In 1962 and 1963, Oldsmobile offered a short-lived turbocharged version of the compact F-85. Called F-85 Jetfire, it used a high-compression aluminum V-8 engine with a complex, troublesome fluid injection system. Chevrolet also developed a simpler turbocharger installation for the air-cooled flat-six engine of the rear-engined Corvair. The Corvair offered turbocharged engines from 1962 to 1966.
Turbocharged and Trouble Prone
By most accounts, the principal service complaints about the Oldsmobile F-85 Jetfire involved running out of antidetonant fluid and complaining that the engine suddenly lost power, which was easily rectified, but spoke to the dubious wisdom of using the fluid injection system in the first place. As an ultra-performance option on a fuel-injected Corvette or other high-performance sports car, it might have added to the mystique, but Oldsmobile had been clear the Jetfire wasn’t supposed to be that kind of car. Fluid injection was just too much hassle for a softly sprung compact sedan that wasn’t ultimately that much quicker than a regular four-barrel Cutlass or Buick Skylark.
Even for owners who understood how it worked, the ADI system was a frequent source of headaches. It could leak at various points, and even if there was fluid in the reservoir, various maladies could leave you without boost: a clogged fluid filter, a stuck check ball, a blocked valve, or a broken or defective pressure cap. Also, the depressure valve didn’t always do its job, which could have expensive consequences if the engine were shut off with the fluid reservoir still pressurized; Oldsmobile issued a service bulletin in June 1964 calling for the installation of a more effective external depressurization valve.
There were other weaknesses as well. Oiling was marginal for a turbocharged engine, which depended on oil flow for cooling as well as lubrication. The shaft seals didn’t always do a great job of keeping contaminants out of the shaft housing between the compressor and turbine housings, and on startup, it could take a while for engine oil to reach the turbocharger shaft. Inadequate oil flow, oil contamination, infrequent use, and disuse could all take a toll on the shaft bearings, which were designed to float on a film of oil while spinning both on the shaft and in their housings. Also, like many early turbo engines, a combination of localized high temperatures and inadequate oil circulation could cause coking, where thermal breakdown of the oil produced carbon deposits in high-temperature areas. Moreover, even the normally aspirated aluminum V-8 was still not the world’s most reliable engine, particularly with regard to cooling. In that regard, the Jetfire’s higher-capacity radiator gave it at least a slight advantage over a standard F-85 or Cutlass, although coolant aeration was still a common problem, and using an incompatible antifreeze could raise all kinds of hell.
It undoubtedly didn’t help that Oldsmobile dealer service technicians weren’t necessarily any more familiar with the Turbo-Rocket engine than were Jetfire buyers. Although the Jetfire went on sale in April 1962, the factory didn’t get around to publishing a service manual supplement describing the turbocharger, fluid injection system, and Model RC carburetor until June.
Missteps like that make it easier to understand why Oldsmobile’s eventual response to many Jetfire problems was to simply remove all the turbocharger equipment and install the standard Cutlass manifolds and four-barrel carburetor — a blow to historians, but a pragmatic solution that involved only a modest sacrifice of performance. (At least a few of those cars have since reacquired turbochargers in collector hands.)
A Limited Engagement
The F-85 Jetfire was a late introduction for 1962, so production was limited, with only 3,765 units built. It returned for 1963, restyled, like the rest of the F-85, with somewhat blockier lines and larger dimensions, though it still looked a lot like a scaled-down Starfire. The 4-inch (101.6-mm) increase in overall length and 2.1-inch (53.4-mm) increase in overall width added about 70 lb (32 kg) to the curb weight, but the only mechanical changes of any note were the use of an alternator rather than the previous generator and newly optional 14-inch wheels with 6.50-14 tires. The latter didn’t do much for handling or braking grip, but increased the Jetfire’s somewhat precarious tire capacity by a useful 180 lb (81.7 kg). List price for the 1963 F-85 Jetfire dropped by $1, to $3,048.
Sales of the turbocharged Corvair were significantly better: The Spyder option was specified by 9,468 buyers in 1962 and 19,099 in 1963. The Monza Spyder returned for 1964, promoted from option package to model series, and sold a further 10,962 units before first-generation Corvair production came to an end in mid-1964. By that time, Corvair sales were starting to skid as buyers interested in compact sporty cars turned their attention to the new Ford Mustang, a trend the attractive second-generation Corvair, introduced for 1965, failed to reverse. However, 39,529 cars in two and a half years wasn’t bad for an expensive and high-strung package that, unlike the Jetfire, wasn’t available with automatic transmission.
