![Marine Hemi](https://upload.wikimedia.org/wikipedia/commons/9/9c/Marine_Hemi.JPG)
The Chrysler Hemi engines, known by the trademark Hemi, are a series of American
V8 gasoline engine
A petrol engine (gasoline engine in American English) is an internal combustion engine designed to run on petrol (gasoline). Petrol engines can often be adapted to also run on fuels such as liquefied petroleum gas and ethanol blends (such as ''E ...
s built by
Chrysler with
overhead valve
An overhead valve (OHV) engine, sometimes called a ''pushrod engine'', is a piston engine whose valves are located in the cylinder head above the combustion chamber. This contrasts with earlier flathead engines, where the valves were located b ...
hemispherical combustion chamber
A hemispherical combustion chamber is a type of combustion chamber in a reciprocating internal combustion engine with a domed cylinder head notionally in the approximate shape of a hemisphere (in reality usually a spheric section thereof). An en ...
s. Three different types of Hemi engines have been built by Chrysler for automobiles: the first (known as the Chrysler FirePower engine) from 1951 to 1958, the second from 1964 to 1971, and the third beginning in 2003. Although Chrysler is most identified with the use of "Hemi" as a marketing term, many other auto manufacturers have incorporated similar designs. The engine block and cylinder heads were cast and manufactured at
Indianapolis Foundry
Indianapolis Foundry was a Chrysler automobile foundry located at 1100 S. Tibbs Avenue in Indianapolis, Indiana. The factory opened in 1890 as the "American Foundry Company" and was purchased in 1946 by Chrysler and operated as a subsidiary. It ...
.
During the 1970s and 1980s, Chrysler also used the ''Hemi'' name for their Australian-made
Hemi-6 Engine and applied it to the 4-cylinder
Mitsubishi 2.6 L engine installed in various North American market vehicles.
Concept
A hemispherical
cylinder head
In an internal combustion engine, the cylinder head (often abbreviated to simply "head") sits above the cylinders and forms the roof of the combustion chamber.
In sidevalve engines, the head is a simple sheet of metal; whereas in more modern ...
("hemi-head") gives an efficient combustion chamber with an excellent surface-to-volume ratio, with minimal heat loss to the head, and allows for two large
valves
A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fitting ...
. However, a hemi-head allows no more than two valves per cylinder, and these large valves are necessarily heavier than in a
multi-valve
In automotive engineering a multi-valve or multivalve engine is one where each cylinder has more than two valves. A multi-valve engine has better breathing and may be able to operate at higher revolutions per minute (RPM) than a two-valve engine ...
engine. The intake and exhaust valves lie on opposite sides of the chamber and necessitate a "
cross-flow Crossflow may refer to:
* Ford Crossflow, the 1967 version of the Ford Kent engine
* Crossflow cylinder head
* Cross-flow fan, a type of mechanical fan
* Cross-flow filtration
In chemical engineering, biochemical engineering and protein purificat ...
" head design. Since the combustion chamber is a partial hemisphere, a flat-topped piston would yield too low a
compression ratio unless a very long stroke is used, so to attain the desired compression ratio the piston crown is domed to protrude into the head at top dead center. The result is a combustion chamber in the shape of the space between where the domed piston stops and the dome shape in the head receiving it.
The hemi-head design places the
spark plug at or near the center of the chamber to promote a strong flame front. However, if the hemi-head hemisphere is of equal diameter to the piston, there is minimal
squish for proper turbulence to mix fuel and air thoroughly. Thus, hemi-heads, because of their lack of squish, are more sensitive to fuel
octane rating; a given compression ratio will require a higher octane rating to avoid pre-
detonation
Detonation () is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations propagate supersonically through shock waves with s ...
in a hemi engine than in some conventional engine designs such as the wedge and bathtub.
The hemi head always has intake and exhaust valve stems that point in different directions, requiring a large, wide cylinder head and complex
rocker arm
In the context of an internal combustion engine, a rocker arm is a valvetrain component that typically transfers the motion of a pushrod to the corresponding intake/exhaust valve.
Rocker arms in automobiles are typically made from stamped steel ...
geometry in both
cam-in-block A cam-in-block engine is where the camshaft is located in the engine block. Types of cam-in-block engines are:
* F-Head Engine
* Flathead engine
* Overhead valve engine (the only type where the valves are above the combustion chamber)
* T-head eng ...
and
single overhead cam engines (dual overhead cam engines may not have rocker arms). This adds to the overall width of the engine, limiting the vehicles in which it can be installed.
Significant challenges in the commercialization of engine designs using hemispherical chambers revolved around the valve actuation, specifically how to make it effective, efficient, and reliable at an acceptable cost. This complexity was referenced early in Chrysler's development of their 1950s hemi engine: the head was referred to in company advertising as the ''Double Rocker Shaft'' head.
World War II
Chrysler developed their first experimental hemi engine for the
Republic P-47 Thunderbolt
The Republic P-47 Thunderbolt is a World War II-era fighter aircraft produced by the American company Republic Aviation from 1941 through 1945. It was a successful high-altitude fighter and it also served as the foremost American fighter-bom ...
fighter aircraft. The
XIV-2220 engine was an inverted V16 rated at . The P-47 was already in production with a
Pratt & Whitney radial engine
The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is ...
when the XIV-2220 flew successfully in trials in 1945 as a possible upgrade, but the war was winding down and it did not go into production. However, the exercise gave Chrysler engineers valuable research and development experience with two-valve hemi combustion chamber dynamics and parameters.
In addition to the aircraft engine, Chrysler and
Continental
Continental may refer to:
Places
* Continent, the major landmasses of Earth
* Continental, Arizona, a small community in Pima County, Arizona, US
* Continental, Ohio, a small town in Putnam County, US
Arts and entertainment
* ''Continental'' ( ...
worked together to develop the air-cooled
AV-1790-5B V12 Hemi engine used in the
M47 Patton
The M47 Patton was an American main battle tank, a development of the M46 Patton mounting an updated turret, and was in turn further developed as the M48 Patton. It was the second American tank to be named after General George S. Patton, comm ...
tank.
