Single Cylinder Spark Plug Engine Calibration at 3600 rpm for Higher Load Applications And Lower NOx And Other Emmisions using GT-Power

Objective:- (1) Determine the engine parameters running at 1800 rpm and record the same.

(2) Further increase the power output obtained at 3600 rpm by 10%.


Model:-  The GT model Of the 1-cylinder engine is shown below:-

Observations (@1800rpm):- 

  •  Air Flow Rate = 24.645 kg/hr.
  • BMP (Brake mean effective pressure) = 9.45 bar.
  • BSFC (Brake Specific Fuel Consumption) = 239.167 g/kw-h

In-cylinder pressure is the pressure given at any crank angle in the cylinder shown below:-

                                                 Fig 1:- In-Cylinder Pressure @1800 rpm

                                                   Fig 2 :- Air flow rate @ 1800 rpm

                                                   Fig 3:- BMEP @ 1800 rpm

                                                   Fig 4:- BSFC @ 1800 rpm

Observation @ 3600 rpm:- 

Initial Parameters @ 3600 rpm:-

  • Inlet conditions:-  Pressure (absolute)   = 1 bar

                                      temperature             = 300 k

                                      Composition             =  air


  • Injection System :- Injection delivery rate = 6 g/s

                                        Fuel ratio specification = Air-fuel-ratio.

                                        Fuel ratio                    = 14.5


  • Cylinder Geometry :- 


  • Case setup:- Engine speed = 3600 rpm.

  • Results :- Brake Power = 16.7 KW

                        IMEP            = 12.85 bar

                        Air flow rate  = 58.6 kg/hr

                        BSFC            = 241.8 g/KW-hr

                        Volumetric effeciency = 93.6 %


                                        Fig :-  Engine Performance Result

                Fig :- Emmision Results.



In order to increase the power of the engine by 10% that is = 18.5 KW (approx.) following calibration has been done :-

  1. Turbocharger :- For more power, better combustion is needed which means more air is required. Therfore, Turbocharger is used to increase the inlet air pressure.
  2. Air-fuel mixture :-  If the  air-fuel mixture is rich then the fuel will burn less and moreover the Hydrocarbon(HC) emmision will be on higher side. And if the mixture is lean, then more power but NOx emission will be on higher side.
  3. Engine Downsizing :-  If the power output is increased by downsizing the engine, then the overall vehicle packaging will be less complicated and also will decrease the manufacturing cost.
  4. Compression Ratio :- The Compression ratio in gasoline engine(SI) must be kept lower atleast below 12.1 ratio, in order to prevent knocking. 


  • Turbocharging:- Pressure  =  2.6 bar , Temperature  = 300K  , Composition = air


  • Air-fuel mixture:- Different values of air-fuel mixture is considered to understand the  behaviour of engine performance and emmisions at different cases i.e.,  (12.1),  (13:1),  (14:1), (14.4:1), (14.5:1), (14.6:1), (15:1).


  • Engine downsizing :-  While calibration, the engine geometry has been downsized to decrease the Brake specific fuel consumption and to improve the vehicle packaging complexity.



  • Compression Ratio :- The compression ratio is decreased from 9.5 to 9 to decrease the chances of knocking.

Results @3600 rpm (calibrated):-  


  1. Engine Performance :-

  • The results shows that at stoichiometric air_fuel ratio (14.5 : 1) [column 5], the power obtained is  8.5 KW (10% more) than the previous one.
  • Moreover, the BSFC = 210.1 g/KW-h which is much lesser than the one obtained before calibration i.e.,(241.8 g/KW-h).
  • The volumetric effeciency at stoichiometric ratio = 226.7% (due to turbocharging).
  • The power output decreases after stoichiometric ratio beacause the air-fuel mixture gets richer thus both combustion effeciency as well as  volumetric effeciency decreases

2.  Emmisions:-


From the emmision results it is clear that only at Stoichiometric ratio (14.5 : 1), the emmisions are at par with the engine performance results.

  1. Power = 18.5 KW
  2. NOX (ppm) =108.5 ppm which is lesser before calibration which is at 180 ppm.
  3. HC (ppm)0.17 ppm.
  4. CO (ppm) = 544.25 ppm which is slightly more than before calibration 514.74 ppm.

Conclusion:-  So, from the above observations we can conclude that the calibration at 3600 rpm has produced significant impact in terms of performance and emmision making the engine much more suitable for practical applications.

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