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Toyota R Engine: A Foundation of Automotive Engineering

An in-depth exploration of Toyota's enduring inline-four engine family, tracing its development, technical innovations, and widespread application from the mid-20th century to the late 1990s.

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Engine Overview

Manufacturer

The Toyota R family of engines was meticulously designed and manufactured by Toyota Motor Corporation.

Production Span

This robust engine series saw continuous production from 1953 through 1997, demonstrating remarkable longevity and adaptability across various automotive applications.

Architectural Layout

Configuration & Materials

The R family is characterized by its inline-four cylinder configuration, a design favored for its balance of compactness and performance. Early iterations utilized cast iron for both the cylinder block and head, ensuring durability. Later models incorporated aluminum for cylinder heads, contributing to weight reduction and improved thermal management.

Valvetrain Systems

Over its extensive production run, the R engine series evolved through several valvetrain designs:

  • Overhead Valve (OHV): Employed in the earliest models, featuring pushrods to actuate the valves.
  • Single Overhead Camshaft (SOHC): Introduced for improved breathing and performance, with the camshaft located in the cylinder head.
  • Double Overhead Camshaft (DOHC): Representing the pinnacle of performance for the R series, featuring two camshafts per cylinder bank for precise valve control.

These engines consistently utilized a timing chain for driving the camshaft(s), ensuring reliable synchronization throughout their operational life.

Combustion & Fueling

Fuel Systems

The R engines were primarily fueled by gasoline. They employed a range of fuel delivery systems:

  • Carburetor: The traditional method used in earlier models, relying on mechanical devices to mix fuel and air.
  • Multi-port Fuel Injection (EFI): Adopted in later variants, offering more precise fuel delivery, improved efficiency, and better emissions control.

Emissions & Forced Induction

To meet increasingly stringent environmental regulations, specific variants incorporated advanced emissions control systems, including adaptations for California standards and the use of Toyota's TTC-V system, a licensed version of Honda's CVCC stratified charge technology. The Hitachi CT20 turbocharger was notably featured on the 22R-TE variant, enhancing power output through forced induction.

Cooling & Lubrication

These engines utilized a conventional water-cooled system, essential for maintaining optimal operating temperatures under demanding conditions. Lubrication was managed via a wet sump system, a standard and reliable method for engine oil circulation.

Performance Metrics

Power and Torque

The performance characteristics of the R engine series varied significantly across its numerous variants and production years. Generally, power output ranged from approximately 45 kW (61 PS; 60 hp) to over 104 kW (141 PS; 139 hp) for high-performance DOHC models. Torque figures spanned from around 108 N⋅m (80 lb⋅ft) to approximately 234 N⋅m (173 lb⋅ft) for turbocharged variants.

Evolutionary Trajectory: The R Family History

The Genesis: R (1953-1964)

The foundational 1.5 L (1,453 cc) R engine marked Toyota's entry into modern engine design. Manufactured initially at the Honsha plant, it featured a cast iron block and head, OHV valvetrain driven by a gear-driven camshaft, and a non-crossflow head. Its bore and stroke were 77 mm × 78 mm. This engine powered early Toyota models, including the first Toyota Crown exported to the United States. While noted for quiet idling, contemporary reviews suggested limitations in high-RPM capability.

Code Power Torque Years Comments
R 45 kW (61 PS; 60 hp) at 4,400 rpm 108 N⋅m (80 lb⋅ft) at 2,600 rpm 1953–1964
R-LPG 1962–1964 LPG variant

Applications: 1953–1955 Toyota Super, 1955–1956 Toyota Master, 1955–1958 Toyota Crown.

Refinement: 2R (1964-1971)

The 1.5 L (1,490 cc) 2R engine evolved from the R, featuring a square design with bore and stroke both at 78 mm. Production gradually shifted to the Kamigo plant. It offered increased power and torque compared to its predecessor.