First generation: FirePower
Chrysler applied their military experience with the hemispherical combustion chamber to their first
overhead-valve
An overhead valve (OHV) engine, sometimes called a ''pushrod engine'', is a piston engine whose valves are located in the cylinder head above the combustion chamber. This contrasts with earlier flathead engines, where the valves were located bel ...
V8 engine
A V8 engine is an eight-cylinder piston engine in which two banks of four cylinders share a common crankshaft and are arranged in a V configuration.
The first V8 engine was produced by the French Antoinette company in 1904, developed and u ...
, released under the name FirePower, not "Hemi," in 1950 for the 1951 model year. The first version of the FirePower engine had a displacement of and produced . Eventually, three of the four Chrysler divisions had their own version of the FirePower engine, with different displacements and designations, and having almost no parts in common. This lack of commonality was due in part to the three engine versions using different bore pitches (the center-to-center distance between adjacent cylinders). Chrysler and
Imperial called their versions the ''FirePower''.
DeSoto called theirs the ''FireDome''. Dodge had a smaller version, known as the ''Red Ram''. Only
Plymouth did not have a version, but retained the Dodge
poly-head engines. There was no Plymouth hemi engine until the 1964 426.
Briggs Cunningham
Briggs Swift Cunningham II (January 19, 1907 – July 2, 2003) was an American entrepreneur and sportsman. He is best known for skippering the yacht ''Columbia'' to victory in the 1958 America's Cup race, and for his efforts as a driver, team o ...
used the Chrysler version in some of his
race cars for international motorsports. A Chrysler-powered
Cunningham C-5R
The Cunningham C-5R was a sports car developed in 1953 for the Briggs Cunningham racing team.
Design
The C-5R was the successor to the C-4R and was built for use in the 1953 24 Hours of Le Mans. The open sports car had a Chrysler V8 engine, that ...
won its class in 1953. Cunningham switched away from these designs in 1959 when Chrysler temporarily abandoned the hemispherical concept in favor of the wedge-head
B engine until 1964.
Carl Kiekhaefer
Elmer Carl Kiekhaefer (June 4, 1906 – October 5, 1983) was the owner of ''Kiekhaefer Mercury'' (later Mercury Marine) and ''Kiekhaefer Aeromarine'' and also a two-time NASCAR championship car owner.
Kiekhaefer Mercury founder
Mr Kiekhaefer ...
also used the Chrysler engines in NASCAR cars owned by him from 1955 and 1956, winning the
Grand National Series The name NASCAR Grand National Series refers to former names of the following NASCAR series:
*National-level stock car series:
**NASCAR Cup Series (known as NASCAR Grand National Series between 1950 to 1970, then the NASCAR Winston Cup Grand Nation ...
championship both years.
Collectively, the 1951–1958 Hemi engines are now commonly referred to as first-generation Hemi engines, and the group can be identified by the rear-mounted
distributor
A distributor is an enclosed rotating switch used in spark-ignition internal combustion engines that have mechanically timed ignition. The distributor's main function is to route high voltage current from the ignition coil to the spark plug ...
and the
spark plugs in a row down the center of wide valve covers.
1951 Plymouth Hemi V6
There were plans in 1951 for a
Plymouth Dual Overhead Cam
An overhead camshaft (OHC) engine is a piston engine where the camshaft is located in the cylinder head above the combustion chamber. This contrasts with earlier overhead valve engines (OHV), where the camshaft is located below the combustion cha ...
Hemi V6 displacing designed by Chrysler's Powerplant Research and Engine Design division. It was meant to be a powerful, fuel-efficient alternative to
Ford's V8 and to replace
Plymouth's venerable flathead 6.
The plans were scrapped due to build costs and because of the then unusual design.
Chrysler and Imperial
All Chrysler FirePower engines are
oversquare; i.e. their
bore is larger than their
stroke.
331
This first FirePower engine, used from 1951 to 1955, has a bore of 3.8125 in and a stroke of 3.625 in for a piston displacement of , and a deck height of 10.32" ("low deck"). The bore pitch, shared by all Chrysler FirePower engines, was 4.5625", the largest of any 1st generation hemi engines. Most used a two-barrel
carburetor and produced , with the famous exception of the 1955
Chrysler C-300 equipped with dual Carter WCFB four-barrel carburetors and rated at .
The 331 engine was used in the following applications:
* 1951–1955
Chrysler New Yorker
* 1951–1954
Chrysler Imperial and 1955
Imperial
* 1951
Chrysler Saratoga
The Chrysler Saratoga is an automobile built by Chrysler. The nameplate was used from 1939 to 1952 and from 1957 to 1960 in the U.S. market, in Canada through 1965, and in Europe from 1989 to 1995. In the beginning, it was introduced as a sport lu ...
* 1952
Chrysler Saratoga
The Chrysler Saratoga is an automobile built by Chrysler. The nameplate was used from 1939 to 1952 and from 1957 to 1960 in the U.S. market, in Canada through 1965, and in Europe from 1989 to 1995. In the beginning, it was introduced as a sport lu ...
Club Coupe
* 1952
Chrysler Imperial Parade Phaeton
* 1955
Chrysler C-300
* 1956
Facel Vega FVS
* The
Chrysler air raid siren. At 138
decibels, it is the loudest siren ever made.
354
The , released in 1956, had a bore of 3.9375 in and stroke of 3.625 in, and the same 10.32" low deck height. The 300B engine was rated at , while the New Yorker and Imperial 354 engine configuration produced . For the 300B an optional version was available, making it the first American V8 to be rated at one horsepower per cubic inch. Note that was before 1972, horsepower was SAE gross. After 1972, horsepower is SAE net.
The 354 was also modified. The hemi was optimized for heavy-duty truck service. These were available with one or two four-barrel carburetors, and were offered in Dodge's heaviest-duty models as the 'Power Giant V-8' from 1957 through 1959; they were the largest of four hemi truck engines offered by Dodge in the 1950s. The 354 was also offered in certain models with
polyspheric
The Polyspheric or Poly engines were V8 engines produced by Chrysler from 1955 to 1958 as lower-cost alternatives to the Hemi engines. These engines were based on the ''Hemi'' engines, using the same blocks and crankshaft parts, but completely ...
heads rather than hemi heads. The combustion chambers on these had similarities to both hemi and wedge heads, but were closer in weight to wedge heads. Thus, both 354 poly and 354 hemi V8 engines were variously available in 1957.
