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The Original Chrysler Hemi Engine

hemi engine

Copyright © 2004 by Curtis Redgap, Orlando, Florida. All rights reserved. Contact Allpar for reprint permission. Based on a large variety of sources.

1954 Hemi engineIn the late 1940s, Chrysler Corporation’s decisions regarding V-8 engines lead to one of the most technologically advanced automotive engine designs in the world. It created new ground in terms of performance. That the engine got the go-ahead from a staunch group of conservative engineers is a testament to the basic design.

It has been well documented that, with the release of the first generation of Hemi headed V-8 engines, Chrysler set off the "horsepower wars" of the early 1950s that lasted into the early 1970s. It forced General Motors and Ford Motor Company to keep upping the ante in making more power from their engines.

If you look at applications running today [this was written in the early 2000s but it’s still true in 2012], you have to go no further than the major drag racing organizations. The top engines for producing huge amounts of horsepower, along with one that continues to set speed records, are those with hemispherical heads on them. The early Hemi lead Chrysler to develop the second generation of the Hemi headed V-8. Even now, a third generation is proving its worth in current Chrysler vehicles.

The hemispherical chamber, as the name implies, is a portion of the sphere. And here you can see the arch shape of the sphere itself. With this we can bring the spark plug into the center of the chamber which is an excellent position for the spark plug. The same shape over in this view allows us to put the valves in a position where when they open, like this inlet valve, it has excellent breathing of the air past the valve seat. This combination of the excellent breathing, of the inlet and the exhaust makes for a very high volumetric efficiency of the engine. — Willem Weertman on the 426 Hemi

Chrysler Corporation began testing various engine designs prior to the beginning of World War II. Pinpointing an exact date is not possible since the records in that era were spotty and were often misplaced (and many were discarded by later generations).

From all indications, the work of making new engines got started in 1937. This work continued during the war. Nothing was left to conjecture, with every imaginable type of engine receiving scrutiny by Chrysler Engineering. This included but was not limited to a 5 cylinder in-line, several 6 cylinder in-lines, 60 degree V-6s, 90 degree V-6s, and 90 degree V-8s. All sorts of different exhaust and intake combinations were tried. The 90 degree V-6 was unsatisfactory because it lacked smoothness. The straight 8 engine was now considered too heavy and too long. Two stroke cycle engines were rejected because they were noisy and smoky.

Chrysler tank engineWorld War II did not stop the engineering department from working on new engines. These men developed a superb tank engine by combining five inline flathead Plymouth 6 cylinder engines in a radial combination. It was rugged, durable, powerful, and fairly economical as well. It went on to power hundreds of tanks that were also being built at the Chrysler Corporation. One of those engines is on display in the Walter P. Chrysler Museum in Auburn Hills, Michigan; another is at the New England Air Museum.

The engineering staff, lead by Supervising Engineer John Platner, began to use a single-cylinder engine to test new head designs or combustion chambers (a practice which continues). Their concern at that time was the loss of volumetric and thermal efficiency due to carbon deposits. Some losses would occur with as little as 10,000 miles on an engine. Once these deposits got started, they would increase until engine power would be down as much as 20% - a noticeable difference.

Pete Hagenbuch wrote: The 30 cylinder tank engine was comprised of five six cylinder engines, each with its own crankshaft, and all driving a common output shaft located in the crankcase. Chrysler built 7500 M4 Sherman tanks using this engine which, while it missed the 500 hp target, proved itself far more reliable than anyone dreamed.

One area that had shown really true promise was the hemispherical combustion chamber. The standard wisdom about such a “Hemi” (that name came far later) was that the engine was rough and liked high octane fuel; but testing results indicated that just the opposite seemed to be true concerning the Hemi. Standard wisdom that the engine was too complex and expensive to mass-produce might have been closer to the mark.

Chrysler created two large hemispherical headed engines during World War II. One was a V-12 for application in tanks and the other was a V-16 operating in a inverted position for the aircraft industry. Neither reached production - not because they weren't good, but because there was just so many other things going on.

The first Chrysler Hemi - an airplane engine


Testing the aircraft engine was just another Chrysler accomplishment that went by unheralded but was nevertheless noted later. This was a V-16 engine dubbed the XIV 2220; the 2220 represented the displacement of the cylinders, in cubic inches. That equals over 36 liters.

V16 Thunderbolt Hemi engine

For testing, a P-47 Thunderbolt, the largest and heaviest single-seater in the Air Force at the time, was selected. Some modifications were made to accommodate the XIV 2220; when done, the slimmed down nose helped reduce the drag produced by the big round radial engine.

Preliminary testing showed promise. The big fighter was coaxed slowly into higher altitudes and higher speeds. Finally the go ahead was given for an all out test. At 15,000 feet, the huge plane, under the Chrysler V-16's power, broke the 500 mile an hour barrier, around 70 mph faster than the original engine. No one thought it was possible for a piston engine to achieve that speed in level flight.

Radar timing shows how powerful that engine was. Flat out, it pulled the huge P-47 along at 504 miles an hour.

Pete Hagenbuch wrote that Mel Carpentier was head of Engine Design at the time. The engine was built by "The Motor Room," part of Engine Development & Testing, which was headed by Bill Drinkard, then Harold Welch, and then by Ev Moeller, who was the manager in early 1956 when Pete arrived on the scene. The contract called for 2500 hp; it was cancelled because the war was tapering off, the engine was not critical to victory, and jets were waiting in the wings.

