Turbos for the Turnpike: The Turbocharged Oldsmobile F-85 Jetfire


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.

In 1962, Chevrolet and Oldsmobile introduced the world’s first turbocharged production cars, the Oldsmobile F-85 Jetfire and Chevrolet Corvair Monza Spyder. In this installment of Ate Up With Motor, we’ll discuss the origins of turbocharging, the development of the Oldsmobile Jetfire, and the turbocharged Corvair that nearly stole its thunder.

1962 Chevrolet Corvair Monza Spyder 'Turbocharged' fender badge by Aaron Severson



Oldsmobile Looks for More Power from the Rockette V-8

In the late fifties, GM’s mid-price divisions, Buick, Oldsmobile, and Pontiac, developed a new line of “senior compact” cars, which became the 1961–1963 Buick Special/Skylark, Oldsmobile F-85/Cutlass, and Pontiac Tempest/Le Mans. All three cars shared a new unitized “Y-body” shell, which had some structural commonality with the rear-engine Chevrolet Corvair, but with front-mounted engines and a longer 112-inch (2,845-mm) wheelbase. Each car offered a lightweight aluminum V-8 engine (in two distinct versions, discussed in greater detail in the sidebar below).

1961 Oldsmobile F-85 Cutlass coupe (B&W) side - 056073 (General Motors LLC / GMMA 26326)

The 1961 Oldsmobile F-85 was initially available only in four-door form. Club coupes were added as a mid-year introduction, convertibles for 1962. Unlike its Pontiac Tempest cousin, the F-85 had a conventional front-engine/rear-drive powertrain layout, with double wishbone front suspension and a four-link live axle. Other than the aluminum V-8 engine, the chief mechanical novelty was a two-piece driveshaft whose front and rear halves were each angled downward (forming a wide “V” shape) and connected by a constant velocity joint, allowing a smaller, less-intrusive driveshaft tunnel. (Photo: General Motors LLC)

As we’ve previously noted, when the 1961 Buick Special, Oldsmobile F-85, and Pontiac Tempest arrived, they were clearly positioned as economy cars, offered only in four-door sedan and wagon forms. Two-door coupes, fancier trim, and (except for Pontiac) more powerful engine options arrived quite late in the model year, probably as a reaction to the popular new Monza version of the Corvair.

Therefore, it’s somewhat surprising to learn that the possibility of supercharging the Olds F-85’s aluminum “Rockette” V-8 was first broached in the fall of 1959, a full year before the 1961 F-85 went on sale and almost 18 months before the introduction of the sportier F-85 Cutlass coupe. Exactly why Oldsmobile was so interested in extracting more power from the Rockette engine at that stage is no longer entirely clear; Gilbert Burrell, Oldsmobile’s chief engine development engineer, said later that it was a response to an emerging market for sporty compacts, but at the time, the introduction of the Corvair Monza was still months away, and if Oldsmobile anticipated a demand for sportier models, there was no evidence of that in the initial merchandising of the F-85.

The more probable explanation is that Oldsmobile was concerned about the Rockette V-8’s growth potential. The 215 cu. in. (3,528 cc) aluminum V-8 was light and relatively economical, but its compact size left little room for bore and stroke increases, and because Buick supplied the engine blocks, Oldsmobile couldn’t increase the engine’s displacement without Buick’s cooperation. The high-compression Cutlass engine would have an additional 30 gross horsepower (22.4 kW), but most conventional means of increasing horsepower much beyond that level would come at the expense of low-end torque and driveability. In the short term, the Rockette was certainly adequate — even in regular-fuel form, its 155 gross horsepower (115.6 kW) made it one of the most powerful engines in its class — but if that changed, Oldsmobile wouldn’t have many practical options. The Y-body engine compartment was cramped enough that even the compact aluminum V-8 was a tight fit, so installing the division’s larger V-8 would likely have required major surgery.

