Garrett G-Series II G42-1325C Compact 73mm Turbocharger

Garrett G-Series II G42-1325C Compact 73mm Turbocharger — Select Turbine Housing

Part Number: 938339-5001S

The Garrett G-Series II G42-1325C is a standard-rotation, dual-ceramic-ball-bearing turbocharger platform designed for high-output street, competition, and specialty-performance applications requiring G42 turbine capacity with Garrett’s compact compressor housing. Garrett currently publishes a 475–1,325 horsepower range in the product-page summary and a 500–1,325 horsepower range in its reference table, with a displacement reference of 2.0 to 7.0 liters. These are potential flywheel-horsepower figures based on compressor-map airflow and are not guaranteed wheel-horsepower ratings.

The G42-1325C uses a 73mm inducer and 91mm exducer compressor wheel with a 65-trim profile and 0.90 compressor-housing A/R. The turbine stage uses an 82mm inducer and 75mm exducer wheel with an 84-trim profile. Garrett identifies the model as a 7375 reference configuration and specifies a maximum allowable turbocharger speed of 120,000 rpm.

The “C” designation identifies the compact compressor-housing configuration. Garrett’s dimensional drawing shows an approximately 4.00-inch hose-style compressor inlet and 3.00-inch hose-style compressor outlet, reducing compressor-cover size compared with the full-size G42 configuration while retaining the G42 turbine stage and housing family. This can materially improve packaging in confined engine compartments without changing the underlying turbine-housing choices.

As part of Garrett’s G-Series II range, the G42-1325C incorporates revised compressor aerodynamics that provide up to 10 percent greater compressor flow than the corresponding first-generation G-Series unit at peak pressure ratio and peak turbocharger speed. Garrett also identifies increased efficiency at high flow rates. G-Series II retains the corresponding first-generation G42 compressor- and turbine-housing interfaces, permitting an existing standard-rotation G42 installation to be upgraded when all reused component part numbers and interfaces are confirmed.

This listing is structured as a selectable-housing product. The Garrett 938339-5001S supercore may be combined with one of six verified standard-rotation G42 turbine housings. Three open-scroll housings use V-band turbine inlets, while three divided housings use T4 turbine inlets. Every available housing uses a V-band turbine outlet and requires an external wastegate. Garrett does not list an internally wastegated G42-1325C assembly.

RAD recommends the 1.15 A/R open-scroll V-band inlet and V-band outlet housing, Garrett part number 757707-0012, as the general catalog default. It occupies the middle of the available A/R range, provides more turbine-flow capacity than the 1.01 housing, and should retain better response than the 1.28 housing. The open-scroll V-band configuration also avoids the manifold and pulse-separation requirements of a divided T4 system. Final housing selection should still be based on engine displacement, airflow, power target, exhaust-manifold design, turbine inlet pressure, and intended operating range.

Key Features

• Garrett G-Series II G42-1325C standard-rotation turbocharger platform
• Garrett published horsepower references: 475–1,325 hp in the page summary and 500–1,325 hp in the reference table
• Garrett displacement reference range: 2.0–7.0 liters
• Garrett turbo reference: 7375
• 73mm compressor inducer and 91mm compressor exducer
• 82mm turbine inducer and 75mm turbine exducer
• Compact compressor housing with hose-style inlet and outlet
• Dual ceramic ball-bearing center section
• G-Series II compressor aerodynamics with up to 10 percent more flow than the corresponding first-generation G-Series compressor at peak pressure ratio and peak turbo speed
• Increased compressor efficiency at high flow rates
• Maximum allowable turbocharger speed: 120,000 rpm
• One-piece center-housing and backplate architecture
• Twin piston-ring sealing on both sides of the shaft assembly
• Inconel turbine wheel with Garrett G-Series aerodynamics
• Stainless-steel turbine housings rated by Garrett for temperatures up to 1,050°C
• Water fittings included with the supercore
• Machined compressor-housing port for an optional Garrett turbo-speed sensor
• Three open-scroll V-band inlet configurations
• Three divided T4 inlet configurations
• V-band turbine outlet on every verified housing
• External-wastegate configuration on every verified housing
• Compatible with the verified standard-rotation Garrett G42 housing family listed below

Kit Includes

• Garrett G-Series II G42-1325C supercore, part number 938339-5001S
• Compact compressor housing
• Forged and fully machined compressor wheel
• Center housing rotating assembly
• Inconel turbine wheel
• Garrett water fittings supplied with the supercore
• Selected Garrett G42 turbine-housing kit when a complete housing variant is ordered
• Garrett gasket kit packaged with the selected turbine-housing kit
• Supercore-only variant excludes the turbine housing

Technical Specifications

Compressor

• Compressor inducer: 73mm
• Compressor exducer: 91mm
• Compressor trim: 65
• Compressor-housing A/R: 0.90
• Compressor inlet: approximately 4.00-inch hose connection
• Compressor outlet: approximately 3.00-inch hose connection
• Maximum allowable turbocharger speed: 120,000 rpm
• Optional Garrett turbo-speed sensor hardware is sold separately

