P dV has conducted performance development testing on internal combustion engines for power and fuel consumption optimization, and also emissions reduction.

Testing performed to date includes:
  • Induction system development: effects of air filter & housing, intake tract, throttle body
  • Camshaft development: lift, duration, lobe centers (intake to exhaust), timing relative to the crankshaft
  • Combustion chamber: compression ratio, knock margin, squish, charge motion, spark plug location, valve angles
  • Exhaust system development: primary pipe diameter and length, backpressure from muffler, resonator effects
  • Fuel system development: air-fuel ratio effects, peak power, lean best torque, fuel mapping across speed/load range
  • Ignition system development: spark timing relative to location of peak cylinder pressure, IMEP, knock limits
  • Electronic Control System mapping: spark timing, fuel rate, and fuel injection timing
  • Emissions testing & measurement (5 gases), including emissions reduction development

  • Attended DSP Technology, Inc.'s training courses on cylinder pressure data acquisition and analysis, and setup and used DSP Redline ACAP systems for cylinder pressure acquisition. Experience includes the ablity to specify and install pressure transducers and optical shaft encoders in various configurations for multiple engine types.

  • Used cylinder pressure data for combustion analysis: mass fraction burned, heat release rates, peak pressures, location of peak pressures, knock/detonation detection, and Indicated Mean Effective Pressure (IMEP) calculation.

  • P dV also wrote LabVIEW software and specified hardware to provide a custom data acquisition system to acquire cylinder pressure data. For additional information, go to Custom Data Acquisition Systems, including Cylinder Pressure.

A high speed engine was set up in a test cell and instrumented to obtain speed, torque, power, fuel flow rate, air-fuel ratio, and engine pressures and temperatures. The engine was connected to a low inertia, high-speed dynamometer to control wide-open throttle loads at speeds up to 14,000 rpm. Cylinder pressure measurement instrumentation was installed on the engine. A fuel control system was used that allowed fine tuning of ignition spark timing, fuel flow rate, and fuel injection timing (relative to intake valve opening). This setup was used to evaluate a matrix of fuels intended for racing applications by measuring power and cylinder pressure while varying air-fuel ratio and spark and injection timing. From the cylinder pressure data, an analysis was made of Indicated Mean Effective Pressure (IMEP), peak pressure, location of peak pressure, knock (if present), and burn rates. With this information, the test fuels could be evaluated for their ability to produce power versus fuel efficiency in terms of fuel consumption.

Flow bench testing of engine intake systems has typically been aimed at providing the maximum amount of air flow at a given pressure drop across the intake. In reality, big air flow numbers do not always mean big power numbers when the intake system is installed on an engine. The intake system must be "tuned" for the engine configuration, aimed at providing the optimum mean flow velocity in the port for best volumetric efficiency. This can be tuned to alter the torque curve of the engine if needed.
There are many other uses for the air flow bench, when coupled with the proper instrumentation. The effects of air-charge motion within the cylinder on combustion is an important parameter to quantify. By testing the intake system on an air flow bench for not only air flow, but swirl and tumble air motions, the effects of port configurations on in-cylinder air motion can be correlated.

P dV has set up test programs for durability testing of engines, including the test cell systems required for sustained engine testing, the data acquisition and control system to monitor and control test conditions, and the test programs themselves. P dV has specified and installed engine health monitoring systems to keep track of engine changes during testing. This includes the measurement of oil consumption, fuel consumption, engine blowby, and periodic checks of compression and leak-down rates. Oil sampling and analyis for wear metals, in combination with One such test monitored engine bearing health with proximity probes measuring crankshaft run-out in two axes 90 degrees apart. Safety limits were set and monitored by the control system to shut down the engine if limits were exceeded. Durability testing often includes the teardown and inspection of engine components at periodic intervals and/or at end of test. P dV has experience in analyzing engine components for wear and for failure analysis.

P dV developed an alternative fuels control system to work with an engine converted to run on natural gas. Several test programs were conducted on the sensors and actuators necessary to implement an electronic control system on an alternative fuel engine. These included the reaction of various types of oxygen sensors to alternate fuels, and for sensors to measure and meter the flow of gaseous fuels such as natural gas or propane. After identifying the sensors and actuators needed for natural gas fuel metering, an engine control system was designed, in partnership with an electronics company, to control the fuel and spark for an engine converted to natural gas. The engine and control system was installed in a commercial vehicle for testing under normal service conditions. The engine control system was mapped and calibrated for the vehicle application, and the vehicle was driven across country on natural gas to the location at which it was placed in service.

Often the engine testing conducted by P dV includes using or working with engine control systems. This includes the calibration of a control system for both fuel delivery and spark timing by mapping the engine at desired speed and load conditions. With an engine installed in a test cell, under the speed and load control of a dynamometer, and with the proper instrumentation and data acquisition, the control system can be mapped to provide the optimum fueling rate and ignition timing to meet the goals of power, fuel economy, or emissions reduction.

P dV has experience with installing the aftermarket electronic fuel control systems of various manufacturers. One such system was installed in P dV's personal race car on a twin-turbocharged small-block Chevrolet engine. The control system was a multi-point fuel injection type, requiring modification to the intake manifold to accept fuel injectors. The control system was mapped and calibrated to run the engine under boost conditions, with several maps generated to run both gasoline and methanol fuels. Separate spark timing maps were generated for use with each fuel type as well.

A test cell was designed for testing of automotive turbochargers independent of the engine on which they are normally installed. Engine installations are expensive to setup and maintain, and are not cost effective for testing of turbochargers. The design criteria for the test cell were:
  • Test to to SAE J1826, “Turbocharger Gas Stand Test Code” standards
  • Turbochargers to be fully mapped, generating compressor and turbine flows, pressure ratios, and efficiency maps
  • Provide pressurized and heated air to the turbine inlet at up to 1.0 kg/s, 1,400 kPa, and 600 degrees C
    (2,000 cfm, 200 psi, and 1,100 degrees F)
  • Throttles on the turbine inlet and compressor outlet control turbo speed and pressure ratios
  • A lubrication system to supply heated and pressurized oil to the turbocharger
  • A PC-based data acquisition system to monitor and record shaft speeds, air flows, temperatures, and pressures
  • Turbocharger parameters (i.e. corrected compressor speed) calculated in real time and recorded with measured data

The design of the turbocharger test cell required special instrumentation for obtaining turbo wheel speed. A laser speed pickup sensor was used to measure the rotational speed of the compressor by aiming the laser at a reflective section applied to the compressor hub. The system was able to detect wheel speed when aimed through a window mounted in the intake tract. This was required since air flow had to be accurately measured at the compressor inlet. A Laminar Flow Element (LFE) air flow meter was installed in the inlet to the compressor for that purpose. Throttles mounted on the compressor outlet and turbine inlet controlled flows and pressure ratios, thereby controlling wheel speeds. The throttles were remotely controlled from the operators console. A large turbine flow meter measured turbine inlet mass flow when required. Pressures and temperatures measured at inlets and exits to both turbine and compressor were used to calculate flow conditions and corrected parameters.
P dV designed and developed the LabVIEW software, and integrated it with an HP hardware setup, to provide the data acquisition system which monitored and recorded data.

Once the turbocharger test cell was commissioned and calibrated, several turbocharger units were placed under test. By following lines of constant corrected compressor speeds, the pressure ratio was plotted versus corrected air mass flow rate, providing a compressor map. By carefully approaching the lower air flow rates, the surge line of the compressor was defined. Software plotting packages allowed using the data to find lines of constant compressor efficiency. By carefully selecting successive compressors for a single turbine, a turbine map could be generated as well.