1962 Oldsmobile F-85 sedan (B&W) engine bay - gm-proving-grounds-archive-images-MPG-5165-0009 (General Motors LLC / GMMA 26326)

Despite its compact exterior dimensions, the aluminum Rockette V-8, photographed in the engine bay of a 1962 F-85 four-door sedan at the GM Proving Grounds on December 26, 1961, was a tight squeeze in the engine bay of the Y-body compact. The label on the radiator bracket, next to the radiator cap, warns of the importance of using only recommended coolants. Early on, Oldsmobile had enormous problems determining which antifreeze formulations were compatible with aluminum engines, and using the wrong coolant could be disastrous, filling the water jacket and radiator core with foamy aluminum sludge one Olds engineer dubbed “frog spit.” (Photo: General Motors LLC)

As Burrell was no doubt aware, the fifties had seen a modest renaissance in mechanical supercharging: using an air compressor to force air and fuel into the cylinders of an engine at higher than atmospheric pressure. Superchargers were popular aftermarket accessories at the time, and Kaiser, Studebaker-Packard, and (briefly) Ford had all offered McCulloch centrifugal superchargers as regular production options. An engine-driven supercharger allowed big increases in power and torque using more or less bolt-on equipment that could be added to an existing engine without too much difficulty. Unfortunately, up to that point, most automotive superchargers had been expensive and rather limited in capability. They were useful in competition, to the extent racing officials were prepared to allow them, but they offered little benefit at lower engine speeds, and driving the impeller off the crankshaft via belts, gears, or chains tended to be noisy as well as consuming a significant amount of power. Their reliability had also left much to be desired, leaving them with a fairly checkered reputation in the U.S.

In considering this, Burrell recalled that the GM Research Laboratories had recently done some experimental work on turbocharging: forced induction using a centrifugal supercharger driven not by the crankshaft, but by the otherwise wasted energy of the engine’s exhaust stream.

Burrell later characterized this research as a single report that had been gathering dust for several years, but in fact a group within the Research Laboratories had recently spent about five years working on turbocharging, beginning in 1954 and continuing into early 1959. Those studies had begun with laboratory simulations and dynamometer testing of single-cylinder test engines, and progressed to include at least one Oldsmobile Rocket V-8 fitted with a turbocharger made by the Schwitzer Corporation (today part of BorgWarner) for diesel engines.

The report to which Burrell referred may have been related to a 1956 presentation by manager of Research Laboratories activities Alfred L. Boegehold, subsequently published in the trade journal Metal Progress, which examined possible directions for future automobile engines, including, among others, turbocharged aluminum Otto-cycle engines, gas turbines, and both two- and four-stroke diesels. That presentation noted that the turbocharged aluminum engine was by far the most efficient of the various engine types in terms of size and weight per horsepower, with only fractionally higher specific fuel consumption (fuel consumed per brake horsepower per hour) than a conventional cast iron engine.

1958 Oldsmobile Super 88 Holiday Coupe front 3q by John Lloyd (CC BY 2.0)

Our information did not indicate the body style of the 1958 Oldsmobile Super 88 in which the Research Laboratories installed their experimental turbocharged engine. (We dimly recall reading years ago that it was a convertible, but we were unable to confirm that point.) This is the two-door hardtop model — Holiday Coupé, in Olds parlance — which combined the shorter 122.5-inch (3,112-mm) wheelbase of the base Dynamic 88 with the more powerful four-barrel V-8 found in the bigger 98. Oldsmobile sold 18,653 Super 88 Holiday Coupés for 1958, a lackluster total in a recession year. (Photo: “1958 Oldsmobile Super 88” by John Lloyd, which is licensed under a Creative Commons Attribution 2.0 Generic (CC BY 2.0) license)

Although Boegehold’s presentation dismissed the idea that turbocharged gasoline engines would be worthwhile for general passenger car use, the Research Laboratories team had continued their work, assembling an experimental turbocharged, fuel-injected 371 cu. in. (6,075 cc) Oldsmobile V-8 engine, which produced 317 hp (236.4 kW) at 4,000 rpm with 5 psi (0.34 bar) boost from a single Schwitzer turbocharger. When finally installed in a car in March 1958, the engine proved powerful enough to catapult the big Oldsmobile Super 88 to 60 mph (97 km/h) in less than 7 seconds and 100 mph (161 km/h) in less than 18 seconds, albeit with significant throttle lag at low speeds. This car was tested throughout 1958, so it seems likely that Burrell would have heard about it even if he didn’t have the opportunity to drive it himself. The Research Laboratories also conducted some experiments involving turbocharged Chevrolet truck engines, using turbochargers supplied by a California company called AiResearch, a division of the Garrett Corporation.

