GReddy Turbocharger Rebuild Service

GReddy
Turbo
Rebuild

Complete in-house rebuild service for the full Trust / GReddy turbocharger lineup. TZ series T517Z through T620Z, T67, T78-29D and T78-33D, T88-34D and T88-38GK, T88H-34D and T88H-38GK. Billet compressor wheel and modern aero upgrades available across the lineup. In-house VSR balancing since 2008.

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TZT517Z T518Z T620Z
T7829D and 33D
T88HBillet Aero Upgrades
Brand
Trust / GReddy Japan
TZ Series
T517Z T518Z T618Z T620Z
T67 / T78
T78-29D T78-33D
T88 / T88H
T88-34D T88H-38GK
Cooling
Oil Only No water jacket
In Shop Since
2008 17+ years
Trust / GReddy --
Made in Japan

GReddy is the performance brand of Trust Co., Ltd., founded in 1977 in Chiba, Japan. Trust manufactures all GReddy turbochargers in-house at their Japanese factory -- not sourced from third-party suppliers. Every turbocharger in the GReddy lineup is built around Mitsubishi Heavy Industries (MHI) TD-series internals with Trust-designed compressor and turbine housings engineered specifically for each application.

The GReddy model designation system encodes the turbocharger size and configuration. The number in models like T78 and T88 indicates the compressor wheel class. The letter suffix -- 29D, 33D, 34D, 38GK -- describes the turbine housing A/R in cm² and the housing type (D = divided twin scroll). Larger suffix numbers mean more turbine housing flow and more top-end capacity but later spool.

One design choice that defines the entire GReddy lineup: oil-only cooling. Every GReddy turbocharger uses oil cooling only -- no water jacket around the center housing. This simplifies installation and reduces engine bay plumbing, but it makes oil quality and change intervals critical. The bearing housing relies entirely on oil to manage heat at shutdown. Running the correct oil, changing it regularly, and proper idle-down after hard driving are non-negotiable on any GReddy turbo.

01
MHI TD-Series Internals
The TZ series uses TD05H-based internals. The T67, T78, and T88 family uses TD07S-based internals. The compressor and turbine housings are Trust-specific designs, but the center sections share MHI architecture -- meaning rebuild knowledge transfers from MHI platform experience.
02
Oil-Only Cooling Throughout
No water lines. No coolant fittings. Every GReddy turbo from the smallest TZ unit to the T88H is oil-cooled only. Simplified installation is the benefit. The tradeoff is strict dependence on oil quality and change intervals to prevent CHRA heat damage at shutdown.
03
Top-End Power Architecture
GReddy turbos are engineered for high peak power rather than fast initial spool. The T78 and T88 in particular are known for significant boost delivery in the upper RPM range. This makes them ideally suited to high-revving inline-six engines like the 2JZ-GTE and RB26DETT where broad powerband is less critical than peak output.
04
Billet Wheel Upgrades Available
We offer billet compressor wheel upgrades for the T78 and T88 series. The OEM cast compressor wheels on these turbos are a genuine limiting factor at higher boost levels. A billet wheel improves flow, increases burst strength, and often picks up measurable power at the same boost level. Contact us when sending a T78 or T88 for a rebuild quote that includes the billet option.
Series Coverage

Every GReddy
Series We Rebuild

GReddy turbos span two distinct families: the TZ series for bolt-on OEM-style replacement on specific JDM platforms, and the T67 through T88H range for external wastegate performance builds. All are fully supported at Boost Lab.

