delivering a world record speed of 152 mph, still at 6mpg. The same year also saw the advent and quick demise of an outboard engined turbine concept car, the T2A, which didn't quite work as planned...
Four years later, Rover was ready to announce its first car specifically designed around a gas turbine engine. The T3 was a Spencer King design, with help from Gordon Bashford and Peter Wilks, and it boasted an two-shaft inboard rear engine producing 100 hp. It was a hugely innovative car that, even apart from the turbine engine, was ahead of its time with its fiberglass body, De Dion rear suspension, back-angled front forks, and four-wheel inboard disc brakes. Also, turbine development had come a long way. Light-up was now at 15,000 rpm, with the compressor's working speed at 52,000 rpm. By now, heat exchanger technology had seen the light of day, hugely improving fuel economy to 13 mpg.
The regenerators were further refined to deliver 20 mpg in the 1961 T4, left. This was a serious motorcar based on the Rover P6 (two years before the regular piston-engine P6 debut), as it gave an impressive 140 hp and a 0-60 time of 8.0 seconds. With a front-mounted engine, front-wheel drive, and stunning looks, there was nothing to take away from it against the usual crop of piston-engine road cars. Still, Rover decided to leave road-car development for what it was and focused on racing its turbine engines.
Although British road-car turbine development came to a halt after the T4, by this time, on the other side of the Big Pond, Chrysler was about to launch its first turbine road car.
Chrysler: Real-World Cars
The first design work on turbines at Chrysler had started as early as 1945. Over a decade of prodigious development got the company to the same level as Rover, with a single-shaft, two-stage regenerating turbine engine that could be front-mounted, with the first-stage power turbine used to drive the compressor and accessory systems such as power steering, power brakes, and even power windows!
In the early sixties ambitious plans were unfolded to produce a batch of 55 cars to hand out to selected "test drivers" across America. For this, Chrysler designed a futuristic body that would be built by the famous Italian coachbuilder Carrozzeria Ghia. The cars were finished and shipped stateside in 1963. Five cars were kept by the Chrysler development team; the rest were doled out in a grand sweepstakes that saw some 30,000 applications. Each of the 50 winners was responsible for testing the cars and handing them back later along with a detailed evaluation.
In total, 203 average citizens got the chance to test the Chrysler Turbine between 1963 and early 1966. Most cars topped a trouble-free million miles before their retirement. The drivers ranged in age from 21 to 70; 180 were men and 23 were women. They lived in 133 different cities. Conversely, car journalists weren't allowed any significant time in the car — what little test experience they got always came with a factory representative in the passenger seat.
The testers' verdict matched the strengths that the designers had already envisioned and the weaknesses they had worked hard to eliminate: The turbine Chrysler was smooth and quiet and its reliability was staggering, but fuel consumption remained a worry. Then again, as Chrysler surmised, this was probably due to test drivers often showing off their car in front of a crowd of impressed on-lookers. With an idle speed of 22,500 rpm, this was a fuel-burning exercise and little else — no wonder the drivers were sworn to secrecy about performance and fuel consumption! Other downsides were acceleration lag and a lack of engine braking. When put in drive, the Chryslers had a basic speed at idle, like a piston-engine automatic. This required applying the brakes at all times.
The STP-Paxton Indy Car
The STP-Paxton turbine car that produced a heartbreaking near miss at the 1967 Indy 500 was the brainchild of Italian-American Andy Granatelli, a racing nut who combined engineering vision with great business acumen. Granatelli was a life-long speed addict: He was once an engineer and chief tester for Studebaker, and he set over 400 land-speed records.
As an engineering enthusiast, having already brought Ferguson Formula four-wheel drive to Indy, Granatelli was quick to see the unfair advantage of a turbine engine matched with four-wheel drive. Thus the STP-Paxton turbine car was born, with a Ferguson four-wheel-drive system coupled to a reduction-gear system supplied by STP's Paxton division. It was built completely in-house by the Granatelli brothers, who wanted to keep the system a secret from their competition. As Granatelli stated during an Indianapolis Legends interview in 2000, "Every single thing on the car except the wheels and the turbine engine was built in-house.
Everything. And the reason we built everything in-house was because we didn't want to go to any outside vendor to have them know that we were building a special race car. And when we built the car, it was built completely in the rules, completely in specifications."