The 354 engine was used in the following applications:
* 1956 Chrysler New Yorker
* 1956 Chrysler 300B
* 1956 Imperial Custom & Crown
* 1957 Dodge D-501
* 1957–1959
Dodge C Series Pickup
392
The 392 raised-deck engine released in 1957 had a bore and stroke. The actual displacement is . The deck height, at , was taller than that of the previous blocks. Because its deck was taller, the heads were cast with wider intake ports so that earlier manifolds could be used with the new heads on the new taller block. For 1958, Chrysler offered the 392 in two configurations: with 9.25:1
compression
Compression may refer to:
Physical science
*Compression (physics), size reduction due to forces
*Compression member, a structural element such as a column
*Compressibility, susceptibility to compression
* Gas compression
*Compression ratio, of a ...
and with 10:1 compression, both with a single four-barrel carburetor. A dual four-barrel version of the 392 available in the 1957-58 Chrysler 300C & 300D cars was rated at ; the 300D, and some marine and industrial engines, used a (now rare) adjustable rocker.
[''Hot Rod'' Magazine online](_blank)
(retrieved March 9, 2018) An extremely rare option available on the 1958 300D was Bendix "Electrojector"
fuel injection, with which the 392 was rated at . Due to reliability problems with the primitive onboard computer which controlled the injection system, however, 15 of the 16 300D cars built with the fuel injection option were recalled and retrofitted with carburetors.
The 392 engine was used in the following applications:
* 1957–1958 Chrysler New Yorker
* 1957–1958 Imperial Custom, Crown, and LeBaron
* 1957
Chrysler 300C
* 1958
Chrysler 300D
* 1958
Facel Vega Excellence (EX)
In the late 1950s and early 1960s,
drag racer
Drag racing is a type of motor racing in which automobiles or motorcycles compete, usually two at a time, to be first to cross a set finish line. The race follows a short, straight course from a standing start over a measured distance, most ...
s found the 392 to be a formidable engine and continued to run them competitively into the 1970s. Usual color of the block was silver.
DeSoto
![FiredomeV8,1952](https://upload.wikimedia.org/wikipedia/commons/0/0d/FiredomeV8%2C1952.jpg)
DeSoto's Hemi engines were called FireDome and served as the naming convention for the
DeSoto Firedome
The DeSoto Firedome was a full-size automobile produced between 1952 and 1959 by DeSoto automobiles, a division of the Chrysler Corporation. Introduced as DeSoto's premium line of vehicles in 1953 and 1954, the Firedome also occupied the least e ...
sedan.
276
In 1952,
DeSoto introduced its version of the FirePower with a bore of and stroke of , for a displacement of . The bore pitch, shared by all DeSoto FirePower engines, was .
Power output was . It was a hot seller, with 50,000 vehicles using the engine until it was replaced in 1954.
291
An increase in displacement to was made for 1955 by increasing the bore to .
330
The DeSoto engine was enlarged for 1956 to . Bore was the same as the 291 at , but stroke was increased to and a taller (raised-deck) block was used.
341
Displacement was increased again for 1956 (DeSoto Adventurer only) and 1957 (Firedome and Fireflite models) to . Bore was now with stroke remaining at .
The DeSoto Adventurer produced using dual Carter WCFB four-barrel carburetors.
The 1956
DeSoto Adventurer
The DeSoto Adventurer is a Full-size car, full-sized automobile that was produced by DeSoto (automobile), DeSoto from 1956 through the 1960 model year. Introduced as a four-seat high-performance sports coupe concept car, the Adventurer ended up be ...
was the premiere named high-performance version—the DeSoto equivalent of the Chrysler 300—using dual Carter WCFB four-barrel carburetors.
The Adventurer engine for 1956 used a displacement of 341 CID (3.78" bore by 3.80" stroke) and had a compression ratio of 9.5:1, using a special hydraulic camshaft profile.
345
The largest DeSoto engine for 1957 was the DeSoto Adventurer offering with square bore and stroke dimensions of 3.80 inches. The DeSoto Adventurer used dual Carter WCFB four-barrel carburetors for a rating of , producing one horsepower per cubic inch (the first American car to do so as standard equipment) utilizing a similar intake manifold to the 1956 341 Adventurer and a similar camshaft. The compression ratio remained at 9.5:1.
Dodge
Dodge's Hemi was introduced in 1953 as the Red Ram.
Dodge did not have a V8 engine until one was developed specifically for the line in 1953 based on the 1951
Chrysler hemi design, but downsized for these smaller cars. They have the smallest bore center distance of any hemi engine at . They do not share any major dimensions or components with the larger Chrysler and DeSoto hemi engines, or the Plymouth A engines. From 1955 to 1958 (see 1956 D500 Dodge D-500 cars and packages: early performance cars) lower-performance versions of the Dodge hemi were introduced by substituting less complex poly (single rocker shaft) heads and valve train parts, including one variant only built as a poly (259"). These were used in low-line 1955-58 DeSotos and Dodges, and 1955-56 high-line Plymouths.
Dodge Trucks marketed their version of the Hemi under the name PowerDome.
241
Dodge introduced the engine in 1953.
Bore was and stroke was . With a low compression ratio of 7.0:1 (in 1953 and for the 1954
Meadowbrook), the 241 produced .
For 1954, the more senior Dodges received thanks to a higher 7.5:1 compression ratio.
[ Lee, p. 270] This engine is not the same as the
Plymouth 241, which had polyspheric, not hemi heads. The 241 only lasted two years, being replaced by the 270 for 1955.