1958 Oldsmobile 371 cu. in. Rocket V-8 engine by Herranderssvensson (CC BY-SA 3.0)

All production 1958 Oldsmobiles had 371 cu. in. (6,075 cc) Rocket V-8 engines with 10.0:1 compression and a choice of two-barrel, four-barrel, or triple two-barrel carburetors. The Research Laboratories’ experimental engine was originally from a 1957 Oldsmobile 98, with 9.5:1 compression, but the original four-barrel carburetor was replaced by an experimental Rochester throttle body fuel injection system, a Schwitzer D4U turbocharger, and water injection, raising output to 317 hp (236.4 kW) at the flywheel — an increase of more than 50 percent from the stock engine. (Photo: “18Aaan17 – Oldsmobile” by Herranderssvensson, which is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0) license; it was resized 2023 by Aaron Severson)

We should emphasize that the Research Laboratories projects had no specific production applications in mind, and the fact that some of those experiments had used Oldsmobile engines didn’t mean that the research was conducted for Oldsmobile, or even with any meaningful divisional involvement. The role of Research Laboratories work was to conduct foundational research in interesting new areas and enable the corporation to stay abreast of noteworthy recent developments, without any particular assumptions about whether or how that research might translate into production.

Blower Background

When the Research Laboratories began that work in the mid-fifties, automotive turbocharging was still largely unexplored territory, although turbocharging (sometimes called “turbo-supercharging”) was already an old idea. A patent filed by Swiss engineer Alfred Büchi (sometimes anglicized as “Buechi”) back in 1905 had proposed combining an exhaust-driven axial turbine, an axial turbo-compressor, and a radial piston engine on a common shaft. From this initial concept, Büchi subsequently developed the now-familiar freewheeling turbo arrangement, with a turbine and centrifugal compressor sharing a common shaft, but with no direct mechanical link to the engine crankshaft. Such a turbo-compressor promised a tidy solution to a problem that had been the downfall of many early attempts to supercharge internal combustion engines: the difficulty of devising a compressor and drive arrangement that would add more power than it consumed.

Although the concept of turbocharging was fundamentally sound, it presented an array of formidable design challenges. The rotating assembly had to be precisely balanced and properly lubricated to allow very high rotational speeds while also keeping the impeller and turbine sides tightly sealed and well insulated from one another — to say nothing of the problem of manufacturing a turbine capable of withstanding exhaust temperatures that in a spark ignition engine could easily exceed the melting point of aluminum.

For those reasons, the most commercially successful early applications of turbocharging were for low-speed diesel engines, whose cooler exhaust temperatures were less of a strain on contemporary metallurgy. In 1919, Büchi succeeded in arranging a deal between SLM (Schweizerische Lokomotiv und Maschinenfabrik, Swiss Locomotive and Machinery Works) and Brown, Boveri & Company to develop his turbo-supercharger designs for large diesel engines. This venture really took off following the introduction of Büchi’s improved “pulse wave” turbocharger design, patented in 1925, which further increased power through better exhaust gas scavenging. By the late thirties, Brown, Boveri & Company was making turbochargers for two- and four-stroke diesel engines with outputs ranging from 150 to 5,500 hp (112 to 4,101 kW), used in locomotives, ships, submarines, and a very wide variety of industrial applications. (The company, which is now called ABB, continued to make turbochargers through 2022, when it spun off that business as a separate company called Accelleron Industries.)

In a 1937 technical review in the Brown, Boveri & Company in-house journal, engineer Emil Klingelfuss confidently predicted that turbo-supercharging would inevitably also find widespread use in aviation, despite the significant additional problems involved in turbocharging high-speed spark ignition engines, with their much higher exhaust temperatures.

