RB26 3.2 mm: A Crucial Detail for the Iconic Skyline Engine

The RB26DETT is the twin‑turbo powerhouse that powered the legendary Nissan Skyline GTR and R32 GT‑R. While the engine’s 2.6 L displacement and 500 hp output are celebrated, many enthusiasts overlook a tiny but vital component: the 3.2 mm bolt that secures the turbocharger to the engine block. In this article we explore why that 3.2 mm fastener matters, how it’s used in the RB26, and what you need to know when building or upgrading a Skyline engine.

Understanding the RB26 Engine Architecture

The RB26DETT is a 2.6 L inline‑six with dual turbochargers, an intercooler, and a 48 mm throttle body. Its design features a cast‑iron block and aluminum heads, which together provide the strength needed for high boost levels. The engine’s turbocharger mounting system is a key area where bolt size and torque play a critical role. In the original factory setup, the turbo is attached to the engine block using a series of high‑strength bolts, the most prominent of which is the 3.2 mm diameter fastener.

The Role of the 3.2 mm Bolt

In the RB26, the 3.2 mm bolt is used to secure the turbocharger’s mounting bracket to the engine block. This bolt must withstand significant axial and radial forces generated by boost pressure and turbo spin. Because the RB26 is a high‑performance engine, even a small deviation in bolt torque can lead to turbo slippage,