An engine manufacturer wants to develop a gasoline engine that produces 300 hP at 6000 rpm. They can achieve 10 bar BMEP at peak power with a naturally aspirated engine, and 20bar BMEP with a turbocharged engine. Most modern light-duty engines have displacements of ~0.5L per cylinder. Determine the displacement and minimum number of cylinders (rounded to nearest whole number) required to meet these specs for: a. A naturally aspirated engine. b. A turbocharged engine.

a). 5 cylinders

b). 3 cylinders

Explanation:

To develop a gasoline engine that produces

Power, P = 300 hp

               = 300 x 746 = 223710 watt

at speed, N = 600 rpm = 100 rps

and stroke volume L

                                   =

a). A naturally aspirated engine

BMEP at peak power = 10 bar

                                    =

Suction volume, V =

                           =

Power produced in one engine cylinder , p = BMEP x V

                                                                        =

                                                                        = 50000 watts

No. of cylinders required, n =

                                              =    

                                             = 4.47

So number of cylinders ≈ 5 nos.

b). A turbo charged engine

   BMEP = 20 bar =

   and Volume V =

Power produced in one engine cylinder, p = BMEP x V

                                                                       =

                                                                       = 100000 watts

Therefore, number of cylinders, n =

                                                        =

                                                        = 2.23

So number of cylinders ≈ 3 nos.