By M. Park Hunter
Photos by the author

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This article originally appeared in the April 1996 issue of Special Interest Autos. Call 800/CAR-HERE (ext. 550) for subscription information.

Turbo before its time

Oldsmobile has always been a technology leader among the General Motors divisions. Hydra-Matic automatic transmissions in 1940, overhead valve V-8s in 1949 and the front-wheel-drive Toronado in 1966 are the most obvious examples.

There's another high-tech Oldsmobile few people remember: the 1962 Oldsmobile Jetfire. Externally, the Jetfire looked like a gussied-up compact car. Under the hood, though, the Jetfire boasted technical specifications many modern sportscars could envy. A turbocharged, fluid injected, small-displacement aluminum V-8 provided the heart and soul of this junior road rocket.

The Jetfire was based on the compact Oldsmobile F-85 introduced in 1961. The F-85, along with Buick's Special and Pontiac's Tempest, was one of GM's second generation compacts. These cars were similar to the Corvair platform, but redesigned for conventional front-engine layouts. Befitting their status as luxury compacts, the Buick and Oldsmobile shared a new aluminum V-8 with only 215 cubic inches of displacement.

This engine was introduced with a two-barrel carburetor and produced 155 hp. Compact cars were not exempt from the horsepower race, though, so for 1962 a power-pack was available which added a four-barrel carburetor and raised compression from 8.8:1 to 10.25:1. In this trim, the little V-8 put out 185 hp. That was still not enough for Oldsmobile engineers.

To extract even more gusto from their little engine would have meant playing with cam timing or compression, which would have affected the smooth-running characteristics of the V-8. Increasing displacement, the other option for more power, would add weight. And in any case, fuel economy would suffer. Oldsmobile chose a more radical route: turbocharging.

Thus, the Jetfire shares the distinction of being America's first mass-produced turbocharged car with the Chevrolet Corvair. Both cars could claim an honest one horsepower per cubic inch (145 for the Corvair, 215 for the Jetfire), but the approach they took was quite different.

The heart of a turbocharger consists of a single moving part, a shaft with turbine impellers at each end. Exhaust pressure is directed against one impeller, causing it to spin. The impeller at the other end of the shaft draws air in and flings it centrifugally into the engine's intake manifold, increasing the air pressure and providing more oxygen for combustion.

The Corvair turbo capitalized on this simplicity. However, without providing a mechanism to limit the turbo's boost, Chevrolet engineers were forced to lower their engine's compression ratio to prevent detonation. The Corvair turbo engine packed a wallop at high rpm, but felt anemic at lower speeds and suffered from a long lag before the power kicked in.

Oldsmobile's approach was much more sophisticated. Gilbert Burrell, Oldsmobile's head engine designer, explained the philosophy in a May 1962 Road & Track article on the new turbochargers:

"A turbo-supercharger unit of approximately the same physical outside dimensions {as the production unit} could have been designed that would have resulted in much higher high-speed power output, but this would not have given the tremendous torque increase in the mid-speed or normal driving range. We wanted a hot-performing street job, not a high speed race car."

Burrell researched previous turbocharger applications and found that aircraft turbochargers were fitted with wastegates, pressure valves which bled off exhaust gases to limit boost. Burrell also knew that a smaller diameter turbine would weigh less and thus react more quickly and spin faster.

Burrell worked with Garrett AiResearch, a manufacturer of industrial turbochargers, to develop these ideas. Designer Gibson Butler and tester Jim Buckley spent a lot of time polishing the details. By combining a small diameter turbo (the compressor impeller is 2.5 inches in diameter, the exhaust impeller just 2.4 inches) with a poppet valve wastegate, Oldsmobile's team achieved their goals.

The Jetfire turbocharger developed boost as low as 1000 engine rpm and gained a torque advantage over the unblown V-8 at only 1200 rpm. Maximum boost pressure of about 5 pounds per square inch (psi) was reached at 2200 rpm and was then limited by the wastegate from going any higher. In contrast, the Corvair turbo didn't produce 5 psi until 3100 engine rpm and hit its maximum of 11 psi at 4500 rpm.