T517Z
TD05H-Based — Bolt-On OEM Replacement
The T517Z is the entry point of the GReddy TZ lineup -- a direct bolt-on replacement for the OEM turbocharger on GTR and EVO platforms using the stock exhaust manifold and intake pipe. Available with P750 actuator for the R32/R33/R34 Nissan Skyline GTR and P765 actuator for EVO/DSM/general applications. Two turbine housing sizes: 8cm and 10cm. TD05H center section. Oil-only cooled. Capable of 300-350 HP as a genuine stock-sized bolt-on replacement.
ApplicationsNissan Skyline R32/R33/R34 GTR (RB26DETT) / Mitsubishi EVO 1-3 (4G63) / DSM / Eagle Talon
Upgrade AvailableBillet compressor wheel with modern aero profile available at rebuild
11500121 11500122 11500123 11500124
T518Z
TD05H-Based — Step-Up TZ
The T518Z sits above the T517Z in the TZ lineup with a slightly larger compressor wheel for improved peak flow while retaining the bolt-on OEM fitment. Used on similar JDM platforms as the T517Z. The T517Z and T518Z share the same TD05H turbine internals -- the distinction is the compressor wheel size and housing configuration. Both are oil-only cooled and designed to install directly onto the factory exhaust manifold without modification.
ApplicationsNissan Skyline GTR / Mitsubishi EVO / DSM / similar JDM inline-4 and inline-6 applications
Upgrade AvailableBillet compressor wheel with modern aero profile available at rebuild
T618Z
TD06S-Based — Mazda RX-8 Specific
The T618Z is a purpose-built GReddy TZ turbocharger for the Mazda RX-8. The RX-8 application requires a specific exhaust outlet configuration to mate with the rotary engine exhaust port layout -- the T618Z uses a unique gasket (GReddy 11900137) not shared with other TZ models. TD06S-based center section. If you have an RX-8 GReddy kit, confirm you have the T618Z variant before shipping as the gasket requirements are different from every other TZ unit.
ApplicationsMazda RX-8 (13B-MSP) -- GReddy bolt-on turbo kit specific
T620Z
TD06S-Based — Larger TZ
The largest TZ series unit and a step up from the T517Z/T518Z in both compressor and turbine housing size. Used on the Toyota Mark II JZX100 GReddy kit and other inline-6 applications where more flow capacity is needed than the T517Z provides. Capable of approximately 330 HP at 0.8 bar and up to 370 HP at 0.9 bar. Retains the bolt-on OEM fitment philosophy of the TZ series but with significantly more headroom than the smaller units.
ApplicationsToyota Mark II JZX100 (1JZ-GTE) / JZX series / various JDM inline-6 bolt-on applications
Upgrade AvailableBillet compressor wheel with modern aero profile available at rebuild
T67-25G
TD06SH-Based — Street Performance
The T67-25G is GReddy's bridge between the TZ bolt-on series and the larger T78/T88 external wastegate units. TD06SH-based center section with a 25G compressor configuration. Used in GReddy turbo kits for various JDM platforms including the Toyota SW20 MR2 and JZX90 / JZX100. The T67 delivers stronger top-end power than the TZ series while being more streetable than the T78. External wastegate. Shares turbine gaskets with the TD06SH family (GReddy 11900130).
ApplicationsToyota SW20 MR2 / JZX90 / JZX100 / FD3S Mazda RX-7 / various GReddy kit applications
Upgrade AvailableBillet compressor wheel with modern aero profile available at rebuild
T78-29D / T78-33D
TD07S-Based — 500-700 HP
The T78 is the entry point to the large GReddy frame. TD07S-based center section with a 65.8mm compressor inducer / 90mm exducer and 65mm turbine exducer / 74mm inducer. The -29D and -33D suffixes indicate turbine housing A/R in cm² -- 29cm² delivers faster spool with less peak flow, 33cm² is the more common choice for 2JZ and RB26 builds targeting 500-700 HP. External wastegate. T4 turbine inlet flange. Shares the TD07S turbine inlet gasket (GReddy 11900150) with the T88 family. We offer billet compressor wheels with modern aero profiles for the T78 at rebuild.
ApplicationsToyota Supra JZA80 (2JZ-GTE) / Nissan Skyline RB26DETT / JZA70 / Mazda FD3S / various 500-700 HP inline-6 builds
11500260 11500261 11500267 11500268 11500330 11500331 11500332 11500333
T88-33D / T88-34D
TD07S-Based — 700-900 HP
The T88 steps up from the T78 with a larger 69.97mm / 95mm compressor wheel -- approximately 70mm inducer -- and larger turbine housing. The -34D turbine housing is the standard T88 configuration and the most common in 2JZ Supra builds targeting 700-900 HP. External wastegate. The T88-38GK uses the same center section with an even larger 38cm² turbine housing for maximum exhaust flow on very high power builds. Compressor housing shares the 4" turbine inlet family. Mitsubishi cross-reference: 49188-02700. We offer billet compressor wheels with modern aero profiles for the T88 series at rebuild.
ApplicationsToyota Supra JZA80 (2JZ-GTE) / Nissan Skyline RB26DETT / large displacement inline-6 builds 700-900 HP
11500314 11500315 11500316 11500319 11500321 11500322
T88H-34D / T88H-38GK
TD07S-Based — 900-1000+ HP
The T88H is the largest production GReddy turbocharger. The H designation indicates a larger turbine wheel than the standard T88 -- same compressor wheel size (69.97mm / 95mm on the 34D, 75.9mm / 98mm on the 38GK) but a turbine wheel with more flow capacity for extreme boost levels. The T88H-38GK is capable of 1,000+ HP on built 2JZ engines. Full boost typically arrives around 5,200 RPM on a 2JZ with supporting modifications. External wastegate. These units are increasingly rare in good condition -- contact us before shipping to confirm parts availability.
ApplicationsToyota Supra JZA80 (2JZ-GTE) -- built engine applications at 900-1000+ HP / Nissan Skyline extreme builds
11500324 11500325
Available Upgrade
Billet Wheels and
Modern Aero Upgrades
The compressor wheel designs across the GReddy lineup -- from the TZ series through the T88H -- were engineered before modern CNC billet profiling and computational aero design were widely available. We upgrade many GReddy models to billet compressor wheels with modern aerodynamic blade profiles at rebuild time. A billet wheel is CNC machined from forged aluminum to tighter tolerances than a casting, delivering better flow characteristics, higher burst strength, and improved compressor map efficiency. The result is typically measurable power gains at the same boost level the original wheel was running, with a higher ceiling for those pushing further. Ask about billet and modern aero upgrade options when submitting any GReddy rebuild -- availability varies by model.
Part Number Reference