Breguet XIV A2 biplane at Musee de l'Air et de l'Espace by Roland Turner (CC BY-SA 2.0)

Adolphe Rateau’s exhaust-driven turbo-compressor, probably the world’s first working turbocharger for a spark ignition engine, was initially tested during World War 1 on a Breguet XIV A2 biplane like this one. (Photo: “Breguet XIV A2, Musee de l’Air et de l’Espace, Le Bourget, Paris.” by Roland Turner, which is licensed under a Creative Commons Attribution-ShareAlike 2.0 Generic (CC BY-SA 2.0) license)

Indeed, by the late thirties, the aircraft turbo-supercharger’s hour was finally approaching after a protracted gestation. Back in 1916, Parisian engineer Auguste Rateau had patented an exhaust-driven turbo-compressor for high-speed aircraft engines, which was built and tested in 1917–1918 on a Breguet XIV A2 reconnaissance aircraft — probably the first working example of a turbocharger for spark ignition engines. Sanford Moss of General Electric (GE) had subsequently developed his own variation on the Rateau turbo-compressor, which was installed on a V-12 Liberty engine and tested on a truck-mounted dynamometer atop Pikes Peak, Colorado, in September and October 1918. However, the practical problems were far from resolved by the time of the armistice, and the lack of suitable high-temperature alloys greatly limited the lifespan of early aircraft turbochargers. Military officials remained ambivalent, preferring crankshaft-driven superchargers (although development of the latter had also been very troublesome). It was not until 1938 that U.S. Army Air Corps brass conceded that the performance benefits of turbocharging, particularly in altitude performance, were worth the bother.

Packard-built, Moss turbocharged Liberty 12 Model A V-12 engine - NASM-A1966004 Open Access image (CC0 1.0)

Produced in large numbers during World War 1, the Liberty-12 engine was a 45-degree V-12, with a displacement of 1,649 cu. in. (27,028 cc) and a dry weight of 844 lb (382.8 kg). This one was built by Packard, whose chief engineer, Jesse G. Vincent, was one of the engine’s chief designers. The experimental turbo-supercharger, developed by Sanford Moss of General Electric based in part on the Rateau turbo-compressor, raised sea level output to 449 hp (334.8 kW). (Photo: “Liberty 12 Model A (Packard), Moss Turbosupercharged, V-12 Engine”, Inventory No. A19660043000, transferred from the U.S. Navy, Naval Supply Center, Cheatham Annex, Williamsburg, Virginia, to the National Air and Space Museum of the Smithsonian Institution (www.si.edu); Open Access image dedicated to the public domain under a CC0 1.0 Universal (CC0 1.0) Public Domain Dedication, resized 2023 by Aaron Severson)

World War 2 saw dramatic improvements in turbocharger technology, thanks in part to the availability of high-cobalt alloys better able to withstand the intense heat of a spark ignition engine’s exhaust gases. The use of turbo-supercharging — often in two-stage installations with separate exhaust-driven and crankshaft-driven compressors — allowed dramatic improvements in takeoff power, speed, and altitude. However, the metallurgical advances that made turbocharged military aircraft engines practical also hastened their end by accelerating the development of gas turbine engines. By war’s end, it was clear that jets would shortly relegate the most powerful aircraft piston engines to second-line duty, if not the scrapyard. At the same time, wartime turbo-superchargers were overkill for civil aviation (turbocharging wouldn’t become popular for light aircraft until the sixties) and were much too big and heavy to be repurposed for auto racing or hot rods.

After the war, turbochargers became increasingly common on smaller diesel engines, like those found in tractors and construction equipment. By the middle of the decade, there was also a growing number of turbocharged diesel engines for large trucks, offered by MAN (Maschinenfabrik Augsburg-Nürnberg, Machine Factory Augsburg-Nuremberg), Volvo, and Cummins.

Cummins had previewed its turbodiesel engine in dramatic fashion by entering a turbodiesel race car, the No. 28 Cummins Diesel Special, in the 1952 Indianapolis 500. The car was powered by an aluminum and magnesium version of the company’s 401 cu. in. (6,570 cc) diesel six, fitted with a Schwitzer-Cummins turbocharger producing up to 20 psi (1.38 bar) boost at 4,300 rpm. Driven by Freddie Agabashian, No. 28 qualified on the pole and set a one-lap speed record of 139.104 mph (223.866 km/h), but turbocharger damage from track debris took the turbodiesel car out of the running on its 71st lap, and rules changes meant that it never raced again.

