Since the end of World War Two the American performance car market was immersed in brutal, large cube V8 engines - "muscle cars." In the early 1960s, however, fuel prices skyrocketed due to a supply crisis and cheaper-to-run European imports - such as the VW Beetle - began stealing a considerable number of sales from the established American 'big car' manufacturers.
In 1961, Oldsmobile, Buick and Pontiac (all divisions of GM) responded to this situation by introducing a range of 'compacts' - the Olds F-85, Buick Special and Pontiac Tempest. All three were based on the same platform (which was derived from Chevrolet's Corvair) and could be purchased with sedan, wagon, coupe or - later - convertible bodies.
Note that the parent company's Corvair used a unique rear engine/rear drive layout (which you've probably heard criticised for its "unsafe handling") while the Buick, Olds and Pontiac vehicles used a more conventional front engine/rear drive layout.
It was one thing to swing American buyers into smaller size cars but quite another to move them away from their adored V8s. The solution was to build a new lightweight and relatively small capacity V8 and it was Buick - who had already developed aluminium engines for a couple of experimental cars - that got the design job. This was a very expensive venture and the engine was trumpeted as something that would be copied for ten years to come.
Buick's final product was an-aluminium OHV 90-degree V8 with a 3.5-inch (89mm) bore and 2.8-inch (71mm) stroke, for a total capacity of 215 cubic inches (3.5-litres). Aluminium engines were almost unheard of in production vehicles of the time and Buick discovered initial problems with the piston to bore interface, necessitating the insertion of iron liners. Hydraulic lifters were also necessary to allow for the increased expansion of the aluminium construction; this maintained the level of valvetrain play and reduced maintenance. Some of the favourable design characteristics of the engine included highly effective combustion chamber squish and short flame travel. The engine was also extremely rigid yet weighed only around 352lb (160 kilograms).
In the early days, the base-spec aluminium 215ci V8 was capable of 155hp (116kW) and 220ft-lb (299Nm) of torque while high output versions - such as fitted to the Oldsmobile Cutlass coupe - sported a 10.25:1 compression ratio and 4-barrel carburettor to push 185hp (138lkW) and 230ft-lb (313Nm)
The groundbreaking new V8 was made available as standard on the Oldsmobile T-85 and Buick Special, but as an option on the cheaper Pontiac (which otherwise used a four-cylinder engine).
Weighing a total of around 2750lb (1249kg), the 215ci V8-powered compact vehicles were very capable all-rounders and sales were going strong - but there was a crying need for a high performance model. It was Oldsmobile that took the very brave plunge....
Developed in conjunction with AirResearch, Oldsmobile revised the existing 215ci V8 platform to suit the world's first production car turbocharger application. This required revised pistons, conrods, main bearings, distributor, coil, fuel pump and a larger radiator.
The turbocharger selected for the role was a Garrett T5, which is noted for incorporating a neat method of controlling boost pressure to a maximum of 5 psi (35 kPa) - an internal wastegate. The T5 was a relatively small capacity turbocharger capable of generating positive manifold pressure from just 1000 rpm, while maximum boost was attained at 2200 rpm.
To keep the turbo installation simple and to keep the number of unique parts to a minimum, the turbocharger was bolted to the intake manifold in the place usually occupied by a downdraught carburettor. The turbo engine's carburettor was situated prior to the turbo compressor (in a 'suck-through' arrangement) and was a purpose designed single-barrel side-draught unit from Rochester.
One of the primary criteria of the project was to minimise lag and maintain strong off-boost performance - many buyers would be stepping over from large capacity V8s, remember. This meant using a static compression ratio that was (and still is) remarkably high for a force induction engine - the same 10.25:1 CR that was specified in the high output 185hp Cutlass!
But this high compression ratio did create some problems when combined with a turbocharger...
In order to avoid detonation, a 50:50 mix of distilled water and methyl alcohol (aka methanol) had to be injected between the carburettor and turbo at times of high engine load. The fluid was pushed from a reservoir (which was pressurised by the turbo) proportional to boost pressure. It is said that, depending on driving style, the content of this 5-quart (4.7-litre) reservoir could be consumed in anywhere from 2240 to just 224 miles (3600 to 360 kilometres) and was to be refilled only with the premixed 'Turbo Rocket Fluid' available from Oldsmobile dealers. Many owners chose to make their own concoction using plain tap water...
The Turbo Rocket Fluid system was not merely a marketing ploy - it was essential for providing maximum power and ensuring engine longevity. Testament to this, a warning light was triggered when the fluid level in the container got low and, once empty, a valve in the throttle was shut thereby reducing performance. A further safety measure was the fitment of twin wastegate actuator diaphragms (just in case one failed) and the cap on the turbo rocket reservoir functioned as a crude overboost valve - it would pop off the reservoir once a certain boost pressure was exceeded!
Backing the turbocharged aluminium V8 was a standard 3-speed synchromesh manual gearbox, but a 4-speed manual and 3-speed Hydra-Matic automatic transmission were available as options. The transmissions were stronger than those used in 155hp naturally aspired versions and, further back, a "high torque" rear-end was specified.
