U.S. Air Force

There were times when General Motors led the charge.

Images: Dale Jackson and the author

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.

Oldsmobile Jetfire:

Image: the author

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.

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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.

Images: ramsheadcollection.com and bringatrailer.com

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:

Image: the author

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.

Images: automotiveaddicts.com and volocars.com

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…

Image: volocars.com

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.

Author: brrrruno

Car brochure collector, Thai food lover, not a morning person before my first cup of coffee

22 thoughts on “U.S. Air Force”

  1. Good morning, Bruno. I was familiar with these two cars, but not in great detail, so thanks for another school day at DTW. I have an inexplicable liking for the Corvair, so you just made my day.

  2. Good morning Bruno. Like Freerk, I was vaguely aware of these cars but had no idea of the complexities of the engineering of the Jetfire. Whoever came up with the name ‘Turbo Rocket Fluid’ was a genius! That said, Oldsmobile’s free offer to replace the turbochargers with a conventional set-up must gave been one of the most expensive recalls per car ever.

    I’m also a fan of the Corvair, especially in Mk2 coupé form, which looks great:

    The owner of this lovely example is clearly also a fan of the car it was meant to emulate: take a look in the garage.

    1. What a cute dog… Wait, you mean the 911. Sorry, I couldn’t resist 😉

    2. Freerk and Daniel- count me among the society of closet Corvair lovers as well 🙂 Especially the second generation version which I personally count among the best looking cars produced in the USA in the sixties.

  3. At the time the Jetfire was launched, I knew all about supercharging – after all I’d built an Airfix Blower Bentley, and devoured articles on the two-stage supercharged BRM V16 – but turbo chargers were a whole new world. It was the concept of water injection that really floored me though, and this piece tells me more detail than the period Autocar description did.

  4. I’m astonished by the high compression ratio of the Jetfire engine. Then turbo pressure can’t have been too high, even with alcohol injection and the high octane fuel available in the US for some time.

    This was the era of wild turbo experiments – when Porsche tried their first blown 911 six without any pressure regulation they watched the test bench show its maximum readout of 1,000 PS for a couple of seconds before engine and test bench exploded.

    1. Dave, my understanding of the reason for the high compression ratio was that Oldsmobile engineers wanted the engine to have good low throttle torque. It is a well thought out system, but it needed more development. My pet peeve about GM is how rapidly they would launch new technologies, and then give up!

    2. After looking at the illustration of the Jetfire, I wondered if a hot valley would have worked in that era. With a suck thru carburetor.

    3. A CR of more than 11 to 1 would have been exceptionally high even for a naturally aspirated engine.
      That’s a value reached only now on a regular basis made possible by the use of knock detectors and fully computerised engine management.
      And of course a turbo engine with a high geometric CR has good torque but can’t take too much supercharger pressure.

    4. The Jetfire had 10.25:1 compression ratio. This was not an uncommon compression ratio for high performance engines of that era, liquid cooled, using high octane leaded gasoline. Using todays gasoline, compression ratios of 12:1, 13: and even 14:1 are found in common production vehicles. I don’t know of another production vehicle with anti detonation fluid though. They took chances!

  5. That jet plane in the picture is the mighty Convair B58 Hustler, a.k.a. the widow-maker. It was a long range supersonic bomber developed for the US Airforce. The aircraft was very sophisticated for its day with lots of electronic flight control systems on board. An amazing feature was the huge flight envelope. Not only could it go supersonic at altitude, it could also fly fast right down on the deck. This was one of the early adopters of flying low, down as low as possible. The idea was to avoid radar.

    The B58 was a very demanding aircraft to fly. It had unusual stall characteristics and could depart for a variety of reasons including fuel swilling causing excess CoG movement. Because it was fast, things could go wrong fast and if the pilots didn’t keep ahead of the aircraft they were in danger of ending up dead fast. Recovery from a departure was not easy and not always possible. Mistakes were expensive indeed. Keeping the plane serviceable and ready for sortie was expensive indeed. People had to learn about a whole new set of technologies related to synthetic and enhanced control systems. That gaining of experience was expensive indeed. In the end it was the expense and the promise of newer, faster, better performing bombers which ended the reign of the B58 (that and horrible politics).

