Model Histories
Terms and Technology
Editorials and Commentary
Contact Us
Admin Login
Support Ate Up With Motor
Search Ate Up With Motor
FTC Disclosure Notice
| Rocket Bomb: The Oldsmobile Rocket 88 and the Dawn of the American Horsepower Race |
 |
 |
| Written by Aaron Severson |
| Tuesday, 19 August 2008 16:31 |
|
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 Rocket. OLDS VS. CADILLACOldsmobile's first postwar engine was born during the UAW strike that shut down GM production from November 1945 to April 1946. During that period, Oldsmobile Motor Group engineer Gilbert Burrell began working privately on new engine concepts. He had no specific assignment; he was simply exploring ideas for his own interest. Burrell examined a wide range of layouts, but the one to which he continually returned was a 90-degree V8, which he judged as offering the best combination of power and packaging efficiency.
About six weeks after he started work, Burrell showed his designs to senior engineer Jack Wolfram and Oldsmobile general manager Sherrod Skinner. Wolfram and Skinner were impressed by Burrell's work, and they put him in charge of an advanced design group to develop a new overhead-valve (OHV) V8 engine. Coincidentally, Cadillac had been working on a very similar engine since 1936, intended to replace its familiar monobloc flathead V8. Exactly how much the Oldsmobile design team knew about the Cadillac engine is the subject of considerable debate. Authors Helen Jones Earley and James Walkinshaw insist that Burrell's group knew nothing of the Cadillac engine until quite late in the development process. In 1985, however, former Cadillac engineer Harry Barr told Special Interest Autos writer Arch Brown that GM's engineer VP, C.L. McCuen -- a former Oldsmobile general manager -- had ordered Cadillac chief engineer Jack Gordon to show his engine design to Oldsmobile, which inspired Burrell's design. Barr did concede that the Olds engineers made a number of important contributions, but he insisted that it was primarily a Cadillac design. In any event, Burrell's team had four development engines running in relatively short order, but GM's Executive Committee hemmed and hawed about approving the V8 for production, briefly terminating development funding. To make matters worse, in 1946, Ford Motor Company poached several senior Oldsmobile engineers. In April 1947, Wolfram and Skinner finally persuaded Charlie Wilson, GM's president, to approve the new engine for production. The first production V8s went on sale a few days before Christmas 1948, in Oldsmobile's 1949 Ninety-Eight models.  1949 Oldsmobiles proclaimed that they had "Futuramic styling" (there's even a "Futuramic" badge on the front fenders), but it was updating a basic body introduced in 1941. The heavily domed hood would continue through 1953. The grilles under the headlights are for the ventilation system, replacing the traditional pop-up cowl vent. They were criticized at the time as unsafe in city traffic, because they picked up their air too close to the tail pipes of cars ahead. The wild rocket hood ornament was technically a $5 option. FLATHEADS, OVERHEAD VALVES, AND HIGH COMPRESSIONThe Olds and Cadillac V8s represented the start of several major trends in American engine design. Let's briefly examine each of them.
OHV VS. L-HEAD
>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.
 Simplified diagram of the cylinder of a flathead engine. (author diagram) 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, and 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.  Simplified diagram of the cylinder of a wedge-head, overhead-valve engine. (Author diagram) The drawback of OHV designs 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 operate the valves by simply pushing them up and down. In an OHV engine, 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, as well (making it 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.  Diagram of a typical pushrod/rocker-arm layout of an overhead-valve engine. (Illustration © 2007 Ian Brockhoff; used under a Creative Commons Attribution ShareAlike 3.0 license) OVERSQUARE VS. UNDERSQUARE
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 at high rpm, the average speeds of the pistons are very high; neither does anything good for 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. HIGH COMPRESSION
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 1. 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.
In the late forties, Kettering's staff had put together an experimental 180 cu. in. (3.0 L) six with a compression ratio of 12.5:1, compared to less than 7:1 for most contemporary engines. They 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 fuel: Kettering's engine required fuel with a considerably higher octane rating than contemporary pump gasoline. The second was that the practical limit for L-head engines was a compression ratio of about 7:1; above that threshold, combustion became unacceptably rough. Overhead valve engines did not have that problem, which gave them the potential for much higher compression ratios. Neither of the new OHV V8s had an exceptionally high compression ratio at first -- the Olds was 7.25:1, the Cadillac 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 was hardly an altruistic effort, since GM still owned a major stake in the Ethyl Corporation, which made the tetraethyl lead that was the primary octane booster used in gasoline.) If better fuels became available, the compression ratios of both engines could be raised as high as 12:1. THE ROCKET V8Oldsmobile's first "Rocket V8" had a larger displacement than the straight-eight it replaced -- it went from 257 cu. in. (4.2 L) to 303.7 cu. in. (5.0 L) -- but it was now significantly oversquare; bore and stroke were 3.75 in (95.3 mm) and 3.44 in (87.4 mm), compared to 3.25 in (82.6 mm) and 3.88 in (98.4 mm) for its predecessor. It was still a physically large engine, but it was smaller in most dimensions and quite a bit lighter than the straight-eight. Power climbed from 110 horsepower (82 kW) to 135 (101 kW), torque from 213 lb-ft (288.5 N-m) to 283 (383.3 N-m), while fuel efficiency improved by around 10%.
