In the mid-1950s, American automakers were engaged in a ferocious horsepower race. By the time the battle reached a temporary ceasefire at decade’s end, the average power of the typical passenger car had (at least on paper) more than doubled. The starting gun of that race was sounded by Oldsmobile, with its advanced new overhead-valve V8 and the new mid-size model that shared its name: the 1949-1950 Oldsmobile Rocket 88.
OLDS VS. CADILLAC
Oldsmobile’s first postwar engine was born during the UAW strike that shut down GM production from November 1945 through March 1946. During that period, Oldsmobile Motor Group draftsman Gilbert Burrell began working privately on concepts for new cars and new engines. This was not an official assignment; he was simply exploring ideas for his own interest and amusement. Burrell examined a wide range of configurations, but the one to which he continually returned was a 90-degree V8, which he judged as offering the best compromise between power potential and physical size.
About six weeks after he started work, Burrell showed his designs to Oldsmobile’s chief engineer Jack Wolfram and Oldsmobile general manager Sherrod Skinner. Deciding Burrell’s ideas had promise, Wolfram and Skinner organized a new advance design group to develop a new overhead-valve (OHV) V8 engine and assigned Burrell to lead it. That July, Burrell was promoted to chief motor engineer for the division.
Coincidentally, Cadillac had been working since 1936 on a very similar OHV engine to replace its familiar monoblock flathead V8. It’s unclear at what point Oldsmobile engineers became aware of the Cadillac engine or how much they knew about it. Olds veterans later told Helen Jones Earley and James Walkinshaw that the Burrell group was completely unaware of the Cadillac project until quite late in the development of the Oldsmobile V8. However, former Cadillac Harry Barr, who led the development of Cadillac’s first OHV V8, later claimed that Charles L. McCuen, then GM’s vice president of engineering (and the former general manager of Oldsmobile) had ordered Cadillac chief engineer Jack Gordon to show Cadillac’s OHV design to Oldsmobile carburetor engineer Tony Wauters. Barr believed the Oldsmobile engine was a direct derivative of Cadillac’s design, although he conceded that Cadillac also benefited from some of Oldsmobile’s work.
Since the advance design group envisioned a 1949 introduction for their new engine, the project was dubbed SV-49. The prototypes, which first ran in November 1946, were 287 cu. in. (4,705 cc) and were designed to take advantage of research that had been done by GM Research VP Charles Kettering on high-compression engines (of which we’ll have more to say below).
Around the end of that year, the project nearly ground to a halt due to objections from Cadillac. Although Oldsmobile (as well as Buick and Pontiac) had used eight-cylinder engines for more than a decade, Cadillac was not happy about the idea of Oldsmobile offering an OHV V8 and convinced corporate management to deny Oldsmobile’s request for development funds. Skinner and Wolfram tried again in March 1947, having decided that alternative engine configurations were impractical, and this time managed to secure production approval from GM president Charles E. Wilson.
Because the high-octane fuels necessary to take advantage of really high compression ratios were not yet available, Burrell ordered the displacement of the production engine (known internally as 8-90) increased to 303.7 cu. in. (4,977 cc). Road tests were conducted later that year and the new V8 went into production a few days before Christmas 1948. The V8 was standard in the new 1949 Oldsmobile 98, replacing the old 257 cu. in. (4,214 cc) L-head straight eight.
FLATHEADS, OVERHEAD VALVES, AND HIGH COMPRESSION
The Cadillac and Oldsmobile V8s represented the start of several major trends in American engine design. Let’s briefly examine each of them.
Prior to the advent of the 1949 Cadillac and Olds engines, many (though by no means all) U.S. engines were L-head, or side-valve, design. As the diagram below illustrates, an L-head engine has its valves in the side(s) of the block. The cylinder head is little more than a cover for the top of the cylinder, which is why L-head engines are commonly called flatheads.
Flathead engines are easy and cheap to manufacture, but they leave a lot to be desired when it comes to performance. First, their volumetric efficiency is poor. Internal combustion engines are essentially air pumps, so their power depends greatly on how much air-fuel mixture can flow into the cylinders to burn. In a flathead engine, the air-fuel mixture has to go around several corners to make its way into the combustion chamber and burned exhaust gases have a similarly circuitous route out of the cylinders. In short, the flathead’s “breathing” ability is only mediocre.