Dan Stroud wrote, “I’ve personally seen the one at the NASM’s Garber facility, and it’s absolutely complete and still on its firewall mounting, and still has most of its cowling for the Thunderbolt intact. The other one I’ve seen photos of is heavily chromed, and I was told it was the one at the Chrysler Museum. Interestingly, as I was collecting many parts from around the world for my own P-47D project, I also managed to save two parts from one of the original XP-47Hs, and at one time I saw the spinner backing plate and the prop hub still in existence, too. So, at least some of the “first hemi” has survived!”

Just to be sure, the test P-47 went out the next day with a different test pilot and again level at 15,000 feet, went through the 500 mile an hour mark. Hand shakes and elation went all around. The engine never went into production, though, because jets had come onto the scene and were clearly the wave of the future.

The important thing to keep in mind, though, was that this was a Hemi headed, push rod valve activated engine. [According to Bob Nist, a Chrysler ad in Space Smithsonian mentioned three of these engines made; one is at the Smithsonian, and the third, according to Don Wagner, is in the New England Air Museum in Connecticut. A Chrysler Museum display says that five were made.

Editor's note: The Continental "Hyper" inverted-V engine featured "spherical" combustion chambers and sodium cooled exhaust valves. The Chrysler Museum display shows it at 2,500 horsepower and 2,220 cubic inches. There is some controversy as to the performance tests cited here. The engine weighed 2,430 pounds. It looks like a 90° but the Chrysler Museum insists it has a 60° angle; and the crank consisted of two mirror-imaged two-plane, four-throw crankshafts placed end-to-end, with the propeller reduction gear between them, at the engine center. This approach was similar to other V-type aircraft engines with symmetrical crank-pin paring, according to the museum; these other V-engines also had an uneven firing interval requiring special magnetos. The valves, two per cylinder, were operated by the camshafts (which would be overhead, but the engine was “upside down,” so they were “underhead”) and rocker arms.

Hemispherical heads in cars: the state of the art

1951 Hemi Firepower

Fred Zeder on why they chose hemispherical heads

At the end of the war, Engineering knew how good the Hemi heads could be. The first recorded use of a hemispherical combustion chamber was the four cylinder engine powering the Welch, which was, depending on the source, a Michigan company or a British design. Hemi heads were used by many famous marques in the automotive industry, including Miller Racing, Duesenberg, Stutz, and Offenhauser — all high performance models.

There is an urban legend about the General Motors engineer Zora Duntov, better known as the father of the Chevrolet Corvette. Before coming to GM, he designed a set of Hemi heads that were retrofitted to the Ford flathead V-8. Legend has it that Chrysler somehow “borrowed” the design from Duntov. Chrysler had, though, entered into Hemi engineering long before Duntov began construction of his aftermarket, bolt-on heads. Great minds travel in the same circles. [See Fred Zeder’s description of prior hemispherical head designs, including the Ardun setup.]

Walter P. Chrysler was always proud of the "boys" in engineering, but he could still disparage them with the best of his well-known temper. The Airflow may have been meant for DeSoto only, but Walter wanted it yesterday for Chrysler. The engineering staff advised it was being rushed and that manufacturing wasn't up to making sure that the line techniques were going to ensure a quality car, but Walter kept up the pressure. That gave General Motors, which was running scared of the design, time and incentive to spread vicious rumors about it.

Engineering held sway at Chrysler at the time. Walter P. Chrysler had gotten his start with a car that was designed and built by three engineers who had been working for Studebaker. Fred Zeder, Owen R. Skelton, and Carl Breer made it possible for Walter Chrysler to introduce the first high-compression in-line 6-cylinder flathead engine in his 1924 Chrysler car — which also had new hydraulic brakes on all four wheels. Breer was also credited or panned, whichever way you choose to look at it, with the styling and engineering development of the 1934 Airflow Chrysler. That model was the first car of its time, from which all modern designs are now based. Had it not been rushed — and had it been developed under greater secrecy —  it would have been a great success.

Working in the engine development area was James Zeder, the younger brother of Fred Zeder; working for James were Ray White, Mel Carpentier, and William Drinkard. Joining this group was a young Ev Moeller, one of the first graduates of the Chrysler Institute in 1939. He came aboard the automobile engine development team in 1947 after working through the war in the aircraft engine development program. These men tested virtually every engine they could find in every combination that they could think of.

One of the engines they tested that truly stood out for power and efficiency was built in England by Riley Motors, and used by Healey. It had twin camshafts, located in the block, which operated push rods for overhead valves in hemispherical combustion chambers. It was a long stroke, small bore engine, yet it made the most power for its size of any engine they had tested to date.

1951 Hemi V8John Platner, testing different configurations on the single-cylinder engine, found the Hemi head was displaying characteristics opposite of what the established doctrine indicated. The Hemi limited knocking. It had far superior volumetric and thermal efficiency. With a compression ratio of 7.0 : 1, the Hemi beat the L-head which required a compression ratio of 10.0 : 1 to achieve the same results. The overhead valve setup was better, but had losses in volumetric efficiency, and the valves did not last.

With hemispherical heads, the intake valve was close to the manifold and carburetor, and the exhaust valve was more efficient. Because of this, the heads extended valve life, aiding in effective uniform valve stem cooling and valve seat cooling inside the chamber.

With that information in hand, James Zeder elected to go ahead and test the head on one of Chrysler's existing engines. A double overhead camshaft driven by a dual chain had to be used with it; with that, a modified Chrysler 6 cylinder engine was installed in a Chrysler car. Wallace Zierer, who was in charge of getting results in actual road test conditions, reported significant power increases, using standard 80 octane fuel. The Hemi head 6 cylinder engine actually being smoother than the flathead 6 cylinder, with a nearly undetectable level of noise and vibration at idle speeds.

Chrysler Corporation at Hemi time: caution and complacency

The Airflow had been a sales flop. It nearly sent DeSoto, which had only an Airflow car, into insolvency. Chrysler brand had a conventionally styled companion (Airstream), which kept the wolf from Chrysler’s door in 1934.

firepower hemi engineWalter Chrysler stepped down from his own company the next year. He complained about his own engineering staff. Some speculate he was displeased with their caution in getting the Airflow to market (see earlier sidebar). It set the mood in Chrysler after the failure of the Airflow.

After allowing the Airflow to die a slow death, Chrysler Corporation did not reach out to any innovative style or new engineering for nearly two decades.

A prime example was transmissions. In 1937, as the Airflow was being left to wither, Oldsmobile (along with, briefly, Buick) introduced a 4 speed semi-automatic transmission with planetary gears. It used a standard pedal operated clutch, but had no fluid coupling. The driver had to declutch in order to shift it into reverse or a forward range when the vehicle was standing still, and also while braking to a standstill. Shifts did not require letting up the accelerator, and there was no "clunking" into the next higher gear. The two forward ranges could be used in sequence to get four speed operation. The transmission would automatically shift into fourth when needed with no pause, as was required in Chrysler's M6. Optionally, the driver could move from a standstill in the "H" range, in which the transmission only used first, third, and fourth. The transmission provided full throttle downshift for passing. Acceleration was leisurely, but it was the first real attempt at innovation in transmissions. It was offered across the board in 1938 (and in the Buick Special, but their rigid torque tube made shifts harsh and hurt reliability, so it was soon dropped). 28,000 installations were recorded. The industry was put on notice with that.

Chrysler's first "torque converter" was technically a fluid coupling, which converted torque into forward motion without a clutch.

Chrysler installed a torque converter ahead of a conventional clutch, which drove a regular three speed transmission. It had the similar effect of clutchless driving in that the car could be left in third gear (or whatever gear was selected) all the time. You only had to use the clutch when shifting gears. Acceleration was leisurely, but it worked, and kept cost of development low.

It took Chrysler two years to get that far. Just after "Fluid Driving" was introduced in 1939, on top of the line Chrysler cars only, Oldsmobile shot by Chrysler with the first fully clutchless truly automatic transmission, the Hydra-Matic, starting on the 1940 model-year cars. People couldn't get enough of the $57 option. Although it operated through a complex set of gears, clutches, and brake bands, it was solid, rugged, and reliable. The next year, Cadillac had the Hydra-matic in its car lines. In 1948 it made its way to Pontiac, and through the 1950s ended up in Nash, Hudson, Kaiser, and Frazier automobiles. (Dates corrected by Randle Blankenship.)

Hemi Anderson, after 48 years as a Mopar mechanic, wrote: “The M6 transmission had no bands. It had synchronized low and high ranges and was governor/solenoid operated. With the fluid drive coupling they were called Gyro-matic and with torque converter (V8 only), it was called Gyro-torque; this was introduced with the 1953 Dodge Red Ram V8, its only year in the Dodge. Powerflite followed in 1954.

Finally, in 1941, Chrysler introduced fluid drive to the Dodge lines and the M6 to the Chrysler and DeSoto lines. (No explanation for not giving either to Plymouth, their best selling car, though cost was probably an issue.) It was a semi-automatic, less complex, using engine vacuum to operate the bands in Low or High ranges for the four speeds. The “Vacu-matic” was less than could have been expected from such a great team of engineers.

Chrysler Corporation, as it entered the war years, was in a period of hibernation. The head of Chrysler, K.T. Keller, described himself as "a machinist by trade." He never developed the skills that his boss had in engineering, styling, sales, and human resources. Keller was more interested in remaking the conference room than new designs; he loved to micromanage, and wouldn't take advice. The problems were being reinforced by the decline of Ford, which pushed Chrysler Corporation into being the number two vehicle producer. This status lasted past the end of the war, with Chrysler remaining number two in vehicle production in 1947 and 1948. Given the high sales figures in the warmed over 1941-style 1947 and 1948 cars, the corporation’s leaders ignored the styling changes and engineering innovations coming from the other car companies, causing them to permanently lose (by a great margin) their #2 status.

The production version of the Chrysler Hemi V8 gets approved, with tough standards

Into this climate came the younger brother of Fred Zeder, James, leading an innovative, aggressive group of engineers, who wanted to build a hemispherical head, compact-block, 90 degree V-8 to power Chrysler cars.

When James Zeder made his presentation for the new V-8, his own brother, Fred Zeder, told the group that Chrysler had made its money on straight engines. Fred would have no part of a V-8 and never would. I can't imagine how James must have felt with that from his own brother.

John Platner and William Drinkard, who had become Manager of the Engine Development Department in 1943, refused to give up on a compact Hemi-headed V-8. Cadillac and Oldsmobile were working diligently on their own compact V-8 engines, for introduction in model year 1949. Taking the concept to the boardroom resulted in some heavy arguments. Research experts were brought in and confusion reigned. Finally, the Chief Operating Officer stepped in.

The normally conservative K. T. Keller, who had been personally selected by Walter Chrysler, said to Drinkard: “Bill, I think you have the right plan.” That settled the issue. Within a few weeks, in 1948, the engineers had a 330 cubic inch 90 V-8 with Hemi heads running in the laboratory. Designated the A182, this engine was used on a dynamometer to evaluate its performance and characteristics. After many tests, Chrysler management was suitably impressed. They gave the O. K. for an engine of this size and type to be designed for production. The Hemi was to be!

With the order in hand, Mel Carpentier's department built the prototype Hemi V-8. Designated model A239, it had a slightly higher displacement at 331 cubic inches, and was shorter and lighter than the A182. It was built with manufacturing in mind. William Drinkard, head of engine development, laid down his demands: he wanted a 100,000 mile engine and would accept nothing less. It was a major effort to achieve those standards, but Drinkard was resolved. No major parts, such as bearings, valves, pistons, and rings, were to be replaced at anything less than 100,000 miles.

