Customized Vehicle Test Systems

Sierra Research has designed and constructed specialized systems for testing vehicular emissions and air pollution for a wide range of public and private clients.  Example systems include:

  • An electric chassis dynamometer and dilution tunnel for sampling exhaust PM2.5 for the State of Alaska, customized to be able to operate down to minus 50° F, together with an IM240 analyzer;   
  • An RG240-type dynamometer for the State of Vermont with a matched IM240-type analyzer; and
  • An audit gas verification test system for the State of New Jersey.  

Sierra also has experience in designing, instrumenting, and/or operating or training others to operate dozens of vehicles to collect on-road emissions and driving pattern data.  Examples of these test systems can be seen in the pictures below.  Examples include:

  • A Chevrolet Lumina instrumented for the California Air Resources Board with a 5-gas tailpipe analyzer and engine sensor monitors to measure mass emissions;
  • Several Chevrolet Caprice chase cars instrumented for vehicle-following with a laser range finder and, for the California Department of Transportation, as a “floating vehicle” to monitor traffic speeds;
  • A variety of purpose-designed vehicles to measure on-road PM concentrations, concentrations behind other (target) vehicles (‘plume-following’); and
  • Measurement of gaseous pollutants including ozone up- and downstream of catalyst-coated radiator patches.

Whatever your monitoring/sampling needs, Sierra can develop a customized and cost-effective solution.  Further details regarding previous programs are presented below.


The system, based on a highly customized Horiba IMVETS, was originally installed in a van so it would be portable for use in parking lots.  Later, Sierra integrated the system with a Realtime electric chassis dynamometer and a dilution tunnel for PM2.5 sampling at Alaska winter temperatures.

Inside the sampling van during a low-temperature test in Fairbanks, Alaska.

Rear view of vehicle being tested at low temperature on a test system desinged by Sierra.  Dynamometer motor has a cover over it (on the right of the picture) to keep it in a heated space during testing.  Transfer line from tailpipe and filtered, heated dilution air (blue insulated wrap) mix at the entrance to the dilution tunnel (silver insulation).


New Jersey audit gas calibration system.  This system was designed by Sierra so that any of the client’s staff could be trained to use the system in as short as 15 minutes.  The system was used to verify the concentrations in audit gases before they are used to audit vehicle inspection test systems throughout New Jersey.


IM240 Analyzer (manufactured by Horiba, modified by Sierra) – System was highly modified to eliminate the use of a critical flow venturi for measuring flow; this change and other modifications were made due to power limitations at the facility where the test system was installed.

RG240 Dynamometer (manufactured by Maha, integrated by Sierra) – An eddy current dynamometer used to address power limitations at the test facility which prohibited the use of an AC electric full inertia simulation dynamometer.


The vehicle-mounted sampling system was used to measure PM2.5 and CO concentrations on-road while following vheicles, to assist in mapping the spatial distribution of PM2.5 concentrations in Fairbanks' PM2.5 nonattainment area, and to investigate complaints of nuisance smoke (commonly from wood burning).  Configuration of the vehicle was designed and prototyped by Sierra and then assembled by Fairbanks North Star Borough staff.

Inside the plume-following vehicle, showing dataRAM4000, GPS, and (realtime) laptop display, observer's data logger (foreground black box), sample line heater, wide angle video camera, temperature logger.  Not shown:  CO2 monitor, remote (outside) solenoid-controlled, mast- and grill-mounted sampling cyclones and termperature probe, and calibration gases.


One of the several Chevrolet Caprices with front grill-mounted laser range finder/velocimeter (Laser Atlanta).