The HKS Capacity Upgrade Kit 3.4L for 2JZ-GTE (21004-AT001) is essentially a complete high-performance stroker bottom end.
It doesn’t merely “increase the engine size”; it replaces the major rotating components so the 2JZ can make substantially more torque and support very high power.
HKS developed it with drag racing in mind.
What changes?
The stock 2JZ-GTE is approximately:
86 mm bore × 86 mm stroke = 2,997 cc
HKS changes it to:
87 mm bore × 94 mm stroke = 3,353 cc
So you get roughly 3.35 L, commonly called a 3.4L 2JZ.
What’s inside the kit?
1. 87-mm forged pistons
The pistons use HKS’s nickel-plating treatment around the crown/top-land area, intended to improve resistance to knock, high combustion pressure and top-land deformation. HKS also specifies a molybdenum coating.
2. 94-mm billet crankshaft
This is the heart of the displacement increase.
Stock:
86-mm stroke
HKS:
94-mm stroke
The HKS crank is fully counterweighted.
3. H-beam connecting rods
The longer stroke requires an appropriately engineered rod/piston/crank combination. HKS supplies high-strength H-beam rods as part of the complete kit.
Why make a 2JZ bigger?
This is the important engineering philosophy.
Imagine two engines both producing 1,000 hp:
3.0L 2JZ
The turbo has to force a lot of air into 3.0 litres.
3.4L 2JZ
The engine naturally moves about 13% more displacement.
That means the larger engine can produce substantially more airflow and torque for a given boost/turbo combination.
The objective isn’t simply:
“More displacement = more horsepower.”
It’s:
More displacement → more airflow → more torque → less dependence on extreme boost for a given output.
HKS specifically describes its capacity-upgrade philosophy as increasing displacement to produce more low-speed torque and help the turbocharger produce performance.
Why is this interesting for your E46 2JZ idea?
This is where it gets seriously interesting.
A hypothetical:
E46 + 2JZ-GTE 3.4L
would be very different from a normal 3.0L 2JZ swap.
You would have:
3.35L
↓
large turbo
↓
huge airflow
↓
very high torque
↓
light E46 chassis
The danger isn’t necessarily the engine.
The drivetrain and chassis become the next engineering problem.
You’d need to think about the entire chain:
3.4L 2JZ
→ gearbox
→ clutch
→ prop shaft
→ differential/LSD
→ half-shafts
→ tyres
→ suspension
→ brakes
→ cooling
rather than treating the HKS kit as a standalone horsepower upgrade.
And there’s an important catch
The HKS kit requires cylinder boring/honing. HKS specifies the 87-mm bore and notes that individual blocks may require additional clearance/recess work.
HKS also gives a 7,500 rpm recommended limit for this kit. Its published in-house result was approximately 1,015 PS and 110 kgf·m, but that is a manufacturer test result, not a guarantee that every engine built with the kit will safely produce that output.
So this is not a “bolt it in and make 1,000 hp” kit.
It’s the foundation for a properly engineered high-output 2JZ.
In one sentence:
The HKS 3.4L kit turns the 2JZ from a 3.0L high-boost monster into a 3.35L large-displacement turbo platform—giving the turbo more engine to work with, substantially increasing torque potential, while replacing the pistons, rods and crank with components designed for the increased displacement and high-output application.
For your E46 project, the fascinating question is actually 3.4L HKS 2JZ vs 3.0L B58: the 3.4L 2JZ has a very different torque-generation philosophy from the B58, even before you choose the turbo.
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