With Chrysler鈥檚 Hemi name revived and Hemi-powered muscle cars having almost mythical status, it seems fitting to review the Chrysler Hemi V-8 engine鈥檚 background.
After the Second World War, auto manufacturers began producing essentially pre-war cars until they could create new designs. But they knew the new models would require more than just revised styling; they required new engines to replace some with heritages dating back to the 1920s.
The work of General Motors鈥� brilliant research head, Charles Kettering, on high compression ratios and engine knock enabled GM to beat other manufacturers to the punch with short-stroke, overhead-valve, high-compression V-8s for the 1949 Cadillacs and Oldsmobile 88. Chrysler had to soldier on with its venerable old inline side-valve sixes and eights until it could design replacements.
When Chrysler鈥檚 new V-8 arrived for 1951, it proved worth the wait. Although displacing only slightly more than the straight-eight it replaced 鈥� 5.4 vs. 5.3 litres (331 vs. 323 cu in.) 鈥� horsepower was increased from 135 to 180.
But the important comparison was not so much with Chrysler鈥檚 former engine, but with rival Cadillac鈥檚 160 horsepower V-8. It would be the first significant shot in the famous Detroit horsepower race of the 1950s and 鈥�60s.
Chrysler had one-upped General Motors by producing an engine displacing exactly the same 5.4 litres (331 cu in.) with identical bore and stroke as the Cadillac, but with 20 more horsepower.
True to its strong engineering heritage, Chrysler didn鈥檛 engineer just another overhead valve V-8 with conventional wedge-shaped combustion chambers. The heart of the new engine was its superior hemispherical combustion chambers created by placing the valves on each side of the combustion chambers and operating them through two rocker arm shafts in each cylinder head. It therefore achieved the efficiency of hemispherical chambers without the cost and complexity of overhead camshafts.
Chrysler called it the 鈥淔irepower鈥� engine, but enthusiasts soon nicknamed it the 鈥淗emi.鈥� Hemispherical combustion chambers gave it superior volumetric efficiency, and breathing in more air per revolution produced more power.
It was a brilliant stroke, and the Hemi soon began building a performance reputation. Smelling a winner, Mechanix Illustrated鈥檚 Tom McCahill took a brand-new Chrysler New Yorker V-8 to the sands of Daytona Beach in February 1951, where he won the NASCAR Speed Week trophy as the fastest American stock car. In spite of rough, sticky sand conditions and a 鈥渟tiff 25-mile quartering wind,鈥� he managed to average 161 km/h in a two-way run.
Even though McCahill鈥檚 New Yorker weighed 1,928 kilograms and had less-than-ideal aerodynamics, the Hemi engine gave the big Chrysler its winning performance.
The Chrysler engine鈥檚 reputation spread quickly. Wealthy American sportsman Briggs Cunningham was building world-class sports cars in West Palm Beach, Florida, in an attempt to win the renowned Le Mans 24-hour race in an American car. He fitted new Hemis hopped up to 220 horsepower with four carburetors and higher compression. Power ultimately went much higher.
Cunningham only managed to finish 18th in his first Le Mans outing in 1951 (McCahill blamed it on the low-octane gasoline provided), but in 1952, a Cunningham finished fourth behind two of the fabulous new Mercedes Benz 300 SLs and a Nash-Healey. In 1953, Cunningham finished third, but would never quite achieve his goal of victory for America.
According to McCahill, one of the modifications Cunningham used to get more power out of the Chrysler engine was fitting Cadillac pistons. A different wrist pin placement reportedly raised the compression ratio of the Hemi from 7.5:1 to 8.5:1, increasing power by almost 10 per cent. They were also lighter than Chrysler pistons.
Road & Track tested a Saratoga V-8 Club Coupe and reported zero to 100 km/h in under 10 seconds and a top speed average of 166 km/h. These were fast times for that period.
McCahill recorded 10.9 seconds for his zero-to-100. Both testers obtained these times by resorting to manually shifting the sluggish 鈥淔luidmatic鈥� transmission.
In addition to its Hemi engine, the 1951 Chrysler made another significant contribution to automotive technology in the form of hydraulically assisted 鈥淗ydra-guide鈥� steering. Power steering was not new; it had been used on trucks and buses for some time, but its use in passenger cars was pioneered by Chrysler.
The introduction of power steering enabled engineers to design steering gear that reduced number of wheel turns and allowed quicker steering, eliminating the compromise between steering effort and steering ratio. Power-assisted steering was a significant advance in safety and driving ease, and although overshadowed by the fabulous Hemi, it further contributed to Chrysler鈥檚 reputation for sound engineering.
