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Specs. on the xB/xA 1nz-fe engine
-1495 cubic centimeters
-75.0mm bore
-84.7mm (3.33-in) stroke
-dual overhead camshafts
(4 valves per cylinder via shimless bucket type tappets)
-valves inclined at 33.5°
-vane type VVT-i continuously variable intake valve timing device.
-valve diameters:
30.5 mm (1.20 in) for intake
25.5 mm (1.00 in) for exhast.
-cylinder block: aluminum with cast-in iron liners.
-cylinder and crankshaft centers are offset to reduce piston slapping.
-the NZ engine is placed transversely, canted rearward, with the intake side facing forward.
-the 1NZ-FE 1.5-L puts out 81 kW (110 hp) at 6000 rpm and 143 N•m (105 lb•ft) at 4200 rpm.

about the fuel system:
the scions have a fuel pressure regulator and fuel filter in the fuel tank. the returnless system means warm fuel from the engine bay does not return to the tank. the internal temperature of the fuel tank therefore stays cooler, reducing evaporative emissions.

about the VVT-i:
toyota’s intelligent continuously variable valve timing system is more advanced than the basic systems in some German luxury vehicles and Japanese small cars.
scions have the latest-generation TMC-developed vane-type VVT-i control, which debuted on Prius and Lexus IS200. VVT-i
provides continual variations of the intake valve timing, to match the engine’s operating conditions. This improves performance and fuel efficiency, and reduces vibration on engine start-up and shut-down.

1NZ-FE's inlet timing can be varied over a range of 60 degrees relative to crankshaft angle, to provide optimum valve timing for the full range of driving conditions.

Inlet camshaft timing is varied according to engine revolutions, throttle position, engine coolant temperature and intake air volume. The maximum retard setting provides zero valve overlap. (There is a five degree period between the exhaust valve closing and inlet opening.) Inlet cam timing is set to the maximum retard position for engine start-up, operation at low engine temperature, idle and engine shut-down. The maximum advance setting provides 55 degrees of valve overlap.

VVT-i Activation:
the scion's VVT-i is a computer controlled and oil-pressure activated push- push type system. The engine ECU can command the system to advance or retard the inlet camshaft timing, thereby providing for faster response. The hardware is a camshaft timing oil control valve mounted adjacent to the inlet camshaft gear wheel and a VVT-i controller mechanism built onto the inlet camshaft timing gear. The camshaft timing oil control valve is a spool valve, controlled via a coil and plunger by the engine ECU. It can signal "advance", "hold" or "retard". The VVT-i controller consists of a housing on the front of the timing wheel, driven from the timing chain, and a four-bladed vane coupled with the intake camshaft.

when the engine ECU requires a change in inlet timing, it signals the oil control valve to provide oil pressure to either the advance or retard side of the four vane chambers. A locking pin in the controller locks the camshaft timing in the maximum retard position for engine start-up and immediately after start-up (until oil pressure is established) to prevent any knocking noise.

other features:

• a long-branch inlet system with resonator, to maximise low-to-mid range torque. The inlet system is made of plastic, to reduce heat transfer from the engine to the inlet charge and hence increase volumetric efficiency

• a plastic engine cover to reduce NVH and increase recyclability

• sequential fuel injection with multiple injector nozzles mounted in the inlet ports, for maximum fuel atomisation and reduced wall wetting

• a hot chip type air flow meter for the EFI, for more accurate air-flow measurement and hence more accurate fuel/air mixing

• stainless steel extractor-style exhaust headers, for maximum performance and durability, and lower emissions

• rearward-facing exhaust, which combines with double-walled front exhaust pipe to improve catalytic converter performance and hence reduce emissions. The catalytic converter has thinner walls to further improve heat-up rate and reduce emission

• a double ball-jointed exhaust pipe connector, to reduce NVH

• a two-stage muffler (as debuted in the Lexus range) to improve high rpm engine performance on the 1.5 litre sedan engine Additional fuel emission saving technology includes computer engine management, individual Toyota Direct Ignition for each of the four cylinders and electronic spark advance with a knock control system.

•the engine ECU determines the spark advance.

•serviceability improvements include Multiplex engine diagnostics (which can detect a malfunction and memorise details of the failure), a vertically installed oil filter and adoption of chain drive to the camshafts.

•the 8mm pitch roller cam chain has a lubricating oil jet and auto tensioner.

•the combustion chambers in the scion engine employ a tapered (oblique) squish design, to improve thermal efficiency and reduce the chance of engine knock (pre-ignition). the squish area has been shaped obliquely along the wall surface of the combustion chamber, improving airflow, promoting swirl and speeding flame travel.
the combustion chambers are almost entirely machined, to ensure minimum variation in combustion chamber volume across the four cylinders. special attention has been paid to cooling the combustion chamber, including provision of a water jacket between the exhaust port and the spark plug boss, to lower the operating temperature at the exhaust valve seat and improve cooling performance.

service mass of the 1NZ-FE engine is 187 pounds.

the 1497cm3 power plant delivers a class-leading 80kW (107HP) at 6000rpm and 142Nm of torque at 4200rpm. it has 16 percent more power and four percent more torque than the superseded 1.5 litre Paseo sports car. the capacity increase to 1497cm3 has been achieved by increasing the stroke from 73 to 84.7mm. unique features of the scions are its variable back-pressure muffler and slightly longer exhaust valve opening duration.

scion xA and xB has a five-speed manual transmission, to suit the class-leading performance of its VVT-i-equipped engines.

clutch diameter is 212mm and facing area is 199cm2. the clutch has a diaphragm spring turnover mechanism to improve operability. the hydraulic control system for the clutch has an integrated reservoir tank and master cylinder to save weight and under-bonnet space.

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THANKS for the 411 Scott!

165 Posts
"rearward-facing exhaust, which combines with double-walled front exhaust pipe to improve catalytic converter performance and hence reduce emissions. The catalytic converter has thinner walls to further improve heat-up rate and reduce emission"

I did not know that. That is a nice thing, I had trouble throwing codes at start-up because all of my other car's cats took to long to heat up.

Anyone know the flow numbers on those cats compared to aftermarket units though????

195 Posts
Something that came to mind the other night. The specs don't call out that the head is aluminum as well as the block and something that I learned with the northstar as it's all aluminum as well is that you never introduce mineralized water into the cooling system on this type of engine contruction. I became a firm believer in the premixed antifreeze as they use distilled & filtered water as a base. Using tap water or water that contains minerals in it caused all sorts of cooling system as well as head gasket and other problems. Being new to the 4 cyl scene I thought I'd throw that out there and see what y'all think.
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