To collect data and analyze performance of a gasoline engine at various loads to determine the torque curve, power curve and performance parameters of BMEP, volumetric efficiency, and Air/fuel ratio, plotting the data vs RPM

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Engine Dynamometer Test

Objectives: To collect data and analyze performance of a gasoline engine at various loads to determine

the torque curve, power curve and performance parameters of BMEP, volumetric efficiency, and

Air/fuel ratio, plotting the data vs RPM.

Equipment: Briggs & Stratton 35 HP Vanguard V-Twin (Four stroke, Disp: 993 cc, 60.6 in3 )

Land & Sea “Dynomite” Dynamometer with instrumentation

Computer with Land & Sea “Dynomax” software

EMS 5002 5 gas analyzer (O2, CO2, CO, NOx, HC)

Tasks:

  1. Familiarize yourself with the operation of the dynamometer test stand & controls

  2. Plug in gas analyzer (if desired for exhaust monitoring)

  3. Connect tube from water tank to pump, open tank valve and turn on pump for water brake.

  4. Start engine and let warm up for approximately 5 minutes

  5. Start computer and open Dynomax software, open “new run’, open ‘default console’ F11

  6. Observe engine run

  7. Save xls data file to thumb drive for analysis; data includes RPM, torque, fuel flow rate, intake CFM,

Intake Patm and temp, etc. A full data set will be provided, along with a shortened set for analysis.

Data Analysis:

  1. Use shortened data set for analysis (preselected to simplify analysis)

  2. For each data point, calculate Power, BMEP, and Volumetric Efficiency.

Note: Data rate is too fast (.005 sec) for smooth data; lots of noise.

Use a 10 or 20 point moving average for all data before analyzing or graphing it.

  1. Make three graphs: one graphing Torque and Power

Equations: Power = Torque x RPM /(5252 ft-lb-RPM/HP)

BMEP = {Pwr / (Displacement Volume Flow Rate)} x conversions to psi

Volume Efficiency = CFM / (Displacement Volume flow Rate)

Write a report with introduction, procedure, results, discussion/conclusion, and raw data appendix. In the report include the Torque & power graph and the Volumetric Efficiency graph.

Questions to address:

  1. How do the torque curve and power curve compare (max values @ same RPM)?

  2. Is volumetric efficiency constant, or varying with RPM..what is trend?

  3. Is BMEP a constant? Does it compare more with torque or power output?

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