1963 was the best year for Y-body F-85 sales, which reached 121,879 units, up 25 percent from 1962. The Cutlass, which now boasted 195 gross horsepower (145.4 kW) with Hydra-Matic, was the bestseller of the line, accounting for 53,492 units. However, Jetfire sales weren’t much greater than in the abbreviated 1962 season, totaling just 5,842 units.
The F-85 Jetfire is often characterized as a commercial debacle, but we’re not sure how many cars Olds could have built if demand had been greater. Oldsmobile didn’t represent the Jetfire as a limited edition, but we suspect that turbocharger availability effectively made it one. The AiResearch Industrial Division had built just 22,000 turbochargers between 1955 and 1960, and in 1965, after the Olds deal had wound down, the division’s total turbocharger production (for all applications) was only about 3,000 units a month, which would have supplied only a modest fraction of F-85 production.
Admittedly, with only 9,607 cars sold in a year and a half, the Jetfire would probably have been considered a sales disappointment even if the target had been only 10,000 units a year. On the other hand, the Jetfire did have considerable publicity value, and it brought Oldsmobile more attention from the enthusiast press than the division had gotten in years, so it wasn’t a total rout.
AiResearch likely didn’t make much of a profit from the Jetfire project, as Wilton Parker had feared, but the indirect benefits of the Olds deal were substantial. Aside from providing valuable experience in dealing with Detroit, the cost analysis GM had funded, which Parker said Garrett probably wouldn’t have undertaken otherwise, enabled the division to completely overhaul its accounting practices and implement much more effective cost controls, which would make AiResearch significantly more competitive in the turbocharging renaissance to come.
From Turbocharger to Turnpike Cruiser
Whatever the pros and cons of the Oldsmobile Turbo-Rocket engine, it’s very likely that the F-85 Jetfire and its turbocharged aluminum V-8 were actually doomed from the start. By the time the Jetfire made its public debut in April 1962, the Y-body senior compacts were already slated to be replaced by the bigger body-on-frame A-body intermediates, and the aluminum V-8’s days were numbered (at least in the U.S.). The lightweight V-8 had proven to be vastly more expensive than originally anticipated, and while some of the early production problems had been resolved, it remained a source of warranty and service headaches, even without the turbocharger and ADI system. Worse, from Oldsmobile’s perspective, the aluminum V-8 was still fundamentally a Buick engine, which meant less control and higher costs. By mid-1962, Oldsmobile engineers were hard at work on the “654” engine, an in-house design that was to power the second-generation F-85 and Cutlass.
All versions of the aluminum V-8 were dropped at the end of the 1963 model year, although Buick continued to produce the 90-degree Fireball V-6, which was a bored-and-stroked six-cylinder derivative of the small V-8, using thinwall iron castings rather than aluminum. Both Buick and Oldsmobile would offer the 90-degree V-6, bored and stroked to 225 cu. in. (3,692 cc), as the base engine for their cheapest models in 1964 and 1965; Oldsmobile then switched to the 250 cu. in. (4,095 cc) Chevrolet six, but Buick continued to use the V-6 through 1967, after which the engine and its tooling were sold to Kaiser Jeep. The divisions parted ways on V-8s: For 1964, Buick replaced the 215 cu. in. (3,528 cc) aluminum engine with a new iron-block 300 cu. in. (4,923 cc) V-8, essentially an eight-cylinder version of the cast iron V-6, while Oldsmobile offered its new cast iron V-8, initially displacing 330 cu. in. (5,404 cc).
Although Olds advertised it as the “Jetfire Rocket V-8,” the new Oldsmobile 330 had little in common with the turbocharged aluminum engine other than the number of cylinders. Constrained by the need to share basic tooling and transfer equipment with Oldsmobile’s “big” Rocket V-8, the 330 was essentially a modernized version of that engine; a tall-deck version of the 330, code-named the “657” engine during development and initially offered in 400 cu. in. (6,548 cc) and 425 cu. in. (6,946 cc) versions, would replace the “big” Rocket engine for 1965. Somewhat ironically, the 654 and 657 engines adopted a modified wedge combustion chamber layout similar to the “slanted saucer” chamber design of the Buick 215, which Oldsmobile had eschewed for its version of the aluminum V-8. Unlike Buick’s iron-block 300, which took advantage of the latest “thinwall” casting techniques and consequently was one of the lightest cast iron engines in Detroit, Oldsmobile made only limited use of hot box core casting for the new engine, which made it substantially heavier than the aluminum Rockette V-8. The new engines were much cheaper than the aluminum Rockette V-8, however, and had better breathing and features like a forged crankshaft. Even the regular-fuel two-barrel 330 was nearly as powerful as the outgoing Turbo-Rocket, with a gross output of 210 hp and 325 lb-ft of torque (equivalent to about 156.6 kW and 440.6 N-m).