[
]
270
The D553 1955/1956 Dodge Red Ram Hemi 270 displaced and was used in premium 1955 and 1956 Dodge vehicles. Bore was and stroke was . It was not the same as the 270 poly-head. In the Dodge Coronet
The Dodge Coronet is an automobile that was marketed by Dodge in seven generations, and shared nameplates with the same bodyshell with varying levels of equipment installed. Introduced as a full-size car in 1949, it was the division's highest tr ...
, running 7.6:1 compression ratio, the 270 produced . In higher trims like the Dodge Royal
The Dodge Royal is an automobile which was produced by Dodge in the United States for the 1954 through 1959 model years.
First generation (1954)
The Royal was introduced for the 1954 model year as the top trim level of the Dodge line, above ...
, the "Super Red Ram" ran the same compression ratio but with a four-barrel carburetor produced .[ Lee, p. 271]
315
For 1956, Dodge increased the displacement to with a longer stroke and a taller raised-deck block and now with a polyspheric heads—no longer a Hemi. But the optional high-performance D-500 version of this engine had a four-barrel carburetor and a larger valved Dodge hemispherical combustion chambered head. Also, a "race only" package called the D-500-1 or DASH 1 was available with a special aluminum dual four-barrel intake that sported a pair of Carter WCFB carburetors similar to the ones on the Chrysler 300B and DeSoto Adventurer. This engine used the same cylinder heads as the base D-500 model.
The D-501 in 57 was the Chrysler 354 engine, not a Dodge-based engine.
325
Dodge released a engine for 1957. The "Super Red Ram" engine used a bore and stroke.
The base engine offering was now a polyspheric chambered head referenced as 'KDS', and a higher performance 325 was offered with hemi heads as the 'KD-500'. Again there was a low volume offering of a 'KD-500-1' with dual four-barrel carburetors. All engines now, however, had hydraulic camshafts even though the hemi headed offerings sported "dimples" in the valve covers for mechanical adjuster clearance.
Second generation: 426
The hemispherical head design was revived in 1964. These were the first engines officially designated Hemi, a name Chrysler had trademarked. Chrysler Hemi engines of this generation displaced . The 426 Hemi was nicknamed the "elephant engine" at the time, a reference to its high power, heavy weight and large physical dimensions. Its deck height and bore spacing made it the biggest engine in racing at the time.
The 426 Hemi of the 1960s was an engine produced for use in NASCAR
The National Association for Stock Car Auto Racing, LLC (NASCAR) is an American auto racing sanctioning and operating company that is best known for stock car racing. The privately owned company was founded by Bill France Sr. in 1948, and ...
, as raced in a Plymouth Belvedere
Plymouth Belvedere is a series of American automobile models made by Plymouth from 1954 until 1970.
The Belvedere name was first used for a new hardtop body style in the Plymouth Cranbrook line for the 1951 model year. In 1954 the Belvedere re ...
in 1964. It was not initially available to the general buying public. The 426 Hemi was not allowed to compete in NASCAR's 1965 season due to its unavailability in production vehicles sold to the general public and because of complaints by Ford regarding its power. However several special production versions of the Dodge Dart
Dodge Dart is a line of automobiles marketed by Dodge from the 1959 to 1976 model years in North America, with production extended to later years in various other markets.
The Dart name originally appeared on a 1956 Chrysler show car featuring ...
, the Plymouth Fury
The Plymouth Fury is a model of automobile that was produced by Plymouth from 1955 until 1989. It was introduced for the 1956 model year as a sub-series of the Plymouth Belvedere, becoming a separate series one level above the contemporary Belved ...
, and later, in 1965, the Dodge Coronet
The Dodge Coronet is an automobile that was marketed by Dodge in seven generations, and shared nameplates with the same bodyshell with varying levels of equipment installed. Introduced as a full-size car in 1949, it was the division's highest tr ...
, were produced with aluminum fenders and bumpers for drag racing and made available to the general public.
Chrysler introduced the "Street" Hemi in 1966 for its intermediate range of cars and sold the required number of Hemi engines to the public to homologate
Homologation (Greek ''homologeo'', ὁμολογέω, "to agree") is the granting of approval by an official authority. This may be a court of law, a government department, or an academic or professional body, any of which would normally work fr ...
its use for stock car racing in NASCAR events in 1966. The "Street Hemi" was similar to the race Hemi but with an inline 2X4-bbl induction system (with automatic choke), lower compression (10.25:1 from 12.5:1) and lower-lift camshaft, with iron exhaust manifolds instead of lighter steel long tube headers.
There were many differences between the Hemi and the Wedge-head big-block, including main cross-bolted bearing caps and a different head bolt pattern. Although all manufacturers were familiar with multi-valve
In automotive engineering a multi-valve or multivalve engine is one where each cylinder has more than two valves. A multi-valve engine has better breathing and may be able to operate at higher revolutions per minute (RPM) than a two-valve engine ...
engines and hemispherical combustion chamber
A hemispherical combustion chamber is a type of combustion chamber in a reciprocating internal combustion engine with a domed cylinder head notionally in the approximate shape of a hemisphere (in reality usually a spheric section thereof). An en ...
s, adding more valves per cylinder
A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base.
A cylinder may also be defined as an infin ...
and designing the complex valvetrain
A valvetrain or valve train is a mechanical system that controls the operation of the intake and exhaust valves in an internal combustion engine. The intake valves control the flow of air/fuel mixture (or air alone for direct-injected engines) ...
they require were expensive ways of improving the high– revolutions per minute (rpm) breathing of production vehicle
Production vehicles or production cars are mass-produced identical models, offered for sale to the public, and able to be legally driven on public roads ( street legal). Legislation and other rules further define the production vehicle within part ...
s. By canting the angle of the NASCAR-mandated two valves per cylinder, significantly larger valves could be used. The Chrysler 426 Hemi and all Chrysler RBs had oversquare bore and strokes. Specifically, the 426 Hemi and 426 Wedge had a bore x stroke of .
The 426 Hemi, in "street Hemi" form, was produced for consumer automobiles from 1965 through 1971. Hemi-powered Dodge and Plymouth cars produced in the model years of 1965 through 1971 have become collector's items. For example, a 1971 Plymouth Barracuda Convertible equipped with the 426 Hemi engine sold at auction for US$3.5 million in 2014.