Turbine

• Turbine inducer: 82mm
• Turbine exducer: 75mm
• Turbine trim: 84
• Turbine-wheel material: Inconel high-temperature superalloy
• Turbine-housing material: stainless steel
• Turbine-housing temperature rating: up to 1,050°C
• Available turbine-housing A/R values: 1.01, 1.15, and 1.28
• Available turbine inlets: open-scroll V-band or divided T4
• Turbine outlet: V-band on every listed housing
• Wastegate arrangement: external wastegate required for every listed housing

Center Housing, Bearings, Lubrication, and Coolant Connections

• Bearing system: dual ceramic ball bearing
• Center-housing construction: one-piece center housing and backplate
• Shaft sealing: twin piston rings on both compressor and turbine sides
• Cooling: water cooled
• Coolant ports: M14 x 1.50 interfaces used with Garrett -6AN water fittings
• Water fittings are included with the supercore
• Oil inlet uses a two-bolt flange interface
• Oil-feed flange, restrictor if required, line, and engine-side adapter must be selected for the application
• Oil-drain flange, gasket, hose, fittings, and engine-side drain provision are not included
• Oil pressure, feed restriction, drain sizing, and drain routing must follow Garrett’s installation requirements for the specific engine and oiling system

Available Turbine Configurations

• 1.01 A/R V-Band / V-Band — Garrett 757707-0011: open-scroll V-band turbine inlet, V-band turbine outlet, external wastegate required.
• 1.15 A/R V-Band / V-Band — Garrett 757707-0012: open-scroll V-band turbine inlet, V-band turbine outlet, external wastegate required. RAD recommended general catalog default.
• 1.28 A/R V-Band / V-Band — Garrett 757707-0013: open-scroll V-band turbine inlet, V-band turbine outlet, external wastegate required.
• 1.01 A/R Divided T4 / V-Band — Garrett 757707-0014: divided T4 turbine inlet, V-band turbine outlet, external wastegate required.
• 1.15 A/R Divided T4 / V-Band — Garrett 757707-0015: divided T4 turbine inlet, V-band turbine outlet, external wastegate required.
• 1.28 A/R Divided T4 / V-Band — Garrett 757707-0016: divided T4 turbine inlet, V-band turbine outlet, external wastegate required.
• Supercore Only — Garrett 938339-5001S: compact compressor housing and complete center rotating assembly supplied without a turbine housing.

Application Notes

• This is a universal performance turbocharger and is not a vehicle-specific bolt-on assembly.
• Garrett’s horsepower figures are compressor-based potential flywheel-horsepower references. Actual output depends on engine airflow, fuel, charge-air temperature, exhaust-manifold design, turbine housing, boost pressure, backpressure, and tune.
• The compact compressor housing reduces compressor-cover size and uses approximately 4-inch inlet and 3-inch outlet hose connections. It does not reduce the size or flow capability of the G42 turbine stage.
• The 1.01 A/R housings prioritize earlier response and may increase turbine inlet pressure as airflow and power rise.
• The 1.15 A/R housings provide the broadest general balance between response and turbine-flow capacity for many high-output applications.
• The 1.28 A/R housings provide the greatest exhaust-flow capacity in the verified G42 family and are best suited to applications that can accept slower boost response.
• The open-scroll V-band housings are generally the simpler choice for custom single-turbo systems because they do not require a true divided manifold and pulse-preserving wastegate arrangement.
• The divided T4 housings should be used with a properly divided manifold and an external-wastegate arrangement that preserves the intended pulse separation. Installing a divided housing on an undivided manifold does not provide the same twin-scroll behavior.
• No internally wastegated G42-1325C configuration is listed by Garrett. An appropriately sized external wastegate system is required.
• The G42-1325C supercore is compatible only with the verified standard-rotation G42 housings listed in this description. Reverse-rotation housings are not interchangeable.
• G-Series II uses the corresponding first-generation G42 compressor- and turbine-housing interfaces, but every existing installation should be confirmed by part number before components are reused.
• Turbine-inlet flange or clamp, turbine-outlet weld flange and clamp, external wastegate, wastegate springs, oil-feed hardware, oil-drain hardware, coolant hoses, intake plumbing, charge piping, exhaust manifold, downpipe, boost-control hardware, and application-specific fasteners are not included unless separately stated.
• Garrett turbo-speed monitoring hardware and electronic boost-control components are sold separately.
• Final turbocharger and turbine-housing selection should be based on an engine-airflow model and intended operating range rather than displacement or peak-power target alone.

Emissions and Competition-Use Notice

This universal performance turbocharger is intended for racing and competition applications. Vehicle modifications must comply with all applicable emissions, registration, noise, and road-use requirements. It is the purchaser’s responsibility to determine whether the product is legal for the intended vehicle and use.