A311 Hemi engine from Chrylser

A major obstacle was camshaft wear. It was Chrysler's first attempt at a production overhead valve engine, and they were not familiar with valve loading, which caused the area between the valve tappets and the camshaft lobe to wear very quickly. Some of the prototype engines failed right in the engine plant. They wouldn't have gone a hundred miles, let alone 100,000.

Burton Bouwkamp wrote: “The first serious problem that I encountered [as a resident engineer at Jefferson Avenue] was premature camshaft lobe wear. We were failing camshaft lobes in the first 20 minutes of engine operation. It took several months of 24/7 laboratory work at Central Engineering to solve this problem. We eventually changed tappet material, added a special coating to the tappet face, changed tappet and cam profiles to promote tappet rotation and added an anti-scuff additive (ZDDP) to the break in oil. We solved the problem - which was so serious that it threatened production of the Firedome V8 engine.”

Bob Rodger (later to be head of development of the 300) was called in with a team to assist in solving the wear problem. With a lot of trial and error, eventually the highly skilled engineers did resolve the issue, with a change in the tappet material and the method in which the face of the tappet was formed, to reduce the valve unit load; they also added a graphite coating and specified an additive for the engine oil.

Another major hurdle was doing spark plug changes without taking off the large valve covers. This was finally resolved by using a steel tube that went through the valve cover, a long ceramic boot over the spark plug, and an O-ring to seal the tube against the valve cover to prevent oil leaks. The spark plug tubes and wires were put underneath a cover that had the wires exiting at the back of the engine which gave the new V-8 a clean look.

bob rodger

Other engine improvements included shot peening the crankshaft to reduce fatigue and having it machined to remove any tool marks or surface roughness. The tappets were hydraulic, quieting and smoothing operation, and increasing valve life through constant control of opening and closing. Chrysler worked with Carter on a water jacketed carburetor with an integral automatic choke, to ensure that the new engine would not stall or develop ice within the carb. A dual breaker ignition was developed to insure constant, hot sparking while maintaining a reserve of ignition voltage.

Chrysler 331 Hemi engineFinally, after over 8,000 hours of rigorous dynamometer testing, and more than 500,000 miles of road testing for reliability, the Chrysler V-8 was ready for production. Based upon the data submitted from all the tests, the engine was finally ready.

Along the way, the new engine had been designated "Fire Power." So certain were the management team of the success of this engine that some months into the testing of the Fire Power, orders had been sent out to DeSoto and to Dodge to submit proposals for a Hemi V-8 of their own. Plymouth seemed to have been left out, a portent for the future, though it might have made sense at the time — a V8 was still a premium engine, and Chrysler’s was a premium unit even for a V8.

Introduced in the fall of 1950 as a 1951 model, the Fire Power V-8 was on option in the Saratoga (except for the coupe), while it was standard in the New Yorker and Imperial. The Windsor made do with the six.

The FirePower was an oversquare engine; the bore (3.81 inches) was larger than the stroke (3.63 inches). The intake valve was 1.81 inches; and positioned 58.5° across the hemisphere was the 1.5-inch-diameter exhaust valve, both actuated by pushrods operating rocker arms. The rockers rode on twin shafts. It was well damped, and the crankshaft rode on 5 main bearings.

Chrysler designed the pistons to be able to "slip" between the crankshaft counterweights at the bottom of the stroke, for a smooth idle, with less friction and slower wear characteristics. The engineers also built the Fire Power to run with slower piston speeds which ensured long piston and ring life.

The block was light, short, and rigid. With a two barreled carb it made 180 horsepower (gross) and 312 foot pounds of torque. The introductory compression ratio was 7.0:1. Some criticism was leveled at the weight of the engine, in particular the Hemi heads; a single Hemi head, fully assembled, weighed 119 pounds, while a Cadillac engine head weighed 93 pounds. Critical comments had less sting because both engines weighed in at 700 pounds. The Hemi beat out Cadillac's V-8 by 20 horsepower while using less squeeze than that Cadillac's 7.5 : 1 ratio. The Cadillac and Fire Power V-8s measured out 331 cubic inches. Whether making the engine the same size was deliberately done on Chrysler's part is a matter for speculation.

From the start, performance was on everyone's mind. Chrysler installed the FirePower into a Saratoga Club Coupe, the lightest Chrysler-brand car of the day; released in July of 1951, the FirePower Saratoga Coupe was a response to Oldsmobile’s installation of a V-8 into their 88 Coupe, in 1950. The Saratoga was a real firecracker right off the production line. It would sprint the car from rest to 60 miles an hour in 12 seconds flat — beating Cadillac's 13.5 second run, and Olds' 12.5 second time. It ran the 1/4 mile in 18 seconds at around 82 miles an hour, about as fast as any stock car off the showroom floor. The Chrysler New Yorker Convertible was chosen as the pace car for the Indianapolis 500 race.

Using a new Chrysler Club Coupe on a New Yorker chassis, Tommy Thompson drove the Hemi to its first win at the Detroit Fair Grounds in front of Ford and GM executives. It was a half mile dirt track of 250 mile duration.

The FirePower had ample reserves of untapped horsepower. For the time being, Chrysler was interested in further development and improvement of the Hemi, but not high performance.

In March of 1952, James Zeder (now Vice President of Engineering) and some of his team presented a white paper to the Society of Automotive Engineers. Right after the meeting he was mobbed by what he called the "hot rod" boys. They were over enthusiastic, boisterous, even obnoxious. But as Zeder recalled, “they were so darn involved with maximum horsepower out of our FirePower, I just couldn't help being intrigued with what they had in mind as well as listening to their suggestions.”

