The Little Aluminum V-8 That Saved Britain’s Bacon
LIKE THE KID WHO FLUNKED FIFTH grade and then grew up to become a decent stockbroker, the troubled youth of GM’s 215-cubic-inch (3.5 liter) aluminum V-8 didn’t hinder its fruitful life. Born in 1961, this resilient engine introduced turbocharging to production cars but failed to earn a sufficient U.S. audience, whereupon it was sent to England to live out its life in everything from Range Rovers to TVRs. Along the way, this mill, commonly known as the “Buick aluminum V-8” for reasons that will soon be explained, inspired countless designs and enabled a cottage sports-car industry. It was the only American engine design ever to win a Formula 1 title. One could argue that GM’s aluminum V-8 was every bit as ingenious as the Chevy small-block.
General Motors began studying aluminum V-8s in 1950 to power its LeSabre and XP-300 dream cars. Although cast aluminum had been used early in the 20th century for crankcases, constructing entire blocks and cylinder heads out of this material was a major breakthrough in the U.S.
In Europe, Alfa Romeo, Ferrari, Lancia, Porsche, Rolls-Royce, and Volkswagen perfected aluminum construction after World War II. The success of VW Beetle imports convinced U.S. automakers they would need downsized cars powered by smaller and lighter engines to compete. In 1960, the Chevrolet Corvair began the move to aluminum engines, followed by Buick, Oldsmobile, Pontiac, Plymouth, and Rambler in ’61.
Aluminum’s appeal is a density, or weight per volume, that is 60 percent lower than that of cast iron or “gray iron,” until then the traditional engine-block material. Per pound, aluminum yields two to three times the bending stiffness and strength of cast iron and three times the tensile strength.
Aluminum’s downside is cost. Iron ore is simply mined, melted, and mixed with a few ingredients before casting, but refining aluminum is a complex, energy-intensive process. First, bauxite ore, a claylike material, is mined. After melting and settling, alumina (aluminum oxide) in the molten ore is purified with an electric current, a process called electrolysis. Because of aluminum smelters’ high electricity consumption, they are typically located near hydroelectric dams, where the electricity is plentiful and cheaper. As a result, aluminum typically costs five times more per pound than gray iron. In the mid-1950s, GM engineer Joseph Turlay, who designed Buick’s first production V-8 for the 1953 model year, topped an experimental cast-aluminum block with hemi heads, a supercharger, and dual carburetors to produce 335 horsepower from 3.5 liters. That V-8’s 550-pound weight was a major breakthrough compared with the typical 700-pound iron-age engine.
GM engineers soon began work on a production aluminum V-8 to power the Buick Special, Oldsmobile F-85, and Pontiac Tempest slated for 1961. Buick won the development and manufacturing assignments, with Turlay overseeing and Cliff Studaker assisting the engineering effort.
GM’s game plan was to use a stretched Corvair unibody to underpin its new compacts. More refined ride and handling would, hopefully, justify higher prices for the upmarket models. In addition, the aluminum V-8 would foster weight savings throughout the chassis, thereby improving performance.
Toward that end, the 3.5-liter V-8 was a showcase of light design. The block, heads, intake manifold, timing chain cover, water pump, and water outlet were all made of GM’s 4097M aluminum alloy containing II-to-13-percent silicon. This added material lowered the aluminum’s melting temperature, helped it flow more readily into molds, and reduced shrinkage during solidification. A touch of copper was added to improve corrosion resistance. The pistons, rocker arms, and carburetor were also aluminum. The final 324-pound dry weight was 200 pounds lighter than Chevy’s small-block and roughly half the weight of Buick’s 6.6-liter V-8.
Turlay’s engineering team applied creative solutions to myriad design issues. Because aluminum bores weren’t durable enough to withstand piston scuffing, cast-in-place iron sleeves with grooved outer surfaces engaging the surrounding aluminum were used. This provided a tough bore surface without sealing concerns. Shrink-fit iron valve seats and guides were incorporated into the aluminum heads, also for durability. A deep-skirt block with five cast-iron main-bearing caps provided a stiff bottom end. The cast-aluminum pistons were linked to the cast-Armasteel crank through forged-steel connecting rods. (Armasteel was GM’s name for a special cast iron manufactured by its foundries.)
Combining an 8.8:1 compression ratio with dished piston crowns and shallow combustion chambers achieved detonation-free operation on regular gas. The spark plugs were located within half an inch of the bore center to minimize flame travel. The 3.50 inch bore and short 2.80-inch stroke minimized piston speed and engine height.