Writing in Motor Trend in December 1963, Roger Huntington suggested hopefully that a turbocharged version of the 330 might soon follow, but it was not to be. The considerations that had led Oldsmobile to develop the Turbo-Rocket engine no longer existed: Oldsmobile now had its own modern V-8 with plenty of growth potential, and the new A-body could accommodate any version of that engine the division cared to offer, limited only by corporate policy (and the subsequent Hurst/Olds demonstrated that there were ways around that as well). Oldsmobile could have turbocharged those engines, or for that matter the 90-degree V-6, but there was longer any no compelling reason to do so.
So far as Oldsmobile was concerned, we think the spiritual successor of the F-85 Jetfire was RPO L66, the Turnpike Cruising Option offered on the 1967 Oldsmobile Cutlass Supreme. Listing for $142.18 (plus an extra $236.97 for the mandatory Turbo Hydra-Matic transmission), it featured a special version of the tall-deck 400 cu. in. (6,548 cc) V-8, with a high-compression head, dual exhausts, a two-throat carburetor, a 2.56:1 axle ratio, and a short-duration camshaft (using the same valve timing as the base 330 cu. in. (5,404 cc) engine, but with more lift). While one might balk at the idea that the normally aspirated Turnpike Cruising package was any kind of successor to the old turbocharged Jetfire engine, the design objectives were quite similar: deemphasizing peak horsepower in favor of plentiful torque at the lower engine speeds used in daily driving, in pursuit of that elusive combination of performance and fuel economy.
The sleepy cam limited the big engine’s gross output to 300 hp (223.7 kW), nothing special for an American car in 1967 and actually 10 to 20 horsepower less than the standard 330 cu. in. (5,404 cc) Cutlass Supreme engine, but gross torque was 425 lb-ft (576.2 N-m) at 2,600 rpm, with over 90 percent of that available from as low as 1,200 rpm. Of course, the RPO L66 engine had no turbocharger or fluid injection, but it had its own trick engine air-induction system, “Climatic Combustion Control,” which enclosed the carburetor and air cleaner in a temperature-controlled tub for more consistent fuel metering.
A Cutlass Supreme with the Turnpike Cruising Option matched the old F-85 Jetfire in acceleration, and its 16 to 19 mpg (12.4 to 14.7 L/100 km) fuel economy was at least as good if not better, despite the substantially greater engine displacement and over 700 lb (317 kg) of additional curb weight. The hefty lump of iron under the hood meant weight distribution was an unimpressive 57/43, but the Turnpike Cruising package included all the 4-4-2 chassis equipment, with stiffer springs and shocks and both front and rear anti-roll bars, so an L66 Cutlass Supreme handled better than its turbocharged predecessor did, and the optional front disc brakes provided much more dependable stopping power.
For all its virtues, the Turnpike Cruising package was too esoteric for most buyers in 1967, too much of an engineer’s car. It didn’t have the raw horsepower needed to attract Supercar-hungry Baby Boomers, and the prospect of up to 19 mpg (12.4 L/100 km) on the highway — on leaded premium — wasn’t likely to dissuade anyone from buying a Volkswagen or Datsun. The L66 package lasted only a single year, although Oldsmobile subsequently applied its basic principles to the rest of the line, which was more than could be said for the Turbo-Rocket engine in the F-85 Jetfire.
The End of One Turbocharged Era and the Beginning of Another
At Chevrolet, the turbocharged Corvair returned for an encore among the all-new 1965 models. The turbo engine was now an option on the new top-of-the-line Corsa series, using the same TRW turbocharger as the outgoing Spyder, but with wilder valve timing and other minor changes. Chevrolet now claimed 180 gross horsepower and 265 lb-ft of torque (134.2 kW and 359.2 N-m), although this still seemed a little anemic when even the most basic two-barrel 289 cu. in. (4,728) V-8 offered on the Ford Mustang boasted 200 hp (147.1 kW).