Code Power Torque Years Comments
2R 55 kW (75 PS; 74 hp) at 5,000 rpm 116 N⋅m (86 lb⋅ft) at 2,600 rpm 1964–1969
2R-LPG 1964–1969 LPG variant

Applications: 1964–1970 Toyota Corona (RT40/RT46V/RT50/RT56), February 1970–January 1971 Toyota Corona (RT80/90/86V), 1968–1971 Toyota Mark II, Toyota Bus RH15B, 1965–1967 Toyota Stout (RK43/RK47), Toyota ToyoAce PK41, Toyota Hilux RN10.

Increased Displacement: 3R (1959-1968)

The 1.9 L (1,897 cc) 3R introduced a larger displacement. It featured variations like the 3R-B and the emissions-compliant 3R-C for the California market. Compression ratios were adjusted across different versions.

Code Power Torque Years Comments
3R 59 kW (80 PS; 79 hp) at 4,600 rpm 142 N⋅m (105 lb⋅ft) at 2,600 rpm 1959–1960 7.7 CR
3R 66 kW (90 PS; 89 hp) at 5,000 rpm 142 N⋅m (105 lb⋅ft) at 3,400 rpm 1960–1968 8.0 CR
3R-B 59 kW (80 PS; 79 hp) at 4,600 rpm 142 N⋅m (105 lb⋅ft) at 2,600 rpm 1960–1968 7.7 CR
3R-C Emissions control – California
3R-LPG 1963–1968 LPG variant

Applications: 1963–1968 Toyota Dyna, 1964–1967 Toyota Stout, 1969–? Toyota Hilux, 1967–1969 Toyota Corona (US), 1959–1967 Toyota Crown, 1960–1967 Toyopet Masterline.

Performance Tuning: 4R & 5R (1965-1986)

The 1.6 L (1,587 cc) 4R and the 2.0 L (1,994 cc) 5R engines continued the lineage. The 5R, in particular, was a long-running OHV engine used extensively in commercial vehicles like the Toyota Dyna and Coaster, known for its torque characteristics.

4R (1965-1968):

  • Displacement: 1.6 L (1,587 cc)
  • Bore × Stroke: 80.5 mm × 78 mm
  • Applications: 1967 Toyota 1600S (Japan).

5R (1968-1986):

  • Displacement: 2.0 L (1,994 cc)
  • Bore × Stroke: 88 mm × 82 mm
  • Valvetrain: 2-valve OHV
  • Power (Standard): 79 kW (107 PS; 106 hp) at 5200 rpm
  • Torque (Standard): 169 N⋅m (125 lb⋅ft) at 3000 rpm
  • Power (Dyna Tuned): 59 kW (80 PS; 79 hp) at 4600 rpm
  • Torque (Dyna Tuned): 145 N⋅m (107 lb⋅ft) at 3000 rpm
  • Variants: 5R-LPG (1968–1983)
  • Applications: Toyota Crown (3rd-6th gen), 1969–1977 Toyota Coaster, Toyota Dyna, Toyota Stout, Toyota ToyoAce, August 1981–? Toyota Corona (6th gen, LPG/auto).

Performance Enhancements: 6R, 7R, 8R (1969-1973)

This era saw further development, including the 1.7 L (1,707 cc) 6R, the 1.6 L (1,591 cc) 7R with its wider bore and shorter stroke, and the significant 1.9 L (1,858 cc) 8R. The 8R marked a departure with its SOHC head, impressing reviewers with its free-revving nature.

6R (1969-1974):

  • Displacement: 1.7 L (1,707 cc)
  • Power: 80 kW (108 PS; 107 hp) at 5,300 rpm
  • Variants: 6R-B, 6R-LPG
  • Applications: Sep 1970–Jul 1973 Toyota Corona, Jan 1972–Aug 1973 Toyota Mark II.