Because aluminum expands significantly more than iron when heated, the engineers worried that steel bolts screwed directly into aluminum threads might loosen in service. Testing proved the bolts would maintain the desired torque if they were well lubricated during assembly.
Aluminum-block manufacturing was the one area where Buick ventured into the unknown. The technique adopted was called semi-permanent mold casting, because it mixed conventional sand cores with permanent steel dies. Sand cores defined the internal coolant passages and the crankcase portion of the block. The reusable steel molds used for the outer flanks, deck surfaces, and valley area saved manufacturing minutes and provided a smoother finish than was possible with sand cores.
Following dyno development and a million miles of durability testing, Buick’s engine was tuned to deliver 155 (gross) horsepower at 4800 rpm and 220 pound-feet of torque at 2400 rpm, with a relatively flat torque curve. Upping the compression ratio to 10.25:1 and adding a four-barrel carburetor hiked output to 230 pound-feet and 185 horsepower, or 0.86 horsepower per cubic inch. Chevy’s 283-cubic-inch V-8 delivered 230 horsepower (0.81 horsepower per cubic inch) with a four-barrel carburetor.
Oldsmobile entered the 1961 model year with a version of this V-8 called the Rockette to evoke a family tie to the Rocket 88. To make efficient use of manufacturing facilities, Buick cast all the blocks and crankshafts, and Olds manufactured its own heads, pistons, valvetrain, and intake manifolds. One significant difference in the blocks was Buick’s use of five head bolts per cylinder whereas Olds preferred six (stay tuned for the reason why). Pontiac equipped most of its Tempests with what it called an Indy Four—basically, a V-8 chopped in half—with the Buick 3.5-liter V-8 available as an extra-cost upgrade.
The racing community was impressed by America’s new small V-8, too. Mickey Thompson concluded that this ultra-light engine was the ideal means of rattling the Offenhauser crowd at Indy. In 1962, Dan Gurney qualified eighth in Thompson’s Harvey Aluminum Special powered by a 4.2-liter Buick V-8, but he dropped out half-way through the race with a broken gearbox.
Unfortunately, the buying public didn’t swarm to the General’s new premium compact cars. Only Pontiac topped 100,000 sales in 1961; combined Special/F-85/Tempest sales exceeded the Corvair’s volume by only 10 percent. The issue was price. The cheapest Olds F-85 cost $118 more than a Chevy Bel Air. Instead of merely hoping sales would rise, Buick and Oldsmobile swiftly rejiggered their game plans. In 1962, Buick moved down-market, and Oldsmobile grabbed the next rung up the price ladder.
Buick’s 1962 companion to the aluminum V-8 was a V-6 made by whacking one cylinder per bank. To spare the higher cost of aluminum, the block and the heads were converted to cast iron. Keeping the V-8’s 90-degree V-angle was hardly ideal from a vibration standpoint, but it did allow machining the new V-6 with existing tools. What began as a crude expedient eventually ended up as GM’s rock-star 3800 V-6, a story for another day.
Oldsmobile promoted its Rockette aluminum V-8 to Jetfire Turbo Rocket status by adding a Garrett AiResearch turbocharger fed by a single-barrel side-draft Rochester carburetor. Beating Chevy’s Corvair Monza Turbo to market by a few weeks gave Olds bragging rights for the world’s first turbocharged production model. Peak power surged to 215 horsepower at 4800 rpm—clearing the one horse-per-cubic-inch hurdle. The torque curve peaked at a potent 300 pound-feet at 3200 rpm. Without major changes to the host engine or any loss of smoothness or drivability, midrange torque rose by 40 percent.
Turbo pinwheels spinning at 90,000 rpm were supported by aluminum sleeve bearings lubed by engine oil. Exhaust gas accelerated the alloy-steel turbine wheel from 40,000 rpm during cruising to 80,000 rpm in less than a second after the throttle was floored. An exhaust waste gate built into the turbocharger limited boost pressure to 5 psi.
Instead of lowering the naturally aspirated V-8’s 10.25:1 compression ratio, which would penalize efficiency, Oldsmobile devised a system that metered Turbo Rocket fluid during boost conditions in a 1:10 ratio with the gasoline consumed. This 50/50 elixir of distilled water and methyl alcohol (antifreeze) with a splash of corrosion inhibitor cooled the gas and air mixture sufficiently to forestall detonation. To their surprise, Olds engineers found that the alcohol content added six horsepower to peak output.
The tank that stored this juice was pressurized by a tap off the turbo’s compressor to force delivery to the carburetor’s float chamber. Safeguards were provided to inhibit boost when the essential fluid was depleted. Testing predicted the 5 quart supply would last nearly 1000 miles.