Find Your Part Number

GReddy part numbers follow the Trust/GReddy catalog format (11500XXX series). Search by GReddy part number, model name, turbine housing configuration, or application.

Showing -- results
GReddy Part # Model Configuration Application Notes
11500121T517Z8cm / P750 ActuatorNissan Skyline R32/R33/R34 GTR (RB26DETT)GTR bolt-on replacement
11500122T517Z10cm / P750 ActuatorNissan Skyline R32/R33/R34 GTR (RB26DETT)GTR bolt-on replacement
11500123T517Z8cm / P765 ActuatorEVO 1-3 (4G63) / DSM / Eagle Talon / generalP765 actuator bolt-on
11500124T517Z10cm / P765 ActuatorEVO 1-3 (4G63) / DSM / Eagle Talon / generalP765 actuator bolt-on
11500260T78-33D33cm² External WGToyota Supra JZA80 2JZ-GTE / Skyline RB26T78 most common config
11500261T78-33D33cm² External WGToyota Supra JZA80 2JZ-GTE / Skyline RB26T78 variant
11500267T78-33D33cm² External WGToyota Supra JZA80 2JZ-GTET78 variant
11500268T78-33D33cm² External WGToyota Supra JZA80 2JZ-GTET78 variant
11500330T78-29D29cm² External WGToyota Supra JZA80 2JZ-GTE / Skyline RB26T78 faster spool housing
11500331T78-29D29cm² External WGToyota Supra JZA80 2JZ-GTET78 variant
11500332T78-29D29cm² External WGToyota Supra JZA80 2JZ-GTET78 variant
11500333T78-29D29cm² External WGToyota Supra JZA80 2JZ-GTET78 variant
11500314T88-34D34cm² External WGToyota Supra JZA80 2JZ-GTE / Skyline RB26T88 standard config
11500315T88-34D34cm² External WGToyota Supra JZA80 2JZ-GTET88 variant
11500316T88-34D34cm² External WGToyota Supra JZA80 2JZ-GTET88 variant
11500319T88-34D34cm² External WGToyota Supra JZA80 2JZ-GTET88 variant
11500321T88-34D34cm² External WGToyota Supra JZA80 2JZ-GTET88 variant
11500322T88-34D34cm² External WGToyota Supra JZA80 2JZ-GTET88 variant
11500324T88H-38GK38cm² External WGToyota Supra JZA80 2JZ-GTE built engine 900-1000+ HPLargest GReddy turbo
11500325T88H-38GK38cm² External WGToyota Supra JZA80 2JZ-GTE built engine 900-1000+ HPT88H variant
11500185TD06SH-20GExternal WGGReddy kit applications -- FD3S RX-7 / 2JZ / generalTD06SH GReddy variant
11500186TD06SH-20GExternal WGGReddy kit applicationsTD06SH GReddy variant
11500195TD06SH-20GExternal WGGReddy kit applicationsTD06SH GReddy variant
11500205TD06S L2-20GExternal WGGReddy TD06S L2 applicationsTD06S L2 GReddy variant
11500206TD06S L2-20GExternal WGGReddy TD06S L2 applicationsTD06S L2 GReddy variant
11500245TD07S-25GExternal WGGReddy large applicationsTD07S GReddy variant
11500250TD07S-25GExternal WGGReddy large applicationsTD07S GReddy variant
11500255TD07S-25GExternal WGGReddy large applicationsTD07S GReddy variant
11510030T78-29D-14cm²T78 Supra KitToyota Supra JZA80 2JZ-GTE -- T78 kit 29D 14cm² R11 WGJZA80 Turbo Kit PN
11510509T78-29D-17cm²T78 Supra KitToyota Supra JZA80 2JZ-GTE -- T78 kit 29D 17cm²JZA80 Turbo Kit PN
11510510T78-33D-17cm²T78 Supra KitToyota Supra JZA80 2JZ-GTE -- T78 kit 33D 17cm²JZA80 Turbo Kit PN
11510516T88-34D-22cm²T88 Supra KitToyota Supra JZA80 2JZ-GTE -- T88 kit 34D 22cm²JZA80 Turbo Kit PN
11900123TD04H / TZ Inlet GasketActuator typeT517Z / T518Z / T620Z turbo inlet gasketGasket Component
11900130TD Inlet/Outlet GasketExternal typeTD05SH / TD06S L2 / TD06SH / T67 inlet and outletGasket Component
11900137TZ Outlet Gasket (RX8)T618Z specificT618Z Mazda RX-8 outlet gasket -- unique to T618ZGasket Component
11900150TD07S Inlet GasketExternal typeTD07S / T78 / T88 / T88H turbine inlet gasketGasket Component
11900151TD07S Outlet Gasket (4-bolt)External typeTD07S / T78 / T88 / T88H turbine outlet 4-bolt gasketGasket Component
11900160TZ Outlet Gasket (ZN/S14/S15/JZX)Actuator typeT517Z / T518Z / T620Z outlet -- S14/S15/JZX/Honda applicationsGasket Component
11900161TZ Outlet Gasket (GTR)Actuator typeT517Z / T518Z / T620Z outlet -- R32/R33/R34 GTRGasket Component
11900190TZ Compressor Inlet GasketActuator typeT517Z / T518Z / T620Z compressor inlet gasketGasket Component
11900191TZ Compressor Outlet GasketActuator typeT517Z / T518Z / T620Z compressor outlet gasketGasket Component
Common Failure Modes

