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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.
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