Let’s first discuss what a “T51R” is…

“T51R” is a Turbocharger model designation which HKS Japan released in the early 1990’s. It was a Garrett based unit, which in modern day model designation correlates to a GT4502R specification.

HKS’s T51R became globally popular when they released the “T51R” Turbo Kit for the Nissan RB26 and Toyota 2JZ-GTE engines. The T51R’s were quite a large turbo for a street/response style engine, so most of them ended up in high horsepower Drag Racing applications.

Although today’s turbocharger technology allows us to improve Turbocharger response and power outputs, they all lack what the T51R was famous for…and that was the noise they produced when they were on song.

HKS’s T51R was fitted with a HKS branded compressor housing, which included an anti-surge design that prevented high gear, low load turbocharger surging. The insert design worked extremely well for it’s purpose, but it’s main attraction was the whistle or “spool noise” that was produced when it was creating positive boost pressure. HKS have since discontinued this Turbocharger from their range, but the aftermarket support and fan base lives on.

Hi Spool Industries spent many hours in R & D to discover exactly how the HKS T51R produced this “spool noise”, and this involved a heap of trial and error and a few housings ending up in the bin! Luckily, the Hi Spool insert has been perfected, and is now available for Turbochargers with inlets from 3″ all the way to 6″. This covers a huge range of Garrett, Borg Warner, Turbonetics, Holset and Precision Turbos, as well as the newly released Aeroflow range.

In reality, the T51R Mod does not result in any improvements in overall power, response or change Turbocharger characteristics in any way. In fact, modifying the surge resistance characteristics of any Turbocharger may actually result in a small loss of power, but this very much depends on the engine application, tuning, boost level and Turbocharger type.

Put quite simply, the modification is a machining and insert process that exaggerates the whistle/noise that a Turbocharger produces when it is making positive boost pressure. People WILL hear you coming from 3 streets away!

How much is the T51R Mod?

3″ – 4″ Inlet Compressor Housings – $440.00

5″ Inlet Compressor Housings – $570.00

6″ Inlet Compressor Hosuings – $690.00

**Note – Some standard compressor housing designs do not allow us to fit a Hi Spool Insert due to their inlet design. Please contact us to make sure we can perform this modification to your turbocharger**