Editing Chrysler Slant-6 engine

{{About|the automobile engine||Slant Six (disambiguation){{!}}Slant Six}}
{{Use dmy dates|date=December 2015}}
{{Infobox automobile engine
| image = 1965 Plymouth Barracuda at 2015 Rockville Show 6of6.jpg
| name = Chrysler Slant Six (G, RG) engine
| caption = "Super 225" in a 1965 Plymouth Barracuda
| aka = 
| manufacturer = [[Chrysler Corporation]]
| configuration = [[Straight-six engine|Straight-6]]
| bore = {{cvt|3+2/5|in|1}}
| stroke = {{cvt|3+1/8|in|1}}<br />{{cvt|3+16/25|in|1}}<br />{{cvt|4+1/8|in|1}}
| displacement = {{cvt|170|cuin|L|1}}<br />{{cvt|198|cuin|L|1}}<br />{{cvt|225|cuin|L|1}}
| length = 
| diameter = 
| width = 
| height = 
| weight = 
| block = [[Cast iron]]<br />[[Aluminum]]
| head = [[Cast iron]]
| valvetrain = [[Pushrod engine|OHV]] 2 [[Poppet valve|valves]] per [[Cylinder (engine)|cylinder]]
| supercharger = 
| turbocharger = 
| fuelsystem = [[Carburetor]]
| fueltype = [[Gasoline]]
| oilsystem = Full pressure w/full-flow filter & [[gerotor]] oil pump
| coolingsystem = Jacketed block, Water pump to [[Radiator (engine cooling)|radiator]]
| power = 
| specpower = 
| torque = 
| compression = 8.2:1–8.5:1
| fuelcon = 
| specfuelcon = 
| oilcon = 
| power/weight = 
| production = 1959&ndash;2000<br>[[Indianapolis Foundry]]<br>[[Trenton Engine Plant]]
| predecessor = [[Chrysler Flathead engine#Straight-6|Flathead 218 and 230" I6]]
| successor = [[Chrysler LA engine#239 V6|{{cvt|239|CID|L|1}} V6]]<br>[[Chrysler Hemi-6 Engine|215-245-265 Hemi-6]] (Australia only)
| engine = 
}}

The '''Chrysler Slant-Six''' is the popular name for an [[overhead valve]] [[straight-six engine|inline-6]] engine  produced by [[Chrysler Motors]] between 1959 and 2000.  Featuring a [[reverse-flow cylinder head]] and [[cylinder bank]] inclined at a 30-degree angle from vertical, it was introduced in {{convert|170|cuin|L|1|abbr=on}} and {{convert|225|cuin|L|1|abbr=on}} displacements for the 1960 model year.   It was a clean-sheet design known within Chrysler as the '''G-engine''', built as a direct replacement for the [[Flathead engine|flathead]] [[Chrysler flathead engine#Straight-6|Chrysler straight six]] that the company started business with in 1925. 

The design proved very successful, being utilized in cars, trucks, boats, and agricultural, and industrial applications.

==Design==
The Chrysler Slant Six engine was a clean-sheet design, led by [[Willem Weertman]], later Chrysler's chief engine designer.<ref name="Weertman_Allpar">{{cite web|url=http://www.allpar.com/corporate/bios/weertman.html |title=Willem Weertman - Chrysler Chief Engineer, Engine Design and Development |publisher=Allpar.com |access-date=10 December 2015}}</ref> Its characteristic 30° inclined cylinder block gave it a lower height, copying the same cant Mercedes-Benz had introduced in 1952 in its [[Mercedes-Benz M186 engine|M186]]-engined [[300SL]] sports car. This enabled Chrysler stylists to lower hood lines, and also made room for the water pump to be mounted with a lateral offset, significantly shortening the engine's overall length. The slanted cylinder block also provides space in the vehicle's engine bay for intake and exhaust manifolds with runners of longer and more nearly equal length compared to the rake- or log-style manifolds typical of other inline engines. The No. 1 and No. 6 intake runners are of approximately equal length, the No. 2 and No. 5 equal but shorter, and the No. 3 and No. 4 equal and shortest. This has the effect of broadening the torque curve for better performance.{{cn|date=February 2025}} The Slant Six manifold configuration gives relatively even distribution of fuel mixture to all cylinders, and presents less flow restriction. This, in turn, provides for relatively good airflow through the engine despite the intake and exhaust ports being on the same side of the head rather than in a [[crossflow cylinder head|crossflow]] arrangement.<ref name="Allpar_Slant">{{cite web|url= http://www.allpar.com/slant6.html |title=The Chrysler Slant Six Engine (170-198-225) |work=allpar.com |access-date=10 December 2015}}</ref>