Second, the combustion chambers of a flathead engine have a lot of surface area; more surface area means more opportunities for the heat of combustion to escape (which engineers call heat rejection) before it’s had the chance to do any useful work. A flathead engine, therefore, also has poor thermal efficiency. These limitations hurt both power and fuel economy. The shape of a flathead’s combustion chambers also limits its maximum compression ratio (the amount the fuel mixture is compressed before burning).
To mitigate these problems, both Oldsmobile and Cadillac adopted an overhead-valve (OHV) layout. In an OHV engine, the valves are placed directly above the combustion chamber, which greatly improves breathing. The placement of the valves also means that the combustion chamber has a smaller surface area and thus greater thermal efficiency — some 20% better than a comparable flathead. OHV engines can also support much higher compression ratios.
The difficulty presented by an OHV layout is finding a way to operate the valves. In a flathead engine, the camshaft is in the block, driven directly by the engine’s crankshaft. Since the valves of a flathead are also in the block, the camshaft can actuate the valves directly by simply pushing them up and down. In an OHV engine, by contrast, the valves are a fair distance away from the crankshaft, which makes operating them far more complicated. Many modern engines deal with this problem by placing the camshaft in the cylinder head along with the valves (an overhead cam (OHC) engine), but there still has to be some way for the crank to drive the camshaft. Both of the practical options available in the 1930s and 1940s — a train of gears or a metal chain drive — were complex, expensive, and noisy.
A cheaper solution (pioneered by Buick back in the days before General Motors was formed) was to leave the camshaft in the block, as in a flathead engine, but add long metal pushrods to allow the camshaft to actuate the valves remotely. A pushrod layout is more expensive than a flathead’s valve gear and the extra mass of pushrods and rocker arms hurts mechanical efficiency. Nonetheless, both Oldsmobile and Cadillac deemed it a good compromise. Other American manufacturers would reach the same conclusion.
Until well into the 1950s, most engines were undersquare, with a narrow cylinder bore and a long piston stroke. A long piston stroke gives more torque, which means better engine response at low speeds. Unfortunately, it also creates more friction and means that the average piston speeds are very high, particularly at high RPM, which is detrimental to engine longevity.
By contrast, both the Cadillac and Oldsmobile V8s were oversquare, with a wide bore and a short stroke. The short stroke allowed the engine to rev more freely while the wider bore provides more room for larger valves, which further improves breathing.
Both the Cadillac and Oldsmobile design teams were strongly influenced by the work of GM research chief “Boss” Charles Kettering, who had been working on high-compression engines since the end of World War I. An engine’s static compression ratio is the ratio of the swept volume of each cylinder to the volume of the combustion chamber; the higher the ratio, the more the engine compresses its fuel mixture before combustion. Raising an engine’s compression ratio allows the engine to extract more energy from the fuel it burns, improving both power and fuel economy.
The desire to raise compression ratios had prompted Kettering and his staff to develop tetraethyl lead as an octane-boosting gasoline additive in the early twenties (as discussed in greater detail in our article on the 1970½-1981 Chevrolet Camaro), but the research staff had their work in hopes of raising compression ratios even higher. Shortly after the war, Kettering’s engineers built an experimental 181 cu. in. (2,969 cc) six with a compression ratio of 12.5:1, where most contemporary engines has ratios of no more than 7.0:1. Kettering’s team demonstrated that the higher compression ratio boosted power and gas mileage by nearly 30%.
Naturally, GM was extremely interested in the potential of high-compression engines for passenger cars, but there were two hold-ups. The first was that Kettering’s engine required fuel with a considerably higher octane rating than any contemporary pump gasoline; better fuel economy was hardly useful if you could only fill up at airports. The second issue was that the practical limit for L-head engines was a compression ratio of about 7.0:1; above that threshold, it became difficult to control combustion roughness. (We should note, however, that Packard’s final L-head eight of 1954 used an 8.7:1 compression ratio with no apparent loss of refinement, although the fact that the 359 cu. in. (5,880 cc) engine was a massive straight eight with nine main bearings may have played a role in that!) Overhead valves did not suffer the same problem, which gave them the potential for much higher compression ratios.
