7 Series Range Turbochargers

The 7 Series is our tried and tested core turbocharger, offering outstanding performance and reliability across the range since 1998. These highly regarded units are developed with two key objectives in mind, namely: performance-led design with minimal cost of ownership.

When it was first introduced, the 7 Series represented a fundamental shift in turbocharger performance, combining market-leading pressure ratio and efficiency levels with excellent reliability due to an innovative layout and bearing design. Since then, new variants have been continually developed in response to customer demands for ever-increasing pressure ratio and flow capabilities.

Today's range is designed to provide customers with flexible, cost-effective solutions that can be tailored to specific requirements and are fully supported by our global service network.

Designed for success
  • Proven reliability with long service intervals for lower cost of operation
  • More power to your engine - do more for less
  • Industry standard efficiency levels
  • Complies with all marine and land-based legislation, and Best Available Technology
  • Compatible with all fuel types, for ultimate flexibility
  • Tailored for use in marine, power generation and rail applications
  • Fully supported by our world-class global service network
7 Series

There are several 7 Series compressor variants available, each tailored to specific applications. The latest variant features pressure ratios up to 5.2:1 with peak efficiencies of 84%.

Napier Turbochargers Engine Output

7 Series Specifications
Model NA297 NA307 NA357 NA397
Engine Power Output Max (MW) 3.5 4.5 6.5 7.5
Engine Power Output Min (MW) 1 1 3 3
Pressure Ratio 4:8 5:3 4:8 5:3
Weight (Kgs) 900 925 1700 1710
Length (mm) 1520 1520 1910 1910
Width (mm) 900 900 1130 1130
Height (mm) 900 900 1130 1130

Napier 7 Series Capacity Curves

7 Series Capacity Curves

Napier 7 Series Capacity Curves - J Compressor

7 Series J Capacity Curves

Napier 7 Series Capacity Curves - L Compressor

7 Series L Capacity Curves

Napier Turbochargers Product Capacity Curves

The current Napier Turbocharger products utilise the latest technologies offering outstanding performance across the range. It's your answer to achieving more power and ef´Čüciency, whilst lowering fuel consumption and emissions.

Typical NA307L Compressor Map

7 Series Compressor Map

7 Series

Wide compressor map thanks to anti-surge technology allowing peak efficiency operation (up to 84%) in different applications, with increased surge margin.

Cost-effective and stress-resistant aluminium alloy compressor which does not compromise performance and durability.

Highest possible levels of efficiency thanks to 3D CFD (Computational Fluid Dynamics) design of all components making up the aerodynamic compressor elements.

Ultimate durability achieved utilising Finite Element Analysis (FEA) to ensure compressor wheel gives optimum performance and minimum wear even under great stress.

Retrofit of engines to achieve IMO11 requirements, reducing emissions and fuel consumption while maintaining the same installation of the earlier 7 Series.


7 Series

Longer lasting components achieved using Finite Element Analysis (FEA) testing to identify high stress points which have then been designed out.

Airflow optimised for better performance by using 3D CFD (Computational Fluid Dynamics) 3D CFD (Computational Fluid Dynamics) software in the design of aerodynamic components.

Heavy Fuel Oil optimisation through rigorous testing and analysis, and investigation into the latest water-washing techniques, for ultimate flexibility.

Additional flexibility to operate with both constant and pulse pressure systems, matching your engine set up.

Lowest possible fuel consumption achieved thanks to ability to move peak efficiency point along the range, reducing cost for your operation.

Turbine image

7 Series

Proven, reliable design suits the pressure ratio requirements of IMO1 engines, while providing utmost reliability under the arduous operating conditions of marine, powerplant and rail traction environments.

More reliable operation and low wear and tear thanks to hydrodynamic journal bearings which feature a squeeze film damper for vibration resilience (semi-floating design).

Compact, space-saving design using our tried and tested bearing arrangement of ergonomically mounting the thrust bearing between the journal bearings.

Innovative shaft sealing means no leakage at very low engine loads.

Wabtech Napier 7 Series Bearing imagery

7 Series

Intelligent, safe design, aircooled for simplicity and efficiency, with proven burst containment meeting all classification society approvals.

Reduced cost and potential for leakage thanks to integrated oil inlet and drain.

Easy to install, compact and flexible, with waste ports on gas inlet and outlets, rotatable casings, and a number of axial and radial gas inlet options to meet a wide range of engine and engine room requirements.

Conforms with SOLAS (Safety Of Life At Sea), answering strict insulation sound and temperature requirements for safety, liability and peace of mind.