With that, performance testing was commenced in the Chrysler engine labs on the Fire Power. While the testing progressed, Mr. Zeder kept in touch with his adopted gang of "hot rod" boys. He listened to and passed along their suggestions on how to make the Hemi "grow."

cutaway view of the Chrysler Hemi engine - 331The first investigation involved the compression ratio and volumetric efficiency. Ratios of 7.5 : 1, 10.0 : 1, and 12.5 : 1 were tried, with the rest of the engine untouched. The 12.5 : 1 pistons achieved a 15 % increase in horsepower; the 7.5:1, a 10% increase. That translated into about 228 horsepower. But it would run only on aviation gasoline of 130 octane.

For volumetric efficiency, the stock exhaust headers were replaced for streamlined units. That alone increased torque from 312 foot pounds to 330, and horsepower went up to 193. Gaining confidence, they explored other areas for improving volumetric efficiency: the valve ports, intake manifolding, carburetors, and camshafts.

The Hemi heads had plenty of room for larger valves. The ports were smoothed, and then opened up .125 of an inch on the exhaust and .25 of an inch on the intake. Engineers developed a set of 4 inline, single barrel carbs, each feeding two cylinders. They experimented with different grinds on the camshaft. Chrysler Corporation, no stranger to electronics by any means, was one of the first companies to utilize computer-generated simulations for camshaft testing.

H. David Braew wrote: Many years ago I worked for the Getty Oil Company. In those days, Getty had its own well servicing equipment (today you hire specialist firms - for more money and less productivity). The best service unit was powered by an industrial 392 Hemi. That thing was known for its ability to pull the pipe out of wells faster and easier than any of the other service equipment, powered by Hall-Scott, Detroit or Cummins engines (in the 1950s and 60s).

Lab results did not really surprise anyone. The test engine, designated K-310, responded well. In the first run with a slightly hotter than stock cam, along with the high flow heads and standard flow carburetion system, the FirePower achieved 225 horsepower and 332 pounds of torque. Next using the midrange camshaft, which gave the best all around performance, the Hemi stepped up to 275 horsepower and 352 pounds of torque. In the final test, a high performance grind camshaft, along with the four carb high speed manifold was tested. The K-310 put out 308 horses with a twist of 361 foot pounds — from stock pistons. To settle the issue, the 12.5 : 1 pistons were installed. This combination spun out 353 horsepower and 385 foot pounds of torque.

Although satisfied, James Zeder maintained his composure. He wrote of the tests that "the basic Fire Power cylinder gives performance comparable with Indianapolis engines, which have been developed for power without regard to any other purpose." In conclusion, he stated: "we remain unalterably convinced that, in the battle of the combustion chambers, the spherical segment chamber has demonstrated unquestionable supremacy."

In the meantime, in 1952, the DeSoto Division introduced its version of the Hemi head V-8. It was a 90 degree design of 276 cubic inches and was rated at 160 horsepower. It resulted in 50,000 installations. While smaller, the DeSoto V-8 had all the same characteristics of the Chrysler Hemi.

Cadillac gave Chrysler a little "touch" in 1952 by upping the horsepower ante to 190 in its 331 V-8, through a boost in compression. Chrysler was not too concerned, the Chrysler was still faster. A 1952 Chrysler was champion of the beach speed trials conducted by NASCAR at Daytona Beach, Florida.

The third and final version of the original Hemi design was introduced by Dodge Division in late 1952 as a 1953 model. It was a 90 degree design of 241 cubic inches that was rated at 140 horsepower.

The original Hemi in racing

In 1953, an engineer who was involved in resolving problems with the Fire Power, a key member of William Drinkard's team, proposed that Chrysler build a car around a high performance Fire Power engine; the car was to ahve excellent handling and unique styling. His idea was taken seriously, and Bob Rodger was instrumental in seeing the Chrysler 300 come to life.

Outside of the Chrysler Corporation, the Fire Power was used in some racing and as power plants for other car makers. Briggs Cunningham was one notable builder that saw the raw potential of the Hemi. His goal was to win the 24 hour race at LeMans. To qualify, he had to build 25 cars. He received some technical information assistance from Chrysler for his efforts, however, any engine modifications were done solely by him with parts he either built or obtained from other sources. He raced his cars for three years, and retired from the circuit in 1955. He did race in LeMans in 1952, finishing in fourth, a remarkable first effort.

James Zeder was immensely proud of the Hemi engine. He also had a desire to see it be used in racing. He had an eye on the Indianapolis 500, the greatest spectacle in racing at the time, and had the lab begin experimenting with the 331 Fire Power.

John Platner and Don Moore were deeply involved in building the "Indy" engine (A311). It was built with 8 Hilborn fuel injectors, big valves and ports, streamlined big exhaust manifolds, and a sort of modified camshaft that made the engine make "burbling" noises at idle. Under the quise of testing tires for Firestone and Good Year, the engine was installed in an Indianiapolis special racer. With the A311 engine, it easily ran the same lap speeds as the specialized Offenhauser and Miller racing machines.

The A311 was put to the test in June of 1954. Shortly after the 1954 Memorial Day 500, Chrysler Corporation dedicated its Chelsea proving grounds. The first four finishing Indy drivers were invited to bring their racers over to christen the 4.7 mile long oval race track. With wide lanes, and banked curves, the drivers were able to hold their cars wide open all the way around. The single fastest lap that day was made at 179 miles an hour. Then the Kurtis Kraft tire test car with the Hemi A311 made a couple warm up laps. Coming out of the 4th turn, the driver opened the engine up. It screamed by the centrally located pits and timing stand. Its deep Hemi bellow could be heard all the way around the long track. When it went by the next time, it was rolling at 182 miles an hour. And then did it again, and then again. Mr. Zeder and his engineers were delighted. They knew that a stock block engine with push rod technology could easily compete at Indy, and most likely, easily win.

