The Toyota R family was a series of inline-four gasoline automobile engines. Designed for longitudinal placement in such vehicles as the Celica and Hilux and in production from 1953 through 1997, usage faded out as many of Toyota's mainstream models moved to front-wheel drive. Overhead cam (OHC) versions featured a chain-driven camshaft.

History of the R family

R

The 1453 cc R family was produced from 1953 through 1964, and was originally manufactured at the Toyota Honsha plant. Bore and stroke was 77x78 mm. In common with new engines of the time, it was made from cast iron (both the block and the head), water cooled, used a three bearing crank, 12V electrics and a side-mounted gear-driven camshaft controlling overhead valves via pushrods in a non-cross flow head (exhaust and inlet manifolds being on the same side of the engine). Induction was by a twin throat down-draft carburettor, the compression ratio was 8.0:1 and the total weight was 155 kg. An LPG version, the R-LPG, was produced for the last two years. The R engine was the Toyota engine used in the 1958 Toyota Crown, the first model to be exported to the United States. Road & Track was unimpressed with the engine on its introduction, noting that it idled quietly but was "not capable of very high revolutions per minute." Applications:

2R

The 1490 cc 2R family was produced from 1964 through 1971. It is a square engine, with bore and stroke of 78 mm. Again, an LPG version, the 2R-LPG, was produced alongside the gasoline version. Production had been gradually transferred from the original Honsha plant to the new Toyota Kamigo plant in 1968. Applications:

3R

The 1897 cc 3R family was produced from 1959 through 1968. When introduced it had a 7.7:1 compression ratio. In 1960 the 3R was uprated to 8:1 and the 3R-B version was offered from 1960 through 1968 with the old 7.7:1 compression ratio. The 3R-C was introduced to comply with California emissions laws. The 3R-LPG variant was produced for the last five years. Applications:

4R

The 1587 cc 4R family was produced from 1965 through 1968. Bore and stroke was 80.5x78 mm. Applications:

5R

The 1994 cc 5R family was produced from 1968 through 1986. An LPG version, the 5R-LPG, was produced from 1968 through 1983. It is a 2-valve OHV engine. Cylinder bore and stroke are 88x82 mm. Output was 106 hp at 5200 rpm and 125 lbft at 3000 rpm. Trucks such as the Dyna received a version tuned for torque, with a maximum power of 80 PS at 4600 rpm and torque of 145 Nm at 3000 rpm. Applications:

6R

The 1707 cc 6R was produced from 1969 through 1974. Output is 107 hp at 5,300 rpm. The 6R-B was produced those same years, while the natural gas powered 6R-LPG was produced from 1970 through 1973.

7R

The 1591 cc 7R was produced from 1968 through 1971 with a twin throat down-draft carburettor. The 7R-B was produced from 1968 through 1969 with dual SU carburetors and higher compression. The 7R-LPG was produced from 1969 through 1970. The 7R was similar in displacement and technology to the 4R except the wider 86 mm bore and shorter 68.5 mm stroke of the 7R gave different power characteristics. Applications:

8R

The 1858 cc 8R The engine was produced from 1968 through 1973. Cylinder bore and stroke was 85.9x80 mm with a five bearing crank. It was also available as the 8R-D, dual SU 8R-B, EFI 8R-E, Californian-spec 8R-C and DOHC 8R-G. It was a major departure for the R family. With a 2-valve SOHC head, it impressed contemporary reviewers – Road & Track praised its quietness and free-revving nature. The 8R engine has a closed chamber head vs the open chamber of the 18R-C. The 8R-B has dual side draft SU-type Aisan carburettors with the float bowl under the body and vacuum activated power valves with strangle plates for chokes and liquid cooled intake with a balance tube. Toyota upped the ante again with the DOHC (but still 2-valve) 8R-G, produced from 1969 through 1972. From 1969 to Feb 1971 it was known as the 10R, but along with a removal of the tensioner gear in the interest of quieter operation, it was renamed the 8R-G to reflect the decision that twin-cam engines were henceforth to be identified by a "-G" suffix. 4,931 twin cam engines were built, all installed in the Toyota Corona Mark II (RT72) 1900 GSS. The 10R/8R-G weighed in at 170 kg and as such was both lighter and more compact than its less powerful predecessor the 9R Applications:

