Toyota RZ series four-cylinder engines
The 2.7 liter engine was part of the RZ engine family, which consisted of three engines: 1RZ, 2RZ, and 3RZ. The 1RZ-E had a 9.0:1 compression ratio, producing 101-108 hp and 118-123 pound-feet of torque; it was used in vans, trucks, and SUVs from 1989 through 2005. None of these made it to the United States.
The original 118-horse 2.4 liter 2RZ-E engine was used in vans only; it was a single overhead cam engine, with two valves per cylinder, and shim-over-bucket valve adjustment. More common was the 2RZ-FE, which had electronic fuel injection, a 9.5:1 compression ratio, and output of 142 hp and 160 lb-ft of torque. The bore and stroke were 3.74 x 3.39; and this version had four valves per cylinder, driven by twin overhead cams. Valve adjustment remained shim-over-bucket, and if the valves were off, the pistons could hit them (interference design). Despite its size, it did not have balance shafts. This engine spawned three China-only designs, the 4RB series; it was used in the Tacoma/Hilux.
The Toyota 2.7-liter four-cylinder engine was a 16-valve design with dual overhead cams, one for intake and one for exhaust; each cylinder had four valves. The engine first saw duty in the 1995 Tacoma/Hilux, was added to the 1996 4Runner (Hilux Surf), and, with major changes, joined the 2009 Highlander. It was used through 2011, and had few changes during that time. Like its predecessors, it was an interference engine.
The “square” engine (both bore and stroke were 3.74 inches) displaced 2694cc—164 cubic inches—and was largely a stroked 2RZ-FE, with added counter-rotating balance shafts (chain driven). The compression ratio was 9.5:1 until the 2005 trucks, when it went up to 9.6:1; that bumped horsepower from 150 to 164 (actually, in 2006, it turned out the power rating had really been 159 hp; that was the model-year when automakers agreed to use SAE standard measurements). The original engines had 177 pound-feet of torque; this was shown as 183 pound-feet in 2005, and “revised” down to 180 in 2006.
The 2009 Toyota Highlander’s version of the 2.7 liter four-cylinder engine used a different block, with a bore of 3.54 inches and a stroke of 4.13 inches; the displacement was almost the same, though. The compression was higher, too, at 10:1, allowing much higher output—187 horsepower at 5,800 rpm, with 186 lb-ft of torque at 4,100 rpm, on regular gasoline. In the Highlander, with the six-speed automatic, it was rated at 20 mpg city, 27 highway, with a 0-60 time of 9.7 seconds.
The 3RZ-FE 2.7 used a dual intake manifold and dual variable valve timing to control phasing of both the intake and exhaust camshafts; that also broadened the torque curve.