It was not to be. The news of the test was given wide publicity. In a flurry of activity, the engine size rule was changed to allow only a 272 cubic inch limit for stock engines. A slight increase in piston stroke easily achieved the 272 size. However, down on power, it didn't qualify. It would not be the last time that rules were changed by sanctioning bodies when Chrysler came out to play.

1953 saw Cadillac reach out and "touch" Chrysler again. The Caddy V-8 now had 210 horsepower. To add sting, Oldsmobile had increased its V-8 to have 165 horsepower; but it was Buick, Chrysler’s direct competitor, that prompted Chrysler to move quicker. GM's prestigious division introduced a 322 cubic inch V-8 that had a top output of 188 horsepower.

On the beach at Daytona in the NASCAR speed trials, Chrysler Fire Power V-8 cars got beaten by Cadillac. The Caddy flew over the sand at 113 miles an hour. It snapped past the Chrysler, reaching 60 in 11.3 seconds. For all its punch, the Oldsmobile took a back seat to the 1953 Dodge which set a record of 102 miles an hour. However, it wasn't that easy. Hudson, with a big flathead 6 cylinder engine, cleaned up on the racing circuit. In another notable first, Lee Petty, who had switched from Plymouth to the V-8 Dodge, gave the Dodge division its first NASCAR victory. Petty had given Plymouth its first NASCAR win in 1949.

The 1954 model year saw the first stages of performance improvements in the Hemi engines from the Corporation. Chrysler Fire Power V-8s now had 195 horsepower by bumping up the compression ratio to 7.5 : 1. Another version had a four barrel carburetor that put out 235 horsepower. That beat out Cadillac, even with Caddy’s increase to 230 horsepower. Buick increased its punch to 200 horsepower. Not to be left out, DeSoto also increased compression to boost output to 170 horsepower. But, Oldsmobile bored out the 303 to 324 cubic inches with an output of 185 horsepower. Dodge bumped the compression ratio for an increase to 150 horses.

Taking note of the previous year’s racing success, and shared information from Chrysler, supplier Offenhauser made an aftermarket manifold for a four barrel carburetor that would fit the Dodge Hemi V-8, sold as a dealer-installed option. Whether this was done in conjunction with, or because of, Dodge's selection as the Indianapolis 500 race pace car has never been clarified. With the manifold and 4 barrel, the 241 cubic inch V-8 was estimated (no actual figures were given) at 180 to 185 horsepower.

Lee Petty drove a 1954 Hemi powered Chrysler to victory in Daytona and went on to win the NASCAR Championship. The big Chrysler also dusted the Cadillac in NASCAR speed trials, setting a record at 118 miles an hour.

The 300: a Hemi showcase and the first production car with 300 horsepower

One of the biggest advances in automotive history was introduced in January 1955. It should have come as no surprise since Chrysler had already built a 300 (claimed) horsepower engine from the 331 Fire Power in 1951! It was used in the K-310 concept vehicle built by Ghia in Italy. In 1952, another concept car, using a similar engine powered the Ghia built C-200. Clear indications for the future.

Chrysler C-200

Chrysler Corporation held its 1955 model year introduction five days after Ford and nine days after Chevrolet, in what was believed would be like saving the best for last. Virgil Exner's "Forward Look" seemed to have just dropped from outer space onto the Chrysler Corporation vehicles. If you put the 1954 cars alongside the 1955s, you would swear that there was no way that they could have been built by the same company. At my Dad's dealership, floor traffic was the heaviest that it had ever been. Yet, the real show stopper was yet to come.

January 7, 1955 was the date that dealers were allowed to place the C-300 on their show room floors. It was an absolute marvel. The first day, it was almost a mob scene! At our store, the show room was jammed all day long and every day thereafter for a whole week.

1955 Chrysler C-300

Bob Rodger's suggested concept in 1953 came through as he had envisioned. The Chrysler C-300 was the first production car to have 300 horsepower. It was unique. It was special. It generated enormous interest. It was the hottest thing on wheels at that time. It blew everybody away. It wasn't inexpensive by any means either. Base price was $4,035. Pretty steep in comparison to a fully loaded Plymouth that could be had for $2,246!

On the street, people would turn and stare when a 300 went by. Curiosity seekers would follow a 300 and bombard the operator with questions when they parked. When one did park, a crowd would gather around it. Hard to imagine, but that automobile created a special niche.

To achieve 300 horsepower, Chrysler followed established performance techniques. High flow heads with larger, cleaner ports and valves that were operated from a speciality camshaft, through solid valve tappets, bumped up compression to 8.5 : 1, combined with dual exhausts, and two four barrel carburetors. It was not exotic. It was totally reliable, required no real special effort to operate, delivered a smooth but firm ride, and had some of the best brakes in the entire industry.

After one of the first road tests of the C-300, Tom McCahill, writing for Mechanix Ilustrated, was effusive in his praise. He consistently got to 60 miles an hour in under 10 seconds; his average was 9.8 seconds. That was a bomb shell, a record like running the four minute mile. He put the C-300 on the highway and got up to 130 miles an hour before he ran out of road. “It was as strong as Grant's Tomb, and 130 times as fast.”

On the beach at Daytona, a stock C-300 confirmed Uncle Tom's finding by posting a 128 mile an hour timed run. It was the fastest vehicle there. Tim Flock, driving a C-300, won the NASCAR Championship. All fitting tributes to the engine that Chrysler advertised as "the most powerful production car built in America" with "the greatest, safest power in any American car." Which it was!

