Toyota R series four-cylinder engines (1953-1997)
The R was an incredibly long-lived (as in made for forty years) series of engines, created for rear wheel drive cars and trucks, with many changes along the way. The first Toyota cars exported to the United States, the Crown, used a small R-series engine. Eventually, R engines were fitted with electronic fuel injection and twin cams.
The original 1.5 liter R engines were made from 1953 through 1964 at a single factory, with a cast iron block and head. They were water-cooled, with a three bearing crankshaft and gear-driven cam; the overhead valves were activated with pushrods. Even then, a two-carrel carburetor was fitted, with 12-volt electrics. It produced around 60 hp (gross) and 80 lb-ft throughout its life, except in propane form (1962-64). The engine was used in the Super, Master, and Crown.
The 3R, oddly, came before the 2R, entering production in 1959 and being dropped in 1968; the reason for its creation is obvious—more torque for the Dyna, HiLux, and Stout trucks (it was also used in the Corona, Crown, and Masterline), with a 1.9 liter displacement. The original compression ratio was 7.7:1, and when, in 1960, the ratio was changed to 8:1, the original was renamed to 3R-B. The 3R-C followed California pollution laws. Power ratings were 79 hp and 105 lb-ft for the low-compression version, and 89 hp (same torque) for the higher compression version.
The 2R, made from 1964 to 1971, had both bore and stroke of 3.07 inches (78 mm), and produced 74 hp (gross) and 86 pound-feet of torque. The differences from the original R are puzzling; the original R had nearly the same displacement (1453 cc vs 1490 cc), and the main difference appears to be a 1 mm greater bore. The 2R was used in numerous vehicles, including the Stout, Bus, Corona, ToyoAce, and popular HiLux pickup. A 4R variant (80.5mm x 78mm bore and stroke) was made from 1965-68 for the Japanese Corona.
The 2-liter version, dubbed 5R, was made from 1968 all the way through 1986; it was both bored and stroked, to 3.46” x 3.23” (88mm x 82mm). The early version was rated at 106 hp and 125 lb-ft, though trucks were retuned for lower power output and greater durability (79 hp, 107 lb-ft). Cars with the 5R included the Crown, ToyoAce, and Corona; trucks were the Dyna and Stout.
For just five years, Toyota made the 6R, a 1.7 liter version (1969-74) pushing out 107 hp for the 1970-73 Corona and 1972-73 Mark II. The 7R had an even shorter span of time; it was essentially a 4R with a wider 3.39” bore and shorter 68.5” stroke, sacrificing a little low-end torque for more responsive revving. The plain 7R was rated at 84 hp and 91 lb-ft, with an 8.5:1 compression; the dual-SU-carburetor 7R-B was good for 101 hp and 98 lb-ft of torque, though it was only sold for two years, 1968-69 (so those figures are, again, gross power). The various 7Rs only made it into Coronas and Mark IIs.
The 8R (1966-73) was a 1.9 liter, 113 cid variant with a five-bearing crank, with California, twin-cam, and dual-carb variants. It was the first Toyota engine to garner critical success in the United States. The original version was rated at 108 hp and 117 lb-ft, relatively tame; the dual-carb 8R-B was good for 110 hp and 112 lb-ft despite a high 10:1 compression ratio. The 8R-C met California emissions with 9:1 compression, 109 hp, and 128 lb-ft of torque. The 8R-G, made from 1969 through 1972, was originally dubbed 10R; it was renamed at about the same time that Toyota took out its tensioner gear. Not many were made—fewer than 5,000—and they were all installed in the Mark II 1900 GSS models. It weighed only 370 pounds but produced a hefty 139 hp and 122 lb-ft.
The 9R, made for just two years (1967-68), was a 1.6 liter with a complex Yamaha dual-cam head, producing 110 hp and 100 lb-ft using twin Solex carbs. Only 2,229 were made, for a single model of Corona.
The 12R, used in Toyota cars and Toyota and Daihatsu trucks, was made from 1969 through 1998; as installed in early Coronas, it was good for 89 hp (net).
The 16R (1974-80) was used in Coronas, Carinas, Mark II Vans, and the HiAce; by 1980, it was rated at 104 hp with a single carb and 108 hp with twin carbs. There were also California and commercial variants.
Within the same year, the attachments were basically the same for various R series engines, so one could swap, say, between an 18R and 22R. Many of the internal parts (but not all of them) could also be interchanged; there were some surprises, including the same crank being used for both the 18R twin cam and single cam setups.
The 19R (we'll get to the 18R later) was made for three years in the 1970s, a 2-liter model with a version of the Honda CVCC combustion chamber, used only in Japan-specific cars.
Despite its name, which many may think stands for “1.8” liters but does not, the 18R was a 2-liter engine. It showed up in first generation Celica (and other cars), at first producing 86-89 hp with 105-107 lb-feet of torque; an 18R-C variant was sold in California from 1971 to 1974, producing 97 horsepower and 106 lb-ft of torque.
The 18R had a bore and stroke of 3.48 x 3.15 inches (88.5 x 80 mm). The short stroke helped it in performance applications. The displacement was 1968cc for both single and twin cam versions.
The original 18R (105 hp gross, 87 net; 105-107 lb-ft) was used from 1971 to 1981 in Hilux pickups that did not have to conform to emissions rules. The 18R-C was used for emissions-controlled vehicles, conforming to California standards; it was rated at 97 hp (gross) and the same torque. The 18R-U was used for Japanese emissions-controlled cars only. Finally, the 18R-E, the first R series to get electronic fuel injection, was sold in Japan only, and was rated 113 hp and 127 lb-ft. Despite the engine's performance goals, they kept the iron blocks and heads of past R series engines.
All 18R and 18R-G engines were chain-driven with dual overhead cams and two valves per cylinder (except racing versions)
Then we had the twin-cam versions, dubbed 18R-G; these directly replaced the 8R-G, and were made from 1973 to 1982. Most or all of these used Yamaha heads, which were stamped with that company’s logo; and they had hemispherical heads for greater efficiency, since the goal was to produce as much power as possible without exceeding the class limit of 2.0 liters. The heads and timing parts were unique, though they shared gaskets with other 18R variants (requiring sealant around the timing cover). As one might expect, though, the single-cam and twin-cam versions had different intake and exhaust manifolds; the twin-cam also had its own exhaust and timing pieces. All the twin-cam versions had hardened valve seats and could use unleaded fuel; they also had aluminum-alloy heads, but with the same iron blocks as the ordinary 18R. The four-valve racing version was called the 152E; but these were not used in production cars.
There were four versions of the 18R-G twin-cam engine: the original (143 hp, 130 lb-ft), used from 1972 to 1981; the low-compression 18R-GR for those wanting to use regular fuel (1973,75, 138 hp and 124 lb-ft); the 18R-GU version to meet Japanese emissions targets; and the 18R-GEU electronically fuel-injected version, producing 133 hp and 127 lb-ft, but meeting Japanese 1978-82 emissions targets.
The twin-cam engines were used exclusively in the Celica GT, Carina GT, Camry GT, and Corona GT, but could be transplanted into any 18R-engined car.
20R: the first truly reliable Toyota four-cylinder engines
The 20R was a revolutionary engine for Toyota, though it was basically a continuation of series which had been running since 1953. Launched in the 1975 Celica, Corona, and Half-ton Pickup, the 20R engine used a semi-hemispherical head for optimal fuel-burning and power generation at high rpm; it was however designed to meet and beat emissions standards as well, without the power-sapping add-ons other manufacturers were resorting to.
(Page to be continued...)