The engine was a Canadian Pratt & Whitney ST6B-62 rated at 550 hp -– and it was mounted to the side of the car! With its side-by-side construction, it looked awkward, but the driver's weight offset the mass of the lightweight turbine. It was also quiet –- hence the car's nickname of "Silent Sam" –- and fast. Very fast. Soon the competition was complaining with USAC, which had already reduced the car's turbine inlet area in order to keep the car from becoming dominant. And there was more bollocking going on. Granatelli still gets mad thinking back to the car's Indy debut: "We were told for example that the flap on the back of the car was distracting the other drivers. Bologna! It never distracted anybody. But they banned that first thing off the bat. With a piston engine, you take your foot off the gas, it's still through the crankshaft, but the compression slows the car down. But with the turbine car, you take your foot off the gas, and it's like putting the car in neutral. You keep going. So we needed something more in brakes. So we built a flap on the back of the car. When you stepped on the brakes, the flap would go up like an aircraft and slow the car down. Well, the drivers complained about that, not because it was too distracting, but to complain."
Nevertheless, and ominously if you weren't part of the STP team, Granatelli had tempted legendary Parnelli Jones into racing it, and Jones, who was on the verge of retirement, was only willing to do that if he had a "lock on the race". Granatelli was very convincing in his affirmation, and soon after the car was too – Parnelli found that it could go everywhere he put it on the track. Up, down, in the middle – the Swooshmobile didn't need a "groove". Amazingly, not a single modification was needed to achieve that, says Granatelli: "We never, ever adjusted a spring, a push-bar, nothing. We didn't change a thing on it. They didn't do a single thing to the car to make it handle it any better. They asked if the car was designed to handle it in the first place. It had equal weight distribution. That's why I put the engine on one side and the driver on the other, because the weight would be equal all the time."
Granatelli was so confident of its reliability that he didn't even consider an engine change between qualifying and the race. He was right about that, but didn't count on the Paxton gearing giving in. Having led 171 laps, Parnelli Jones coasted to a halt on lap 196 of 200 – with just 7.5 miles to go. It was truly the nearest of misses. The Swooshmobile had been running away with the race when a five-dollar bearing in the gearcasing failed, at a point where Parnelli had almost a lap in hand on his nearest rival, AJ Foyt – and that was after spinning earlier in the race and having to claw his way back through the field.
The last-gasp loss didn't help easing up USAC's stance. Horrified by Silent Sam's domination it changed the 1968 rules to further strangle the turbine's inlet area to 15,399 sq in, bringing down its output to around 450 hp. This is testimony to the complete package of his cars, Granatelli said in 2000, when asked about this tumultuous era of Indy racing: "Contrary to popular belief, the turbine car did not have a lot of power. It only had 480 horsepower while the other cars had 750 horsepower. But what the car did have was the ability to go along the corner anywhere on the track you wanted to put it. Under the groove, in the groove, under the white line, out in the gray stuff, it made no difference. The car could go wherever you pointed it."
The Howmet TX Sports Car
The Howmet TX Continental sports car was conceived concurrently with the STP-Paxton Indy car, but made its debut one year later, as it was campaigned extensively in 1968. The original car, chassis 01, was built up from a McKee Can-Am car, with cars 02 and 03 specifically built for the turbine engines. The Continental TS325-1 helicopter engine, its calculated equivalent of 2958cc producing an approximate 330 hp, drew from a center-mounted fuel tank carrying 32 gallons of Jet A fuel.
It was designed for the FIA Group 6 3-litre prototype class through the sponsorship of the Howmet Corporation of America, a metal company working as a large subcontractor to the aircraft turbine industry. The man with the vision was sportscar racer-cum-engineer Ray Heppenstall, who convinced his racing pal Tom Fleming, a board member at Howmet, to start a publicity-gaining racing programme. As such the Howmet-Continental TX was entered for the World Sportscar Championship in the days it was still covering such glamorous events as the Daytona 24 Hrs, the Sebring 12 Hrs, the 6 Hr events at Brands and the Glen, the Targa Florio, the 1000 km events at the ‘Ring, Monza and Spa, and the Austrian Sportscar Grand Prix.
The Lotus 56: Indy, Again
The new-for-1968 air inlet rules called for a lighter car than the heavy STP-Paxton, and Granatelli found an ally in Colin Chapman, who had been watching the turbine development with great interest. In a meeting of two of the most innovative minds in world motor racing, the pair matched an uprated Pratt & Whitney ST6B-70 engine to the lightweight wedge-shaped Lotus 56, with sponsoring coming from STP. Here it is seen at its presentation at Hethel, with Graham Hill rolling out the car under Chapman's watchful eye.
