Technical Paper on the Development of the 1ZZFE

In the United States, 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 now also used in the current Celica, and then adopted in the larger Japanese-market Vista. Here it is fitted with the VVT-i continuously variable intake-valve-timing system and given the FE suffix. The 1ZZ-FE produces 107 kW (145 hp) at 6400 rpm and 170 N•m (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 used in the Celica GT-S and is 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 140 kW (190 bhp) at 7600 rpm and 180 N•m (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 (3.44 in), 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 (0.08 in) thick, leaving 8.5 mm (0.33 in) of metal between cylinders. The engine has a long stroke of 91.5 mm (3.60 in) relative to the 79-mm (3.11-in) bore, obtaining a total displacement of 1794 cm3. Measuring 639 mm (25.2 in) long, 586 mm (23.1 in) wide, and 632 mm (24.9) tall, the 1ZZ-FE is about 25 mm (1 in) shorter than Toyota's own 4A 1.6-L unit. It has a mass of 102 kg (225 lb).

The 2ZZ-GE features a shorter stroke of 85 mm (3.35 in) to a large 82-mm (3.23-in) 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 (0.22 in) 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 (0.3-in) 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 (1.26 in) for intake and 27.5 mm (1.08 in) for exhaust, and their lifts are 9.3 and 8.4 mm (0.37 and 0.33 in), 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 (1.34 in) for intake and 29.0 mm (1.14 in) 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.)

Toyota's VVT-i (Variable Valve Timing - Intelligent) has been spreading to more and more of its models, from the tiny Yaris (Vitz) to the Supra. Its mechanism is more or less the same as BMW’s Vanos, it is also a continuously variable design.

However, the word "Integillent" emphasis the clever control program. Not only varies timing according to engine speed, it also consider other conditions such as acceleration, going up hill or down hill.  Combining cam-changing VVT and cam-phasing VVT could satisfy the requirement of both top-end power and flexibility throughout the whole rev range, but it is inevitably more complex. At the time of writing, only Toyota and Porsche have such designs. However, I believe in the future more and more sports cars will adopt this kind of VVT.

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