The Toyota Y engine is a design that's a combination of the Toyota T engine, and the Toyota R engine, in a way that's similar to how the Toyota F engine is a design of the Toyota Type B engine, and the Chevrolet inline-six. The Y engine has mostly only been used in commercial and off-road vehicles.
The valve arrangement from the Toyota K engine is interchangeable with this engine.
Translated from Japanese Wiki ja:トヨタ・Y型エンジン
There is also the 1Y-J, with the "J" suffix meaning that the engine is built to meet emissions standards for light commercial vehicles.
OHV, eight valvesCapacity: 1,626 ccBore × stroke: 86.0 × 70.0 mmReference output: 84 PS (62 kW), 13.8 kg·m (135 N·m) (gross figures, apply to both 1Y and 1Y-J)Applications:
Toyota HiAce truckToyota LiteAce (YM20, first generation)Toyota ToyoAceToyota TownAce (YR10)The 2Y engine is an OHV, eight valve construction just like the 1Y. It shares that engine's 86.0 mm bore, but stroke is increased to 78.0 mm for a displacement of 1.8 litres. There are also 2Y-J and 2Y-U engines with differing emissions control equipment.
OHV, eight valvesCapacity: 1,812 ccBore × stroke: 86.0×78.0 (mm)Compression ratio: 8.8Reference output (2Y): 79 PS (58 kW) at 5,000 rpm, 14.3 kg·m (140 N·m) at 3,200 rpm (net)
95 PS (70 kW), 15.5 kg·m (152 N·m) (gross)Applications:
5th generation Toyota Mark II Van (YX76V, 2Y-J)3rd generation Toyota HiAce van (YH50V/60V)Toyota HiluxToyota TownAce van (YR25V)Toyota LiteAce wagon (YM20/30G)Volkswagen Taro (a rebadged Hilux)OHV 8 valve (LPG)Capacity: 1,812 ccBore × stroke: 86.0×78.0 (mm)Specifications: 51 kW (70 PS) 4,600 rpm 132 Nm (13.5 kg-m) 2,200 rpm (net)
63 kW (85 PS) 5,000 rpm 142Nm (14.5 kg-m) 3,000 rpm (gross)LPGApplications:
Toyota Corona (YT140)Toyota Mark II (YX70)There is also the emissions cleaned 3Y-U engine.
OHV 8 valveCapacity: 1,998 ccBore × stroke: 86.0 × 86.0 mmCompression ratio: 8.8Reference output: 65 kW (88 PS) at 4,800 rpm, 155 Nm (15.8 kgm) at 3,400 rpmApplications:
3rd generation Toyota HiAce truck/van/wagon (YH51G/61G/71G)HiluxDyna/ToyoAceThis is the low emissions motor with catalytic converter exhaust system
OHV 8 valveDisplacement: 1,998 ccInside Bore × Stroke: 86.0 mm ×86.0 mmCompression ratio: 8.8Reference output: 63kW at 4,600 RPM, 155 Nm at 3,400 RPMApplications:
LiteAce XTRA TRACK Wagon YM40(RGMDSQ),YM41(RVMDSQ)Toyota Townace Van 30 series YR39OHV 8 valveCapacity: 1,998 ccBore × stroke: 86.0 × 86.0 mmCompression ratio: 8.8Reference output: (97 PS) at 4,800 rpm, 160 Nm (16.3 kgm) at 3,800 rpmApplications:
Toyota Mark II (YX78V, fifth generation)Toyota Hilux (YN60)Daihatsu Rocky (Australia)OHV 8 valveCapacity: 1,998 ccBore × stroke: 86.0 × 86.0 mmReference output: 85 kW (115 PS) at 5000 rpm, 179 Nm (18.3 kg-m) at 3600 rpm (gross)
97 PS (71 kW) at 4800 rpm, 160 Nm (16.3 kgm) at 3800 rpm (net)Applications:
Hilux Surf/4Runner (61G)TownAce Wagon/MasterAce Surf (YR21G)Daihatsu Delta Wagon (YB21G)OHV 8 valve (LPG)Capacity: 1,998 ccBore × stroke: 86.0 × 86.0 mmOutput: 79 PS (58 kW) at 4,600 rpm, 15.0 kgm (147 Nm) at 3,000 rpmApplications:
Crown(YS130)Mark II(YX80)OHV 8 valve (LPG)Capacity: 1,998 ccBore × stroke: 86.0 × 86.0 mmReference output: 66 kW (90 PS) at 5,000 rpm, 157 Nm (16.0 kg-m) at 3,000 rpm (gross)
79 PS (58 kW) at 4,600 rpm, 147 Nm (15.0 kg-m) 2,000 rpm (net)Applications:
Crown (YS120)OHV, eight valvesCapacity: 1,998 ccBore × stroke: 86.0 × 86.0 mmCompression ratio: 10.5Reference output: 60 kW (82 PS) at 4,600 rpm, 157 Nm (16.0 kgm) at 2,400 rpm (1989 July? 1995 November)
79 PS (58 kW) at 4,400 rpm, 160 Nm (16.3 kgm) at 2,400 rpm (1995 December? )Applications:
1989.06–199? Crown YS1301995.12–2008 Crown Comfort/Sedan YXS10Comfort YXS11Mark II YX70Mark II YX80OHV eight-valveCapacity: 2,237 ccBore and stroke: 91.0 × 86.0 mmThis engine was available either carburetted (4Y) or fuel injected (4Y-E, called the 491Q-ME for Chinese manufacture). As fitted to a 1989 Daihatsu Delta truck, the carburetted 4Y produces 70 kW (95 PS; 94 hp) at 4400 rpm (SAE net) and 182 N·m (18.6 kg·m; 134 lb·ft) at 3000 rpm.
ApplicationsToyota Van (Town Ace overseas specification, Tarago in Australia)Hiace third generation (overseas specification)1979-1988 Toyota Stout (YK110)Daihatsu DeltaToyota Industries forkliftsToyota 4Runner (Australia)Volkswagen Taro1985-1993 Toyota Hilux (South Africa)