It was introduced in two [[Engine displacement|displacements]] in 1960: The {{cvt|170|cuin|L|1|adj=on}} "LG" (low-G, referring to the relatively short [[engine block]] casting and [[crankshaft]] stroke) in the compact [[Plymouth_Valiant#First_generation_(1960–1962)|Valiant]], and the {{cvt|225|cuin|L|1|adj=on}} "RG" (raised-G, referring to the relatively tall engine block casting and crankshaft stroke) in full-size [[Plymouth (automobile)|Plymouth]] and [[Dodge Dart]] models. In 1960, the engine was called the "30-D Economy Six" engine by Plymouth marketers,<ref>{{cite web|last=Knutson |first=Lanny |url=http://www.allpar.com/history/plymouth/1960.html |title=1960 Plymouth Cars: Fins' Final Fling |publisher=allpar.com |access-date=10 December 2015}}</ref><ref>{{cite magazine|url= https://books.google.com/books?id=JVUEAAAAMBAJ&pg=PA66 |page=66 |magazine=Life |title=Solid for '60... (Plymouth advertisement) |date=19 October 1959 |volume=47 |issue=16 |access-date=10 December 2015}}</ref> referring to the 30° cylinder block angle.

The G-engine was offered in various configurations in the North American market until 1983 in cars, 1987 in trucks, and 1991 for marine, agricultural, and industrial use. Replacement engines were built in Mexico through 2000. The G-engine was used by Chrysler's international operations in locally produced vehicles. It was also purchased by other original equipment manufacturers for installation in commercial vehicles, agricultural and industrial equipment, and boats.

{{Listen
 |filename = 225 Slant Six.ogg
 |description = A 225 slant Six engine in a 1965 Canadian Valiant starts and runs
 |title = -
 |type = sound
 |pos = right
 |header = Hear a slant-6 engine
}}
The G-engine gained a reputation for reliability and durability. The basic design is rigid and sturdy, in part because the engine was designed to be made of either iron or aluminum. An aluminum block was produced in 1961–1963, but most blocks were made of iron.<ref name=Allpar_Slant/> The block is of a deep-skirt design, with the crankshaft axis well above the oil pan rails for structural rigidity. Although only four [[main bearing]]s are used, they are of the same dimensions as those in the 2G 5-bearing (1964–1971) Hemi, and fewer mains results in a crankshaft better able to withstand the effects of torque.{{cn|date=February 2025}} Efficient cooling and lubrication systems, a favorable ratio of [[connecting rod]] length to stroke, and a [[forged steel]] crankshaft (on engines made through mid-1976) all contributed to the engine's strength and durability.

The G-engine was designed for utility and economy, and gave better overall performance than its competitors at its 1960 introduction.{{cn|date=February 2025}} It generally kept up through the 1960s and early-1970s with its direct competition,{{cn|date=February 2025}} though specialty 6-cylinder engines like the [[Pontiac Straight-6 engine#Overhead Cam|Pontiac OHC Six]], a brief GM outlier designed for its sporty [[Pontiac_Firebird#First_generation_(1967–1969)|Firebird]] [[pony car]], bested the performance of most versions of the Slant-6. After an early factory racing program was discontinued by 1962, the Slant Six did not receive much performance development. Most Slant Sixes were equipped with a single 1-barrel [[carburetor]]. Starting in the early 1970s, primitive [[Vehicle emissions control|emission controls]] adversely affected driveability and power, though a version of the 2-barrel carburetor package first released for marine and export markets in 1967 was offered in North America from 1977 to 1983 under the "Super Six" name. Performance figures were only slightly higher, but driveability was substantially improved.<ref name="Hagenbuch_Allpar">{{cite web|url=http://www.allpar.com/corporate/bios/hagenbuch-interview.html |title=Interview with Pete Hagenbuch, Chrysler engine development engineer |publisher=allpar.com |access-date=10 December 2015}}</ref>

Other Chrysler engines were released with more advanced [[combustion chamber]]s, electronic fuel injection, and other modern improvements, but the length of the Slant Six precluded its use in Chrysler's front-wheel-drive cars. A new {{cvt|3.9|L|cuin|0}} [[V6 engine]] was created for the 1987 [[Dodge Dakota]] compact pickup truck by removing two cylinders from the corporate {{cvt|318|cuin|L|1|adj=on}} [[Chrysler LA engine|LA V8 engine]]. It replaced the Slant-6 in the rest of the Dodge truck line at the end of the 1987 model year.<ref name=Allpar_Slant/>