In operation, Oldsmobile's tiny turbo could spin as fast as 90,000 rpm (reached at 4000 engine rpm) and accelerate to that speed almost as rapidly as the engine required. Chevrolet's somewhat larger turbo maxed out at 70,000 rpm and took a noticeable amount of time to rev up. Previous supercharger turbines, which were usually 6-7 inches in diameter, had topped out at only 36,000 rpm and weren't expected to react quickly to throttle input.

Such high speeds placed great stress on the turbine impellers, plus the exhaust side had to endure temperatures up to 1450 degrees Fahrenheit. Oldsmobile used some sophisticated materials engineering to handle this punishment. The exhaust impeller and shaft were made out of super-hard Haynes Stellite steel. The aluminum intake impeller was then pressed onto the shaft and the whole assembly was precision balanced.

The exhaust turbine housing was made out of ductile iron to keep it from warping at high temperatures. The center housing was cast of grey iron to reduce heat transfer to the intake side, and the intake housing was aluminum for weight savings. The impeller shaft rode in two aluminum alloy bearings mounted in the center housing and lubricated by the engine's pressurized oil system. The bearings spun both on the shaft and in their housings, saving wear by letting them rotate at only about half the turbine's speed.

The turbocharger mounted on the intake manifold where the carburetor normally squatted. A single-barrel side draft carburetor designed specifically for the Jetfire by GM's Rochester carburetor division hung off the turbocharger's side. The entire installation weighed 36 lbs.

To maintain fuel economy and low-end engine performance, Oldsmobile engineers kept the engine's compression ratio at 10.25:1, same as the four-barrel carbureted version. Even though maximum boost was limited, there were still potential problems with detonation which could quickly destroy the engine.

This was solved by adding a fluid injection system. A tank of "Turbo-Rocket Fluid" (a 50-50 mix of water and alcohol with some rust inhibitor added) was mounted under the hood. When the turbocharger operated, it also pressurized this tank and caused a small amount of the fluid to be injected into the intake between the carburetor and the turbocharger. The fluid evaporated, absorbing heat from the intake air and preventing detonation.

Oldsmobile was famous for conservative engineering, and the Jetfire turbocharger installation was no exception. A warning light informed the driver when the Turbo-Rocket fluid ran low. If it was allowed to run out, a butterfly valve in the throttle body closed to prevent full-power acceleration. The wastegate was operated by two diaphragms in case one failed. Even if that happened, the cap on the Turbo-Rocket fluid tank would pop off to prevent overboost. And if boost pressure was still too high, the butterfly valve would again shut down the party. One Olds engineer told Car and Driver, "It's 'safetied' to death."

Engines intended for turbocharging were slightly revised versions of the 185-hp V-8s. The pistons were redesigned, main-bearing caps were built for heavier loads, and heavy-duty aluminum alloy was used for all bearing inserts. The intake valves were aluminum coated, and the distributor and coil were revised for higher voltage. Oldsmobile also fitted all Jetfires with bigger radiators and reinforced transmissions.

All this work paid off with a 30 hp boost over the 185-hp power-pack option and a massive 70 lb.-ft. improvement in maximum torque (to 301 lb.-ft.). Better yet, torque was over 280 lb.-ft. from 2000 to 3800 engine rpm, smack in the range most drivers used. Car Life tests showed the Jetfire could turn 0-60 times of 8.5 seconds, versus 10.9 seconds for the 185 hp F-85 Cutlass. They also reported the Jetfire was almost 10 seconds faster to 100 mph.

To distinguish the Jetfire from lesser F-85 siblings, Oldsmobile gave the car special aluminum side trim and two chrome spears on the hood instead of the usual one. A new Jetfire logo incorporating a rocket ship was pasted on the front fenders and trunk lid. Although a single exhaust pipe left the turbo outlet, after the muffler it split out into twin outlets.