The street Hemi version was rated at at 5000 rpm SAE gross and at 4000 rpm of torque equipped with a pair of four-barrel Carter AFB carburetors. In actual dynamometer
A dynamometer or "dyno" for short, is a device for simultaneously measuring the torque and rotational speed ( RPM) of an engine, motor or other rotating prime mover so that its instantaneous power may be calculated, and usually displayed by ...
testing, it produced and of torque in purely stock form. Chrysler's sales literature published both the gross and net ratings for 1971.
The street version of the 2G Hemi engine was used (optionally, in all but the last case) in the following vehicles:
* 1966–1970 Dodge Coronet
The Dodge Coronet is an automobile that was marketed by Dodge in seven generations, and shared nameplates with the same bodyshell with varying levels of equipment installed. Introduced as a full-size car in 1949, it was the division's highest tr ...
/Plymouth Belvedere
Plymouth Belvedere is a series of American automobile models made by Plymouth from 1954 until 1970.
The Belvedere name was first used for a new hardtop body style in the Plymouth Cranbrook line for the 1951 model year. In 1954 the Belvedere re ...
* 1966–1971 Plymouth Satellite
The Plymouth Satellite is a mid-size automobile introduced in the 1965 model year as the top trim model in Plymouth's "B" platform Belvedere line. Available initially in two-door hardtop and convertible models, the Satellite remained the top-of- ...
* 1966–1971 Dodge Charger
* 1966-1971 Jensen FF
The Jensen FF is a four-wheel drive grand tourer produced by British car manufacturer Jensen Motors between 1966 and 1971. It was the first non all-terrain production car equipped with four-wheel drive and an anti-lock braking system. The powe ...
* 1966-1971 Jensen Interceptor
The Jensen Interceptor is a grand touring car which was hand-built at the Kelvin Way Factory in West Bromwich, near Birmingham in England, by Jensen Motors between 1966 and 1976. The Interceptor name had been used previously by Jensen for the ...
* 1967–1971 Plymouth GTX
Plymouth () is a port city and unitary authority in South West England. It is located on the south coast of Devon, approximately south-west of Exeter and south-west of London. It is bordered by Cornwall to the west and south-west.
Plymouth' ...
* 1968 Dodge Dart Super Stock
* 1968 Plymouth Barracuda
* 1968–1971 Dodge Super Bee
* 1968–1971 Plymouth Road Runner
The Plymouth Road Runner is a mid-size car with a focus on performance built by Plymouth in the United States between 1968 and 1980. By 1968, some of the original muscle cars were moving away from their roots as relatively cheap, fast cars as t ...
*1969 Dodge Charger R/T
* 1969 Dodge Charger Daytona
Dodge produced three separate models with the name Dodge Charger Daytona, all of which were modified Dodge Chargers. The name was taken from Daytona Beach, Florida, which was an early center for auto racing and still hosts the Daytona 500, NASC ...
* 1970 Plymouth Superbird
The Plymouth Superbird is a highly modified, short-lived version of the Plymouth Road Runner with applied graphic images as well as a distinctive horn sound both referencing the popular ''Looney Tunes'' cartoon character the Road Runner. It was ...
* 1970–1971 Plymouth Hemi 'Cuda
* 1970–1971 Dodge Challenger
* 1970 Monteverdi Hai 450
To avoid confusion with earlier (1951–58) and current Hemi engines, the 426 is sometimes called the "2G" or "Gen 2" Hemi.
In racing
There were many differences between the racing Hemis and the street Hemi, including but not limited to compression ratio, camshaft, intake manifold
In automotive engineering, an inlet manifold or intake manifold (in American English) is the part of an engine that supplies the fuel/ air mixture to the cylinders. The word ''manifold'' comes from the Old English word ''manigfeald'' (from the ...
, exhaust manifold. Some 1960s NASCAR and NHRA Hemi engines featured magnesium cross-ram intake manifolds and magnesium oil pan
A sump is a low space that collects often undesirable liquids such as water or chemicals. A sump can also be an infiltration basin used to manage surface runoff water and recharge underground aquifers. Sump can also refer to an area in a cave ...
s in an attempt to reduce the massive weight of the overall engine, along with chain-driven internal dry sump
A dry-sump system is a method to manage the lubricating motor oil in four-stroke and large two-stroke piston driven internal combustion engines. The dry-sump system uses two or more oil pumps and a separate oil reservoir, as opposed to a con ...
oil systems. Today, aftermarket blocks, heads, intakes, rods, and pistons are usually made of aluminum.
The 426 Hemi also was used in NHRA
The National Hot Rod Association (NHRA) is a drag racing governing body, which sets rules in drag racing and hosts events all over the United States and Canada. With over 40,000 drivers in its rosters, the NHRA claims to be the largest motorsp ...
and AHRA drag racing. Its large casting
Casting is a manufacturing process in which a liquid material is usually poured into a mold, which contains a hollow cavity of the desired shape, and then allowed to solidify. The solidified part is also known as a ''casting'', which is ejected ...
allowed the engine to be overbored and stroked to displacements unattainable in the other engines of the day. Top-fuel racing organizers limited the bore spacing of engines until very recently, when under pressure from Ford and other manufacturers, the bore spacing allowed was increased to —this allows other engines such as the Ford 385 series to begin to compete. The engines based on the old Chrysler design predominate Top Fuel and Funny Car classes due to plentiful parts, a large amount of research and development, as well as decades of experience with the problems of the engine's design. In drag racing today, it is usually equipped with a large Roots type supercharger
The Roots-type blower is a
positive displacement lobe pump which operates by pumping a fluid with a pair of meshing lobes resembling a set of stretched gears. Fluid is trapped in pockets surrounding the lobes and carried from the intake si ...
and short individual exhaust pipe
An exhaust system is used to guide reaction exhaust gases away from a controlled combustion inside an engine or stove. The entire system conveys burnt gases from the engine and includes one or more exhaust pipes. Depending on the overall system ...
s, and fueled with nitromethane
Nitromethane, sometimes shortened to simply "nitro", is an organic compound with the chemical formula . It is the simplest organic nitro compound. It is a polar liquid commonly used as a solvent in a variety of industrial applications such as in ...
