Small-Engine Technology

To address increasing cost and performance demands while meeting stringent emissions requirements, small-engine manufacturers require leading-edge technology, particularly in high-speed engine and high power-density designs. Southwest Research Institute (SwRI) designs and develops stationary and vehicle powertrains for motorcycle, utility, and recreational vehicle applications from concept design to production validation. SwRI has assembled a focused small-engine development group to assist motorcycle, recreational vehicle, and small-engine manufacturers in their efforts to produce world-class products.

The Institute offers a wide variety of services, including:

• Powertrain component simulation
• Engine design and optimization
• Engine control development
• Hardware-in-the-loop evaluation
• Transmission and drivetrain development
• Frame and suspension evaluation
• Laboratory and dynamometer testing
• Emissions determination and reduction
• Environmental testing
• Engine design and optimization
• Emissions research and development

Engine Design and Optimization

SwRI strives for a balanced combination of real-world experience and theoretical design. Using advanced development and analysis tools, Institute engineers determine optimum engine parameters, including:

• Intake and exhaust system layout
• Piping length and diameter
• Plenum volume
• Cam profile
• Valve sizes
• Compression ratio
• Bearings

Institute engineers use three-dimensional solid modeling to develop and optimize engines and components.

Institute engineers use advanced computational fluid dynamic techniques to model and
simulate the action of numerous gases and liquids in engine-related components and
systems, including:

• Combustion chamber
• Fuel injection system
• Fuel mixing
• Intake and exhaust ports
• Engine block and cylinder head cooling

SwRI conducts finite element analyses of all major engine assemblies and components such as:

• Cylinder heads
• Blocks
• Pistons
• Connecting rods
• Crankshafts
• Valve trains
• Fuel system components

Institute engineers conduct static and dynamic analyses. Static analysis includes linear, non-linear, plasticity, and multibody contact analyses. Dynamic analysis includes linear modal and nonlinear transient analysis with multibody contact.

Emissions Research and Development

SwRI develops low-emission solutions for a wide range of spark-ignited and diesel small engines, including:

• Motorcycles
• All-terrain vehicles
• Snowmobiles
• Personal watercraft

SwRI engineers have extensive experience in the following areas:

• In-field data acquisition to understand real-world operating conditions
• Analysis of in-field data to develop application-specific test cycles
• Determination of engine or vehicle emissions - both regulated and unregulated - under a variety of operating conditions
• Determination of evaporative emissions, and engine and vehicle development to reduce evaporative emissions
• Development of low-emission solutions through engine calibration and application of aftertreatment
• Measurement and characterization of particulate emissions including particle-size analysis

SwRI engineers evaluate emissions and performance of a range of recreational vehicles including snowmobiles and all-terrain vehicles.

Engine Control Development

Using sophisticated design and analysis techniques and state-of-the-art test facilities, SwRI engineers adapt advanced fuel and ignition control systems and develop optimized control algorithms and calibrations that balance the often conflicting requirements of performance, fuel economy, and emissions.

SwRI has developed a full-authority engine controller that provides:

• Real-time, model-based control
• Diagnostic functions
• Classic control
• Adaptive learning algorithms
• Advanced signal processing

An SwRI-developed electronic controller uses advanced model-based algorithms to provide optimal engine and transmission performance.

Transmission and Drivetrain Development

Drivetrain development focuses on efficiently delivering engine power to the tire and road interface. SwRI optimizes the input/output ratios at the primary drive, transmission, and secondary drive while simultaneously maximizing the power density of each component. Institute engineers model, design, and analyze a wide array of power-transferring technologies, such as:

• Belts, including rubber and steel
• Chains
• Gears
• Automatic transmission
• Continuously variable transmission

SwRI engineers maximize drivetrain efficiency through a variety of techniques, including:

• Reducing gear deflection
• Minimizing shaft bending
• Reducing windage and churning losses

To achieve maximum power density, engineers significantly reduce weight through:

• Material selection
• Surface improvements
• Dry-film lubricants
• Controlled material processes

SwRI engineers design, develop, and validate advanced transmissions and drivetrains for a variety of small-engine vehicle applications, including recreational vehicles, motorcycles, and snowmobiles.

Environmental and Laboratory Testing

Using state-of-the-art equipment and sophisticated laboratories, SwRI engineers and scientists provide a broad spectrum of environmental and performance tests, including:

• Emissions
• Braking
• Noise, vibration, and harshness (NVH)
• Handling fatigue
• Endurance and durability
• Electromagnetic compatibility
• Oil and fuel analysis

Because of the special requirements around the rider and the energy transmitted to the rider's body, SwRI emphasizes NVH issues, including:

• Intake- and exhaust-radiated noise
• Total airborne noise
• Shift quality
• Ride harshness

During controlled chassis dynamometer testing, Institute engineers evaluate engine performance and vehicle emissions of on- and off-road recreational vehicles.

Engine Performance Mapping and Development

SwRI develops and tests spark-ignition and diesel engines ranging from model airplanes to locomotives. SwRI engineers regularly conduct tests to evaluate engine performance, emissions, and fuel economy development. Using a wide range of sophisticated engine measurement techniques and development tools, engineers provide the following services:

• Camshaft development
• Intake system design and tuning
• Exhaust system optimization
• Electronic fuel system development and testing
• Cylinder head flow measurement and analysis
• Motoring friction analysis
• Combustion chamber and piston development

SwRI engineers assess the performance of various fuel formulations using an instrumented, high-speed motorcycle engine.

During the engine development process, SwRI uses state-of-the-art diagnostic tools and techniques, including:

• Combustion system visualization
• Knock and misfire detection
• In-cylinder airflow and fuel-air mixing measurement
• Real-time oil consumption measurement
• Piston and ring motion measurement
• Computer cycle simulation

SwRI staff monitor and inspect all pertinent operating parameters during the development process to ensure optimal engine operating efficiency, performance, and emissions.

Vehicle and Engine Benchmarking

Institute engineers evaluate, analyze, and compare vehicles and electrical and mechanical systems to provide a scientific, nonbiased comparison with any vehicle. The Institute's testing, research, and development program includes a comprehensive range of research areas, such as:

• Performance
• Emissions
• Fuel consumption
• Drivetrain efficiency
• Vehicle handling
• Fuel system components
• Engine component design

Engine Durability Testing

Using industry standard or user-specified test cycles, SwRI routinely performs continuous, long-term engine testing to evaluate engine reliability and component durability. Open- or closed-loop control of the engine and test conditions is provided with a variety of hardware and software platforms. Specially equipped test cells allow a wide spectrum of test capabilities, including altitude simulation, low-temperature environment  (-35ºC), thermal cycling, and continuous engine monitoring.

Experienced engineers and technicians perform extensive standard and customized test procedures and practices. Engine health monitoring and inspections are integral to all engine tests. SwRI staff members provide extensive services for monitoring engine operation, including:

• In-cylinder combustion pressure monitoring and analysis
• Combustion heat release analysis
• Coolant, oil, exhaust, and radiated heat rejection determination
• Engine teardown inspection
• Exhaust emission evaluation
• Failure analysis
• Fuel analysis
• Real-time component wear measurement
• Real-time oil consumption measurement
• Thermal imaging
• Blowby monitoring
• Air filter efficiency evaluation
• High-pressure leakdown analysis

Institute engineers provide rapid and cost-effective endurance testing and competitive engine evaluation.

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