BEATING CHEVY’S CORVAlR MONZA TURBO TO MARKET BY A FEW WEEKS (AND BMW AND PORSCHE BY A DECADE) GAVE OLDS BRAGGING RIGHTS FOR THE WORLD’S FIRST TURBOCHARGED PRODUCTION MODEL.
Osmobile’s 1962 JetRocket V-8 topped by a Garrett AiResearch turbocharger fed a single-barrel Rochester downdraft carburetor. Five psi of boost raised output to 215 horsepower at 4800 rpm and 300 pound-feet of 3200.
Those extra head bolts? Oldsmobile designed them into its version of the 215 to help avoid warpage and blown head gaskets on the turbo variant. The pistons, the bearings, and the valves were also upgraded.
Proud of their achievement, Oldsmobile engineers Gil Burrell, Frank Ball, and James Lewis concluded their Turbo Rocket tech paper by saying, “This engine is a development that will be appreciated by all engineers, performance enthusiasts, and other people interested in advanced mechanical powerplants.” Car and Driver technical guru Roger Huntington dubbed the engine “the most radical design from an American factory in many years.” He rated the ’62 Olds Cutlass F-85 Jetfire “an elegant and comfortable high-performance car of medium size”.
Unfortunately, GM’s hot small engine was caught out by radical changes sweeping through the industry. For the 1964 model year—the dawn of the muscle-car era-—GM’s premium compacts grew into intermediate A-bodies powered exclusively by iron engines. Buick and Olds kept the V-6 and added larger V-8 options. Pontiac used a Chevy inline-six for base power and offered V-8s ranging from 326 to a wild 421 cubic inches.
The aluminum 215 V-8 lasted only three model years, in part because it was a costly indulgence. The casting process suffered from porosity issues—seepage through the cylinder-block walls—and the high scrap rates gave top management the willies. If the porosity wasn’t discovered upfront, coolant contamination of the oil triggered an expensive warranty claim. Customers who used the wrong antifreeze suffered radiators clogged with aluminum deposits. Mechanics hurriedly changing spark plugs occasionally stripped threads in the aluminum heads.
Oldsmobile F-85 Jetfire owners often ignored the dash light urging them to replenish their Turbo Rocket fluid. The most pressing issue was fewer than 10,000 turbo cars sold, resulting in its cancellation after only two model years. Some dealers even stooped to removing the booster for disgruntled customers. The Corvair Monza Spyder also failed to top 10,000 sales in 1962, suggesting that turbochargers were too mysterious for most small-car buyers.
On the opposite side of the earth, Oldsmobile’s light, compact V-8 was held in higher regard. Australian racing driver Jack Brabham commissioned auto-parts supplier Repco to base a Formula 1 V-8 on the Olds block endowed with SOHC heads and a flat plane crankshaft to produce more than 300 horsepower from 3.0 liters. That shrewd move earned Brabham the 1966 drivers’ and constructors’ titles. This was the first and last time an engine with American production-car roots prevailed in Formula 1.
Britain’s Rover also took advantage of GM’s aluminum V-8. By the early 1960s, the 3.0-liter F-head inline-six that powered its flagship sedan was overdue for replacement. On a visit to the States, Rover’s managing director, William Martin-Hurst, stumbled across a Buick V-8 that Mercury Marine intended to install in a boat. The engine was instead shipped to England, where Rover engineers concluded it would suit their needs.
In 1965, Rover inked a deal with GM that included all rights to the aluminum V-8, tech data, blueprints, and a few used engines. Designer Turlay, about to retire from Buick, moved to England to assist the production restart. Apparently, it didn’t occur to anyone at GM that Rover would be competing against GM’s own European brands, Opel and Vauxhall, with the exiled engine.
Rover switched block manufacturing to conventional sand casting with pressed-in cylinder liners to solve the porosity problem for good. Starting with the P5 sedan in 1967, Rover’s 184-hp V-8 graduated to the P6 a year later and to the Range Rover luxury SUV when it debuted in 1970. The enduring success of the Land Rover brand in our market is the direct result of its arrival with a smooth, potent engine.
Growing in steps to 5.0 liters, the aluminum V-8 thrived in MGS, Morgans, Triumphs, and TV Rs and stayed in production until 2004. The remanufacturing firm MCT then took the baton to continue the supply of engines to Britain’s low-volume specialty brands until 2010. Without this V-8, the Japanese would have annihilated British sports cars as quickly as they had laid the U.K.’s motorcycle industry to rest.
GM’s courageous aluminum and turbocharging initiatives yielded several worthy permutations of the original Buick 215 V-8, notable racing success, and millions of satisfied customers.