Toyota 1AZ vs. 2AZ: Which is Better?

The Toyota inline-fours are always on their toes to prove which is better than the other; more efficient, more power-driven, more accepted as a symbol, and the list goes on and on. That is absolutely unavoidable. But here, we will put out the essential pieces of information and necessary details for you to decide which engine is better than these two according to the numbers and specifics we have gathered.

The engines that we are talking about are the Toyota 1AZ and 2AZ engines. Let’s get right to it!

What are AZ Engines?

Let’s start with the family.

Toyota Motor Corporation produced the AZ engine family from 2000 until 2018. Its primary purpose is to replace the S engines.

On its initial production, AZ engines are planned to wear the cast-iron material as their material for the cylinder block; however, the attempt was denied for some reasons. They would go on to replace the cast-iron blocks with lighter material in aluminum and top it off with cast-iron liners. In addition to that, Toyota placed the cylinder axle against the crankshaft axis to allow the sleeves to ventilate and loosen the area’s tension.

The 1AZ-FE Engine:

  • Production Run: 2000 – Present
  • Cylinder Head Material: Aluminum
  • Cylinder Block Material: Aluminum
  • Configuration: Inline-4
  • Bore: 86 mm
  • Stroke: 86 mm
  • Valvetrain: DOHC 4 Valves Per Cylinder
  • Displacement: 2.0 L (1998 cc)
  • Compression Ratio: 9.6 (1AZ-FE)
  • Weight: 290 lbs.
  • Maximum HP: 152 HP at 6,000 RPM
  • Maximum Torque: 148 lb-ft at 4,000 RPM

The Toyota 1AZ is a straight-four, naturally aspirated, 2.0 L gasoline engine. It has two engine versions, the more common basic 1AZ-FE and the direct-injection supplied 1AZ-FSE. The 1AZ-FE engine produces 145 HP at 6,000 RPM with 140 lb-ft of torque available at 4,000 RPM. In addition to that, Toyota Rav4 and Ipsum machines released a different power rating and were rated at 150 HP at 6,000 RPM and 142 lb-ft of torque available at 4,000 RPM. It has a compression rating of 9.6.

The cylinder block of the 1AZ-FE is made of die-cast Aluminum with cast-iron liners, a die-cast Aluminum lower crankcase, and a stamped oil pan. It also employs an offset in the cylinder banks and on crank centers. It has spiny-type cast-iron liners which are externally cast to form a large and uneven surface. These exterior casts are designed to link a better adhesion between the cylinder block and liners.

This engine has an 86.0 mm bore, 86.0 mm piston stroke, and a 9.6 compression rating. The cylinder block has water jacket spacers which inhibit the water flow on the center of the jacket and let the coolant flow guide through to circles around the cylinder bores. That results in reduced back pressure from the bottom of the pistons; a better airflow due to additional air passageways employing holes in the crankshaft bearing area of the cylinder block. 1AZ-FE was integrated with an air-conditioning compressor and oil filter brackets in the crankcase.

The crankshaft is made out of strong forged steel fully balanced and supported with five main journals, eight balance weights, and roll-finished pin and journal fillets. The crankshaft offset is measured at 10 mm to the thrust side of the cylinder bore centerline to minimize friction and lower the fuel consumption by as much as three percent.

A gear is driven by the two balancing shafts placed at the lower crankcase, between the first and second bearings. These two balancing shafts are incredibly vital in the reduction of engine vibrations. These polymeric helical gears are made from such materials for noise reduction.

The 1AZ-FE connecting rods and caps are made from high-strength steel. Toyota resorted to using nut-less type plastic region tightening bolts for an added weight reduction.

The pistons are made from Aluminum alloy with two compression rings and a single oil ring, with heads formed to a taper squish shape for better combustion. It piston skirts are coated with resin to reduce friction losses.

The 1AZ-FE cylinder head is made from Aluminum alloy. The head is mounted to a steel-laminate type head gasket which Toyota used a shim around the cylinder bore to earn a better surface for more tight sealing. It has dual overhead camshafts and acts on four valves per cylinder via bucket tappets. These two camshafts are driven by a single-stage roller chain, five main bearings for support, and are lubricated by an oil jet spray. The chain tensioner uses a ratchet-type non-return mechanism, a spring, and oil pressure to regulate the timing chain tension so it does not break or loose easily.

Contrary to what we know, the 1AZ-FE supplies fuel to the chambers via fuel injection but not Toyota’s D-4S. But instead, it uses an electronically controlled sequential fuel injection through a 12-hole injector nozzle placed on the inlet ports to avoid wall wetting and fuel contact within the port walls. It is also installed with two air-fuel ratio sensors at the exhaust side for better response, especially if you run in a stoichiometric air-fuel mix. To add to that, hot-wire L-type airflow meters are used to measure the intake volume. This engine also has slanted squish pentroof-type combustion chambers designed to improve thermal efficiency and lower the margin of engine knock.