7R (1968-1971):

  • Displacement: 1.6 L (1,591 cc)
  • Bore × Stroke: 86 mm × 68.5 mm
  • Variants: 7R, 7R-B (dual SU carbs), 7R-LPG
  • 7R: 63 kW (86 PS; 84 hp) at 5,500 rpm, 123 N⋅m (91 lb⋅ft) at 3,800 rpm, 8.5 CR.
  • 7R-B: 75 kW (102 PS; 101 hp) at 6,200 rpm, 133 N⋅m (98 lb⋅ft) at 4,200 rpm, 9.5 CR.
  • Applications: 1968–1970 Toyota Corona, 1970 Toyota Corona (RT82), 1968–1970 Toyota Corona Mark II, 1968–1971 Toyota Corona Mark II Wagon.

8R (1968-1973):

  • Displacement: 1.9 L (1,858 cc)
  • Bore × Stroke: 85.9 mm × 80 mm
  • Valvetrain: 2-valve SOHC
  • Variants: 8R, 8R-D, 8R-B (dual SU), 8R-E (EFI), 8R-C (Californian), DOHC 8R-G.
  • 8R: 81 kW (110 hp; 111 PS) at 5,500 rpm, 153 N⋅m (113 lb⋅ft) at 3,800 rpm, 9.0 CR.
  • 8R-B: 82 kW (111 PS; 110 hp) at 6,000 rpm, 152 N⋅m (112 lb⋅ft) at 4,000 rpm, 10.0 CR.
  • 8R-C: 81 kW (110 hp; 111 PS) at 5,500 rpm, 174 N⋅m (128 lb⋅ft) at 3,600 rpm, 9.0 CR.
  • Applications: 1970–1971 Toyota Hilux, 1971–1973 Toyota Corona, Toyota Corona Mark II, Toyota Corona Mark II GSS (8R-G).

Yamaha Collaboration & DOHC: 9R, 10R, 8R-G (1967-1972)

The 1.6 L (1,587 cc) 9R was essentially a 4R with a DOHC head co-developed with Yamaha, featuring direct valve actuation. The 1.9 L (1,858 cc) 10R and its successor, the DOHC 8R-G, represented significant performance steps, utilizing Yamaha's expertise for high-revving, potent engines.

9R (1967-1968):

  • Displacement: 1.6 L (1,587 cc)
  • Valvetrain: 2-valve DOHC (Yamaha design)
  • Power: 82 kW (111 PS; 110 hp) at 6,200 rpm
  • Torque: 136 N⋅m (100 lb⋅ft) at 5,000 rpm
  • Weight: 174 kg (384 lb)
  • Applications: Toyota Corona (RT55) 1600 GT hardtop.

10R (1967-Feb 1971) / 8R-G (1969-1972):

  • Displacement: 1.9 L (1,858 cc)
  • Valvetrain: 2-valve DOHC (Yamaha design)
  • 10R: Power 104 kW (141 PS; 139 hp) at 6,400 rpm, Torque 166 N⋅m (122 lb⋅ft) at 5,200 rpm.
  • 8R-G: Power 145 PS (107 kW; 143 hp) at 6400 rpm, Torque 18 kg⋅m (177 N⋅m; 130 lb⋅ft) at 5200 rpm, Weight 170 kg (375 lb).
  • Applications: Toyota Corona Mark II RT72/RT75 GSS.

Mainstream & Commercial Use: 12R, 16R, 19R (1969-1980)

The 1.6 L (1,587 cc) 12R served as a reliable workhorse, particularly in commercial applications. The 1.8 L (1,808 cc) 16R offered improved performance, while the experimental 2.0 L (1,968 cc) 19R explored stratified charge combustion for emissions reduction.

12R (1969-1988):

  • Displacement: 1.6 L (1,587 cc)
  • Bore × Stroke: 80.5 mm × 78 mm
  • Valvetrain: OHV
  • Power: 90 PS (66 kW; 89 hp) SAE at 5400 rpm
  • Variants: 12R-M (Philippines), 12R-LPG
  • Applications: 1971–1978 Toyota Corona, 1971–1972 Toyota Hilux, 1977 Toyota Hiace, Daihatsu Taft (F20), Delta Mini Cruiser.