1952 No. 28 Cummins Diesel Special turbodiesel race car by Jeff Hart (CC BY 2.0)

Developed specifically for the 1952 Indianapolis 500 race, the No. 28 Cummins Diesel Special provided a dramatic preview of the forthcoming Cummins JT-600 turbodiesel engine, which was launched in 1955. Even with an aluminum block, aluminum cylinder head, and magnesium crankshaft, the racing version of the big diesel six still weighed about 750 lb (340 kg), so it was mounted in the body at a 85-degree angle to keep its center of gravity as low as possible. Output was normally quoted as 380 hp (283 kW), but some sources credit the engine with as much as 430 hp (321 kW). For comparison, the production JT-600, which had the same 401 cu. in. (6,570 cc) displacement, was initially rated at 175 hp (130.5 kW). (Photo: “Cummins Engine” by Jeff Hart, which is licensed under a Creative Commons Attribution 2.0 Generic (CC BY 2.0) license)

Turbodiesel light trucks and passenger cars wouldn’t arrive until the seventies, so other than the Cummins Diesel Special, the only notable attempt at automotive turbocharging during this period was an aftermarket kit designed in the late thirties by Ray Besasie of Besasie Engineering in Milwaukee, Wisconsin. First advertised around 1940 and marketed again after World War 2, it produced about 3 psi (0.21 bar) boost at 22,000 to 30,000 rpm, which Besasie claimed was good for a 25 percent increase in engine power. Few were sold, and we’re not sure how durable they were; the Besasie turbocharger was essentially a shade-tree engineering project. Nonetheless, some of Ray Besasie’s family and friends claim that GM engineers consulted with Besasie as part of the corporation’s early turbocharger research.


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  1. Pleased to see this. Impressive, as usual.

  2. 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.

    1. 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.

  3. 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.

    1. 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.)

  4. Aaron,

    Great article as usual! Thanks.

  5. 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.

    1. 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.

      1. 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.

        1. 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.

  6. Marvelous. As usual.

    I am–again–impressed with both your research and your ability to write about it.

    Thank you.

  7. Another great article, and I thank you for it. BMW and SAAB both claiming ‘firsts” annoys me. Once again Detroit doesn’t get it’s due credit

  8. Stellar work Aaron! Thank you very much for the depth and breadth of your research and excellent explanations. I feel blessed to be able to read your work. As a warm up to another comment I might make on the Tempest article, a recycling of ideas I have about GM, don’t feel obliged to read closely.

    I find GM an interesting corporation where short term profit, and lots of it, were so important and yet long term engineering development seems only to apply to the largest and cheapest construction engines and chassis. I like the idea of turbo’s, but both applications seem suspect. The Corvair, with it’s limited cooling ability, is somewhat suspect as a turbo candidate. The Olds, with excellent cooling and a strong enough block is much better. I like the ADI concept, but I don’t understand the requirement for alcohol in the ADI in areas that don’t freeze! Certainly in the summer it’s not freezing anyway. Given the technology they had available, perhaps more development might have reduced the issues, but as a mass market engine the Jetfire seems like a significant misunderstanding of the American motoring public. Of course, that same misunderstanding would occur again with the Vega and its lack of a coolant reservoir…


    1. In principle, if you lived in a climate where it never dropped below freezing, you might have been fine just running distilled water, but even in desert areas, low nighttime temperatures might make that dicey. Also, trying to change the fluid type based on climate seems troublesome: For instance, if you had been running distilled water in the ADI tank, but planned a trip into the mountains to go skiing, how would you get back to a suitable water/alcohol mixture, short of draining the tank and refilling it with the recommended fluid? I’m sure Oldsmobile engineers reviewed some of the extensive wartime data on ADI systems (there were several SAE papers on that subject), which found that a 50/50 water/methanol mix offered better detonation-limited power as well as resistance to freezing, and concluded that would be the best compromise for year-round use.

      I just don’t think ADI is very practical for general-use passenger vehicles. It’s one more maintenance item to keep track of, and it requires too much knowledge for the average owner. If you use it regularly, the added cost of the fluid is a hassle (unless you throw caution to the wind and run distilled water), and using it infrequently increases the risk of something going wrong, even if that just means “not noticing when you finally run the reservoir dry.” I don’t see any real way around that; it’s a conceptual shortcoming rather than a problem of flawed execution (although in this case the execution was a bit flawed as well).

      The Vega’s lack of a coolant reservoir was the opposite problem: It was a disastrous cost-cutting measure that could (and should) have been completely avoided!

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