Inside, the center console held a "Turbo Charger" gauge with a needle swinging into either economy or power ranges as manifold pressure varied. This gauge had no numbers marked on it and was roundly criticized by testers as poorly positioned and useless. The "Add Fluid" warning light for the Turbo-Rocket Fluid reservoir was incorporated into the bottom of the boost gauge.

The publicity dividend reaped by Oldsmobile from the Jetfire was amazing. Car magazines from Hot Rod to Road & Track flocked to test the Jetfire. Generally, they raved about its performance and hailed the turbo as the wave of the future. Even Motor Trend, which tested a Jetfire in September 1962 and was less impressed, was back in April the next year with an article on circumventing the turbo's safeties for more performance.

Unfortunately, the Jetfire was short-lived. After selling 3765 of them in 1962 and 5842 in 1963 (4% and 5% of F-85 production, respectively), Oldsmobile pulled the plug for '64. Most experts cite mechanical problems with the fluid injection, but there were other reasons as well.

As with any new technology, the turbocharger had teething problems. Bruce Sweeter is an expert on the Jetfire who owns four of the cars and sells parts to other collectors. He believes the problems were "fifty-fifty caused by people and mechanical problems."

"People would let them run out of fluid," Sweeter says, "then complain about the performance." On the mechanical side, he says gaskets and diaphragms leaked. There were enough complaints the factory sponsored a recall.

"In '65 they offered to convert people's turbos over to four-barrel carbs for free. They did a really good job and changed everything over," says Sweeter. New intake and exhaust manifolds, a new distributor and a new vacuum advance were all part of the package. Dealers even took out the Turbo-Rocket Fluid tank.

The Jetfires shared some other weaknesses with other F-85s. The engine suffered from cooling problems which were sometimes blamed on aluminum chips left from the casting process getting lodged in the radiator. Sweeter says the Jetfire used a larger crossflow-type radiator which helped this problem somewhat. Antifreeze occasionally reacted with the aluminum block, too.

In the driveline, the automatic transmission could get out of adjustment and shift harshly. The driveshafts were another weak link. Sweeter knows a friend who drives his car hard and always carries a spare driveshaft in the trunk.

Are these problems why Olds dropped the turbo after only two years? Sweeter disagrees.

"I don't think it was reliability," he says. "{The Jetfires} were probably ahead of their time. They were small, they were neat, but people were looking for power and cubic inches."

Ford's medium-size Fairlane was a big success in '62 and '63. For 1964, Oldsmobile radically changed the F-85 series to move into the Fairlane's market. Gone were the little unibodies and pocket rocket turbo engines. In their place was a intermediate car with body-on-frame construction. The technological tour-de-force of turbocharging was discarded in favor of brute size. As the top model, the Jetfire disappeared and was replaced by Oldsmobile's soon-to-be famous 4-4-2 package packing a hairy 330 cubic inch, 310 horsepower V-8.

Driving impressions

Our test car is owner Joe Lezza's second Jetfire. His bought his first one as a used car in 1967 while dating the woman who would eventually become his wife. He enjoyed the sporty little coupe, but had to sell it after a year when he joined the military.

Fast forward to 1993: Lezza, now married and with a young son, was going to car shows with his family. He started thinking it would be nice to have a car of his own to take to the shows. His wife, remembering the car they courted in, suggested he get another Jetfire.

Lezza took his time, looking for a nice example. Finally, at an Oldsmobile show in Somerset, New Jersey, he met a Jetfire owner who suggested he call Greg Hurley. Hurley, whose family collects Oldsmobiles, was thinking about selling a red Jetfire similar to Lezza's first car.

Hurley had purchased the car from its original owner, Raymond German of Illinois. German had purchased the car in early 1963 and drove it until 1985, pampering it and keeping it garaged during the winters. German sent Hurley a letter in 1980 (which Lezza now has) detailing the very few changes he'd made over the years: three sets of spark plugs, three mufflers, one new exhaust pipe, a new thermostat, and new Goodyear tires.

It was obvious German had cared for the car and taken pride in it. Hurley felt the same way. Lezza says, "He and I went back and forth for six months. I think he wanted to sell the car, but to someone who really wanted to own it."