Why GReddy Turbos
Fail

Every GReddy turbo failure we see has a direct connection to oil. The oil-only cooling design means there is no fallback cooling system -- the bearing housing lives and dies on oil quality, pressure, and change intervals.

01
Hot Shutdown Oil Coking
This is the most common GReddy failure cause by a significant margin. All GReddy turbos are oil-only cooled -- there is no water jacket to absorb and dissipate heat after the engine shuts down. When you shut off a hot engine running a GReddy turbo, oil trapped in the CHRA immediately begins to bake against the hot bearing housing. Over time -- and this happens faster than most owners expect -- the baked oil deposits restrict the small oil passages and starve the bearings on every subsequent cold start. A turbo timer or a consistent idle-down period after any hard run is essential on every GReddy-equipped car.
02
Extended Oil Intervals
The same oil that lubricates the bearings is also the primary cooling medium in a GReddy turbo. Degraded oil loses its viscosity and film strength under heat, which accelerates bearing wear exactly when the turbo needs it most -- under boost and at high shaft speeds. GReddy explicitly recommends frequent oil changes and quality full synthetic on their turbocharged vehicles. Many failures we see at teardown show the characteristic black, varnish-like deposits from degraded oil that the owner ran well past its service life.
03
TZ Series Actuator Failure
The T517Z, T518Z, and T620Z use internal wastegate actuators (P750 for GTR, P765 for general applications). The actuator diaphragm deteriorates over time from heat cycling and boost pressure. A failed actuator allows uncontrolled boost -- either overboosting if the gate sticks closed or underperformance if it sticks open. The actuator failure itself does not typically damage the turbo internals, but running significantly overboost conditions stresses the bearings. Actuator condition is checked on every TZ rebuild.
04
T78 / T88 Compressor Wheel Fatigue
The OEM cast compressor wheels on the T78 and T88 series are old designs. Cast aluminum wheels develop micro-cracks at the bore over time, especially on turbos that have been run at elevated boost levels or experienced any compressor surge. A compromised wheel is not always visible externally -- the cracks propagate from the bore outward and can fail suddenly under boost. Every T78 and T88 teardown includes compressor wheel inspection. If any bore cracking or unusual stress marks are found we recommend the billet wheel upgrade rather than reinstalling a wheel of unknown fatigue history.
05
Oil Feed Line Restriction
GReddy turbos use a banjo-bolt oil feed connection on most applications. The banjo bolt passage is small and prone to restriction from sludge buildup in engines that have seen extended oil intervals or oil degradation. Restricted oil feed on cold starts -- when the oil is thickest and the turbo is spinning up from zero -- is a guaranteed path to accelerated bearing wear. Cleaning or replacing the oil feed line, banjo bolt, and crush washers is part of every GReddy rebuild.
06
T88H Age and Wear
The T88H is increasingly old hardware. These turbos were popular on 2JZ Supras in the late 1990s and early 2000s and many have covered significant mileage and boost events since. Sourcing replacement components for a T88H is more difficult than for the T78 or standard T88. Contact us before shipping a T88H -- we will confirm component availability and turnaround before you commit to the rebuild.
Common Questions