 Oldsmobile engineers originally wanted to call this the Kettering Engine, after GM research head Charles Kettering, whose work on high-compression engines helped to inspire it. GM had a rule prohibiting cars or engines from being named after living people, so Sherrold Skinner suggested the "Rocket" name instead. Some Oldsmobile employees strongly disliked that moniker, but it would be associated with Olds well into the 1960s. The early Rocket V8 weighs a bit over 700 pounds (318 kg) and has a rating of 135 gross horsepower (101 kW). Many believe it was deliberately underrated to avoid offending Cadillac, which was concerned about its sister division outmatching the new Cadillac V8. The new V8 was designed with plenty of extra room in the block for future displacement increases, but Gilbert Burrell and his team originally intended to make it smaller once higher-octane fuel became available. They hoped to eventually reduce the engine's displacement to 288 cu. in. (4.7 L), the size of the early development engines, but use a much higher compression ratio, maintaining the same power with better fuel economy. By the time high-octane fuel did become available, however, the industry was more interested in power than gas mileage. The Rocket would only get bigger, not smaller. ROCKET LAUNCHPerhaps the most significant thing about the Rocket V8 was not the engine itself, but the decision about what models it was available. At the start of the 1949 model year, Oldsmobile had two basic model lines: the six-cylinder Seventy-Six, which shared the body shell of Chevrolets and Pontiacs, and the big, eight-cylinder Ninety-Eight, which shared its body with Buicks and lesser Cadillacs. When the '49 models went on sale late in 1948, the V8 engine was available only in Ninety-Eights. During testing, though, Olds engineers had installed several development engines in the smaller Seventy-Six chassis, which produced formidable performance.
Harold Metzel, who at the time was Oldsmobile's chief transmission engineer, asked Sherry Skinner if they could offer the V8 in the 76 body, as well as in the big car. Skinner liked the idea, and he took it to the Executive Committee for approval. He met with considerable resistance from Cadillac's managers, who were concerned about having their performance supremacy eclipsed by one of the middle-class divisions (which Buick had done back in 1941-42). The top brass equivocated, but Skinner finally got the green light, and the new, mid-sized "Rocket Eighty-Eight" went on sale in early February 1949.  In shape and size, the Rocket Eighty-Eight is not much different from the Pontiac Streamline and Chevrolet Fleetline whose body shell it shares. (Its wheelbase is four and a half inches longer than the Chevy, but half an inch shorter than the Pontiac.) Either was substantially cheaper than the Oldsmobile, but the Olds name carried more prestige -- and the V8 would leave Pontiac's elderly straight-eight or Chevy's Stovebolt Six for dead. The Rocket Eighty-Eight was hardly a small car, even by American standards: 202 inches (5,131 mm) long and 75.2 inches (1,910 mm) wide, riding a 119.5-inch (3,035-mm) wheelbase, and tipping the scales at around 3,800 pounds (1,725 kg). Even so, it was 11 inches (279 mm) shorter, 3.5 inches (89 mm) narrower, and around 350 pounds (159 kg) lighter than the Olds Ninety-Eight for which the Rocket engine had been intended. The combination of the lighter body and the powerful new engine made the Eighty-Eight, in the parlance of the day, quite a bomb. Even with the standard Hydra-Matic transmission, the Eighty-Eight was capable of 0-60 mph (0-97 kph) in less than 13 seconds, with an absolute top speed of around 97 mph (156 kph). Some competitors could outrun it to about 30 mph (50 kph), and a few could eek out a slightly higher top speed, but the new Olds was one of the fastest cars in America. It would vacuum the chrome off formerly hot numbers like V8 Fords, and it would take a semi-exotic like the new Jaguar XK-120 to beat it soundly. Although Oldsmobile's official involvement in racing was limited, the Eighty-Eight promptly preceded to clean up in competition. NASCAR held nine Grand National races in 1949, of which stock Rocket Eighty-Eights won six. The following year, Eighty-Eights won 10 out of 19 races and set a new speed record at Daytona. An Eighty-Eight also won the first grueling Carrera Panamericana, the 2,176-mile (3,500-km) Mexican Road Race. (Ten of the twelve Eighty-Eights that entered that race managed to finish, itself an impressive feat.) Basically stock Rocket Eighty-Eights 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 1949 were around 294,000, up more than 60% from the year before, and some 100,274 of those sales were the Rocket Eighty-Eight . Any interest in fuel economy was quickly forgotten; gas was cheap, and it was clear that speed would sell more cars than parsimony. (Indeed, in 1951, Olds dropped its six-cylinder engine in favor of the more popular and profitable V8; the division would not offer a six again until 1964.)  