. Yet, this variant is used in Top Fuel, Funny Car, and Pro Modified classes.
Third generation: 2003-present
The current-production "HEMI" engine heads are flatter and more complex than the 1950s–'70s Hemi V8 chamber. The combustion chambers are no longer truly hemispherical. It uses a coil-on-plug distributor-less ignition system and two spark plugs per cylinder to shorten flame travel leading to more consistent combustion and reduced emissions. Like most of Chrysler's past-model Hemi-head engines, the 5.7 version is rated at approximately one horsepower per cubic inch (the current engines are SAE net, whereas the old Hemi engines were rated SAE gross). For the 2009 model year power was increased to 357-395 horsepower (266-291 kW) and 389-410 lb·ft (527-556 N·m) depending on application. It also achieved 4% better fuel economy. Variable valve timing (VVT) was also introduced.
A new variable displacement Variable displacement is an automobile engine technology that allows the engine displacement to change, usually by deactivating cylinders, for improved fuel economy. The technology is primarily used in large, multi-cylinder engines. Many automobil ...
technology called Multi-Displacement System Chrysler's Multi-Displacement System (MDS) is an automobile engine variable displacement technology. It debuted in 2006 on the 5.7 L modern Hemi V8. Like Mercedes-Benz's Active Cylinder Control, General Motors' Active Fuel Management, and Hon ...
(MDS) is used in some versions which can shut off two cylinders on each bank under light load to improve fuel economy.
5.7
The 5.7 L HEMI was released for model year 2003 on the Dodge Ram
The Ram pickup (marketed as the Dodge Ram until 2010) is a full-size pickup truck manufactured by Stellantis North America (formerly Chrysler Group LLC and FCA US LLC) and marketed from 2010 onwards under the Ram Trucks brand. The current fi ...
pickup trucks to complement the Magnum 5.9 engine. it was the only available gasoline engine in the Ram Heavy Duty. Chrysler later made the 5.7 L Hemi available in all models of the 2004 Dodge Ram
The Ram pickup (marketed as the Dodge Ram until 2010) is a full-size pickup truck manufactured by Stellantis North America (formerly Chrysler Group LLC and FCA US LLC) and marketed from 2010 onwards under the Ram Trucks brand. The current fi ...
, Dodge Durango
The Dodge Durango is a mid-size sport utility vehicle (SUV) produced by Dodge in three generations starting with the 1998 model year. The first two generations were very similar in that both were based on the Dodge Dakota and Ram Pickup, both ...
, the 2005 Chrysler 300C, Dodge Magnum R/T, Jeep Grand Cherokee
The Jeep Grand Cherokee is a range of mid-size SUVs produced by the American manufacturer Jeep. At its introduction, while most SUVs were still manufactured with body-on-frame construction, the Grand Cherokee has used a unibody chassis from the ...
, the 2006 Dodge Charger R/T, Jeep Commander
The Jeep Commander is an automobile nameplate used by Jeep since 2005 for several SUV models:
* Jeep Commander (XK), a mid-size SUV produced from 2005 to 2010
* Jeep Commander (2022), a mid-size crossover SUV based on the Jeep Compass produced ...
, the 2007 Chrysler Aspen
The Dodge Durango is a mid-size sport utility vehicle (SUV) produced by Dodge in three generations starting with the 1998 model year. The first two generations were very similar in that both were based on the Dodge Dakota and Ram Pickup, both ...
, the 2009 Dodge Challenger R/T, and the 2022 Jeep Wagoneer
The Jeep Wagoneer is a sport utility vehicle (SUV) nameplate of Jeep vehicles, with several models marketed for the 1963 through 1993 model years and again since the 2022 model year.
Various versions of the Wagoneer were manufactured in the US ...
. For manual transmission applications (Challenger and 3/4- and 1-ton Ram pickups), cylinder deactivation is not included.
The Hemi in the Ram delivered and , but and for the 300C and Magnum R/T, which is exactly more than the old 5.9 engine. It is a 90-degree V8, 2-valve pushrod
A valvetrain or valve train is a mechanical system that controls the operation of the intake and exhaust valves in an internal combustion engine. The intake valves control the flow of air/fuel mixture (or air alone for direct-injected engines) ...
design like the past Magnum series engines, displacing , with a bore of and a stroke of .
The 5.7 L Hemi is made at Chrysler's Saltillo Engine plant in Ramos Arizpe
Ramos Arizpe () is a city and seat of the surrounding municipality of the same name in the Mexican state of Coahuila. Ramos Arizpe is located 11 km from the state capital of Saltillo. It is part of the Saltillo metropolitan area. The city ...
, Mexico.
The Hemi was on the Ward's 10 Best Engines 10 of the World's best engines is an annual list of the ten ''"''best''"'' automobile engines available in the U.S. market, that are selected by '' Ward's AutoWorld'' magazine. The list was started in 1994 for Model Year 1995, and has been drawn ev ...
list for 2003 through 2007, and again in 2009.
This engine is used in the following vehicles:
* 2003–present Ram Pickup
The Ram pickup (marketed as the Dodge Ram until 2010) is a full-size pickup truck manufactured by Stellantis North America (formerly Chrysler Group LLC and FCA US LLC) and marketed from 2010 onwards under the Ram Trucks brand. The current f ...
* 2004–2009, 2011–Present Dodge Durango
The Dodge Durango is a mid-size sport utility vehicle (SUV) produced by Dodge in three generations starting with the 1998 model year. The first two generations were very similar in that both were based on the Dodge Dakota and Ram Pickup, both ...
* 2005–2008 Dodge Magnum ''R/T''
* 2005–present Chrysler 300
The Chrysler 300 is a full-size luxury car manufactured and marketed by Stellantis North America (and its predecessor companies) as a four-door sedan and station wagon in its first generation (model years 2005–2010) and solely as a four-d ...
