170 The 170 engine was offered in model years 1960 through 1969 in North America, and through 1971 for export markets. The first vehicle to offer the 170 slant-6 was the 1960 Valiant. The engine has a bore of and a stroke of for an actual displacement of . Connecting rod length is . The "LG" low-deck block was unique to the 170 engine.
198 The 198 was introduced in the North American market for model year 1970 as a more powerful base-model engine than the previous 170 engine. The increased displacement gave improved vehicle performance and lower manufacturing cost, for it was achieved with the tall RG block also used with the 225 engine by installing a crankshaft with stroke and connecting rods long, for an actual displacement of . Manufacturing costs were reduced by eliminating using two different blocks for the two different available sizes of slant-6 engine. The 198 engine was available through the 1974 model year.
225 The 225 used the RG (tall) block with a bore, a stroke and connecting rods, for an actual displacement of . This
undersquare geometry was a departure from the emerging trend towards
oversquare engines. It provided strong low-rpm torque characteristics for automobiles and trucks, as well as other commercial and marine applications. The 225 was originally designed and introduced in 1960 for use in full-size models, and it eventually became the best known of the Slant Six engines. The original Chrysler 225 Slant Six produced around at 4,000 rpm and of torque at 2,800 rpm. In 1982, Chrysler signed an agreement with
Perkins Engines to build a dieselized version of the 3.7, with seven main bearings and turbocharged as well as naturally aspirated (and also of the
2.2-liter inline-four) in
Windsor, Ontario. Design work had started in 1975, but with the collapse of the diesel market in North America, these plans were cancelled in 1983.
Aluminum block 225 Between late model year 1961 and early model year 1963, approximately 52,000
die-cast aluminum RG blocks were produced and installed in passenger cars. These open-deck blocks used integrally cast high-nickel iron
cylinder liners, and bolt-in iron upper and lower main bearing caps. Internal components (crank, rods, pistons, etc.) were the same as used in the iron engine, and an iron
cylinder head was used with a special copper-
asbestos gasket. The aluminum block weighs about less than the iron RG block. Although serviceable examples can still be found, the aluminum RG tended to undergo delamination between the iron cylinder liner and the surrounding aluminum. Severe corrosion within the block is also commonly found because of the general tendency in the 1960s and 1970s to fill cooling systems in summer with plain water without
corrosion inhibitors. Moreover, the open-deck design and primitive head gasket technology are not sufficiently robust to withstand the increased seal demands of increased compression or forced induction.
High-performance variants Most G-engines were equipped with small-capacity
carburetors (such as the ubiquitous
Holley 1920) and exhaust systems adequate for standard passenger car usage at low altitudes, but which tended to hamper maximum available performance at high altitudes, in heavy or race-purpose vehicles and/or where quicker
acceleration was desired. To meet the demand for improved responsiveness, modified engine configurations were made available in various markets over the years.
Hyper Pak The
Hyper Pak was a parts package made available from 1960 through 1962 at Chrysler Corporation dealer parts counters. The parts were made available to comply with the regulations of sanctioning bodies for racing events in which Valiants had been entered by factory-backed teams: All parts used had to be "stock" parts, the definition of which meant that they were available through normal factory parts channels. The Hyper Pak consisted of a very-long-ram
intake manifold meant to accept an AFB 4-barrel
Carter Carburetor, the AFB carburetor itself and an appropriate
air cleaner, dual (front-3 and rear-3) cast-iron
exhaust headers, a large-diameter exhaust Y-pipe to connect to these dual cast-iron headers, a larger muffler, a 276°-duration
camshaft with appropriate valve springs and pushrods, a heavier-duty
clutch, a manual choke control, a starter motor modification template and, in the full-race version of the package, high-compression pistons designed to increase the engine's
compression ratio to 10.5 from the stock 8.5. The Hyper Pak was recommended for installation only on vehicles equipped with
manual transmissions, for the camshaft was of such characteristics that a high idle speed was required to prevent engine stall-out. The Hyper Pak was primarily intended for competition driving, its road manners involving rough idling and poor cold-engine driveability, a high power band and poor
fuel economy. In competition events it proved unbeatable. Seven factory-backed Valiants entered the 1960
NASCAR compact car race at
Daytona Beach, and humbled the competition. The Valiants came in first through seventh. A high-fidelity reproduction of the Hyper Pak intake manifold was created by Slant-6 builder Doug Dutra in the late 1990s. Subsequently the tooling was sold to a marketer of performance equipment (Clifford Research, 6=8) for inline six-cylinder engines.
Multiple carburetors For the 1965–1968 model years, Chrysler Argentina equipped Valiant GT models with a system of dual 1-barrel
Holley RX 7000 A carburetors and other engine specification changes. Claimed output was , compared to the single-carburetor version of the engine producing
2-barrel carburetion Export 2-barrel setup For the 1967 model year, a 2-barrel carburetor setup was released for export production. This configuration, similar to that found on marine G-engines beginning in 1965, consisted of an iron intake manifold with open-plenum 2-barrel carburetor mounting pad, a Carter BBD carburetor, and associated air cleaner, linkage and plumbing changes. Also installed on these export 2-barrel engines was a slightly hotter camshaft (244° duration rather than 240°), and a distributor with modified advance curves. This engine, rated at , was popular in Central and South America, South Africa, Australia and New Zealand. Driveability characteristics were generally superior to those of the 1-barrel engine, but to avoid cutting into sales of the more expensive V8 engine, this 2-barrel setup was not offered in the North American market. Of particular note is the automatic choke design found in this export 2-barrel setup. Most Chrysler products used remote automatic chokes, with a
bimetal coil spring mounted on the exhaust manifold, exposed to exhaust heat and operating a pushrod which rotated the
choke lever on the carburetor. The export 2-barrel setup used an integral heat-tube style automatic choke: Air heated by the exhaust manifold was routed to a round
bakelite housing on the carburetor air horn, which contained a bimetal spring acting directly on the choke lever.
Slant Six 225 high performance At the end of 1973 Chrysler Argentina returned to the fight for the high performance 6 cylinders. Since 1972 Chrysler had not offered a 6 cylinder with sports aspiration but that would change with the release of the Dodge Polara RT, it was a hard top coupe equipped with the new high-performance Slant Six RG 225 or commonly known as Slant Six RT, thanks to the addition of a new Holley 2300 two-barrel carburetor, "3a1" exhaust manifolds, a more violent camshaft with 273° duration; and a compression ratio of 8.5:1 this version produced and torque of , this engine coupled to a 4-speed gearbox and a differential with a ratio of 3.07 to 1 launched the Dodge Polara RT to a maximum speed of 181 km/h or 113 mph and an acceleration of 0 to 63 mph in 11 seconds.
Super Six By the mid-1970s in the North American market,
emission control regulations were reducing engine performance at the same time as safety regulations were making cars heavier. An increase in performance was required for the G-engine, so a 2-barrel setup was released for the 1976 model year. This was not the same as the export 2-barrel package; the intake manifold used a
throttle-bored
plenum rather than an open one, and had provisions for an
EGR valve. The carburetor, a Carter BBD similar but not identical to the one used on Chrysler's
V8 engine, used a standard Chrysler-style remote automatic choke. A exhaust head pipe was also provided, as well as 2-barrel-specific advance curves in the ignition distributor. This package, called "Super Six" by the marketing division, brought rated
horsepower from and torque from , while improving throttle response and driveability while maintaining compliance with emission laws. ==Applications==