    The B58 has some interesting features, especially in its control systems. But let’s look at just one of the structural features which make it different. There was a centre-line drop tank. You can see it in the photo. It isn’t just any old conventional drop-tank though. This one had a nuclear warhead within its streamlined shell. The idea was that once the target was reached there was sufficient fuel in the B58’s airframe to return home. Since the drop-tank would be discarded anyway, why not put the warhead in it? Why not indeed? One advantage was that more fuel could be carried inside the plane itself, since all the payload was outside. Range was improved and the drag was reduced for the highest escape speed possible (which you’d definitely want to avail yourself of in order to not be around when the warhead did its thing). Development of the drop-tank continued and it ended up being divided into an upper and lower section- bomb upstairs and fuel downstairs. The two portions could be jettisoned separately. Innovation at work.

    Now there happens to be a connection between this aircraft and the world of automobiles and automobile racing which is not well known.

    There was a keen amateur racer running Jaguar XK120s and 140s in the ’60s. He was Robert Widmer. On one occasion he took his son to the Nassau race meeting. There the young Widmer watched his father, Robert, run one of the Jaguars, but what really caught his eye was the Corvette Grand Sport designed by Zora Duntov. Apparently Robert was impressed with that race car as well.

    Robert Widmer was the designer of the B58 Hustler. He was an exceptional talent – brilliant in aviation engineering. Since he’d designed it, he was offered a flight in a B58 shortly after the Nassau races. He accepted the invitation and was able to enjoy a fast ride at extremely low altitude. His interest in racing cars dimmed after that. In fact it was all but extinguished. He stated that the ride in the B58 Hustler made racing seem pointless…… and slow.

    Meanwhile his son, Widmer the younger, turns out to be none other than the brilliant Larry Widmer. Larry is one of the best cylinder head and engine developer/builders alive. He’s been at the leading edge of race engines since the 1970s. His concept of the “soft head” ushered in the advanced combustion chamber geometries we enjoy presently.

    Larry Widmer never forgot about the Grand Sport. He purchased a replica a few years back and took his father, Robert, for a ride. Robert was impressed and considered that perhaps he’d been premature in abandoning high performance terrestrial vehicles after all. He lived to the grand age of 95. Larry, despite bouts with cancer, is still alive and very active. He is proof that the apple does not fall far from the tree. His expertise in the aerodynamics of internal flows in engines parallels the expertise of his father in external flows around aircraft.

    Re the Corvair air-cooled engine.
    There was a successor in the works. It was designed to overcome all the issues of the Corvair flat-six. For example, this replacement engine avoided the oil leakage problem around the pushrod tubes that the Corvair engine suffered. It was a modular engine which could be made in flat-four, flat-six, flat-eight, flat-ten, flat-twelve and flat-sixteen versions. Apart from some flat-four and flat-six prototypes, a couple of working flat-ten engines were erected and fitted to running vehicles for evaluation. GM did this prototype and research work since they were concerned about the massive sunk cost they had in the air-cooled engine production plant they’d built. They wanted to keep it busy. Alas they chose to ditch their air-cooled developments and build the aluminium Vega engine there in stead. That was the engine they had Cosworth develop for them at great expense. It failed and the plant died. There was, for a brief time, the possibility that the standard GM engine would not be a two-valve single cam-in-block pushrod vee engine but an air cooled flat one instead!

    1. Thank you JT for the fascinating information on the B58 Hustler; I did not know very much about it and frankly chose it for the opening illustration because it is such a good looking airplane. I contemplated using another Convair product, and one of my favorite airplanes, the B36 Peacemaker but couldn’t find a suitable illustration for it. Not a “pretty” airplane by any stretch of the imagination but so menacing. The model kit I made of it hung above my bed for years when I was a kid!

    2. Now that you mention it, Bruno, I built a model kit of the B58 ‘Hustler’ as a youngster. It was made by Monogram (I think), who were an American company and their kits were of considerably higher quality to that of Airfix, Revell et al. (More expensive too) It is a handsome looking aircraft, albeit, looked a bit spindly without its drop tank. The B36 was a monster, a bit like a Superfortress on Steroids. Other Monogram models I recall building included a Porsche 930 Turbo and an American-spec ‘Midnight’ Capri II.

      The background on the B58 was interesting indeed. Thanks JT.

    3. Hello Eòin,
      Monogram definitely made good quality kits, Revell were bit hit and miss and Airfix often required patience, cutting, heating/melting, filing and creativity. Tamiya were the best in my experience (at least among the “mainstream available” manufacturers). Like you, I also built that black Ford Capri once but I blew it up with fireworks -together with a few others- one new years eve….
      To finish and just for fun, we don’t want this to turn into DTB (Driven To Build) or DTF (Driven To Fly), but here is the cockpit of the B36. Imagine sitting there as a novice and the pilot saying “Right, I’m off for a wizz- please keep an eye on these and check for any unusual stuff” 🙂

    4. That’s an impressive cockpit. I was in the cockpit of Concorde once. I won’t post a photo here as I want to keep my DTW membership 😉

  6. Dave

    I’m not so sure about that 911 engine. If I recall correctly, the first time Porsche saw 1,000 bhp or more on their dyno (with a turbocharged engine) it was with twelve cylinders and it was for a variant of the 917.