16R (1974-1980):

  • Displacement: 1.8 L (1,808 cc)
  • Valvetrain: OHC
  • Power: 105 PS (77 kW; 104 hp) at 5,600 rpm (standard), 110 PS (81 kW; 108 hp) at 6,000 rpm (twin carb).
  • Variants: 16R-B, 16R-J (commercial).
  • Applications: Oct 1975–Feb 1977 Toyota Carina, Toyota Mark II Van, Toyota Corona, Toyota HiAce.

19R (1974-1977):

  • Displacement: 2.0 L (1,968 cc)
  • Valvetrain: SOHC
  • Features: TTC-V stratified charge system
  • Power: 80 PS (59 kW; 79 hp)
  • Applications: 1974–1977 Toyota Carina, 1974–1977 Toyota Corona.

The Performance Era: 18R, 20R, 21R (1971-1987)

The 2.0 L (1,968 cc) 18R series, particularly the DOHC 18R-G, became synonymous with performance, powering models like the Celica GT. The 2.2 L (2,190 cc) 20R and the 2.0 L (1,972 cc) 21R further refined the SOHC designs, emphasizing torque and reliability, especially in the 20R which featured significant internal revisions.

18R Series (1971-1981):

  • Displacement: 2.0 L (1,968 cc)
  • Bore × Stroke: 88.5 mm × 80 mm
  • Valvetrain: 2-valve SOHC (most variants), DOHC (18R-G)
  • 18R-G (DOHC): Power 145 PS (107 kW; 143 hp) at 6400 rpm, Torque 18 kg⋅m (177 N⋅m; 130 lb⋅ft) at 5200 rpm.
  • 18R-E (EFI): 84–96 kW (114–131 PS; 113–129 hp) at 5600 rpm.
  • Applications: Toyota Celica, Corona, Cressida, Hilux.

20R (1975-1980):

  • Displacement: 2.2 L (2,190 cc)
  • Bore × Stroke: 88.5 mm × 89 mm
  • Valvetrain: 2-valve SOHC
  • Key Changes: Crossflow head, hemispherical combustion chambers, strengthened internals, longer stroke.
  • Power (Initial): 72 kW (98 PS; 97 hp) at 4800 rpm.
  • Applications: Toyota Hilux, Celica, Corona, Stout, Coaster.

21R (1978-1987):

  • Displacement: 2.0 L (1,972 cc)
  • Bore × Stroke: 84 mm × 89 mm
  • Valvetrain: 2-valve SOHC
  • Power (Export): 74 kW (100 PS; 99 hp) DIN at 5,000 rpm.
  • Variants: 21R-C (Emissions), 21R-U (Japan).
  • Applications: Toyota Carina, Celica, Corona, Mark II/Cressida, HiAce.

The Final Frontier: 22R (1981-1997)

The 2.4 L (2,366 cc) 22R series represents the final evolution of the R engine. Known for exceptional durability and torque, it featured significant revisions around 1985. The 22R-E introduced EFI, and the 22R-TE offered a turbocharged option. Its reliability cemented Toyota's reputation.

Code Power Torque Years Comments
22R 72 kW (98 hp; 98 PS) at 4,800 rpm 174 N⋅m (128 lb⋅ft) at 2,800 rpm 1981–1990 Carburetor, dual-row timing chain ('81–'82), single-row ('83–'90)
22R 81 kW (109 hp; 110 PS) at 5,000 rpm 187 N⋅m (138 lb⋅ft) at 3,400 rpm 1990–1995
22R-E 78 kW (106 PS; 105 hp) at 4,800 rpm 185 N⋅m (136 lb⋅ft) at 2,800 rpm 1983–1984 EFI, single-row timing chain
22R-E 84 kW (114 PS; 113 hp) at 4,800 rpm 190 N⋅m (140 lb⋅ft) at 3,600 rpm 1985–1997 EFI, single-row timing chain (revised internals)
22R-TE 101 kW (137 PS; 135 hp) at 4,800 rpm 234 N⋅m (173 lb⋅ft) at 2,800 rpm 1986–1988 Turbocharged, single-row timing chain

Applications: Toyota Hilux, Celica, Corona, Pickup, 4Runner, Land Cruiser II/Bundera, Volkswagen Taro.