Outright power was not the goal of Oldsmobile's turbocharging exercise - the aim was to provide the mid-range thrust that previous owners of large cube V8s had enjoyed. As such, peak power rose only 16 percent over the 10.25:1 CR high output version on which it was based - the total output was 215hp (160kW) at 4600 rpm. Peak torque, meanwhile, was boosted by 30 percent over the high output 185hp engine with a massive 300ft-lb (408Nm) at 3200 rpm. Note that more than 280ft-lb (381Nm) was available from just 2000 to 3800 rpm, providing a very 'grunty' driving experience.
The straight-line performance of the turbocharged 2860lb (1298kg) vehicle was unchallenged in its class. Standing starts to 60 mph (96 km/h) took 8.5-seconds in the 4-speed manual vehicle, and its top speed was approaching 110 mph (177 km/h). Aerodynamics was not a strong point. In comparison, the naturally aspirated high output 10.25:1/4-barrel engine took 10.9-seonds to hit 60 mph, while the base 155hp model took a leisurely 14-seconds.
Here is an Oldsmobile Jetfire Turbo Rocket advert from its first year of sales in 1962:
JETFIRE! The hottest new Olds since the high-
Aside from its Turbo Rocket engine, the Olds Jetfire was quite a well-equipped vehicle. Standard features included everything from the high-spec Cutlass including bucket seats, a centre console, DeLuxe armrests, fully carpeted floor and lower door trims, two-tone instrument panel, heater, defroster and a safety padded instrument panel. There was also a boost gauge (with only basic Economy and Power ranges) and a warning light for the Turbo Rocket Fluid level on the centre console.
Externally, the Jetfire Turbo Rocket - available as a hardtop coupe only - featured twin chrome bonnet trims (rather than the single trim on lesser models), a fibreglass packed dual outlet muffler plus exclusive brushed aluminium side trims and 'Rocket' badges. The styling of the car is quite bland, however, when compared to some of the winged creations from just a few years earlier.
At the front, the car was suspended on upper and lower control arms with coil springs and an anti-roll bar, while the rear employed a 4-link coil arrangement with "twin triangle stability" and a live axle. Self-adjusting drums provided braking forces with a 130 square inch (839 square centimetre) lining area, and steering was by way of a recirculating ball set-up. Some vehicles were equipped with optional power steering.
Standard rims were steel 13 x 6.5-inchers wearing 4-ply rayon tyres. Overall on-road handling was regarded as competent at the time, but - from all accounts - appalling in a modern context.
In service, the Oldsmobile Jetfire had its share of reliability and maintenance issues. Its engine was prone to cooling system problems, carbon build up in the combustion chambers (probably due to the relatively crude carburettor fuelling system) and the Turbo Rocket Fluid injection system proved notoriously unreliable. One rumour is that the fluid would seep through the metering valves when the car was shut off overnight and work its way into the combustion chambers; this could lead to a hydrostatic lock and bent conrods when driven the next day.
Further to these problems, many Jetfire owners would let the Turbo Rocket Fluid reservoir run out, complain about a lack of performance and - in some cases - damage the engine. Some of those people that opted to mix their own Rocket Fluid also experienced problems. Making matters worse, it is said that a large portion of Oldsmobile's dealer service network wasn't prepared for the complexities of the Jetfire turbo engine.
Before long, Oldsmobile recognised there were some major problems in the field and backed a scheme where unsatisfied owners could take their car into a local dealer to have the entire turbo system removed and replaced with a conventional 4-barrel carburettor - a stunning move for a car manufacturer!
During its first partial year on the market - 1962 - only 3765 Jetfire units were sold, while in 1963 5842 units were shifted. The average price was kept quite affordable at US$3049 but, still, the model accounted for a very small percentage of Buick, Oldsmobile and Pontiac (aka 'BOP car') compact sales. For 1964, the Jetfire was dropped; the fuel crisis had ended and US car manufacturers could return to their methods of pumping out big cube iron muscle. The world would have to wait nearly ten years for the release of the next production turbocar - the mechanically fuel injected BMW 2002 turbo.
And what happened to the wonderful aluminium 215ci V8 engine? Well - since GM and its American subsidiaries were happy to resume working on big iron V8 engines - the 215ci V8's design, tooling and manufacturing rights were sold to British Leyland (Rover/Jaguar/Triumph). Since then we have seen the same basic engine design progress through many capacities, tunes and power outputs; the original Buick design was employed in the Rover P5, Land/Range Rover, SD1, TR8, MGC, TVR and more. The 'Rover' V8 was also fitted with racing DOHC, 4-valve heads - developed by Repco - and was used to win the 1966 Formula One championship.
And the engine's lineage continued elsewhere...
Buick carried over the fundamentals of the 215ci V8 design to various big bore and stroke iron V8s, as well as venturing to lop off a pair of cylinders to create a 90-degree V6. The first of these cut-down V6s displaced 198ci (3.2-litre), while a revised version was 232ci (3.8-litre) was later devised. Australian Holden Commodore V6 owners should pay attention here because that's the engine you depend upon for day-to-day duties - the 3.8-litre V6 as used in the 1988 VN-onward Commodores. It should come as no surprise, therefore, to learn that certain 'front-end' parts of the old 215 engine are interchangeable or, at least, remarkably similar.
Buick was understating it when they said their new aluminium V8 would be copied for ten years to come - it's still being used (in much chopped-and-changed form) forty years into the future!