JUN Auto Mechanic: The Big Power 2JZ Specialist
JUN Auto Mechanic in Tsuchiura has built 2JZ engines since 1990. Their Stroker 3.4 kit, valvetrain components, and hand-balanced rotating assemblies set the global 2JZ tuning standard.
JUN Auto Mechanic: The Big Power 2JZ Specialist
JUN Auto Mechanic was founded in 1990 in Tsuchiura, Ibaraki, and built its reputation almost entirely on the Toyota 2JZ-GTE engine. While HKS, Mine's, and Trust/Greddy were chasing multiple chassis platforms, JUN focused on making the 2JZ faster than anyone else thought possible.
The Stroker 3.4 Kit
JUN's most famous product is the Stroker 3.4 kit for the 2JZ-GTE. By machining the crank, fitting longer rods, and using larger pistons, JUN increased displacement from 3.0L to 3.4L. The resulting engine produced:
- 700+ PS with stock twin turbos
- 1,000+ PS with a single large turbo
- Reliable operation at 800+ PS (with proper supporting modifications)
The Stroker 3.4 became a global benchmark. JUN sold the kit as a complete parts package, and other tuners worldwide would send their 2JZ blocks to JUN for machine work.
Japan's First Street-Legal 1,000 HP Supra
In the late 1990s, JUN built the first street-legal 1,000-horsepower MK4 Supra in Japan. The car was daily-driven by JUN's head engineer and made appearances in Option Magazine throughout 1998-2000. The build used:
- JUN Stroker 3.4 kit
- JUN hand-balanced crank and rods
- JUN-spec valvetrain (cams, retainers, heavy-duty valve springs)
- Single large turbo
- Upgraded fuel system
The car was a proof of concept. It could idle in traffic, drive to the local convenience store, and then lay down 1,000+ hp on the dyno. The 1,000-hp street Supra has been a JDM tuner archetype ever since.
The Parts Catalog
JUN's catalog is 2JZ-heavy but covers a few other engines:
- 2JZ Stroker 3.4 kit (complete rotating assembly)
- RB26 rotating assembly (JUN also makes an RB stroker)
- SR20 and 4G63 stroker kits (smaller product lines)
- Valvetrain (cams, springs, retainers, lifters)
- Oil pumps (heavy-duty)
- Gaskets and bearings
The Racing Program
JUN also competes in All-Japan GT (now Super GT) and Super Taikyu endurance racing. The JUN BP Supra was a Super GT GT300 entry in the early 2000s. The racing program validated JUN's parts catalog — if a JUN rotating assembly could survive a 24-hour race at Suzuka, it could survive your street Supra.
The Philosophy
Unlike Top Secret's showmanship or Mine's refinement, JUN's philosophy is peak numbers with race-grade engineering. JUN engines are not particularly refined, not particularly quiet, and definitely not smooth at idle. They make power. That's the point.
Why JUN Matters
JUN defined what a "big power" tuner was in the 1990s. Every shop today that offers a "1,000-hp crate engine" program owes a debt to JUN's original Stroker 3.4 work. The modern global 2JZ community — Titan Motorsports, Real Street Performance, HPA Motorsports — all use techniques JUN refined first. When 2JZ tuning was still considered experimental, JUN was already producing reliable 1,000+ hp builds.