There were times when General Motors led the charge.
It is an easily overlooked fact that, despite enjoying widespread publicity and -in two cases at least- being successful additions to their existing model range, the BMW 2002 Turbo, Porsche 911 Turbo and SAAB 99 Turbo were not the first roadgoing, commercially available turbocharged passenger cars(1). The USA beat even the first amongst this European trio -the BMW- by a decade and while neither of today’s two protagonists could ever be declared a true commercial success, they still deserve their place in the spotlight.
America was no stranger to forced induction: starting in the early thirties the likes of Graham, Duesenberg and Cord employed superchargers, as did Kaiser and Studebaker around two decades later. The turbocharger, however, was thus far an unapplied technique for carmakers, although the idea had already been patented in the early twentieth century(2) and turbocharged engines had seen use in airplanes during World War Two.
Introduced within weeks of each other in the spring of 1962, the Oldsmobile Jetfire and Chevrolet Corvair Monza Spyder were both developed within the mighty GM empire but each took its own approach with the application of turbocharging technology.
A few months before the public introduction of a new aluminium 215 cubic-inch (3.5-litre) V8 in Oldsmobile, Buick and Pontiac compacts, work on a more powerful variant of this powerplant started at the Oldsmobile division. Veteran Oldsmobile engineer Gib Butler headed the program. Initially a Rootes supercharger was also considered, but the focus quickly shifted to turbocharging. The turbochargers were supplied by Garret AiResearch, a company which already had years of experience with turbocharging diesel engines in commercial vehicles.
The resulting Turbo Rocket V8 delivered 215 horsepower and thus attained the coveted ‘one horsepower per cubic inch’ accolade. The standard and four-barrel carburettor versions of the same engine put out 155 and 185 horses respectively, so turbocharging definitely provided the engine with worthwhile extra muscle. The new Oldsmobile, the first turbocharged passenger car in the world, was christened Jetfire. Available as a two-door hardtop only, a Jetfire was yours for US $3,045. This was about US $350 more than a regular Cutlass hardtop with a normally aspirated V8.
Both four-speed manual and three-speed Hydramatic transmissions were offered. Oldsmobile claimed a 0 to 60mph (97km/h) time of around seven seconds for the manual Jetfire, although auto magazine test results were typically a second or so slower than that.
In the interest of preventing unwanted knocking or detonation, the maximum boost was limited to a relatively low 5 psi, although the engine’s compression ratio was a then rather high 10.25:1. A further measure against detonation was the application of a water-alcohol injection system, derived from similar systems used in turbocharged WW2 airplanes. The mixture, named ‘Turbo Rocket Fluid’, was a 50/50 mix of methyl alcohol and distilled water, with a tiny amount of anti-corrosion additive. The fluid was stored in a 4.7-litre tank and was injected between the carburettor and turbocharger. Refills were available at the service counter of every Oldsmobile dealer in the country.
The fluid injection setup was effective in preventing detonation, but in spirited driving (which was, after all, what the car was meant for) the reservoir could be emptied within about 250 miles. When the Turbo Rocket Fluid was all used up, a safety measure sprang into action: an auxiliary throttle valve was actuated which limited the boost pressure. The car could still be driven without any problems although there was, of course, a noticeable drop in performance. Even though Oldsmobile had fitted a yellow warning light to indicate when the fluid level was getting low, many drivers apparently did not notice it and complained at their dealers, tarnishing the car’s image.
To be fair, the powerplant was certainly not without problems. Being carburetted, it was difficult to meter the fuel in a pressurized environment and produce a consistent fuel flow, even with a modest 5 psi boost. The oil pump did not generate enough pressure to lubricate and cool the bearings of the turbocharger properly and the pressurized Turbo Rocket Fluid reservoir could leak after the engine was switched off, resulting in fluid being pushed into the cylinders. A depressurization valve was later fitted in a nationwide service recall to fix that particular problem.
The Jetfire’s ongoing driveability and reliability issues prompted Oldsmobile in 1965 to offer owners a free replacement of the entire turbocharging system with a conventional four-barrel carburettor setup. Reportedly, around 80% of Jetfire owners had their cars converted, making an original turbocharged Jetfire quite rare these days.
Arriving in mid-model year 1962, the first Jetfire found just 3,765 owners while in the full 1963 model year 5,842 were sold. This modest sales performance coupled with the myriad teething problems associated with the engine caused Oldsmobile to leave it at that.