==Significant production changes==
* The combustion chamber shape was slightly modified for 1967 to promote more complete combustion and reduce exhaust emission toxicity.
* All G engines used [[forge]]d [[steel]] crankshafts until the middle of model year 1976, when a less costly [[cast-iron]] crankshaft was introduced. The cast crankshaft uses a different block, different main and connecting rod bearings and different connecting rods.
* The counterbore in the rear flange of the crankshaft was {{convert|1+1/4|in}} diameter until 1967. For 1968, it was enlarged to {{convert|1+1/2|in}}. This difference has implications when swapping engines with [[automatic transmission]]s.
* All G-engines used solid valve [[tappet|lifters]] through the 1980 model year, with the exception of a small production test of [[hydraulic lifters]] in the 1978 model year. For model year 1981, all North American G-engines received top-fed hydraulic lifters. Retrofitment in both directions is possible.
* Emission control devices and systems, carburetor make and specification, and engine assembly details changed over the years to comply with market requirements and preferences.
* [[Electronic ignition]], which had been made available on [[V8 engine]]s late in 1971, was made standard equipment on all engines including the RG in 1973.
* [[Induction heating|Induction]]-[[hardening (metallurgy)|hardened]] exhaust valve seats and upgraded exhaust valves were made standard in 1973 to withstand prolonged operation on [[unleaded gasoline|no-lead fuel]].

==Configuration variants==

===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 {{cvt|3+2/5|in|mm|1}} and a stroke of {{cvt|3+1/8|in|mm|1}} for an actual displacement of {{cvt|170.2|cuin|L|1}}. Connecting rod length is {{cvt|5.707|in|mm|1}}. 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 {{cvt|3.64|in|mm|1}} stroke and connecting rods {{cvt|7.006|in|mm|1}} long, for an actual displacement of {{cvt|198.3|cuin|L|1}}. 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===
[[File:Dodge Challenger conv six eng.jpg|thumb|Slant-6 in a first-generation [[Dodge_Challenger#First_generation_(1970–1974)|Dodge Challenger]]]]
The 225 used the RG (tall) block with a {{cvt|3+2/5|in|mm|1}} bore, a {{cvt|4+1/8|in|mm|1}} stroke and {{cvt|6.699|in|mm|1}} connecting rods, for an actual displacement of {{cvt|224.7|cuin|L|1}}. 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 {{cvt|145|hp|kW|0}} at 4,000&nbsp;rpm and {{cvt|215|lbft|Nm}} of torque at 2,800&nbsp;rpm.<ref>{{Cite web|url=https://www.onallcylinders.com/2014/01/20/top-10-engines-time-6-chrysler-225-slant-six/#:~:text=The%20original%20Chrysler%20225%20Slant,4%2C000%20rpm%20and%20215%20ft.|title = Top 10 Engines of All Time (#6): Chrysler 225 Slant Six|date = 20 January 2014}}</ref>

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 [[Chrysler 2.2 & 2.5 engine|2.2-liter inline-four]]) in [[Windsor, Ontario]].<ref name=JMC16>{{cite magazine | title = Chrysler Engine Plans Through 1985 | editor-first = Jim | editor-last = McCraw | date = November 1982 | ref = JH82 | page = 16 | magazine = [[Motor Trend]] | publisher = Petersen Publishing Co. | volume = 34 | number = 11 }}</ref> Design work had started in 1975, but with the collapse of the diesel market in North America, these plans were cancelled in 1983.<ref name=CCslantD>{{cite web | url = https://www.curbsideclassic.com/automotive-histories/automotive-history-diesel-chrysler-slant-sixes-in-house-and-otherwise/ | archive-url = https://web.archive.org/web/20210925190114/https://www.curbsideclassic.com/automotive-histories/automotive-history-diesel-chrysler-slant-sixes-in-house-and-otherwise/ | archive-date = 2021-09-25 | first = Daniel | last = Stern | title = Automotive History: Diesel Chrysler Slant-Sixes, In-House and Otherwise | date = 2020-05-19 | work = Curbside Classic }}</ref>

====Aluminum block 225====
Between late model year 1961 and early model year 1963, approximately 52,000 [[Die casting|die-cast]] aluminum RG blocks were produced and installed in passenger cars. These open-deck blocks used integrally cast high-nickel iron [[cylinder liner]]s, 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 {{cvt|80|lb|kg|0}} 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 inhibitor]]s. 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.<ref>{{cite web |url= http://slantsix.org/articles/dutra-blocks/alm-block-sl6.htm |title=Aluminum Slant Six Engine Overview |last=Dutra |first=Doug |year=2001 |work=Slant Six Forum |access-date=10 December 2015}}</ref>