Neither of GM’s new OHV V8s had an exceptionally high compression ratio at first — Oldsmobile’s was 7.25:1, Cadillac’s 7.5:1 — but that was mostly a reflection of the low octane of the gasoline of the time. Most commonly available premium fuels had an octane rating of only 80 RON, not nearly enough for the ultra-high compression ratios Kettering proposed. GM embarked on a vigorous campaign to persuade the major oil companies to offer higher-octane premium gasoline for civilian use. (This can’t be viewed as an entirely altruistic effort, since GM still owned a major stake in the Ethyl Corporation, the principle producer of the tetraethyl lead additive that was the primary octane booster used in contemporary gasoline.) If better fuels became available, both the Cadillac and Olds engines had the theoretical potential for compression ratios as high as 12:1.
THE ROCKET V8
Oldsmobile’s first OHV V8, dubbed the “Rocket” engine, had a 3.75-inch (95.3mm) bore and a 3.44-inch (87.3mm) stroke, compared to 3.25 inches (82.6mm) and 3.88 inches (98.4mm) respectively for the straight eight the Rocket replaced. The OHV V8 was still a large engine externally, but it was shorter and lower than the straight eight and weighed quite a bit less. The new V8 was also more powerful: Rated output climbed from 110 to 135 gross horsepower (82 to 101 kW) while torque increased from 213 to 283 lb-ft (289 to 383 N-m), allowing an Oldsmobile 98 with Hydra-Matic to reach 60 mph (97 km/h) in a brisk (for 1949) 13.5 seconds, with a top speed of 96 mph (155 km/h). The icing on the cake was that fuel consumption was reduced by about 10% compared to the old L-head engine.
The new V8 was designed with plenty of extra room in the block for future displacement increases, but Gilbert Burrell and his team actually hoped that Oldsmobile could return to the 287 cu. in. (4,705 cc) displacement of the original prototypes once higher-octane fuels became widely available, raising compression ratios to maintain the same output with lower fuel consumption. That never happened; by the fifties, the industry was far more interested in advertised horsepower than gas mileage. The Rocket would only get bigger, not smaller.
THE OLDSMOBILE ROCKET 88
As mentioned earlier, the Rocket V8 was initially offered only in Oldsmobile’s flagship 98, a big luxury car that gave away little to Cadillac in size or appointments. The development testing, however, had been done using the smaller B-body Olds 78 as a test mule. The B-body Oldsmobiles rode a 6-inch (152mm) shorter wheelbase and were 11 inches (279 mm) shorter and 3.6 inches (91mm) narrower than the C-body 98 and weighed 250 pounds (227 kg) less. The Rocket-powered 98 was already a very respectable performer, so installing the new engine in the lighter body made for quite a hot number.
Oldsmobile’s engineering staff already knew what the Rocket could do in the B-body cars and there was no question that it fit, so Harold Metzel, then Oldsmobile’s chief transmission engineer, asked Sherry Skinner if Oldsmobile could offer that combination in production. Skinner liked the idea, but it had to be approved by corporate management, which brought a new round of objection from Cadillac — the 98 was already a close match for Cadillac in performance and V8-powered B-body Oldsmobile would undoubtedly be faster. The top brass equivocated, but Skinner finally got the green light. The new, mid-sized Oldsmobile Rocket 88 went on sale February 6, exactly seven weeks after the 98.
Like the test mules, the Rocket 88 was, in the parlance of a somewhat later era, a real bomb. Even with the standard Hydra-Matic transmission, the 88 was capable of 0-60 mph (0-97 km/h) in a bit over 12 seconds and could reach an absolute top speed of 97 mph (156 km/h). Some competitors were a bit faster all-out and a few could beat the Olds off the line, but the 88 was one of the fastest cars in America in 1949. The Rocket 88 would vacuum the chrome off V8 Fords (unless the Ford’s owner had made a substantial investment in aftermarket parts) and it took a semi-exotic like the new Jaguar XK-120 to soundly beat the Olds.
Although Oldsmobile’s official involvement in racing was limited, the Rocket 88 promptly proceded to clean up in competition. NASCAR held nine Grand National races in 1949, of which stock Rocket 88s won six. The following year, 88s won 10 out of 19 Grand National races and set a new speed record at Daytona. An 88 also won the first grueling Carrera Panamericana, the 2,176-mile (3,500-km) Mexican Road Race. (Ten of the 13 88s that entered that race managed to finish, itself an impressive feat.) More-or-less stock Rocket 88s continued winning their classes at the drag strip well into the 1950s.
