Motoring Memories: Oldsmobile F 85 Jetfire Turbo motoring memories
1963 Oldsmobile F-85 Jetfire turbo. Click image to enlarge

Story and photo by Bill Vance

Turbocharging has an alluring charm for engineers because it enables the recovery of “free” power from the engine’s exhaust flow: by inserting a gas turbine into the exhaust stream and using it to turn a compressor, the engine can be supercharged with more air than it would breathe normally. And the more air that can be packed into an engine, the more power it produces.

Like so many things automotive, turbocharging has a long history, dating back to the early twentieth century. In 1905 Alfred Buchi, a Swiss engineer, patented an exhaust-driven supercharger for use on a diesel engine. Buchi planned to use pressure as high as 30 pounds per square inch (psi), a high pressure even today.

As 1920 approached, research on turbocharging was also under way in the United States in the hope of maintaining sea-level performance in aircraft engines in the thinner air of high altitudes. Dr. Sanford Moss of the General Electric Co. spearheaded this work, and eventually became known as the “Father of Turbocharging.”

In 1918 Dr. Moss fitted a GE turbo to a V12 Liberty aircraft engine and tested it at Pikes Peak, an altitude of 14,000 feet. At this altitude it developed 230 horsepower in naturally aspirated form, but with the turbo installed the power jumped to 356. It was a dramatic demonstration of the effectiveness of turbocharging.

Turbocharging gradually gained acceptance in aircraft – the turbocharged 1937 Boeing B-17 “Flying Fortress” bomber was a landmark – and really flowered during the Second World War. They were also used in heavy-duty engine applications, and by the 1950s turbos were becoming popular on line-haul diesel trucks. Turbos were also used in a few automobile racing engines, but it wasn’t until 1962 that they found their way onto production passenger cars.

Oldsmobile pioneered the use of turbochargers in production cars with the introduction of the 1962 F-85 Jetfire Sport Coupe in April of that year. It beat Chevrolet’s turbocharged Corvair Monza Spyder to market by about a month.

The F-85 had been introduced as a trim and attractive compact Oldsmobile in 1961, powered by an overhead valve, 3.5-litre aluminum V-8 that developed 155 horsepower. For 1962 an optional 185-horsepower version of the same engine was offered, although still naturally aspirated.

But the bigger news for 1962 was the addition of an even hotter version, the turbocharged “Turbo-Rocket” engine, which brought the horsepower up to 215, or the then-vaunted one horsepower per cubic inch. The engineers had done their homework in an attempt to make the turbo installation durable and trouble-free. To counteract detonation, or pinging, with the high 10.25:1 compression ratio, a fluid injection system was fitted. This device, commonly known as water injection, used a mixture of half water and half methyl alcohol carried in an underhood reservoir. The fluid was injected into the intake manifold when maximum power was called for, and the rate of use varied with the heaviness of the driver’s foot. Under easy driving one might get up to 3200 km (2000 miles) out of a litre; a hot rodder could use it all in 360 km (200 miles).

The internal components of the engine, such as pistons and bearings, were strengthened to withstand the higher operating pressures due to turbocharging. A larger radiator was also fitted. In the further interest of engine durability, maximum turbo boost pressure was limited to a conservative five psi.

The Jetfire proved much quicker than the normally aspirated models. The zero to 96 km/h (60 mph) acceleration time dropped from 10.9 seconds in the 185 horsepower model (it was 14.0 for the 155 horsepower) to a very respectable 8.5, as reported by Car Life magazine’s testers (5/62). The Jetfire’s zero to 80 mph time was improved to 16.4 seconds from the 185′s 20.2.

The Jetfire was engineered more for mid-range passing and hill climbing performance than for high speed. Thus its top speed was only 5 km/h (3 mph) higher – 172 km/h (107 mph) compared with 167 (104). This was mostly because boost was reduced to four psi above 121 km/h (75 mph).

Alas, GM’s brave experiment didn’t last long. In an era of cheap gasoline, there wasn’t much incentive for powerplant innovation. More power was easier and less expensive to obtain with a bigger, thirstier engine. And if there is one thing Detroit really knew, it was how to turn out millions of huge V8s.

Oldsmobile offered the turbo engine for just two model years, producing a total of 9607 of them. Chevrolet would carry on with its turbo until 1966, by which time its air-cooled flat-six was developing 180 horsepower from 2.7 litres. Turbocharging then disappeared from the automobile scene until 1975 when Porsche introduced it on its evergreen 911 sports car. Saab followed in 1977 with its turbocharged Saab 99.

General Motors got back into turbos in 1978. This time it was in response to fuel economy concerns; Buick was seeking eight-cylinder performance from a six-cylinder engine. Turbochargers went on to enjoy wide use in the 1980s and they are still being used, particularly on diesel engines for which they are especially well suited.

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