The Corsa sold only 28,644 units for 1965, of which only 7,206 had the turbocharged engine, and an additional 10,472 units for 1966, of which just 1,951 were turbocharged. Both the Corsa series and the turbo engine were dropped for 1967. Chevrolet would experiment with turbocharging on and off through the seventies, but Chevrolet wouldn’t offer another turbocharged gasoline engine as a regular production option until 1980.
Around the same time the second-generation Corvair debuted, the International Harvester Company introduced an optional turbocharger for the 4-152 (2,488 cc) Comanche slant four that powered the International Harvester Scout. The Thompson turbo increased the four’s output from 93.4 hp to 111.3 hp (69.6 to 83.0 kW), although low-speed response was sluggish despite a seemingly respectable rated torque output of 166.5 lb-ft (225.7 N-m) at 3,200 rpm. Few 4-152T engines were sold, and International discontinued the option in 1967 in favor of a less-troublesome normally aspirated 196 cu. in. (3,203 cc) slant four and an available 266 cu. in. (4,355 cc) V-8.
An observer in 1967 might well have concluded that automotive turbocharging was merely a fad that had run its course, but in fact it was gearing up for Round Two.
By the late sixties, turbocharging was beginning to find wider acceptance for racing use. The first Offenhauser turbos arrived for 1968, and in 1969, BMW entered a turbocharged version of its 2002 sedan in European Touring Car Challenge (ETCC) competition. In 1972, Porsche launched its first turbocharged competition engine, for the 12-cylinder 917, and the following autumn, the 1973 Frankfurt auto show saw the debut of a limited-production BMW 2002 Turbo for the street. (Many sources, including BMW, continue to erroneously assert that the rare 2002 Turbo was the first turbocharged production car, but the Corvair Monza Spyder and F-85 Jetfire beat it to market by over a decade and outsold it by a substantial margin, although the 2002 Turbo was never officially exported to the U.S.). The turbocharged 2002 was short-lived, but it was followed in 1975 by the first Porsche 911 Turbo (930), whose turbocharged 2,994 cc (183 cu. in.) flat-six made it one of the fastest and hairiest production cars of its era.
Perhaps the most important turbocharging-related developments of this period, however, came in 1978, and reflected the more immediate automotive preoccupations of the day: exhaust emissions and fuel economy. 1978 saw the introduction of the Mercedes-Benz 300SD, the world’s first production turbodiesel passenger car; the Saab 99 Turbo, which combined turbocharging and Bosch K-Jetronic fuel injection with a three-way catalytic converter and feedback control, perhaps the two most vitally important advances in reconciling emissions performance and driveability; and the first Buick production cars powered by the turbocharged version of the division’s reborn 90-degree V-6. (All of these cars, it’s worth noting, used AiResearch turbochargers, as did the subsequent turbocharged versions of the Ford Lima four.)
Development of the Buick turbo V-6 had begun in the fall of 1975, less than 18 months after GM had arranged to buy back the tooling for the old V-6. As we’ve previously recounted, less than three years after Kaiser Jeep bought the V-6 engine, it became one of the assets included in the sale of Jeep to American Motors, which had no need for the 90-degree V-6 and sold the tooling back to GM in 1974. Buick almost immediately put the V-6 back into production, boring it to 231 cu. in. (3,791 cc), and the reborn “3.8 Litre” V-6 quickly became one of GM’s most important corporate engines: a compact, relatively lightweight six offering acceptable power and decent fuel economy. Turbocharging was intended to improve the former quality without compromising the latter, helping Buick to meet the new federal Corporate Average Fuel Economy (CAFE) requirements that took effect for 1978.
In turbocharging the 90-degree V-6, Buick engineer Tom Wallace essentially combined the better features of the old F-85 Jetfire and Corvair Spyder engines. Like the Olds Turbo-Rocket V-8 (of which the V-6 was a first cousin), the turbo V-6 had a mild cam profile and a small wastegate-controlled turbocharger (with a 2.56-inch (65-mm) turbine driving a 2.36-inch (60-mm) impeller), designed to minimize turbo lag and reach peak boost as early as possible. Like the Spyder engine, the Buick turbo used the same relatively low compression ratio as the normally aspirated base engine (8.0:1) and relied on spark management rather than fluid injection to prevent detonation, although the electronic spark control system and electromagnetic knock sensor were considerably more sophisticated than the boost-controlled spark advance unit in the Spyder. (Buick later added an intercooler, but not until 1986.)