GM also said its goodbyes to the aluminium 215 cubic-inch V8 altogether after 1963 as traditional cast iron V8s were considered to be more cost-effective. The tooling for the small V8 was sold to the British Rover company and the engine would famously enjoy a long and happy afterlife in exile powering a wide variety of vehicles, some of them turbocharged.
Corvair Monza Spyder:
Amidst the widely publicised troubles of the Corvair, the early sales success of the sporty Monza version tends to be overshadowed. And yet, it was in no small part due to the exploding sales of the Corvair Monza (fewer than 12,000 sales in 1960, over 140,000 the following year and almost 220,000(3) sales in 1962) that Ford felt confident enough to go ahead with the Mustang.
Clearly, there was a lucrative market segment waiting to be exploited of young -or at least young at heart- drivers who enjoyed piloting a compact, responsive and nimble car. With lots of aftermarket performance-enhancing accessories for the Corvair available from both Chevrolet and aftermarket suppliers, one could produce a respectable performer for not too many dollars.
As their Mustang was not yet ready to enter (and, as it would turn out, conquer) the market, Ford fitted a 260 cubic-inch (4.2-litre) V8 in its bestselling Falcon(4) in an effort to lure buyers away from Chevrolet’s Corvair Monza in the meantime.
Chevrolet responded by making a turbocharged engine available in the Corvair Monza. In coupé guise, the car, named Monza Spyder, was slightly cheaper than the Oldsmobile Jetfire at US $2,847. A convertible version was also offered at US $3,077.
Potentional detonation was also an issue for the turbocharged Corvair engine, which is why its compression ratio was reduced from 9:1 to 8:1. Chevrolet steered away from the more complex set-up that Oldsmobile went for and its engine was the better for it. The 145 cubic-inch (almost 2.4-litre) air-cooled horizontally opposed six was beefed up to cope with the added stresses of turbocharging: stronger intake and exhaust valves, a forged crankshaft, different camshaft, heavy-duty pistons and stronger connecting rods were the main changes. Oddly enough, the differential remained the same as that used on regular Corvairs and this would turn out to be a mechanical weak spot of the car.
The TRW(5) turbocharger was mounted on top of the engine, connected to a Carter YH side-draft carburettor. With a maximum boost of 10 psi, the result was 150 horsepower (up from 102) and a 57% increase in torque. 0 to 60mph (97km/h) was dispatched in 8.5 seconds. Chevrolet did not apply a wastegate but rather fitted restrictions to the air filter and mufflers, although this impeded the free spinning of the turbocharger and reduced its responsiveness markedly.
Initially, a four speed manual was standard when choosing a Monza Spyder, but, a few months into the model year, this was replaced with a three speed gearbox. Automatic transmission was not available. Also for the first few months after its introduction, the Monza Spyder received a heavy-duty suspension and front anti-roll bar as well as sintered metal brake linings as standard equipment. These became options during the model year, although the majority of buyers had them fitted- a wise choice in view of the Corvair’s handling idiosyncracies…
When Ford’s Mustang arrived on the scene, the writing was on the wall for the Corvair. Quite apart from Ralph Nader’s ‘Unsafe at any speed’ exposé on the car’s handling deficiencies, the Corvair was relatively expensive to build and its powerplant also had a limited enlargement potential, while Ford could -and would- drop ever larger and more powerful V8’s into the Mustang.
There was just no way the Monza Spyder could keep up, so that would become the Camaro’s job from 1967 on. The Corvair was also consistently outsold by its stablemate, the Chevy II, as well as the Ford Falcon, which further eroded its chances of survival.
The last turbocharged Corvair, by then renamed Corsa, was built in model year 1966. The turbocharged engine remained available as an option until the end came in 1969, but not many people bothered by that stage. A total of 9,468 Corvair Monza Spyders in convertible and coupé guise were sold for 1962, and a little over 19,000 in 1963, handily beating Oldsmobile’s technically more sophisticated but fragile alternative, but still insufficient to save the Corvair nameplate.
(1) The term being applied very loosely in the case of the Porsche 911 Turbo.
(2) By the Swiss Büchi, 1904.
(3) This constituted 75% of total Corvair production that model year.
(4) The sales success of the Falcon would in turn prompt Chevrolet to bring out the similarly conventional Chevy II.
(5) Thompson Ramo Wooldridge Inc.