===High-performance variants===
Most G-engines were equipped with small-capacity [[carburetor]]s (such as the ubiquitous [[Holley Carburetor|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====
[[File:Hyperpak.jpg|thumb|Reproduction Hyper-Pak intake on a Slant-6 engine]]
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 header]]s, 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 transmission]]s, 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 automobiles|fuel economy]]. In competition events it proved unbeatable. Seven factory-backed Valiants entered the 1960 [[NASCAR]] compact car race at [[Daytona Beach, Florida|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 Performance Products|Holley]] RX 7000 A carburetors and other engine specification changes. Claimed output was {{cvt|180|bhp|PS kW|0}}, compared to the single-carburetor version of the engine producing {{cvt|145|bhp|PS kW|0}}

====2-barrel carburetion====

=====Export 2-barrel setup=====
[[File:Hp225.jpg|thumb|Air cleaner decal from Australian-market 1967–70 2bbl Slant-6 installed on US-market 1976–79 2bbl 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 {{cvt|160|bhp|PS kW|0}}, 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 valve|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 {{cvt|174|bhp|PS kW|0}} and torque of {{cvt|245.6|lbft|Nm|0}}, 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, [[Vehicle emissions control|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 chamber|plenum]] rather than an open one, and had provisions for an [[Exhaust gas recirculation|EGR]] valve. The carburetor, a Carter BBD similar but not identical to the one used on Chrysler's [[Chrysler LA engine#318 V8|{{cvt|318|CID|L|1}} V8 engine]], used a standard Chrysler-style remote automatic choke. A {{convert|2+1/4|in}} 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 {{cvt|100|to|110|hp|PS kW|0}} and torque from {{cvt|170|to|180|lbft|Nm|0}}, while improving throttle response and driveability while maintaining compliance with emission laws.

==Applications==

===Passenger cars, trucks, vans===
{{hidden begin
|title = Cars, trucks and vans using G- and RG-engines
|titlestyle = background:#99FF99; text-align:left;
|bodystyle = text-align:left;
}}
* 1980-1983 [[Chrysler Cordoba]]
* 1982-1984 [[Chrysler Fifth Avenue]]
* 1977-1981 [[Chrysler LeBaron]]
* 1962-1970 [[Chrysler Valiant]]
* 1975-1980 [[Dodge Aspen]]
* 1970-1971 [[Dodge Challenger]]
* 1969-1974 [[Dodge Charger (B-body)|Dodge Charger]]
* 1965-1976 [[Dodge Coronet]]
* 1960-1976 [[Dodge Dart]]
* 1971-1972 [[Dart Demon|Dodge Demon]]
* 1971-1988 [[Dodge Ram Van]]
* 1977-1983 [[Dodge Diplomat]]
* 1960-1962 [[Dodge Lancer]]
* 1980-1983 [[Dodge Mirada]]
* 1965-1967 [[Dodge Monaco#First|Dodge Monaco]] (Canada)
* 1977-1978 [[Dodge Monaco]]
* 1969-1973 [[Dodge Polara]]
* 1981-1987 [[Dodge Ram]]
* 1978-1981 [[Dodge St. Regis]]
* 1964-1970 [[Dodge A100|A-series truck and van]]
* 1960-1987 [[Dodge D100|D-series truck and van]]
* 1961-1987 [[Dodge W100|W-series 4WD truck]]
* 1964-1971 [[Plymouth Barracuda]]
* 1962-1967 [[Plymouth Belvedere]]
* 1969-1976 [[Plymouth Duster]]
* 1960-1973;1975-1978 [[Plymouth Fury]]
* 1980-1984 [[Plymouth Gran Fury]]
* 1971-1974 [[Plymouth Satellite]]
* 1955-1956;1962-1964 [[Plymouth Savoy]]
* 1960 [[Chrysler Valiant|Valiant]]
* 1961-1976 [[Plymouth Valiant]]
* 1975-1980 [[Plymouth Volare|Plymouth Volaré]]
{{hidden end}}

==References==
{{reflist|30em}}

==External links==
{{commons category}}
* [https://www.youtube.com/watch?v=OvnMmh5EijM Newsreel: Valiant wins 1960 Compact Car race at Daytona Beach]

{{DEFAULTSORT:Chrysler Slant-6 Engine}}
[[Category:Chrysler engines|Slant 6]]
[[Category:Straight-six engines]]
[[Category:Slant engines]]
[[Category:Gasoline engines by model]]