9R

The 1587 cc 9R was produced from 1967 through 1968. Bore and stroke 80.5x78 mm. It was essentially a 4R with a DOHC head designed by Yamaha. The cam lobes activated the valves directly via a bucket over shim arrangement. This same arrangement was used on the 2M, 8R-G, 10R, 18R-G, 2T-G, 4A-GE and 3T-GTE engines (all designed by Yamaha). Output was 82 kW at 6,200 rpm and 136 Nm at 5,000 rpm. It was a 2-valve DOHC design with two Solex carburettors and weighed 174 kg. A total of 2,229 9R engines were built. Applications:

10R

The twin cam 1858 cc 10R was produced from 1967 through Feb 1971, when it was renamed the 8R-G. The later 8R-G version did not receive a timing chain tensioner in an effort to make it more silent. Output was 104 kW at 6,400 rpm and 166 Nm at 5,200 rpm. Applications:

12R

The 1587 cc 12R was produced from 1969 through 1988. It was also built in the Philippines as the 12R-M, by Toyota's local affiliate Delta Motors Corporation. Technical Specs (Finnish Owner's Manual from 1973 Corona Mark 1) – Four cylinder, 4-stroke, OHV – Bore × stroke: 80.5x78 mm – Compression ratio: 8.5:1 – Maximum power: 90 PS at 5400 rpm SAE The 12R-LPG, was produced from 1969 through 1983. Technical Specs: 1975 59 kW redline 4,400 rpm Applications:

16R

The OHC 1808 cc 16R was produced from 1974 through 1980. Power output as mounted in a 1980 Mark II was 105 PS at 5,600 rpm, while a twin carburetted version produced 110 PS at 6,000 rpm. The 16R-B was produced for the first two years. There was also a 16R-J version for various commercial vehicle applications. Applications:

18R

The 18R series shared a 1968 cc block; cylinder bore and stroke was 88.5x80 mm. The 2-valve, SOHC versions were as follows: Applications:

18R-G

The 2-valve DOHC 18R-G and its variations were produced from 1973 to 1982, replacing the 8R-G and providing a performance engine which took advantage of the entire 2-litre limit of Japan's "small car" class. While most 18R-Gs had a head designed and made by Yamaha, a very few had Toyota heads. Yamaha's tuning-fork logo can be seen on the Yamaha heads. Except for the head and related timing components, most parts were shared or interchangeable with the SOHC 18R. Combustion chambers were hemispheric. In 1975, air injection was added to the Japan-market 18R-GR for improved emissions. This used Solex carburettors. A fuel injected and catalyzed Japan-market version, the 18R-GEU, was produced from 1978 through 1982. There was also a catalyzed carburetted version, the 18R-GU. Competition versions of the 18R-G and -GE include those used in rally Celicas of the period, one of which finished second in the 1977 RAC Rally. These had 4-valve heads and were called 152E, they were of 89x80 mm bore and stroke and 1995 or (depending on the source). The Group 4 rally version of the 152E had two twin-choke carburettors, and developed 240 PS at 9000 rpm. Higher tuned engines developed as much as 300 PS at 9,200 rpm. German racing team Schnitzer also developed a turbocharged silhouette racing version of the Celica, to take on the Porsche 935. With a KKK turbocharger, the Group 5 Celica developed 560 PS but reliability was less than satisfactory. Applications:

19R

The 2-valve SOHC 1968 cc 19R was produced from 1974 through 1977. Cylinder bore and stroke was 88.5x80 mm. Its dimensions are the same as of the 18R, but it featured TTC-V, Toyota's licensed version of Honda's CVCC stratified charge combustion system. Output is 80 PS. The 19R was a short-lived experiment by Toyota, and was only offered in Japanese market cars. Applications:

20R

The 2-valve SOHC 2190 cc 20R was produced from 1975 through 1980. Cylinder bore and stroke was 88.5x89 mm. Aluminum alloy heads were used. Initial output was 72 kW at 4800 rpm (90 hp in California) and 162 Nm at 2,800 rpm. Power was down slightly from 1978 through 1979 at 71 kW at 4800 rpm and 165 Nm at 2400 rpm. The final version, from 1979 through 1980, was down again at 67 kW at 4800 rpm (still at 95 hp in Canada) and 165 Nm at 2400 rpm. The 20R and subsequent models featured important design changes relative to the earlier SOHC R-series engines. The head was changed from a reverse-flow to a cross-flow type with hemispherical combustion chambers and shorter valve rockers. The timing chain was strengthened. The lower block bearings were strengthened against wear, safeguarding oil pressure, and the stroke was lengthened. The changes increased torque substantially and shifted peak power and torque towards the lower speed range. The later R series engines did much to establish Toyota's reputation for reliability, which had previously been indifferent at best. Applications:

21R

The 2-valve SOHC 1972 cc 21R was produced from 1978 through 1987. Cylinder bore and stroke are 84x89 mm. Output for export markets, largely unconstrained by emissions, was 100 PS DIN at 5,000 rpm and 154 Nm at 4,000 rpm. Air injection and federally compliant emissions equipment for the 21R-C (1982–1985) dropped power down to 90 hp SAE net at 5,000 rpm. The air-injected Japanese version, the 21R-U, produces 105 PS JIS at 5,200 rpm and 162 Nm at 3,600 rpm but dropped to 100 PS at 5,400 rpm and 154 Nm at 4,000 rpm in 1986. Applications:

22R

The 2-valve SOHC 2366 cc 22R was produced from 1981 through 1997. Cylinder bore and stroke was 92x89 mm. Initial output was 72 kW at 4,800 rpm and 174 Nm at 2,800 rpm. By 1990 the 22R was producing 81 kW at 5,000 rpm and 187 Nm at 3,400 rpm. The first fuel injected 22R-E engines appeared in August 1982. Output of these engines is commonly rated at 78 kW at 4,800 rpm and 185 Nm at 2,800 rpm. In 1985, the engine was significantly reworked, output was up to 84 kW at 4,800 rpm and 190 Nm at 3,600 rpm. Many parts from the newer 22R/R-E are not compatible with those from the older pre-1985 engine. Non-compatible parts include the cylinder head, block, pistons and many of the associated parts such as the timing chain and cover, and water and oil pumps (although the oil pump internals are the same). These changes also affected the 22R, therefore one can consider the 85–95 22R-E as a fuel injected version of the 85–90 22R with only minor differences, if any. Toyota swapped the dual-row timing chain used in older engines for a single-row chain with plastic guides in 1983. The new system reduced drag on the engine but introduced a new maintenance problem. After about 100000 mi of operation, the chain may stretch to the point that the hydraulic-operated chain tensioner cannot take up any more slack. The timing chain then impacts the plastic driver's side chain guide, breaking it within a short period of time and creating a noticeable chattering sound in the front of the engine, especially when cold. If the engine continues to be operated without the guide restraint, the chain will vibrate excessively on the driver's side and stretch rapidly. The result is any of several failure modes. First, the loose chain will reduce ignition timing accuracy, which usually results in noticeably rough running. Second, it may jump a tooth on the drive sprocket or break entirely, which almost always results in major damage to an interference engine. Third, the stretched chain can slap against the side of the timing cover and wear through the metal into the coolant passage behind the water pump, resulting in major damage to both the oil and cooling systems (sometimes mis-diagnosed as a head gasket failure). The damaged aluminum timing cover is difficult to repair effectively and is typically replaced after such an event. Aftermarket timing-chain kits for the 22R/R-E typically include steel-backed guides that do not readily break even after the initial chain stretching has occurred, permitting the chain to run beyond the 100000 mi point without further incident. However, some Toyota mechanics will recommend the plastic guides as they will break when the timing chain is stretched; When the guides break a noticeable chatter is heard from the timing chain slapping on the cover, warning the operator of a worn timing chain. The turbocharged 22R-TE (sold from late 1985 through 1988) produced 101 kW at 4,800 rpm and 234 Nm at 2,800 rpm. These engines are extremely well known for their durability, decent fuel efficiency and good low to mid range torque. However, its weakness is high-end power. The 22R has a large displacement and a strong block, but its comparatively long stroke and restrictive head limit its use in high revving applications. Thus, the Toyota 18R-G, 2T-G, 4A-GE and 3S-GE 4-cylinder engines are better suited for performance applications. A popular modification to the early 22R is to use a 20R head. Contrary to popular lore, the 20R head does not have smaller combustion chambers. The misunderstanding originated when the 22R came out and an advantage was its higher compression ratio, so swapping a 20R block with a 22R, there was a compression increase. The 20R head has straight ports, so can flow better than the 22R head, improving high RPM power. The 20R head is a simple bolt-on modification for the pre-1985 block, but also requires the use of the 20R intake manifold, making it almost impossible (there's a lot of matching necessary) to use with the 22R-E EFI system. For blocks 1985 and onwards, further modifications are required. Applications: