Why Is the 2JZ Engine So Good? (Explained)
Updated: Dec 15, 2021
Hello fellow engine heads, in this article, I cover a truly iconic engine; the 2JZ.
A combination of one number and two letters, known by pretty much every petrolhead on planet earth. The 2JZ engine is associated with massive power.
I will cover its history, its specs, and its tuning capability.
Table of Contents:
I promise you this won't be a boring wall of text about the 2JZ; this will be much more.
I will dive deeper into the details of the anatomy and learn about the mechanics of the 2JZ engine. I'm going to explain everything about this iconic Toyota engine.
So after reading this article, I promise you that you will have a complete understanding of what makes the 2JZ engine so good.
What Is the 2JZ?
The Toyota JZ engine family is a series of inline six-cylinder engines. It was a replacement for the M-series inline six-cylinder engines.
The JZ series of engines were 24-valve, dual overheads cam (DOHC) engines.
The 2JZ engine was a 2,997 cc engine with a bore and stroke of 86mm x 86mm, making it a "square" engine due its 1:1 stroke-to-bore ratio.
There are a few types of this engine, the most sought after type being the 2JZ-GTE. The GTE version had a power output of 280hp in Japan, and 320hp in Europe and the USA.
In 1978 Toyota wanted a car that would compete with Nissan's hugely successful 'Z' car.
However, they didn't feel like designing a whole new platform, so they took their existing Celica, stretched it out a bit gave it a bit of a superficial redesign.
They packed an inline six-cylinder under the hood and called it the Celica Supra. Although the name sounds strange today, back then, it made more sense.
'Supra' means above and beyond the limits of something, and this was what the Celica Supra was.
It was beyond the limits of the regular Celica.
It had more power, it was larger, and it looked different, so the Celica Supra (although it's the equivalent of saying Toyota Prius today) back in the late 70s made more sense.
It was a pretty desirable car, but it didn't manage to come anywhere near the sales figures of the Nissan Z, but it did do something historically significant.
It created the bond between the word Supra and the inline six-cylinder engine.
Unlike the Celica upon which it was based, which had a four-cylinder engine, the Supra Celica got an inline six-cylinder engine.
Toyota's 'M' engine came just three years later, 80's design came knocking and as a result, the entire Celica lineup was redesigned.
Along with it, of course, the Celica Supra, the second-generation cars arguably differ more from each other than the first-generation cars.
Although the second-generation Celica Supra was very different outside from the Celica inside, it still shared many components with the Celica.
It was larger, more luxurious, better equipped, and had an inline six-cylinder, but it was still a Celica.
Now, everywhere the name 'Celica Supra' was still retained, except in Japan, where Celica Supra wasn't called the 'Celica Supra'.
Both the first-generation and the second-generation of the Celica Supra in Japan were known as the Celica Double X.
The second-generation Supra also did something important; it was the first instance of turbocharging in a Supra.
In February 1986, something significant would happen; the word Celica would get amputated from the Celica Supra.
Celica and Supra were now two separate models, and they went different ways.
The Celica would become a front-wheel-drive vehicle, while the Supra would retain a rear-wheel-drive configuration.
The Supra was no longer mechanically associated with the Celica; it was now based on the Toyota Soarer platform.
The Soarer was a more extensive platform, giving the Supra room to grow. Using the larger platform, Toyota would develop the Supra into a proper performance vehicle.
The Supras' suspension was upgraded to a double-wishbone setup and received some pinnacle technology from the 80s.
Some of this technology includes a 3-channel ABS and TEMS, which stands for Toyota-electronically-modulated-suspension, which gave the supra variable dampening.
In the engine department, the third-generation Supra received the last and the greatest iteration of the 'M' family of engines.
These 7M engines increased displacement to 3 litres, a number that would become synonymous with the supra model in its turbocharged form.
The 7M-GTE engine made some impressive power; although it had a weak head gasket, it still made the Supra a genuine high-performance vehicle.
But the third-generation Supra was important for one more reason; it was the first Supra to get a 1JZ.
In Japan, only the third-generation of the Supra became available with the 1JZ engine, the successor to the 7M engine.
It showed a glimpse of what the future would look like for the Supra, and in 1993, we would find out just how amazing the future would be.
Toyota started production of the fourth-generation Supra, it continued on the path set by the previous generation, but it was so much more.
Because for the fourth-generation Supra, Toyota went all out and used all of its 90s over-engineering skills to create a genuinely spectacular car.
Under the hood was the brand new 2JZ engine; the 2JZ and the 7M engines seemed very similar on paper.
Both of these engines existed in naturally aspirated and turbocharged variants, and both engines were 3-litre inline six-cylinder engines, but that's where the similarities end.
The 2JZ wouldn't just fix the minor issues that the 7M had, but it was a power unit with a much greater potential, and only time would unveil just how significant that potential was.
But the engine wasn't the only impressive thing; the fourth-generation Supra, despite its better safety, larger brakes, larger wheels, an extra turbo and a host of other stuff, managed to be almost 100kg lighter than the previous generation.
This weight saving is because Toyota used aluminium and magnesium alloys in various parts of the Supra to make it lighter.
The Supra could accelerate from 0-60 in just over four and a half seconds, and it could clear the quarter-mile in 13.1 seconds.
Unfortunately, the fourth-generation Supra didn't last very long.
A rising yen and a weakening high-performance car market ended the production of the fourth generation pretty quickly.
It was over in 1996, in Canada, sales stopped in 1998. In Europe and the USA, it would last another four years. In Japan, it was finally over for the supra in 2002.
The world would have to wait two decades for a successor to the mk4 Supra.
Arguably, those two decades are more critical for the supra and the 2JZ engine than the years during which it was in production.
In 2001, the fast and the furious movie was released, and the world fell in love with the Supra and its insane engine capable of crazy power.
In the early 2000s, tuners across the world started to push the power output of the 2JZ, but the early tuning was rudimentary.
You needed three different ECU's for three different things, and it was messy.
The aftermarket for the 2JZ and the Supra started to evolve pretty rapidly, and soon it gave tuners the tools needed to find the limits of the 2JZ engine.
But it seemed that the word 'limit' wasn't in the 2JZ's dictionary. Doubling of the engine's horsepower seemed too easy, soon triple-digit horsepower became the norm and expected.
Anything less was underwhelming. Dynos worldwide reported crazy power outputs from engines that used more stock components than anyone believed was possible.
The legend of the 2JZ was forged long before Toyota announced the successor to the supra and the 2JZ.
In 2019, Toyota revealed the fifth-generation Supra, and along with it, disappointment resounded across the world.
Supra fanatics expected a successor to the 2JZ, something that would walk the steps of the 2JZ.
Instead, they got a BMW engine, and although the new engine and the car itself is good, fans weren't happy.
Soon people started necessitating that the 20+ year old engine be swapped into the new Supra, and if this isn't a testament to how incredible the 2JZ is, then nothing is.
Anatomy of the 2JZ
Now let's dive deep into the anatomy of the 2JZ and see why it's such a good engine.
Below is an overview of this engines features.
Perfectly balanced inline six-cylinder
Heavily reinforced engine block and bottom end
Closed deck block with oil return holes
Multi-layered steel (MLS) head gasket
Forged fully balanced crankshaft
Forged connecting rods
High-pressure cast hypereutectic pistons
Internal oil gallery pistons with thermal and friction coatings
Dual overhead camshafts
8.5:1 compression ratio
The 2JZ engine is an inline six-cylinder, and all inline-6 engines are superbly balanced.
In essence, an inline-six is two inline three-cylinder engines mirrored and attached, meaning that the primary and secondary forces within inline-six engines are perfectly balanced.
Unlike some V6 engines, which can suffer from an imperfect rocking moment between the cylinder banks, the inline six-cylinder is beautifully smooth.
This perfect balance means you can rev it higher, rev it longer and rev it safely, which creates an ideal platform for improving power output.
There's a Toyota engine similar to the 2JZ engine, with two cylinders less, that engine is the Toyota 3S-GTE.
It shares both the bore and stroke with the 2JZ and both engines are "square". Being square by design means they have the same bore-to-stroke ratio, a 1:1 ratio.
They also share the same diameters of the intake and exhaust valves, which are pretty decent.
A square engine design tries to balance power and torque, and the 2JZ is an excellent example of a square engine that managed to do just that.
Next, let's talk about the engine block, something that's often discussed with regards to the 2JZ engine.
The 2JZ has a solid reputation because it's a cast-iron, closed-deck block design. Although this is true, it's an incomplete explanation.
Because as we all know, there are plenty of cast iron inline six-cylinder engine blocks out there. Somehow, the vast majority of them can't do what the 2JZ engine block can do.
To understand why the 2JZ block is so strong, we have to take a more detailed look at its anatomy.
Let's compare it to a different inline six-cylinder cast-iron, closed-deck engine block.
A good example is the 2JZ's predecessor, the 7M engine block, from a 7M-GTE turbocharged engine.
Although the 7M is a good engine block and can take quite a bit of power, it can't take as much power as the 2JZ.
Looking at these two blocks, what's the first thing that you notice?
The 2JZ has a lot more reinforcement. You can see those massive and very pronounced reinforcement rods pretty much everywhere on its engine block.
As you can see, the 7M block doesn't have reinforcement rods that are nearly as pronounced as those on the 2JZ.
Now let's compare the 2JZ with the 3S engine.
This is a 3S-GTE engine block, and as you can see, one half does have those large reinforcement rods, but the other half doesn't.
The 2JZ has large reinforcement rods on both sides of the engine block. These reinforcement rods are actually used as oil return holes.
When looking at the block from above, you can see that these are oil return holes, and the 2JZ has many of them.
This is a good feature because oil return is an essential thing for an engine, and if it isn't addressed correctly, you can have many different problems.
Without proper oil return, issues like oil starvation can occur when the engine is at full load.
The oil return holes on the 2JZ are outside of the main boundary of the engine block deck; they have been moved outside for two reasons.
To leave more material in the block
To act as reinforcement rods
More material in the engine block is a good thing.
Although it does increase the weight a little bit, ~5kg extra isn't a big deal when you're getting a more robust engine block that can withstand more power.
The second reason the oil return holes are outside the boundary of the deck is that they have been used as reinforcement rods.
The 2JZ engine block is one of the most heavily reinforced engine blocks ever to be manufactured.
When you pair that with a lot of material and the cast iron material itself, you get something that's pretty much indestructible.
On top of that, the main journals of the crankshaft and the main bearing caps are giant.
They are large, and although they are not cross-bolted like in some other engines, they are still exceptionally strong.
All of this explains why tuners can take the 2JZ engine block to massive power levels.
Toyota also designed a girdle that bolts to the block's underside, and then the oil pan bolts to this girdle.
This girdle ties together the bottom end of the engine block, further reinforcing it and making it even stiffer and more robust.
On the top of the engine block is the cylinder head gasket and the one on the 2JZ is multi-layer steel (MLS) head gasket composed of three layers of steel.
This head gasket was a big step up from the 7M-GTEs' fibre-based head gasket.
The engine internals are solid; the crankshaft features very robust journal bearings and is a fully a counterweighted forged steel crankshaft.
The connecting rods are also solid; they are also forged, just like the crankshaft.
The only instance of slightly weaker connecting rods on the 2JZ is on the naturally aspirated generation 2JZ engines that featured variable valve timing.
The pistons of the 2JZ are not forged; they are high-pressure cast hypereutectic pistons.
Toyotas production and quality control from the 90s was excellent.
Although these pistons are not forged, they are solid and very well made, and there's no inconsistency in the quality of these pistons.
Although they are cast, they're capable of surviving 700-800 horsepower on this engine.
These pistons feature both friction-reducing coatings on the skirt and a thermal coating on the piston crown.
Another unique feature is these pistons have an internal oil gallery; this is something only the turbocharged 2JZ engines have.
This internal oil gallery is coupled with the oil squirters you can find in the 2JZ turbocharged engine block.
These oil squirters squirt oil right onto the underside of the piston, right into the oil gallery within the piston.
That directly cools the piston crown, reducing the chances of knock.
The compression ratio is higher in the naturally aspirated engines.
The low 8.5:1 compression ratio in the turbocharged engines, although a bit outdated by modern standards, is pretty helpful because it allows you to crank up the boost quite a bit safely.
The cylinder head on the 2JZ shares many things in common with the cylinder head of the Toyota 3S-GTE engine.
These engines are dual overhead cam engines, which means a timing belt directly drives both cams.
There are four valves per cylinder, giving a total of 24 valves for the 2JZ.
The valve angle for the 2JZ is 45° which is relatively wide.
The intake ports on the 2JZ feature a more modern design compared to the 3S engine, especially to the first generation of 3S engines, which featured Toyotas variable intake.
The shapes of the intake and exhaust ports of the 2JZ are pretty decent, and the 2JZ head does flow well.
However, there are some inline six-cylinder engines from the same time that will outflow the 2JZ head.
When tuners seek power increases beyond 800hp, it is often necessary to slightly reshape the ports and the head.
The 2JZ is a non-interference engine design, which means the valves and pistons never occupy the same space in the cylinder.
This non-interference design is excellent for peace of mind and engine safety, but it also means that the 2JZ has mild camshaft specs.
2JZ-GTE JDM Stock Cam Specs:
Intake Duration: 224°
Exhaust Duration: 236°
Intake Lift: 7.80mm
Exhaust Lift: 8.41mm
2JZ-GTE Export Stock Cam Specs:
Intake Duration: 233°
Exhaust Duration: 236°
Intake Lift: 8.26mm
Exhaust Lift: 8.41mm
As you can see, this engine has mild duration and pretty mild lift.
One of the easiest ways to make more power with the 2JZ engine is to change the camshafts.
The turbo version of the 2JZ features sequential twin turbos; this means that it has two turbos, one spools at low rpm and the other turbo spools at higher rpm.