The engine placement in the 56 was also offset – this time to the right, in order to make space for the 4WD drivetrain on the left – but this was covered up by the car's broad appearance. Front and rear suspension used inboard spings and dampers, while the cockpit had a very finished and modern look. Through a Morse chain the turbine's output shaft connected to a Ferguson centre diff behind the driver's left shoulder. This was a development coming over from Ferguson's road-car technology. The chain replaced the Paxton transfer gears, which had been the STP-Paxton's achilles heel.
But before the race was on, the team was struck by double tragedy. First, Jim Clark died at Hockenheim. And then Mike Spence, the BRM number two lured over by Chapman to drive the 56 at Indy, was killed in a practice crash.
It didn't stop the team's eventual driver trio from occupying the first two places and ninth on the grid, with Joe Leonard and Graham Hill upfront and Art Pollard on the fourth row. Although Hill spun into the wall on lap 111, the turbines looked all set for a reprieve of 1967, only to come in for more heartbreak right at the end. Having been through one caution period to many, the leading Leonard car broke a fuel pump shaft on lap 192, with Pollard's machine doing likewise only seconds later. What had happened? The drivers had been running at reduced power under yellow, and when they floored the throttle when the green was waved, the sudden load caused the extension shaft in the fuel pumps of both cars to snap. This was the result of Pratt & Whitney insisting on the heat-sensitive shafts carried over from their passenger aircraft engine technology. These would fail-safe under overheating and this proved their undoing during the yellow-flag periods. Before the race, this had been the subject of, let's say, intense discussion between Lotus and P&W, with the eventual compromise that Hill's car would run with a solid shaft and the two Americans' cars with the original ones. If only Hill had been running to the end…
So, another narrow miss, and yet the USAC rules committee stepped in again. They'd seen enough, the turbines had to go. In hot-blooded Italian fashion Granatelli started off a trial of lawsuits, which took the warring parties to the High Courts, with the sporting authority coming out unharmed for the plain reason that it chose not to follow the rules committee's lead of banning turbines outright. Instead USAC cunningly slammed another restriction on the turbines. Short from actually banning them this rendered them useless for any further attempts at winning Indy. At the end of 1969, the death knell was further tightened by USAC's ban on four-wheel drive, as this technology wasn't held to be "within the mainstream of automotive development". Oh, what poor vision… This meant an effective ban on turbines, too. This was precisely Granatelli's accusation of USAC – that they had banned 4WD as a front to get rid of the turbines. He was probably right.
Lotus 56B: Grand-Prix Swan Song
It was probably the form the 56s showed during the rest of the 1968 season – on USAC road courses! – that convinced Colin Chapman to give the 56 a try in the Grand Prix environment. Here, four-wheel drive was still alive, probably due to its lack of success in 1969. And so, after having emotionally dealt with the losses of Clark and Rindt, Chapman sprung a major surprise in 1971 by launching the Lotus-Pratt & Whitney 56B. Indeed, this was the turbine Indycar adapted to F1 regulations, with a 500-hp P&W STN76 engine.
It is said that the bulky 56B was only intended as a testbed for a sleeker turbine challenger to come in 1972, but the fact remains that Chapman's driver diplomacy went awry in the same fashion as in 1969, when his beloved Jochen Rindt had publicly decried the Lotus 63 4WD car. This time, it was Fittipaldi and Wisell who took every opportunity not to drive it. And why would they when they had a totally sorted 72, now at its peak, waiting for them? This resulted in young Aussie Dave Walker taking the role that John Miles was forced into with the 63 – a junior driver being thrown into the deep end of developing and debuting an unloved car based on a revolutionary concept.
Granted, the team's lead driver drove the 56B on its true debut, but this was a non-championship event that could be used for development without any harm. Moreover, Emerson left Brands Hatch seriously underwhelmed by the car's potential in the dry. This was borne out by Wisell's poor performance at Silverstone and by Fittipaldi at Monza, taking a black-and-gold liveried "World Wide Racing" 56B (the Italian investigation into Jochen Rindt's death still in full swing) to the only finish (8th) in its short career.
In Chapman's mind it was an opportunity wasted. He blamed the weight and complexity of the car and wanted to pursue a rear-wheel drive version. In other people's minds the wet-weather performances had all come because of the four-wheel drive, no thanks to the turbine. We will probably never know. In 1972 Lotus had a serious stab at the World Championship and all efforts were directed to helping Emerson win his first title. And so, Monza '71 was not just the last we'd seen of four-wheel drive in F1, it was also the turbine's grand-prix swan song.
8W, part of Forix.Autosport.com, is a motorsport history portal. The site covers the "drivers, cars, circuits, eras and technology that shaped the face, sounds and smells of motor racing." This story originally appeared on 8W in slightly longer form on May 19, 2003.
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