Two versions of the ZZ-series 1.8-liter inline four-cylinder engine with dual overhead camshafts and four valves per cylinder have replaced the 3S-series 2.0-L (Japanese) and 2.2-L (U.S.) engines in the previous-generation Celica. The type 1ZZ was first launched in the current U.S. built Corolla, and then adopted in the larger Japanese-market Vista. Below it is fitted with the VVT-i continuously variable intake-valve-timing system and given the FE suffix. The 1ZZ-FE produces 145 hp at 6400 rpm and 125 lb-ft torque at 4200 rpm on a 10.0:1 compression ratio with regular-grade unleaded gasoline. The 2ZZ-GE is a new-generation engine equipped with a two-stage variable valve lift/timing system called VVT-L on both the intake and exhaust sides, combined with the VVT-i continuously variable intake-valve timing. The 2ZZ-GE puts out 190 bhp at 7600 rpm and 133 lb-ft at 6800 rpm on a raised 11.5:1 CR with premium unleaded fuel.
The two engines share the common bore pitch of 87.5 mm, but have different block constructions and cylinder dimensions. The 1ZZ-FE's aluminum block has cast-in gray iron liners, which are 2.0 mm thick, leaving 8.5 mm of metal between cylinders. The engine has a long stroke of 91.5 mm relative to the 79-mm bore, obtaining a total displacement of 1794 cm3. Measuring 639 mm long, 586 mm wide, and 632 mm tall, the 1ZZ-FE is about 25 mm shorter than Toyota's own 4A 1.6-L unit. It has a mass of 225 lb.
The 2ZZ-GE features a shorter stroke of 85 mm to a large 82-mm bore to attain a higher redline of 7800 rpm versus the 1ZZ-FE's 6800 rpm. The block is made of fine-ceramic-fiber- and grain-reinforced aluminum-silicon alloy. The piston's rubbing surface is iron-plated, and the pistons are internally cooled by oil jets. The 2ZZ-GE's cylinders are tightly packed, with only 5.5 mm of metal between the adjoining bores. The cylinder block is split at the crankshaft centerline, and the cast aluminum lower block carries five main bearing caps.
Dual overhead camshafts are driven by a single-stage silent chain of 8.0-mm pitch in both engines. The 1ZZ-FE's camshafts act on four valves per cylinder via shimless bucket-type tappets. The new upright intake port design allows a narrow valve included angle of 33.1°. Valve diameters are 32.0 mm for intake and 27.5 mm for exhaust, and their lifts are 9.3 and 8.4 mm, respectively. The 1ZZ-FE adopts Toyota's VVT-i vane-type continuously variable intake valve timing system.
The high-performance 2ZZ-GE's cylinder head is unique to this engine. Valves are inclined at a wider angle of 43° for freer breathing through the upright intake ports. Valves are larger in diameter, at 34.0 mm for intake and 29.0 mm exhaust. The 2ZZ-GE combines the VVT-i continuously variable intake-valve-timing device with the new VVT-L, a Honda VTEC-like variable-lift and -timing system, employing two sets of cam profiles for both intake and exhaust. Below 6000 rpm, the VVT-L employs the low- and mid-speed cam profiles, and above 6000 rpm, the high-speed profiles. The high-revving 2ZZ-GE's camshafts are sprayed with lubricant oil. Timing and lift characteristics of the 1ZZ-FE and 2ZZ-GE engine are shown in the table.
Toyota betters Japan's transitional low emission vehicle standards, achieving NOx emission of 0.06 g/km, HC emission of 0.06 g/km, and CO emission of 0.67 g/km on the country's urban 10/15-model cycle. (The forthcoming 2000 national standards stipulate 0.08 g/km, 0.08 g/km, and 0.67 g/km, respectively.)
VVTLi explained
The VVT-i portion of the system continuously varies intake valve timing throughout the rev range by hydraulically rotating the camshaft relative to its drive gear. Note that VVT (without the "i") did not do this continuously. The VVL portion of the system is similar to Honda's VTEC system, incorporating two distinct cam profiles. However, the actual mechanism is quite different. Both cam lobes operate a single wide rocker arm that acts on both intake or both exhaust valves. A needle-bearing roller on the arm follows the low-rpm, short-duration, low-lift lobe, forcing both valves to open and close on that profile. The roller design and roller bearings on the rocker arm pivot help to minimize valvetrain friction. The high-rpm, higher-duration, longer-lift lobe rubs on a hardened steel slipper follower mounted to the rocker arm with a spring. Even though the high-rpm lobe is pushing down further than the low-rpm lobe, the spring absorbs the extra movement. At 6000rpm, the ECU sends a signal to an oil control valve at the end of the camshaft that puts oil pressure behind a lock pin in the rocker arm, sliding the pin under the spring-loaded slipper follower, locking it to the rocker arm and forcing the arm to follow the high-rpm cam profile.
Linear Mode