If anyone at GM had had doubts about offering the big engine in the smaller body, the sales alone would have been enough to convince them. Total Oldsmobile sales for the 1949 model year, including exports and Canadian production, were almost 294,000, a 64% improvement from the year before. Of those sales, 100,273 were the Rocket 88.
Inevitably, the 88 overshadowed Oldsmobile’s cheaper 76, which still used a 257 cu. in. (4,213 cc) L-head six. Any interest in better fuel economy was quickly forgotten; gasoline was cheap and speed sold more cars than parsimony. The 76 lingered for one more model year and then was dropped entirely; the division wouldn’t offer a six again until 1964.
Cadillac’s OHV V8, released around the same time as the new Oldsmobiles, was itself an important and influential engine that earned Motor Trend‘s first Car of the Year Award, but it was the Oldsmobile Rocket 88 that started an avalanche. One by one, every other American manufacturer brought out its own OHV V8 engine: Chrysler and Studebaker in 1951; Lincoln in 1952; Buick and Dodge in 1953; Ford and Mercury in 1954; Chevrolet, Pontiac, Plymouth, and Packard in 1955; and AMC in 1956. Each of those engines had its own peculiarities, but they were all in the mold of the Oldsmobile Rocket engine. The OHV V8 would dominate the American industry well into the 1980s, resulting in some staggeringly powerful engines whose output has only recently been surpassed.
Oldsmobile’s reign as the hottest performer in the land proved to be short-lived. By 1952, the 88 was growing inexorably bigger and although Oldsmobile engineers had little trouble getting more power out of the Rocket engine — by 1955, it boasted 202 gross horsepower (151 kW) — newer, lighter cars soon surpassed its performance. The Rocket 88 model name was dropped after 1957.
The original Oldsmobile Rocket V8 soldiered on until 1964, eventually reaching 394 cu. in. (6,460 cc), which was about the limit of the original block design. Compression ratios never approached the 12.5:1 level that Kettering had proposed, peaking at about 10.5:1. Power increased — the final Rocket was rated at 345 gross horsepower (257 kW) — but fuel economy eroded. The 1949-50 Rocket 88 was good for 15-16 miles to the gallon (15 L/100 km) overall and up to 18 mpg (13 L/100 km) if driven carefully; a 1964 Oldsmobile Starfire struggled to reach 12 mph (20 L/100 km), a decline of around 30%.
In a 1972 interview with Michael Lamm, then editor of Special Interest Autos, former Cadillac chief engineer Jack Gordon lamented the trend to ever bigger and thirstier engines, noting that he had tried unsuccessfully to convince oil companies to develop ultra-high-octane fuels so that Cadillac could adopt more fuel-efficient high-compression, small-displacement engines. The oil industry wasn’t interested, nor was the auto industry, nor, it must be said, was the contemporary American public.
We think it was probably just as well that the proposed ultra-premium fuels never materialized; as it was, increasing the octane rating of pump gasoline from the 70 RON of typical mid-forties regular fuel to the 98 RON level of later super-premium fuel increased the amount of lead in each gallon by more than 40%, with significant public health consequences. The super-fuels the engineers wanted would probably have added even more.
Concern about diminishing oil reserves is nothing new — in the twenties, some engineers feared the U.S. would be out of oil within 30 years — but it was not until the seventies that those fears entered the public consciousness. Even in markets where fuel is substantially more expensive than in the U.S., fuel efficiency was widely regarded in purely economic terms. It’s tempting to speculate what might have happened had the the U.S. industry’s push in the 1950s been for efficiency rather than the (ultimately Pyrrhic) horsepower race, although that would admittedly have been unlikely. It’s taken economic downturns, the occasional oil embargo, and mounting signs of environmental capacity to get Americans to take a real interest in how much fuel they burn, and even then, it never seems to last for long after the latest crisis has passed.
Engineers today are wrestling with questions very similar to those faced by their counterparts of 70 or even 90 years ago. The difference is that many of the things earlier generations feared (such as heavy dependence on foreign oil the associated political ramifications) are now a reality rather than speculation. Still, the same quandary exists that faced Gordon Burrell and Jack Gordon in the late forties: New technologies — in this case, direct injection, turbocharging, and even hybrid powertrains — can benefit both performance or fuel economy and emissions, but one still almost always wins out over the other. The means exist to do the same work while burning less fuel; the question is whether a meaningful number of people will accept those means while there’s still fuel left to burn.
NOTES ON SOURCES
Our sources for this article included the Auto Editors of Consumer Guide, Encyclopedia of American Cars: Over 65 Years of Automotive History (Lincolnwood, IL: Publications International, 1996); Arch Brown, “Similar But Different: 1949 Cadillac vs. 1949 Oldsmobile 98,” Special Interest Autos #149 (September-October 1995), reprinted in The Hemmings Book of Oldsmobiles: driveReports from Special Interest Autos magazine, ed. Terry Ehrich (Bennington, VT: Hemmings Motor News, 2001), pp. 34-41; Arch Brown, Richard Langworth, and the Auto Editors of Consumer Guide, Great Cars of the 20th Century (Lincolnwood, IL: Publications International, Ltd., 1998); F. Gibson Butler, “History of the Rocket Engine,” originally written 15 November 1977 and excerpted in Desert Rocket Report: Newsletter of the Oldsmobile Club of Arizona October 2004, pp. 1, 3-5; www.azoldsclub. com/ newsletter/ 2004-10_OCAZ_Newsletter.pdf, accessed 15 June 2015; Helen Jones Earley and James R. Walkinshaw, Setting the Pace: Oldsmobile’s First 100 Years (Lansing, MI: Oldsmobile Division of General Motors Corporation, 1996); John Gunnell, ed., Standard Catalog of American Cars 1946-1975, Rev. 4th Edition (Iola, WI: Krause Publications, 2002); Maurice Hendry, “Hillbilly Genius: The Great ‘Boss Ket,'” Special Interest Autos #51 (June 1979), pp. 20–27; Jamie Kitman, “The Secret History of Lead,” The Nation March 2000; Allen Hunt, “Horsepower from Detroit, Part IV: Cadillac, Oldsmobile and the horsepower race,” Car Life Vol. 9, No. 6 (July 1962), pp. 26-31; Roger Huntington, “1965 Engines,” Motor Trend Vol. 16, No. 12 (December 1964): 36-47; William Kovarik, Ph.D., “Charles F. Kettering and the 1921 Discovery of Tetraethyl Lead In the Context of Technological Alternatives,” originally presented to the Society of American Engineers Fuels & Lubricants Conference, Baltimore, MD, 1994, revised 1999, www.radford. edu/~wkovarik/ papers/fuel.html, accessed 30 May 2008, and “Henry Ford, Charles Kettering, and the ‘Fuel of the Future,'” Automotive History Review #32 (Spring 1998), pp. 7-27; Michael Lamm, “Two Very Important Cars! 1948 & 1949 Cadillac Fastbacks,” Special Interest Autos #11 (June-July 1972), pp. 10-17, 56; Richard M. Langworth, “1954 Packard Pacific: Last of the Great Straight Eights,” Special Interest Autos #51 (May-June 1979), reprinted in The Hemmings Book of Postwar American Independents: driveReports from Special Interest Autos Magazine, ed. Richard A. Lentinello (Bennington, VT: Hemmings Motor News, 2002), pp. 74-81; Bob McVay, “Oldsmobile Starfire Road Test,” Motor Trend Vol. 17, No. 9 (September 1964), reprinted in Oldsmobile Muscle Portfolio 1964-1971, ed. R.M. Clarke (Cobham, Surrey: Brooklands Books Ltd., 1999), pp. 18-23; Jim Richardson, “Rocket Power: Oldsmobile’s 1950 convertibles: The rocking 88 versus the jazzier 98,” Special Interest Autos #188 (March-April 2002), pp. 46-52; “Testing the 212 HP Packard Patrician,” Science and Mechanics June 1954, reprinted in Packard Gold Portfolio 1946-1958, ed. R.M. Clarke (Cobham, Surrey: Brooklands Books Ltd., 1988), pp. 78-79; and Josiah Work, “1949 Rocket 88: This Is Not Your Grandpa’s Oldsmobile,” Special Interest Autos #139 (January-February 1994), reprinted in The Hemmings Book of Oldsmobiles, pp. 26-33.