C, 300S V8 (2010, 2012–Present)
* 2005–present Jeep Grand Cherokee
The Jeep Grand Cherokee is a range of mid-size SUVs produced by the American manufacturer Jeep. At its introduction, while most SUVs were still manufactured with body-on-frame construction, the Grand Cherokee has used a unibody chassis from the ...
* 2006–present Dodge Charger ''R/T''
* 2006–2010 Jeep Commander
The Jeep Commander is an automobile nameplate used by Jeep since 2005 for several SUV models:
* Jeep Commander (XK), a mid-size SUV produced from 2005 to 2010
* Jeep Commander (2022), a mid-size crossover SUV based on the Jeep Compass produced ...
* 2007–2009 Chrysler Aspen
The Dodge Durango is a mid-size sport utility vehicle (SUV) produced by Dodge in three generations starting with the 1998 model year. The first two generations were very similar in that both were based on the Dodge Dakota and Ram Pickup, both ...
* 2009–present Dodge Challenger ''R/T''
* 2022–present Jeep Wagoneer
The Jeep Wagoneer is a sport utility vehicle (SUV) nameplate of Jeep vehicles, with several models marketed for the 1963 through 1993 model years and again since the 2022 model year.
Various versions of the Wagoneer were manufactured in the US ...
2009 5.7 revisions
Chrysler made various revisions to the 5.7 L for the 2009 model year. The first for all applications is what Chrysler calls Variable Camshaft Timing or VCT. VCT (which is essentially variable valve timing
In internal combustion engines, variable valve timing (VVT) is the process of altering the timing of a valve lift event, and is often used to improve performance, fuel economy or emissions. It is increasingly being used in combination with var ...
) uses an oil control valve that controls oil flow to a unique camshaft sprocket that contains a phasing device, which depending on the operation of the oil control valve either advances or retards camshaft timing.
Cylinder heads have been revised to increase flow. Though the intake manifold has also been changed on all applications, it is however model specific. Dodge Ram, non-Hybrid Electric Vehicle (HEV) Chrysler Aspens, and non-HEV Dodge Durango utilize an active intake manifold with a short runner valve to optimize torque and horsepower. At lower engine rpm the valve is closed, resulting in improved low-end torque from the longer runners. At higher engine rpm the valve is opened, diverting the incoming air into the center of the manifold. The shorter runners result in improved horsepower. Passenger cars, Jeep vehicles, as well as HEV Chrysler Aspen and HEV Dodge Durango do not use this manifold; instead, these vehicles utilize a passive intake manifold, which does not have a short runner valve. Also, the new cylinder head came with different spark plugs seats: tapered seats was replaced with gasket seats. This change made it impossible to use the old OE Champion RE14MCC4, so the new spark plugs that came with 5.7 HEMI become NGK LZFR5C-11. Besides different seats, new spark plugs got increased gap from .039" (1.0 mm) to .043" (1.1 mm).
Six-speed manual transmission and all Heavy Duty truck applications will differ by not having the Multi-Displacement System Chrysler's Multi-Displacement System (MDS) is an automobile engine variable displacement technology. It debuted in 2006 on the 5.7 L modern Hemi V8. Like Mercedes-Benz's Active Cylinder Control, General Motors' Active Fuel Management, and Hon ...
(MDS). The new version of the 5.7 L has five different camshaft profiles. All will have VCT.
* Active intake with MDS
* Active intake without MDS
* Passive intake with MDS
* Passive intake without MDS
* HEV Application (modified version of passive intake with MDS)
Power Numbers
* 300C/300S V8: ,
* Charger R/T: ,
* Challenger R/T Automatic: ,
* Challenger R/T 6 Speed Manual: ,
* 2009-2012 Ram 1500 Truck: ,
* 2013+ Ram 1500 Truck: ,
* Ram 2500/3500 Truck: ,
* Jeep Grand Cherokee and Jeep Commander: ,
* 2011+ Dodge Durango: ,
* 2009 Chrysler Aspen and Dodge Durango non-HEV: ,
* 2009 Chrysler Aspen and Dodge Durango HEV: ,
* 2022 Jeep Wagoneer: ,
6.1
The Hemi is also available in a version. The engine's bore x stroke is and many other changes were made to allow it to produce at 6,200 rpm and of torque at 4,800 rpm. The engine block is different from the 5.7, with revised coolant channels and oil jets to cool the pistons. A forged crankshaft, lighter pistons and strengthened connecting rods aid durability. A cast aluminium intake manifold
In automotive engineering, an inlet manifold or intake manifold (in American English) is the part of an engine that supplies the fuel/ air mixture to the cylinders. The word ''manifold'' comes from the Old English word ''manigfeald'' (from the ...
is tuned for high-rpm power and does not include variable-length technology. Chrysler's Multi-Displacement System Chrysler's Multi-Displacement System (MDS) is an automobile engine variable displacement technology. It debuted in 2006 on the 5.7 L modern Hemi V8. Like Mercedes-Benz's Active Cylinder Control, General Motors' Active Fuel Management, and Hon ...
is not used on the 6.1.
Applications:
* 2005–2010 Chrysler 300
The Chrysler 300 is a full-size luxury car manufactured and marketed by Stellantis North America (and its predecessor companies) as a four-door sedan and station wagon in its first generation (model years 2005–2010) and solely as a four-d ...
C ''SRT-8''
* 2006–2008 Dodge Magnum ''SRT-8''
* 2006–2010 Dodge Charger ''SRT-8''
* 2006–2010 Jeep Grand Cherokee
The Jeep Grand Cherokee is a range of mid-size SUVs produced by the American manufacturer Jeep. At its introduction, while most SUVs were still manufactured with body-on-frame construction, the Grand Cherokee has used a unibody chassis from the ...
''SRT-8''
* 2008–2010 Dodge Challenger ''SRT-8''
6.2 Hellcat
For 2015, Chrysler introduced an all-new high performance supercharged variant of the Hemi engine, called the Hellcat (named after the Grumman F6F Hellcat
The Grumman F6F Hellcat is an American carrier-based fighter aircraft of World War II. Designed to replace the earlier F4F Wildcat and to counter the Japanese Mitsubishi A6M Zero, it was the United States Navy's dominant fighter in the second ha ...