Meanwhile, the DeSoto Hemi was bored a bit to make 291 cubic inches; with a four barrel carburetor and dual exhausts, it made 200 horsepower. Over at Dodge, the smallest version of the Hemi was also bored to make 270 cubic inches. A special modification engine package, dealer installed, pushed output to 193 horsepower and 245 foot pounds of torque.

For 1956, the 331 cylinders were bored out 0.130 of an inch, to expand cubic inches to 354.06. Compression was raised in an altered set of heads to 9.0:1. The exhaust manifolds were changed. Overall, the 300B gained a rated horsepower of 340; a dealer-installed, optional set of heads bumped the compression ratio to 10.0 : 1 and gave the 300B a 355 horsepower rating. It also made it the first production engine to exceed one horsepower per cubic inch. Chrysler wasted no time to point that out.

Tom McCahill was again enthusiastic about the 300, calling it "motorized dynamite, a connoisseur's car not meant for timid driving" and "Unmatched in a class by itself."

426 Hemi

Mr. McCahill, who owned several 300s for his personal cars, also praised the suspension and handling qualities of the 300B by adding: "these cars hunker in to a corner like a starving dog clamped on a bone." The engine wasn't all there was to the 300: he called it the "best handling car I have ever driven straight from the showroom." Over several timed runs, Uncle Tom got an average 0 to 60 mph times of 8.2 seconds.

With the new 355 horsepower V-8, the 300B allowed Chrysler to again clean up the beach at Daytona. It set a new record of 139 miles an hour. Tom McCahill pointed out that running on wet sand was not a real good way to determine speeds. He was correct in stating that it in no way provided the best surface for traction. His own speed tests on a dry asphalt road got very near 140 miles an hour with the 340 horsepower engine.

Buck Baker was crowned NASCAR Champion driving a 1956 Chrysler 300B.

The Hemi also powers DeSotos and Dodges

Chrysler also paid attention to the two other Hemi engines in its corporate stable. The DeSoto got a new raised block with a 3.72 inch bore and a 3.80 stroke it made 330 cubic inches. With a power pak option, it had 255 horsepower. But it wasn't quite over for the 1956 DeSoto Hemi engine. Introduced as a late edition, the new Adventurer model had its own unique Hemi.

A small bore increase to 3.78 inches in the 330 came out to 341 cubic inches. Output rose to 320 horsepower - pretty close to the Chrysler Hemi. DeSoto brought a couple of cars to the Daytona Speed Week; however, after the Adventurer made a run of 144 miles an hour, it mysteriously had major engine problems and did not return. Perhaps a politically correct move so as to not embarrass the 300? Shortly after, a DeSoto Adventurer convertible was chosen to pace the Indianapolis 500.

Sister Dodge also introduced a new raised block that had a bore of 3.63 inches combined with a stroke of 3.60 inches which translated into a 315 cubic inch displacement. In standard trim, it was rated at 218 horsepower. There were two other factory options. One was a 230 horse offer, and the other gave out 260 horsepower. As well, in what seemed to be a standard at Dodge, a dealer-installed option which consisted of a twin four barrel carburetion manifold was also offered. No figures were made public, however, it was generally accepted that this engine made 290 to 295 horsepower. In the newly introduced D-500 trim, that option turned the Dodge car into a racing terror at drag strips all over the country. It also propelled the 1956 Dodge down Daytona's beach at 130 miles an hour.

1957 was a banner year, especially at the Chrysler Corporation. Industry leading styling combined with industry innovative engineering sent the public clamoring back to Chrysler Corporation dealer showrooms in droves. A hotly debated issue concerned the body quality of all Chrysler divisions in 1957.

The 1957 styling had been intended for introduction in 1960. Virgil Exner pushed to get the 1960 style introduced in 1957. Engineering did not have much time, so a whole lot of corners were cut to get the cars on the production line. Fit and finish left much to be desired. Inappropriate rattles, squeaks, wind noise, and terrible water leaks were built right in! Each car sold to a friend in 1957 turned them into enemies within a few short weeks! However, in all fairness, it should be pointed out that by doing so, Chrysler then dropped itself to the approximate level of the norm of the rest of the American auto industry. Ford was no better, and may have actually been worse. Chevrolet seemed better because they produced so many cars, in reality they were not of any better quality.

The area that the 1957 Chrysler Corporation shone in was the hardware underneath those "rust in place" bodies. The Fire Power was boosted again in displacement by boring to 4.0 inches and stroking to 3.90 inches. That equated to 392 cubic inches. In standard form it belted out 325 horsepower. Remember, this is still the same block introduced in 1955.

For the new 300-C, the output went up to 375 horsepower. Higher compression heads made 390 horsepower.

Along with the new bodies came the torsion bar suspension, and the ultimate in automatic transmissions, the Torqueflite three speed.

1966 chrysler street hemi enginesTom McCahill again went enthusiastic about the performance. Utilizing several runs, he whipped the big car from 0 to 60 mph in an 7.8 seconds. On the highway, he made 140 miles an hour. He praised the handling due to the torsion bar set up, claiming that it "set into a groove better than a needle on a record." He effused that the 300 series were a collection of "beautiful brutes" suggesting that they were for "hairy chested drivers." He went on to describe the driving experience as about as "subtle as wearing velvet boxing gloves."