Even with its new split-pin “Even Fire” crankshaft, the Buick turbo V-6 was not nearly as smooth as its departed Oldsmobile cousin, but net output was similar: 150 hp (111.9 kW) and 245 lb-ft (332.2 N-m) of torque with a two-barrel carburetor, 165 hp (123.0 kW) and 265 lb-ft (359.3 N-m) with a four-barrel, not bad for 1978. Rated at 19 to 21 mpg (11.2 to 12.4 L/100 km) on the old EPA combined scale, depending on model, turbocharged Buicks were thriftier than the long-departed Olds Turnpike Cruising package and, unlike the Jetfire and Spyder, could run on 91 RON (87 pump octane) regular gasoline. The turbo V-6 wasn’t perfect, but it worked well enough to enjoy a 10-year career under Buick hoods, with a spectacular send-off in the form of the Regal GNX.
These were just the first rumblings of the avalanche of turbocharged cars to come. Not all were successful, and the popularity of turbocharging (at least for gasoline engines) waxed and waned over the next 30 years, but turbos never entirely went away, and each resurgence brought worthwhile improvements. (In the eighties and nineties, there was also a minor renaissance in crankshaft-driven supercharging, in larger part as a response to the limitations of contemporary turbochargers.)
Today, approximately one-third of all new passenger cars and light trucks sold in the U.S. are turbocharged. Automotive water injection systems have popped up now and then as well: Throughout the eighties, Saab offered a dealer-installed kit for its turbo engines, which was standard equipment on a few limited-edition models, and in 2016 Bosch announced its new “WaterBoost” system, which made its production debut on the GTS version of the previous-generation (F82) BMW M4. Fluid injection has some potential emissions benefits (reduced carbon dioxide and nitrogen oxide emissions) as well as from preventing detonation in high-performance applications, but the inconvenience of needing to regularly replenish an additional fluid supply means that such systems are likely to remain specialist equipment. (Most modern turbocharged gasoline engines use direct fuel injection, whose charge-cooling effect helps to reduce knock even with surprisingly high compression ratios.)
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Pleased to see this. Impressive, as usual.
There may have been an antidetonant for other applications at the time. If so, I’m betting that the manufacturer never explicitly marketed it to Jetfire owners.
I’m not sure if Thompson was still selling Vitane by this point, but it wouldn’t have been ideal for the Turbo-Rocket V-8 anyway. At any rate, Oldsmobile literature most emphatically discouraged using substitute fluids, which was understandable, since using a different fluid risked either diminishing the effectiveness of the system or risking it freezing in cold weather.
There were a number of technical papers published toward the end of WW2 summing up wartime experience and best practices with regard to fluid injection, which I suspect the engineers at Oldsmobile (or perhaps Rochester, who designed the final injection system) read and took to heart, as they followed those recommendations quite assiduously.
I remember reading that the F85 – in its earliest development stage – was to have a transverse 60 degree V6, and an automatic transaxle that used the hardware from the Roto-5 automatic but with three chains to connect engine to gearbox to wheels. It was killed early in the development stage – due to cost, of course – but we did get something useful from that project. The 60 degree V6 developed by Olds engineers sat on the shelf until the late 1970s when a narrow V6 was needed for the upcoming X car. The Olds design was handed to Chevrolet to get them started and then they finalized the engine for production. But if you look carefully at the 2.8/3.1 V6 from the early 80s, you can see details in the block – notably timing chain area – that look a lot like the small block Olds V8. In fact, it looks a lot more like an Olds motor than a Chevy.
What hit the showrooms in late 1960 was fairly conventional, but looking at the MSRP that would be in the high $20k in 2023 dollars, there wasn’t much engineering magic they could include without pricing the car out of the market or losing a lot of money on every one they sell.
It’s true that Oldsmobile did experiments with FWD for a car the size of the F-85, but the timetable makes it unlikely it would have been for 1961. The first FWD test mule wasn’t built until early 1960, when the initial production F-85 was very close to pre-production. At that point, the FWD project was at a rather nascent stage (the test mule weighed about 600 lb more than a RWD F-85, the chain drive was still quite crude, they were still evaluating whether they needed two CV joints per side, and I think it was using pieces of an older four-speed Hydra-Matic), so even if the division had been enthusiastic and corporate management had signed off on it for production, I think it would likely have been for a second-generation F-85. There simply wouldn’t have been time to get it into producible shape for 1961.
