Garrett G30: Specs, Fitment, and Is It Worth It

The Garrett turbocharger G30-825 G-Series II is the entry point into the G-Series II super core lineup -- a complete turbocharger assembly rated for up to 825 horsepower and built on Garrett's updated second-generation G-Series aerodynamic platform. Unlike the larger G42, G45, and G55 super cores which ship as CHRA-only assemblies, the G30 is available as a complete unit with turbine housing and compressor cover included, configured in the 0.83 A/R V-band in, V-band out, internal wastegate format. This makes the G30 a more accessible starting point for a performance build than the larger super cores: major housing selections are made for you, and the assembly installs with the specified V-band connections rather than requiring fully custom housing selection and fabrication. This guide covers G30-825 specs, what build levels it supports, where it sits in the G-Series II lineup, and whether this Garrett turbocharger is the right choice for the intended application.

G30-825 Specs and Sizing

The Garrett G30-825 G-Series II Turbocharger (934118-5003S) in the 0.83 A/R configuration includes the complete assembly: compressor wheel, CHRA, turbine housing with 0.83 A/R and V-band inlet, V-band compressor outlet, and internal wastegate. Key specs:

• Power rating: up to 825 horsepower
• Series: G-Series II -- Garrett's updated lineup with refined aerodynamics and improved efficiency mapping over the original G-Series
• Configuration: complete turbocharger assembly -- turbine housing, compressor cover, and internal wastegate included, not a CHRA-only super core
• Turbine housing A/R: 0.83 with V-band inlet and V-band outlet
• Wastegate type: internal wastegate (IWG) -- boost controlled without a separate external wastegate required
• G-Series II position: entry point into the G-Series II lineup for builds targeting up to 825 horsepower, below the G42 at 1,585 hp and G55 at 2,250 hp

The G30 occupies the space between a dedicated platform-specific turbo upgrade and the larger G-Series II super cores. Where the G42, G45, and G55 require the builder to source and fit turbine housing and compressor cover separately, the G30 in this configuration comes ready to install in an application that accepts the specified V-band connections. For a 4-cylinder or smaller-displacement 6-cylinder engine building toward 600-825 horsepower, or for a modified diesel application where the 825 horsepower ceiling is the right target, the G30 avoids the full housing-selection process of the larger super cores while delivering the G-Series II compressor wheel quality and updated aerodynamic efficiency.

The 0.83 A/R turbine housing is sized for applications where spool response and boost onset are priorities alongside the 825 horsepower ceiling. A larger A/R housing supports higher peak flow at the cost of slower spool. The 0.83 A/R is the balance point Garrett selected for this configuration -- efficient operation at the target power level without excessive turbine back pressure at the low end of the RPM range where the engine needs to build boost quickly.

Top Picks: G30 and the G-Series II Lineup

The Garrett G30-825 G-Series II Turbocharger 0.83 A/R (934118-5003S) is the starting point in the G-Series II lineup for a build targeting up to 825 horsepower where the V-band in/out configuration and internal wastegate are the right fit. The complete assembly format resolves housing selection -- the builder focuses on mounting location, oil and coolant connections, and charge pipe routing rather than also sourcing and fitting separate turbine housing components.

For a build targeting above 825 horsepower in the G-Series II lineup, the Garrett G42-1585 G-Series II Super Core (938339-5003S) is the step up at 1,585 horsepower. The G42 is a super core assembly requiring separate housing selection, which allows the builder to optimize the A/R ratio and housing geometry beyond what the fixed G30 configuration provides. For diesel platform-specific direct-fit upgrades on the 2004.5-2009 Duramax, the Garrett GT3794VA Stage 1 Turbo Kit is the complete bolt-on solution at the factory location with no housing selection required. Browse the full Garrett turbocharger catalog for all G-Series II assemblies and platform-specific upgrade kits.

Match to the Build

The G30-825 is the right Garrett turbocharger for the following situations:

• High-output 4-cylinder builds targeting 500-825 hp: Modified 4-cylinder engines in purpose-built performance applications where the 825 horsepower ceiling fits the target and the V-band in/out housing configuration matches the exhaust and intake routing. The G30 compressor map is designed for this power range and runs efficiently across the RPM band rather than only at peak output.
• Smaller-displacement 6-cylinder performance engines: A built inline-6 engine targeting this power range benefits from the G30 compressor map and the complete assembly format. The internal wastegate controls boost without an external wastegate installation.
• Builds where the complete assembly format simplifies installation: For an application where the V-band connections match the exhaust and charge pipe layout, the G30 complete unit removes the housing-selection step from the build process compared to the G42 or G45 super cores. The trade-off is less flexibility in housing geometry customization.
• Builds requiring internal wastegate boost control: The IWG configuration controls boost via the integrated wastegate door rather than requiring a separate external wastegate and associated plumbing. For a street or mixed-use build where simplicity of the boost control system is a priority, the G30 IWG is the practical choice.

Signs the Current Turbo Is the Constraint

A builder evaluating the G30 as an upgrade is typically replacing a smaller unit that can no longer meet the fuel system demand:

• Boost pressure ceiling hit before the fuel system reaches its delivery limit -- the existing compressor is at maximum flow while the engine could accept more fuel
• Compressor outlet temperatures elevated at moderate boost -- the existing wheel is running outside its efficiency island, generating heat rather than efficiently pressurizing air
• EGT rising faster than expected relative to fuel delivery when the fuel system is confirmed not to be the constraint
• Intercooler outlet temperatures elevated under sustained boost from hot compressed air generated by an inefficient compressor
• Power plateau at a level consistent with the existing turbo rated maximum, not with the fuel system or tune limit

Frequently Asked Questions

Does the G30-825 work on diesel engines?

Yes, but the G30 at 825 horsepower is sized for applications at or below that ceiling. For built diesel engines targeting significantly above 825 horsepower -- a built 5.9L or 6.7L Cummins or a high-output Duramax -- the G42, G45, or G55 super cores are the appropriate choices. The G30 is most commonly used in high-output 4-cylinder applications and smaller-displacement 6-cylinder builds where the 825 hp ceiling and the compact G30 compressor map match the engine airflow requirement.

Is the G30 available in other A/R configurations?

Yes. Garrett offers the G30 in multiple A/R and housing configurations beyond the 0.83 V-band IWG unit covered here. A smaller A/R spools faster but reaches its flow ceiling sooner; a larger A/R supports higher peak flow at the cost of slower spool onset. The correct A/R is determined by engine displacement, target RPM range, and power target. The 0.83 A/R is a well-balanced choice for the 600-825 hp range on the applications this unit is typically built for.

What is the difference between the G30 complete unit and the G-Series II super cores?

The G30 in this configuration ships as a complete turbocharger: CHRA, turbine housing, compressor cover, and internal wastegate are all included. The G42, G45, and G55 are super core assemblies -- CHRA only -- and require the builder to source and fit the turbine housing and compressor cover separately, allowing full housing geometry customization. The G30 complete unit resolves housing selection in advance for the builder whose application fits the specified V-band configuration, at the cost of the housing flexibility the super core format provides.

Bottom Line

The Garrett G30-825 G-Series II in the 0.83 A/R V-band IWG configuration is the right Garrett turbocharger for a performance build targeting up to 825 horsepower where the complete assembly format simplifies installation and the V-band inlet and outlet match the application. The G-Series II compressor wheel delivers updated aerodynamic efficiency at this power level. For builds targeting above 825 horsepower, the G42 and G55 super cores are the next steps with custom housing selection. Confirm the A/R, V-band sizing, and wastegate type against the build requirements before ordering.