With the 300C, Chrysler again lead the way at the Daytona Speed Week. However, the performance was off, with the fastest 300 making a one way run of 138 miles an hour. At first the Chrysler engineers thought that the beach surface, which varied from year to year, was the culprit. Certain that they had a 145 mile an hour car, they took the same car to the Chelsea Proving Grounds outside the Chrysler Headquarters. Opened up on the 5 mile track, the 300C only made about 140 miles an hour. The driver reported a heavy wind whistle at high speed. Finally, it was recognized that the windshield trim for the front of the roof stuck out nearly an inch, making an effective air brake. Using clay they formed the top of the windshield into a smooth, clean shape with no edges. The same car went out and ran 146 miles an hour with the clay covering the windshield trim. (Editor’s note: the lesson was unfortunately only applied to performance and racing cars.)

The 392 C300 engine (used only in the 300C)

Not forgetting its other Hemi engines, Chrysler boosted DeSoto and Dodge in 1957. The 1957 DeSoto was bored out slightly again to 3.80 inches with a 3.80 inch stroke, a totally "square" engine. It measured 345 cubic inches. With two four barrel carburetors, it also produced 345 horsepower, an industry first. Chrysler did not capitalize on it as it should.

Technically, the 300B had more than one horse per cubic inch, however, that was a specialized optional engine. Chevrolet was crowing about their new 283 ci V-8 making 283 horsepower. That too was a specialized engine, and a $536 option at that! Big money in 1957. The DeSoto 345, on the other hand, was a standard engine that required no special order. An Adventurer with the 345 was good to get to 60 in 8 seconds. It was tested by Mechanix Illustrated and Motor Trend where both testers obtained top speeds of 140 miles an hour.

At Dodge, the 315 Hemi was bored to 3.69 inches with a 3.80 stroke that came to 325 cubic inches. It was available with three different power choices, starting at 245 horsepower, moving up with increased compression to 260 horses, and, optional for the D-500, a full 285 horsepower. A dealer installed manifold and dual four barrels boosted this 325 to 310 horsepower. However, the new body style did not lead itself to racing as had the 1956. Dodge cars were losing out. Quick action by Dodge management made the Chrysler 354 Hemi an option, but 1957 was an off year for Dodge performance.

With quality looming large in 1957, not much money was allocated to restyling for 1958. To its credit, Chrysler engineering was engaged in a crash "reverse" engineering project to improve quality. They were successful, especially for ending the water and dust leaks. Somewhere, along the way going into 1958, a little bit of sting was lost, and Chrysler no longer actively sought a performance image; perhaps it sought to not draw as much attention to that due to the high incidence of poor quality control exhibited by the 1957 models. Most of the Corporation cars stood pat for 1958, so the public still saw quality problems in the same style cars.

The first-generation Hemi fades away

fuel injected badgesThe former fierce growl of the Hemi was about to be silenced. 1958 was the last hoorah. The 300D had the same engine as the 300C, except the D was rated at a standard 380 horsepower. Experimenting with fuel injection, Chrysler had Bendix build an electronic system that produced 390 horsepower from the 392 Hemi. It was troublesome and only 16 cars had it installed; all were changed to carburetors for free by Chrysler. [Electrojector system]

The Hemi had reached its safe limit for boring out and the manufacturing process for the 1958 engine run had changed. The hardened crankshaft was replaced by a drop steel forged unit. The optional "chassis package" was not offered. The rear axle ratio options were drastically reduced.

At the Daytona Speed Week, the 300D was not what the earlier marques had been. It won the flying mile, but was beaten by Pontiac for top speed, although the Pontiac was still not up to the 139 mile an hour mark set by the 300B in 1956. Tom McCahill still called it "America's best sedan." He could whip the 300D to 60 in 9.0 seconds. The 1957 and the 1956 could outrun the 1958. The "D" managed a top speed of 135 miles an hour.

There was only one other Hemi engine left in 1958. That belonged to Dodge. It was the 325 cubic inch model. It was sad because it was relegated to mundane hauler duties in two different tunes. The first had a rating of 252 horsepower and was standard in the Coronets. The step up was 265 horsepower and that was the standard engine in the Royal. The top engines were now wedge heads. Dodge had two in different configurations.

DeSoto made no pretext in 1958. Its Hemi bellow was forever silenced. Now it made due with two wedge head V-8s that were "corporate sized," displacing the same as Dodge.

For 1959, Chrysler Corporation no longer offered the Hemi in its Chrysler marque cars. However, the Hemi wasn't quite gone yet. The standard engine in the Crown Imperial (yes, the top of the line) was the 325 horsepower 392 Hemi V-8. But that was the end for the first generation Hemi engines, at least the ones built by Chrysler.

The Don Garlits Museum of Speed in Ocala, Florida has numerous first-generation Hemis; Don loved those engines. All of his “Swamp Rat” dragsters were powered by the Chrysler Hemi. He also built stock-appearing Fords that had the Hemi stuffed under the hood.

So great was the potential of the Hemi V-8 that two specialty manufacturers sprang up, devoted to building only that engine. A host of aftermarket parts were manufactured solely for the Chrysler Hemi engines. The Hemi headed Chrysler based V-8 engine is responsible for virtually all the drag racing records in the world. You cannot compete in the top fuel categories in any class in the IHRA or the NHRA unless it is a Hemi V-8 [even if it has Ford decals stuck over it]. James Zeder is still smiling, wherever he is. Bill Drinkard is probably with him and just as proud too.

While they may be rather rare today, there are still some undiscovered first generation Hemi V-8 engines out there waiting to be reborn. They were not just used in cars, either. Dodge trucks had them. Many farm applications like sprayers and water irrigation pumps had them. They also powered several manufacturers' boats. And in a very special application, they cranked up the Federal mandated civil defense sirens in big cities, towns, and villages all across America in the 1950s and 60s. Check those wrecking and junk yards closely. You never know.

Also see Fred Zeder on why they chose the Hemi • Original Allpar Old Hemi coverage

Classic Hemis 426 HemiOld Hemi History • 392 Crate HemiDevelopmentPlane Hemi
