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
HW.
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:
- Familiarize yourself with the operation of the dynamometer test stand & controls
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Plug in gas analyzer (if desired for exhaust monitoring)
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Connect tube from water tank to pump, open tank valve and turn on pump for water brake.
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Start engine and let warm up for approximately 5 minutes
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Start computer and open Dynomax software, open “new run’, open ‘default console’ F11
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Observe engine run
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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:
- Use shortened data set for analysis (preselected to simplify analysis)
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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.
- 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:
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How do the torque curve and power curve compare (max values @ same RPM)?
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Is volumetric efficiency constant, or varying with RPM..what is trend?
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Is BMEP a constant? Does it compare more with torque or power output?