Applications of 1AZ-FE Engine:

  • 2002 – 2006 Toyota Camry (Asia Version)
  • 2006 – 2009 Toyota Camry (Aurion Version)
  • 2000 – 2003 Toyota RAV4
  • 2003 – 2006 Toyota RAV4 Euro
  • 2001 – 2009 Toyota Ipsum

2AZ-FE

  • Production Run: 2000 – Present
  • Cylinder Head Material: Aluminum
  • Cylinder Block Material: Aluminum
  • Configuration: Inline-4
  • Bore: 96 mm
  • Stroke: 88.5 mm
  • Valvetrain: DOHC 4 Valves Per Cylinder
  • Displacement: 2.4 L (2362 cc)
  • Compression Ratio: 9.6 (1AZ-FE)
  • Weight: 280 lbs.
  • Maximum HP: 168 HP at 6,000 RPM
  • Maximum Torque: 165 lb-ft at 4,000 RPM

Like the 1AZ-FE engine, the 2AZ-FE is an inline-four gasoline engine. It uses an all-aluminum lineup for its cylinder block with cast-iron cylinder liners and cylinder head with a dual overhead design.

The 2AZ-FE has an open deck engine design for better cooling efficiency. It also adopted the 1AZ-FE’s technological advancements such as the Toyota’s variable valve timing, VVT-i on the intake camshaft, offset on the cylinder and crank center, and slant-squish combustion chambers. To add to the lineup, the ETCS-i (Electronic Throttle Control System – intelligent) is equipped, Electronic Spark Advance (ESA), Sequential MPFI fuel injection system, Direct Ignition System (DIS) with one ignition coil for each spark plug.

The cylinder bore and piston stroke of the 2AZ-FE are larger than 1AZ-FE; 88.5 mm for the bore and 96 mm for the stroke. The engine production also increased significantly, at 168 HP at 6,000 RPM and 165 lb-ft of torque available at 4,000 RPM.

Connecting rods and caps, dual overhead camshafts design, pistons, balancing shafts, and overall architecture are shared with the 1AZ-FE.

Other components such as the cylinder head cover, head cover gasket, and the spark plug gasket are integrated to reduce the total number of parts.

Two other versions of the 2AZ engine are apart from the 2AZ-FE: The 2AZ-FSE features a direct injection system and has a higher compression rating. It also has a higher power output at 161 HP and 170 lb-ft of torque. Unfortunately, this engine is only used in the Toyota Avensis.

The other version is the 2AZ-FXE which is a Toyota special—primarily made for hybrid electric vehicles. It uses an Atkinson cycle design which reduces the power output but increases the engine efficiency significantly. The 2AZ-FXE has a 12.5 compression rating because of the Atkinson cycle.

Applications of 2AZ-FE Engine:

  • Toyota Avensis
  • Toyota Camry
  • Toyota Previa
  • Toyota Corolla
  • Toyota Highlander
  • Toyota Alphard
  • Toyota Ipsum
  • Toyota Blade
  • Toyota Sai
  • Lexus ES240
  • Lexus HS 250h
  • Scion tC
  • Scion xB
  • Pontiac Vibe

Engine Potential

Both engines are used economically, and raising the power output and the torque might result in an unpleasant surprise. However, there are available superchargers for both, so it is suitable for these two engines.

If you passed the first stage by bolting a supercharger, you would still have to deal with replacing the other internal components; ECU, camshafts, and many more.

So, for tuning, 1AZ and 2AZ do not fit the performance-based category due to their physical, ability, and component limitations. They are far better used in the low to mid RPM range for a longer useful life.

Problems Surrounding the Engines

The problems of the 1AZ engines are quite a handful, such as a cylinder head bolts thread wearing out, engine vibrations, and soot formations. These are primarily associated with leaks, dirty throttle bodies, neglected maintenance, and overall disregard for the engine’s condition.

For the 2AZ engine, leaks and excessive oil consumption festered the engine, especially in the 2007 – 2009 Toyota Camry. We all know that excessive oil consumption leads to engine overheat if not properly treated. It can also affect the piston rings and the cylinder head bolts.

But have issues to overcome since they are made of almost the same components; they also share most of the problems.

Summary

1AZ and 2AZ engines are closely related to each other, having been brought up on the same engine family that includes the material composition, features, technologies, and many more. But these two engines have their characteristic in terms of development; what upgrades did they take from the previous model.

1AZ produces less power and torque than the 2AZ, in which the maximum power output is 168 HP, and the former at 152 HP; in parallel to that, torque production of the 2AZ is more larger.

They have the same blocks and heads, but they differ in the measurements of the cylinder bore and stroke. 1AZ is more of a square dimension having the stroke and bore equal, while the 2AZ have different sizes -and are more extensive. 2AZ is more efficient due to a larger bore that produces more power with bigger valves and longer stroke, which is also significant from the low to mid RPM range. That is also evident in their capacities.

For other factors such as tuning potential and issues, they share most of it. They are different, and the most considerable margin for both of these two is their power production. 1AZ is efficient in its way, with more balanced power and torque against the larger bore and stroke of 2AZ for a more revving engine.

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