Frequently Asked

Both the T88 and T88H use the same compressor wheel size on the -34D configuration (approximately 70mm inducer / 95mm exducer). The H designation indicates a larger turbine wheel. A larger turbine wheel flows more exhaust gas at high RPM, raising the peak power ceiling. The tradeoff is that the turbine wheel has more inertia, which pushes the point where full boost arrives slightly higher in the RPM range. For reference the -38GK configuration on both T88 and T88H uses a still larger turbine housing (38cm² vs 34cm²) for even more top-end flow. Most Supra builds targeting around 600-750 HP use the T88-34D. Builds targeting 800 HP and above typically move to the T88H.
No. Every turbocharger in the GReddy lineup is oil-cooled only -- there is no water jacket or coolant circuit. Trust made this a deliberate design choice to simplify installation and eliminate coolant line routing in the engine bay. The tradeoff is that without water cooling to absorb and dissipate heat after shutdown, proper idle-down and oil quality become even more critical than on a water-cooled unit. If your GReddy kit has a coolant line going to the turbo, it is aftermarket -- not factory Trust/GReddy.
The D stands for Divided -- meaning the turbine housing is a twin-scroll divided volute design rather than single scroll. The number before the D is the turbine housing A/R measured in cm² -- a Mitsubishi measurement convention. So T78-33D means a T78 frame with a divided twin-scroll turbine housing of 33cm² effective area. The 29D has 29cm² for slightly faster spool with less peak flow, and the 33D has 33cm² for more top-end. The GK suffix on the T88H-38GK indicates an even larger 38cm² twin-scroll housing.
The compressor wheel designs across the GReddy lineup date back to an era before modern CNC billet machining and computational fluid dynamics were widely applied to aftermarket turbocharger development. Cast aluminum wheels are less precise than billet, develop micro-cracks at the bore over time, and leave aerodynamic efficiency on the table compared to what modern blade profiles can achieve. A billet compressor wheel is CNC machined from a solid aluminum forging to tighter tolerances, with blade geometry optimized using modern aero tools. The result is better flow, higher burst strength, and improved compressor map efficiency -- which frequently translates to real power at the same boost level, plus more headroom for those running higher. We can upgrade many GReddy models at rebuild time. Availability varies by specific model -- ask when you submit your rebuild request and we will confirm what is available for your unit.
Inconsistent boost on a TZ actuator-type turbo almost always points to the actuator diaphragm first. The diaphragm deteriorates from heat cycling and develops small cracks that allow boost to bleed through rather than actuating cleanly. This causes the wastegate to open inconsistently, producing erratic boost. If you are hearing noise from the turbo or seeing oil in the intake, that points to bearing or seal issues inside the CHRA. If the turbo is quiet and oil-clean but boost is inconsistent, the actuator is the first thing to check. We can diagnose both at teardown.
Drain any residual oil from the inlet and outlet ports. Plug all ports to prevent contamination during transit. Double-box with foam or bubble wrap padding on all sides. Ship via UPS or FedEx to 37833 Pineapple Ave Unit A, Dade City, FL 33523. Include the GReddy model number if known -- even a photo of the nameplate tag helps us pull the right components before teardown. Contact us before shipping and we will send a receiving confirmation.
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Ready to Rebuild?

Start your rebuild request in our repair system. TZ series through T88H, all supported. Billet compressor wheel and modern aero upgrades available across the lineup. Every job documented from intake through return with in-house VSR balancing.

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sales@theboostlab.com theboostlab.com Dade City, FL