This 1950 Rocket 88 has the Deluxe trim, with a dashboard clock; Deluxe models cost $78 more than the standard-trim version. This car has the push-button radio, which cost about $96. Full instrumentation is standard -- Olds had not yet succumbed to the allure of warning lights. Note the quadrant for the Hydra-Matic atop the steering column. Early Hydra-Matics had no "Park" position (although there was a parking pawl if you engaged reverse), and unlike later versions, there's no way to keep the transmission in third gear, which can be inconvenient. This car's turn signals may be an aftermarket addition -- turn signals were originally a $15 option on this car. OVERTAKENThe Eighty-Eight and its engine started an avalanche. One by one, almost 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 even AMC in 1956. Each of those engines had its own peculiarities, but they were all in the mold of Oldsmobile's Rocket V8. The overhead-valve 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 Eighty-Eight had started getting inexorably bigger. Although engineers had little trouble getting more power out of the Rocket engine -- by 1955, it had topped the 200 gross horsepower (149 kW) mark -- newer, lighter cars soon surpassed its performance. By the end of the 1950s, the 4,400-pound (2,000-kg) Eighty-Eight was no longer a rocket, except in name. The Rocket V8 soldiered on until 1964, eventually reaching 394 cu. in. (6.5 L), 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, while a big-engine '64 averaged closer to 12 mpg (20 L/100 km, a drop of around 30%. In a 1972 interview with Special Interest Autos editor Michael Lamm, former Cadillac chief engineer Jack Gordon lamented the trend to ever bigger and thirstier engines. He said that he originally hoped to persuade the oil companies to develop a higher-octane gasoline so that the industry could switch to more fuel efficient high-compression, small-displacement engines, but the oil industry wasn't interested. We think it was probably just as well -- increasing the octane rating of automotive gasoline from the 70 RON of typical mid-forties regular gas to the 98 RON level of late-1950s super-premium raised the amount of lead in each gallon of fuel by more than 40%; the super-fuels the engineers wanted would have added even more. Given the public health impact of tetraethyl lead, the likely consequences would not have been pleasant.  Until 1951, Oldsmobile offered a choice of fastback and notchback body styles, as well as the convertible. Two-door fastbacks, like this one, were known as Club Sedans; the four-doors were called Town Sedans. Base price for the Deluxe Club Sedan was $1,982 in 1950, and 16,388 were sold. The '50s were considerably cheaper than the '49s, although that was largely because Hydra-Matic, which had been standard equipment on all 1949 V8-powered cars, reverted to a $185 option. Adding turn signals, backup lights, windshield washers, and heater tacked an additional $112 to the price -- these items wouldn't be standard for several more years. It's tempting to speculate where America would be today if the push in the 1950s had been for efficiency, rather than the (ultimately Pyrrhic) horsepower race. Admittedly, that would have been unlikely; it's taken economic downturns, the occasional fuel crunch, and signs of impending ecological catastrophe to get Americans to care about how much fuel they burn, and it never seems to last much beyond the latest crisis. Engineers today are wrestling with the same issue faced by their counterparts of 60 or even 90 years ago, except that many of the things that earlier generations were afraid of -- like a heavy dependence on foreign oil -- have become reality, rather than speculation. Automakers now face a quandary much like that faced by Gordon Burrell and Jack Gordon in the late forties when it comes to technology like turbocharging, direct injection, and hybrid systems. Like the high-compression OHV engine, these technologies can be used to improve fuel economy or performance, and one almost always wins out over the other. The means exist to burn less fuel; the question is whether enough people will accept them while there's still fuel left to burn. # # #
NOTES ON SOURCESOur principal sources for this article were Arch Brown, "Similar But Different: 1949 Cadillac vs. 1949 Oldsmobile 98," Special Interest Autos #149, September-October 1995, reprinted in Terry Ehrich, ed., The Hemmings Book of Oldsmobiles (Bennington, VT: Hemmings Motor News, 2001); Helen Jones Earley and James R. Walkinshaw, Setting the Pace: Oldsmobile's First 100 Years (Lansing, MI: Oldsmobile Division of General Motors Corporation, 1996); Michael Lamm, "Two Very Important Cars! 1948 & 1949 Cadillac Fastbacks," Special Interest Autos #11, June-July 1972 (Vol. 3, No. 3), pp. 10-17, 56, (which includes Jack Gordon's lament for the poor fuel economy of later American V8s); 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; and Josiah Work, "1949 Rocket 88: This Is Not Your Grandpa's Oldsmobile," Special Interest Autos #139, January-February 1994, reprinted in Terry Ehrich, ed., The Hemmings Book of Oldsmobiles (Bennington, VT: Hemmings Motor News, 2001).
Comments (15)
Please do not post copyrighted content or images you don't own!
User comments do not necessarily reflect the opinions of Ate Up With Motor, and we accept no responsibility for their content. Publication of a comment does not constitute Ate Up With Motor's endorsement of any opinion, product, or service. Please click here to read our Comment Policy. Joomla components by Compojoom
|
...or is that not an Avanti peeking into the frame on the right side of the last photo? And just where is this crazy car heaven where Rocket 88 Oldsmobiles and Avantis are parallel parked on the street side by side?