). It features the same bore as the 6.4 L Hemi and the same stroke as the 5.7 L, giving it a total displacement of . The supercharger is a twin-screw IHI unit with integrated charge coolers, capable of producing of boost. This engine is rated at at 6,000 rpm and at 4,000 rpm of torque and has a compression ratio of 9.5:1. This engine was the most powerful engine produced by Chrysler as well as the most powerful production engine ever in a muscle car
Muscle car is a description according to '' Merriam-Webster Dictionary'' that came to use in 1966 for "a group of American-made two-door sports coupes with powerful engines designed for high-performance driving." The '' Britannica Dictionary'' ...
until the Dodge Demon was introduced. This engine is not equipped with Chrysler's Multi-Displacement System Chrysler's Multi-Displacement System (MDS) is an automobile engine variable displacement technology. It debuted in 2006 on the 5.7 L modern Hemi V8. Like Mercedes-Benz's Active Cylinder Control, General Motors' Active Fuel Management, and Hon ...
. In 2017, Mopar announced that it would sell it as a crate engine
A crate is a large shipping container, often made of wood, typically used to transport or store large, heavy items. Steel and aluminium crates are also used. Specialized crates were designed for specific products, and were often made to be reusa ...
under the name Hellcrate. A Redeye version with debuted in the Dodge Challenger in 2019, followed by the Dodge Charger in 2021.
Applications:
* 2015–Present Dodge Challenger SRT Hellcat
* 2015–Present Dodge Charger SRT Hellcat
* 2018–present Jeep Grand Cherokee Trackhawk
* 2021 Dodge Durango SRT Hellcat
* 2017 Ram 1500 Rebel TRX Concept
* 2021–Present Ram 1500 TRX
6.2 Demon
The Demon version of the Hemi V8 features a number of improvements over the Hellcat variant. It is fitted with a larger, 2.7 L twin-screw supercharger, as well as reinforced reciprocating components, a new camshaft, and several other valvetrain upgrades. With these improvements, the Challenger SRT Demon is rated at 808 horsepower on 91-octane pump gasoline, and 840 horsepower when running on 100-octane unleaded racing gasoline. Cooling is aided by a functional Air-Grabber hood scoop, as well as a unique charge cooling system that makes use of the air-conditioning coolant to lower the intake charge air temperature.
Applications:
* 2018 Dodge Challenger SRT Demon
6.4
Chrysler displayed a larger and more powerful 392-cubic-inch (6.4 L) HEMI in 2005 with a factory-rated output of and torque. It is equipped with high-strength forged aluminum alloy pistons. This engine has been available since 2007, as a crate engine
A crate is a large shipping container, often made of wood, typically used to transport or store large, heavy items. Steel and aluminium crates are also used. Specialized crates were designed for specific products, and were often made to be reusa ...
under the name 392 HEMI.[
The production version of the 392 HEMI was launched in the 2011 Dodge Challenger SRT8 with variable camshaft timing as well as MDS in cars with automatic transmissions. The new 392 HEMI, codenamed "Apache," is based on the third-generation 5.7 L HEMI, codenamed "Eagle," and shares few parts with the 392 crate engine.
Special-Edition Chargers and Challengers equipped with this engine, and the engines themselves, will bear "392 HEMI" badging in commemorative reference to the first-generation engine of the same displacement.] In other applications, the engine is badged as "6.4L HEMI".
Output is and ;
For the 2015 model year, horsepower was increased to and torque to in the Charger and Challenger ''SRT 392'' (2015-2018) and ''R/T Scat Pack'' (2015–present) models; the Grand Cherokee SRT only saw a 5 bhp increase. Export models of the Chrysler 300 SRT retained the and output.
Applications:
* Chrysler 300 SRT
* Dodge Challenger SRT 392
* Dodge Charger SRT 392
* Dodge Durango SRT
* Jeep Grand Cherokee SRT
* Jeep Grand Wagoneer
* Jeep Wrangler Unlimited Rubicon 392
HD Truck and Cab Chassis version
Starting in model year 2014, the Ram 2500 and 3500 trucks, and Ram 3500, 4500, and 5500 Cab Chassis offered a revised version of the 6.4 L, being re-tuned for better fuel economy and a power band more suitable for hauling and towing than the all-out power of the SRT Version. In 2016 it replaced the 5.7 L as the standard gas engine in the Cab Chassis models.
Power Numbers
* 2500 and 3500 Pickup, 3500 SRW Cab Chassis with RFE transmission: ,
* 3500 Mega Cab, 3500 DRW Cab Chassis with RFE transmission, 3500 SRW/DRW with Aisin Transmission: ,
* 4500 and 5500 Cab Chassis: ,
Mopar 426 HEMI (2012–present)
At the 2012 North American International Auto Show in Detroit, Dodge debuted a Mopar Customized Dodge Charger "Redline" that featured a modern 426-cubic-inch (7.0 L) HEMI V8 engine rated at .
Mopar 426 HEMI 'Hellephant' (2018-present)
The Hellephant name is a spin on the nickname of the original 426 cubic inch HEMI, Elephant, and the modern Supercharged 6.2L Hellcat HEMIs. It is a crate engine, supercharged as standard, producing 1,000hp and 950lb.-ft of torque.
Marketing
From February to April 2005, DaimlerChrysler hosted a "What Can You HEMI?" contest promoting alternative uses of the HEMI engines. The top five finalists include HEMI Snowblower, HEMI-Go-Round carousel, HEMI on Ice ice resurfacer, HEMI-Shredder, HEMI Big Wheel, i.e. the child's tricycle of the 1970s. The winner was the HEMI Big Wheel, which had a 5.7 L Hemi in the back that was installed backwards, thus reverse became the only forward gear. Plate steel was the predominant material, while a rolled tube of steel had to be utilized for the front tire as there were no such tires in diameter that were as narrow as needed for this project.
Notes
References
External links
How a hemi engine works
A Body Hemi engine swaps
Mopar HEMI Gen II page
Mopar HEMI Gen III page
{{DEFAULTSORT:Chrysler Hemi Engine
Hemi
V8 engines