(There is some confusion on the timeline, stemming in part from the fact that both Oldsmobile Advanced Design Group and the corporate Engineering Staff were working on the project concurrently in different ways. (Oldsmobile asked Engineering Staff to develop a gear-drive transfer unit, which involved a Buick Dual Path Turbine Drive two-speed automatic.) However, Andy Watt, who was head of Advanced, said unequivocally that until early 1960, Oldsmobile FWD prototype development was still only at the stationary test rig stage.)
I have seen Oldsmobile engineers attribute the Chevrolet 2.8-liter V-6 to the abortive Oldsmobile FWD project. However, I’m very skeptical of the idea that it “sat on the shelf” until the seventies or that an almost 20-year-old design for an unproduced Oldsmobile experimental engine would be “handed” to Chevrolet. Weird things happen sometimes, so I suppose it’s not outside the realm of possibility, but it seems more like a piece of internal folklore born of old divisional rivalries. I’ve never found any substantive details about the V-6 used in the FWD mules (neither the SAE paper nor the GM Engineering Journal articles about Oldsmobile FWD development even mention its displacement), and since that engine never got close to production, it’s not a claim that seems particularly verifiable. Also, the “small block” Oldsmobile V-8 — by which I assume you mean the 330/350/307 rather than the aluminum Rockette engine — didn’t yet exist as such in 1960 (the bulk of its initial development was in 1962 and early 1963), although it’s possible that the experimental V-6 previewed certain details later used on that engine. To the extent that the 2.8-liter V-6 looks “like an Olds motor,” it seems more plausible that the source of inspiration was the smaller Oldsmobile V-8, which WAS a production engine, and a very familiar one by the time the FWD X-body cars were in development.
(At a glance, the most obvious resemblance between the 2.8-liter V-6 and the Oldsmobile V-8 is the way the block forms a kind of integral shroud for the timing chain. Oldsmobile said they did that because they wanted to be able to use a flat timing chain cover, while Chevrolet’s explanation was that it allowed them to avoid using a steel backing plate for the cam drive.)
Great article as usual! Thanks.
Not only did turbocharged Corvairs have a cylinder head temperature gauge, there was also an under-dash buzzer that alarmed if the head temp get too high. I’ve read that Chevrolet engineers were worried about sustained high loads like pulling a trailer or climbing a long, steep mountain pass and wanted an audible alarm to get the driver’s attention to back off the throttle.
Some of the period testers noted that while there was a cylinder head temperature gauge, the gauge didn’t provide any specific indication of how high was too high, so supplementing it with a buzzer was prudent. That notwithstanding, adding the new instruments rather than simply an amber “HEAD TEMP” light in the existing panel was a worthwhile move, and suggested that despite the comparative simplicity of the Spyder package, Chevrolet engineers had a clearer idea of its potential market and what those buyers might want.
I think it had all three: a gauge, an idiot light, and a buzzer. I’ve never driven a Corvair turbo but I’ve had several Corvairs and all had a combination head temp/oil pressure idiot light. As far as I know the turbo kept that and added the gauge and buzzer.
Your extensive follow up on later turbocharged cars was fascinating, especially the point about Porsche not producing a 911 turbo until 1975, 13 years after the Corvair turbo. It seems as if the Corvair wasn’t so much a poor man’s Porsche, rather, the 911 turbo should rightly be considered a rich man’s Spyder.
Porsche’s 1978 SAE paper on their turbocharging development makes clear that they were aware of the Spyder and Jetfire (as one would expect), but were not terribly familiar with them, asserting, for example, that they were made only in 1964 and 1965.
At any rate, what’s distinct about how Porsche approached turbocharging was that it was an offshoot of their racing efforts; their first turbocharged 917 was for the 1972–73 Can-Am series, and the development of the 930 and 935 followed that. Competition has shaped a lot of automotive turbocharging development, and so it’s notable that it WASN’T a factor in the creation of the Jetfire or Spyder. Oldsmobile didn’t develop the Jetfire as an homologation special, and while Chevrolet created the Spyder in large part to try to bolster the credibility of the Corvair Monza as a sporty car, it was neither developed for or as a street version of any racing project.
Marvelous. As usual.
I am–again–impressed with both your research and your ability to write about it.