Note on Timing Chain: Early 22R engines used a dual-row timing chain, replaced by a single-row chain with plastic guides from 1983. While lighter, the single-row system introduced potential wear issues over time, often addressed by aftermarket upgrades or careful maintenance.

Key Variants & Innovations

Valvetrain Evolution

The progression from basic OHV designs to sophisticated SOHC and DOHC configurations, often in collaboration with Yamaha, significantly boosted the performance potential of the R series, particularly in sporting applications like the Celica GT models.

Fuel Injection Adoption

The integration of Electronic Fuel Injection (EFI), notably in the 18R-E and 22R-E variants, marked a critical shift towards improved fuel efficiency, reduced emissions, and more consistent engine performance compared to traditional carbureted systems.

Emissions Compliance

Toyota actively adapted R engines to meet global emissions standards. This included specific variants like the 3R-C and 21R-C, and the implementation of technologies such as air injection and stratified charge combustion (19R), demonstrating a commitment to environmental responsibility.

Turbocharging

The 22R-TE variant showcased the application of turbocharging to the R engine, providing a substantial increase in power and torque for applications demanding higher performance, such as in certain Hilux and 4Runner models.

Vehicle Applications

Diverse Integration

The R engine family's versatility allowed it to be implemented across a wide spectrum of Toyota vehicles, from compact passenger cars and sports coupes to robust trucks and commercial vans. Its adaptability and reliability made it a cornerstone of Toyota's product line for decades.

Key Vehicle Models Powered by R Engines:

  • Toyota Crown: A foundational model for the R engine, spanning multiple generations.
  • Toyota Corona: A consistent recipient across various R engine displacements and configurations.
  • Toyota Celica: Particularly the performance-oriented variants utilizing SOHC and DOHC R engines (e.g., 8R-G, 18R-G).
  • Toyota Hilux / Pickup: A primary application for many R engines, especially the larger displacement and torque-focused variants (20R, 22R).
  • Toyota 4Runner: Utilized the durable 22R and 22R-E engines.
  • Toyota Mark II / Cressida: Featured various R series engines throughout its history.
  • Toyota Dyna / ToyoAce / Coaster: Commercial vehicles that heavily relied on the robust, torque-oriented R engines (e.g., 3R, 5R).
  • Toyota Stout: Used several R engine variants during its production.
  • Toyota Carina: Equipped with several R engine options.
  • Daihatsu Taft: Notably used the 12R engine.
  • Volkswagen Taro: A badge-engineered Toyota Hilux, also featuring the 22R-E.

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References

References

  1.  Toyota Twin Cam, p. 6
  2.  Toyota Twin Cam, p. 25
  3.  Toyota Twin Cam, p. 7
A full list of references for this article are available at the Toyota R engine Wikipedia page

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Disclaimer

Important Notice

This page has been meticulously generated by an Artificial Intelligence, drawing upon a comprehensive analysis of publicly available data. Its purpose is strictly informational and educational, aiming to elucidate the technical history and specifications of the Toyota R engine series.

This content does not constitute professional automotive engineering advice. The information presented is based on data available at the time of generation and may not reflect the absolute latest specifications, modifications, or historical nuances. Toyota Motor Corporation's official documentation and consultation with qualified automotive professionals should always be prioritized for specific technical inquiries or applications. No liability is assumed for any errors, omissions, or actions taken based on the information herein.