Engine Friction & Wear
Office of Automotive Engineering

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Engine friction vs. engine speed can be measured for internal and external engine components and systems

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Friction measurements are obtained from a connecting rod bearing with variable load applied to quantify changes in bearing design and lubricant properties.

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Superhard, thick nanocomposite coatings are applied on piston rings for reduced friction and wear.

Related Brochure

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The automotive industry continues to strive for improved fuel economy of both light-duty and heavy-duty vehicles. One method of improving fuel efficiency is to reduce engine friction. SwRI engineers offer a full spectrum of technologies, capabilities and expertise to assist manufacturers in quantifying and reducing engine friction.

Friction Assessments

Friction assessments of production engines are conducted with rigorous test methods to ensure accuracy and repeatability of results. Procedures are used to quantify total engine friction, contributions of accessories and internal components as well as lubricant and lubricant additive effects. Measurements of client engines may be compared to our internal database of engines to quickly assess any abnormal characteristics.

Friction Modeling in Engine Simulation

Friction modeling is conducted with commercially available software packages. Models are often calibrated using component test fixtures such as journal bearing spin loss and ring-on-liner reciprocating rigs. Frequently modeled interfaces and components include:

  • Bearing and shaft
  • Piston and bore
  • Piston ring and bore
  • Valve trains
  • Oil and water pumps


A fully functional tribology laboratory with extensive capability supports client-funded and internal research programs with innovative ideas, technology and equipment. Using a combination of standard tribological and surface analysis bench top analytical equipment, custom designed component test fixtures and single-cylinder research engines, SwRI can quantify friction and wear of virtually any engine mating surfaces.

Real-Time Wear Measurements

Friction induced component wear is measured in real time using radioactive tracer technology (RATT®) developed by SwRI. Three types of RATT methodology are used including bulk activation, surface-layer activation and nuclear recoil implantation. These techniques produce wear data in minutes rather than hours or days, thus allowing component wear at many engine operating conditions to be characterized quickly.

Surface Engineering

Advanced coatings such as diamond-like and nanocomposite coatings are applied to engine components to provide attractive surface properties such as wear resistance, low friction coefficients and corrosion resistance. In addition to coating sample components for evaluation purposes, SwRI can transfer coating technologies to engine component manufacturers for full production applications.

Related Terminology

engine friction  •  fuel efficiency  •  tribology  •  RATT  •  radioactive tracer technology  •  surface analysis  •  engine wear  •  friction modeling  •  reciprocating rigs  •  advanced coatings  •  diamond-like coatings  •  DLC  •  nanocomposite coatings

Benefiting government, industry and the public through innovative science and technology
Southwest Research Institute® (SwRI®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 9 technical divisions.