    1. The engine I meant was a two litre 911 engine. It was the first turbo experiment at Porsche and their reasoning was that the engine needed some kind of pressure regulation.
      The 917-30 turbo, the car that killed CanAm racing, indeed had 1450 PS from 5.4 litres in its latest version. The engine had so much torque they couldn’t use a differential and fitted a rigid rear axle, forcing Mark Donhue to develop a unique cornering technique.
      Conventional wisdom had been that an air cooled car engine could not have more than 800 PS but somebody forgot to tell Ferdinand Piech. In the end the 917 engine needed about 100 PS to drive its cooling fan (via bevel gears).

  7. Hmm. I had a ’66 Turbo Corsa convertible. Typical GM muck. Underdeveloped. The turbo motor ran hot, pushrod tube seals’ life was a few months. Corvair Society of America later came up with teflon, if I recall correctly, seals that lasted much longer. GM didn’t bother trying.

    Thing was, the pushrod tube retainers were held in place by nuts on the head bolts. Undoing the nuts also unscrewed the head bolts, which went straight into the aluminum crank cases. Over time, the bolts fretted in the cases, eventually the threads failed, and after that … Lancia, at least with the Fulvia, put helicoils in the aluminum crankcase. GM, never. I could go on at length with examples of unnecessarily poor design decisions in the second series Corvair.

  8. In the late 1970s and 1980s I owned 2 1963 Jetfire cars and quite a few Corvairs including second gen turbo Corsas. My first Jetfire had been retrofitted with the 4-barrel carb setup and was a low-mileage car. I bought the second Jetfire [a rusty hulk] because it still had the complete turbo set-up, and I ended up transferring the turbo parts over to car #1. No matter what I did to make the car reliable, it ran rough and could be damn near impossible to start when the outside temperatures were above 95f with 95% humidity.

    I found out later that the previous owner had mixed regular methyl alcohol with simple tap water, because the Olds dealer rarely had the bottles of “turbo fluid” in stock. As their home had well water with high levels of iron and calcium, the minerals had clogged the internal passages. I ended up chemically “boiling” the various parts to get them clean. Once that was completed and the carb restored, the car ran like a scalded cat!

    And I love to mention the fact that the 215/3.5 V8 engine, deemed by GM to be a worthless engine for what GM had planned for future cars, was the ONLY 1960s GM engine that, once in Rover’s capable hands, was able to consistently meet US EPA regulations for 60 more years. That sale was likely one of the biggest mistakes GM ever made. The 4-barrel conversion I kept and used on a customer’s 1970 Rover 3.5L.

    I’ve had so many Corvairs it’s had to remember some details for specific cars, but I do know the power difference between the 4-carb 180hp and the turbo engines was not very much. My 1965 turbo Corsa had a 4-speed, but my 1967 turbo ‘vair was fitted with a Powerglide, a VERY rare combination, and that car was always a slacker in acceleration, compared to the 4-speed car. I later discovered the ’67 was a COPO [special-order] vehicle, and only a couple of them were sold.

    I did some track racing for a couple of years, and I preferred the 4-carb & 4-speed Corvair over the Turbo & 4-speed, due to the persistent lag when pressing the go pedal hard. The lag was always different depending on the car’s speed, and trying to plan ahead to compensate for the lag was a pain. My last Corvair was a very late 1967 4-door hardtop with factory A/C and I drove it as my daily driver for a couple of years.

  9. Another school day on DTW. Thanks to Bruno and the commentators.

    And thanks also to Daniel for posting the picture of one of the most beautiful cars from the USandA.

  10. Hi Brrruno

    Your picture looks to be of the flight engineer’s console for the B36. He would have been a busy fellow! If he was lucky his colleague was as sharp as he was. Amongst other things he had to regulate fuel (moving it from tank to tank to help trim the aircraft as it was burned off and the flight profile/mode changed throughout the mission), monitor and control various engine parameters (such as fuel mixtures, temperatures, boost, timing, torque, propeller pitch) and so on. The B36 was hugely complex! It was an all steam-gauge manual control aircraft with a grand total of ten engines, six twenty-eight cylinder radials and four turbo-jets. Hence the descriptor applied to the B36 Peacemaker, “six turning, four burning.”

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