What Is A Toyota 2JZ Engine?
The 2JZ engine is a six-cylinder, double overhead cam engine that Toyota developed in the early nineties. The engine has a closed deck, cast iron block, aluminum heads, four valves per cylinder, and direct sequential fuel injection. The motor was produced in three variants (2JZ-GE, 2JZ-GTE, and the 2JF-FZE). (In Toyota terminology, the “G” means a dual overhead cam setup, the “T” refers to turbocharged, and the “E” represents electronic fuel injection).
The two most common variants are the naturally aspirated 2ZJ-GE (220 hp and 210 lb-ft of torque) and a twin turbo-charged version 2ZJ-GTE (267 hp and 318 lb-ft of torque). In 1995, Toyota improved the engine by introducing Variable Valve Timing), and adding DIS (Direct Ignition System), which sent the electrical charge directly from the coil to the plugs.
What Are The Features Of The 2JZ Engine?
Due to the strength and durability of its cast iron block, the turbo-charged engine quickly became the darling of performance enthusiasts. Toyota knew that while an aluminum block might be lighter, the lighter metal was not as forgiving of thermal temperature changes and fatigue stressors. (Toyota had plenty of experience with these kinds of iron block/aluminum cylinder head motors with the 7M series and applied those lessons to the 2JZ’s development).
The Strongest Block They Could Make
The engine designers fashioned the block from cast iron, using a closed deck with a robust girdle between the block and the oil pan. The configuration made for stronger cylinders, with combustion chambers that could withstand significant boost pressures. Adding the girdle at the bottom of the block gave access to the rotating assembly of the crankshaft but helped to eliminate the “swing” from the main caps that can cause failure in other engines.
In addition to the closed deck and cast iron, the Toyota engineers added molded side ribs to the block for support. The ribs served a dual purpose of providing an added layer of protection against cracking due to extreme thermal temps. Still, they also worked as oil return holes, ensuring the free flow of oil around the internal components.
Steel Gaskets Are Better
Where fiber gaskets would generally have been used on the head and oil pan, Toyota opted for less corrosive three-layered steel gaskets (many aftermarket gaskets are steel), which were less likely to fail when the engine was pushed to its limits. In addition, the head is secured to the block with 14 bolts, arranged in a pattern so that each bore is secured at each corner, again helping to ensure an effective seal.
Strong Internals Provide Support
Toyota improved the internals wherever they could. The 2JZ motors had a perfectly counterweighted forged steel crankshaft with reinforced main bearings and hardened steel connecting rods. While many inline sixes had long cranks like the 2JZ (weaker connecting rods can be a point of engine failure), Toyota decided to forge rather than cast them for additional rigidity and strength.
With high-pressure aluminum pistons, the engine could withstand the stresses that Toyota believed would be inflicted by drivers on and off the track. The Toyota 2JZ - GE (non-turbocharged) motor (with VVT-i) was given a 10.5:1 compression, while the twin-turbocharged version (2JZ - GTE) has recessed piston tops which produced a much lower compression ratio at 8.5:1.
Each piston has two compression rings and a single oil ring. The top of the higher compression ring is chromium-plated, which provides higher wear resistance and reduced friction capacities. The lower compression also made the 2JZ - GTE especially attractive for higher boost applications.
The Secret To More Power
The real secret to the engine's power comes from the forced induction. The 2JZ-GTE used sequential twin turbos, one that operated at low rpms and the other that kicked in when the rpms reached around 4,000. Since the turbos were perfectly aligned and the same size (which was an unusual configuration for its day), they aided in smoothing out the powerband throughout the rev cycle. The smoother power output is reflected in how balanced the turbocharged engines perform even when stressed, which adds to their durability and performance. While the factory twin turbochargers provided more than enough induction to produce a 4.6-second track time, many owners were swapping them for a single turbo to increase power levels.
In short, Toyota overengineered the motor, and their desire for excellence is why many tuners hunt this engine down to gain more power for their own vehicles.
Large Injectors Provide More Boost
The fuel system differed on the 2JZ motor depending on whether you lived in the US or Japan. The American version of the 2JZ received larger 550 cc injectors, while the Japan market did not (440 cc). Toyota used a top feed design, and many Supra owners were swapping out their fuel injectors, looking for big power.
One Coil, Two Plugs
Many people believe the 2JZ engine has a coil-on-plug ignition, but this is not true. The engine uses a system where one coil is perched above the plug at the center of the combustion chamber while a spark plug wire connects to the second cylinder via a spark plug wire. Both cylinders receive a spark when the piston is about to reach the top dead center, but one is the compression stroke, and the other is the exhaust stroke. The spark on the exhaust stroke is considered “wasted,” but it solves the issue of needing a coil for every cylinder. Even though some owners have replaced the Supras coil system with a COP (coil on plug), most find that the stock form provides more than enough spark.
Toyota designed the 2JZ with dual knock sensors tied to the ECU, helping the engine detect any issues. Once a sensor is activated, the 2JZ - GTE could shut down, limit power outputs, and enter into “limp mode” to keep drivers from unintentionally damaging the engine.
The fact that even after over twenty years since the last 2JZ engine, racers are still searching for them as a viable engine option is a testament to the quality of this build. Many feel that the 2JZ engine was the best fashioned by Toyota ever.