Finally, in February 1994 the deal was made. Lezza and his young son Joey flew up to Rochester, New York. They rented a big U-Haul truck and brought the Jetfire home to New Jersey. Lezza has since put on a set of original shock absorbers and some chrome tailpipe tips. At just under 46,000 miles, the engine, transmission and turbo still do their jobs flawlessly.

Lezza has an entire spare engine which carries the Jetfire's "J" code on the block and "T" code on the heads. He also has four used turbos with the side draft carburetors still attached and one NOS turbocharger. Lezza is particularly glad to have the extra carburetors. He says, "There's a better chance of finding a turbo than the carb."

Lezza drives the Jetfire about once a week if the weather is nice. He enjoys taking it to car shows. Nine-year-old Joey has developed an interest in the car. Father and son are fanatical about keeping the Oldsmobile polished.

For Lezza, the Jetfire's appeal is nostalgic. For Joey, the best part of the shows is "all the the compliments we get on the car." He drops his chin and does a little-boy growl to imitate a typical car show spectator: "Ain't many of these around anymore!"

Out of respect to the Jetfire's age and originality, Lezza has never pushed the car to its limits. As I get behind the wheel, he encourages me to drive briskly but asks me not to "floor it."

The bucket seats are comfortable and the cockpit is easy to settle in. This is obviously a compact car, but the hardtop styling gives the cabin an airy feel. The speedometer is right in front of me and easy to read through the steering wheel. When I start the car, suddenly it seems much newer than its thirty years would indicate. The exhaust note of the aluminum V-8 has a metallic bark rather like a modern GM performance V-6.

We cruise smoothly out to highway 36, where I dip into the throttle a bit more. Off-the-line performance doesn't sock me into my seat, but the small-displacement V-8 revs like a weed whacker and the rasping exhaust note is soon joined by the shrill whistle of the turbo. There is no flat spot in the acceleration; it feels like it will keep building until the engine spins apart. The mid-range and high end are where this car exults.

The transmission also reminds me of modern GM products. It shifts with that peculiar hesitation inherent to every GM automatic I've ever driven. Upshifts seems to take a half second or so and are accompanied by a smooth surge. It's not unpleasant, just peculiarly GM. I've been in 1960 Impalas and 1987 Trans Ams that shifted the same way.

In action, the chrome shift lever feels tall and imprecise. I have to wobble it a bit to make sure I'm in gear. The boost gauge is mounted too low to use while driving, but it isn't indexed to provide any specific information anyway. The turbo's whistle is an audible indicator of its operation.

Steering is as good as any early '60s automobile. There's some lean in corners, enough to remind you that this is a compact coupe and not a true sports car. Otherwise, the handling is tight. The brakes are also more than adequate to the demands of in-town driving. I don't know how they would hold up under continuous high-speed use.

In traffic, the size of this car feels quite contemporary. It's not a land barge in the traditional American sense. Lezza tells me many people think the Jetfire is just a few years old. Driving it, I also feel like GM could have built this car yesterday. If this was my father's Oldsmobile, today's struggling division could benefit by making new cars a bit more like it.

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Heavy breathing

Most people assume that turbochargers and superchargers are two different animals. In reality, the turbocharger is just a special type of supercharger. According to HPBooks Auto Dictionary, a supercharger is a "Compressor which pumps air into an engine's induction system at higher than atmospheric pressure." How it manages this trick is another story.

The first supercharger was probably fitted to a Chadwick in 1908 by hill-climber and race driver Willie Haupt. By pumping more air into the combustion chambers, Haupt hoped to overcome the six-cylinder Chadwick's poor breathing, allowing it to burn more fuel and produce more power.

Other companies picked up where Haupt left off. American companies such as Auburn-Cord-Duesenberg and Franklin experimented with supercharging in the '30s. Mercedes had spectacular success with supercharged racing and sports cars around this same time. In the '50s, both Kaiser and Ford would supercharge some engines, and Studebaker picked up the idea in the '60s.

