Introduction
Toyota’s 3RZ-FE was a 2.7-litre four-cylinder petrol engine that was offered in Toyota’s commercial and four-wheel drive vehicles. Key features of the 3RZ-FE engine included its cast iron, aluminium alloy cylinder head, double overhead camshafts, four valves per cylinder and 9.5:1 compression ratio.
[su_table responsive=”yes”]
| Engine | Trans. | Years | Peak power | Peak torque | |
|---|---|---|---|---|---|
| ToyotaMk.6 Hilux | 2.7-litre petrol I4 | 5sp man., 4sp auto |
1997-05 | 108kW at 4800rpm | 235Nm at 4000rpm |
| Toyota90-Series LandCruiser Prado | 2.7-litre petrol I4 | 5sp man., 4sp auto |
1996-02 | 112kW at 4800rpm | 240Nm at 4000rpm |
| Toyota120-Series LandCruiser Prado | 2.7-litre petrol I4 | 5sp man., 4sp auto |
2003-04 | 112kW at 4800rpm | 240Nm at 4000rpm |
[/su_table]
3RZ-FE block
The 3RZ-FE engine had a deep-skirt cast iron block with 95.0 mm bores and a 95.0 mm stroke for a capacity of 2694 cc. The 3RZ-FE engine had twin counter-rotating balance shafts within the crankcase to cancel the secondary inertia forces that were inherent in an in-line four-cylinder engine. Since each piston reached its maximum speed – both rising and falling – at a point just above the centre of the stroke, the upward inertial force of the two rising pistons was greater than the downward inertial force of the two falling pistons. To offset this, the twin gear-driven balance shafts counter-rotated at twice the speed of the crankshaft.
Crankshaft, connecting rods and pistons
The 3RZ-FE engine had a fully balanced, forged crankshaft with eight counterweights. For durability, the crankshaft had hardened pins and journals, and rolled fillets. Furthermore, the crankshaft had a torsional damper pulley to reduce noise and vibration. Plastic region tightening bolts were used for both the crankshaft main bearings and connecting rods.
The 3RZ-FE had connecting rods that were forged from carbon steel to withstand high operating speeds and pressures. For increased strength and durability, the connecting rods were also shot-peened.
The 3RZ-FE engine had aluminium alloy pistons with resin-coated skirts to reduce friction. In each big-end bearing, an oil jet sprayed oil to cool the underside of the pistons.
Cylinder head and camshafts
The 3RZ-FE engine had an aluminium alloy cylinder head which used plastic region tightening bolts for the cylinder head.
The intake camshaft was driven by a timing chain which had a hydraulic chain tensioner and oil jet for lubrication. The exhaust camshafts were driven via a scissors gear from the intake camshaft; a scissors gear was chosen for compact packaging, to control backlash and suppress gear noise.
Valves and timing
The 3RZ-FE engine had four valves per cylinder – two intake and two exhaust – that were positioned for a 19 degree included valve angle. While the intake valves had a 37.5 mm diameter, exhaust valves had a 30.5 mm diameter. For valve adjustment, a shim over bucket arrangement was used.
As per the table below, the 3RZ-FE engine had valve overlap of 7 degrees, intake duration of 230 degrees and exhaust duration of 224 degrees.
[su_table responsive=”yes”]
| 3RZ-FE Valve Timing | ||
|---|---|---|
| Intake | Open | 5° BTDC |
| Close | 45° ABDC | |
| Exhaust | Open | 42° BBDC |
| Close | 2° ATDC | |
[/su_table]
Intake
The 3RZ-FE engine had long intake runners to increase torque output, while dual inlet ports (per cylinder) were used to maximise the benefit of having two inlet valves per cylinder. Induction noise was minimised by fitting a large capacity intake air resonator to the intake air connector and air cleaner hose; the 3RZ-FE engine also had a 7.1 litre air cleaner.
Injection and ignition
The 3RZ-FE engine had electronically controlled, multiport fuel injection in which intake air mass was measured using a hot-wire type mass airflow meter. With its pentroof-type combustion chambers, the 3RZ-FE engine had a compression ratio of 9.5:1.
The 3RZ-FE engine had ‘Electronic Spark Advance’ (ESA) whereby ignition timing was determined by the ECM based on inputs from sensors and adjusted according to knocking.