Mechanically driven by belt, chain or gear, however, the supercharger has a serious drawback: friction. According to Car Life's May 1962 technical assessment the typical automotive supercharger sapped 10-15 bhp to pump all that air whether the extra boost was needed or not. This partially offset the power gain from supercharging and hurt fuel economy across the board.

One solution was to steal the supercharger's power source from otherwise untapped energy blowing out the exhaust pipe. A turbine could use the waste heat and pressure of exhaust gas to drive a supercharger with only a 4-5 bhp drain on the engine.

This approach, pioneered by Packard engineer Jesse Vincent way back in 1918 on Liberty aircraft engines, was common on World War II fighter planes and postwar industrial engines. General Motors engineers were the first to seriously consider adapting a exhaust-powered supercharger to the varying demands of automotive use.

A turbine-driven supercharger has another significant advantage. Unlike mechanically-driven versions, it is self-regulating. As an engine produces more power, it pumps more exhaust and the turbine spins faster. Best of all, when demand for power is low, the turbine and supercharger naturally idle along, using minimal power.

The proper name for a turbine-driven supercharger is "turbo-supercharger." In popular use the name was quickly abbreviated to turbocharger. Whatever the name, the idea is still with us. When engineers in the '80s wanted to increase power without hurting fuel economy too much, the turbocharger saw resurgent popularity.

The second life of a GM V-8

Even though GM stopped building the aluminum 215 cubic inch V-8 in 1963, it has enjoyed a long career across the Atlantic. In the mid-'60s, the British Rover corporation was looking to increase exports. J. Bruce McWilliams, the head of Rover's American operation, believed a more powerful engine was needed to compete in American markets. Rover gave him the okay to look at American V-8s in January of 1964.

McWilliams first looked at Chrysler powerplants, then discovered the Buick-Oldsmobile engine. The small aluminum engine would fit easily into British cars designed for lighter, smaller powerplants than most American cast-iron designs.

With help from Rover's William Martin-Hurst, McWilliams aggressively courted GM until they agreed to sell the design. In January 1965, Rover acquired rights to the V-8 and GM shipped the original drawings, some leftover tooling, and production information across the Atlantic. GM also let Joe Turley, Buick's head engine designer who was nearing retirement, move to England as a consultant.

Turley's input was important: GM production changes to the engine necessary to make it more reliable were not reflected in the drawings. Also, English manufacturers didn't have the technology to die cast the block with cast iron cylinder linings in place as GM had done. Rover finally found a supplier who could sand cast the blocks. The iron sleeves were then pressed into place.

Rover topped the engine with a new manifold supporting two SU carburetors. Lucas designed its first V-8 distributor for Rover's new engine, and a British-made oil pump was fitted. New pistons completed the makeover. Cam blanks, timing chains and gears, and hydraulic tappets were (and still are) supplied from the U.S.

The Rover-ized V-8 debuted in 1965 in the old Rover P5 sedan, which was renamed the Rover 3.5 litre after its new engine. Since then, versions of the engine have appeared in the MGB GT V-8, MG RV-8, Triumph TR-8, Rover 3500, TVR Chimera, and various Morgan specials. Heavily modified, the old GM design is again for sale in the United States installed in Land Rovers and Range Rovers.

While Rover was adapting the design to its production cars, the 215 V-8 enjoyed a brief moment of glory in motorsports. Several racers used the light engine to power cars, and one of these specials became the first McClaren race car. In 1966, Jack Brabham won the world Formula 1 championship driving another car using an Oldsmobile block heavily modified by Britain's Repco auto company.

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Unfortunately, image quality is currently limited by my hardware. These pictures may be updated with higher resolution and greater color clarity in the future...
Compact dimensions gave the Jetfire more room to play on the road.
The Jetfire was based on the standard F-85, but carried distinctive trim including the twin chrome hood spears.
Sharp contours in the sides carried a subtle thrust theme. The styling doesn't look that out-of-date today.
The dash layout carried over from the F-85. Gauges and controls were placed logically and comfortably.
The turbo gauge was mounted in the center console ahead of the transmission selector. Basically a vacuum gauge, its two vague readings were "economy" and "power."
The turbo setup bolted in place of the standard carburetor. From front to back in this picture: the aircleaner, special Rochester carburetor, intake impeller and exhaust impeller.
Adding "Turbo-Rocket Fluid" to the underhood tank was a regular maintenance chore. Owners who neglected this suffered a loss of power and risked toasting their engine.

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1962 Oldsmobile Jetfire
Front-engine, rear-drive hardtop coupe
Base price$3049
TypeTurbocharged OHV aluminum V-8
Bore x stroke3.50 in. x 2.80 in.
Displacement215 cu. in.
Compression ratio10.25:1
Compression pressure140 psi
CarburetorSingle one-barrel side-draft Rochester
Power215 bhp at 4600 rpm
Torque300 lb.-ft. at 3200 rpm
Valve liftersHydraulic
Main bearings5
Fuel systemVacuum pump, camshaft driven
Exhaust systemSingle with dual outlets
TypeGarret AiResearch
Compressor impeller diameter2.5 in.
Turbine impeller diameter2.4 in.
Idle and cruising speed6,000 to 50,000 rpm
Full throttle50,000 to 90,000 rpm
Maximum boost5 psi
Boost limiterpoppet exhaust-bypass valve
Anti-detonant system50/50 water-alcohol fluid injection
Weight of turbocharger/carburetor assembly36 lb.
Type12-volt coil
Point gap.016 in.
Timing5 degrees BTDC
Spark plug type46FF
Spark plug gap.035 in.
Type3-speed Hydra-Matic automatic
Transmission gearGear ratio (:1)
1st 3.03
2nd 1.58
3rd 1.00
TypeHypoid, semi-floating
Ratio (:1)3.36
TypeRotary valve (torsion bar) type power
Turns lock-to-lock4.75
Turning circle37.1 ft.
TypeHydraulic, cast-iron drums
Drum diameter9.5 in.
Effective area127 sq. in.
Body constructionUnitized, welded steel
Body styleTwo-door hardtop
FrontIndependent coil springs, upper and lower control arms, double-acting tube shocks and anti-roll bar
RearLive axle, coil springs and control links, double-acting tube shocks
Tire size6.50x13 4-ply rayon
WheelsSteel disc, 4 lug
Wheelbase112.0 in.
Length188.2 in.
Width71.6 in.
Height52.3 in.
Frontal area20.8 sq. ft.
Ground clearance5.5 in.
Tread (f/r)56.0/56.0 in.
Weight2860 lbs.
Weight distribution (f/r)54/46%
Head room (f/r)38.8/36.6 in.
Shoulder room (f/r)55.2/53.2 in.
Hip room (f/r)58.4/51.6 in.
Leg room (f/r)43.9/36.3 in.
Knee room (r)23.9 in.
Trunk capacity13.5 cu. ft.
Cooling system (with heater)12.5 qt.
Engine oil5.0 qt.
Fuel tank16.0 gal.
Fluid injection (Turbo-Rocket Fluid) tank5.0 qt.
Transmission12.0 pt.
Rear axle2.5 pt.
Horsepower per c.i.d.1.0
Weight per bhp14.7 lb.
Weight per c.i.d.13.3 lb.
Stroke/bore ratio.80
Engine revs per mile2860
Piston travel1335 ft./mile
0-30 mph2.9 sec.
0-60 mph8.5 sec.
0-100 mph28.2 sec.
Top speed107 mph
Quarter mile16.5 sec. at 80 mph
Fuel consumption14.1 mpg
Car and Driver (6/62), Car Life (5/62), Motor Trend (9/62), Today's Motor Sports (6/62), Chilton's Auto Repair Manual 1954-1963, Joe Lezza (owner)

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MPH -- 62 Jetfire/M. Park Hunter/park@mphinteractive.net/October 1996

Copyright 1996 M. Park Hunter. This page and its contents written, photographed, designed, slaved over, etc. by the author. Please do not copy anything without my permission.

Reset May 20, 1997.