Question

A V-8 four-stoke petrol engine is required to give 186.5 kW at 4400 rev/min. The brake thermal efficiency can be assumed to be 32% at the compression ratio of 9/1. The air-fuel ratio is 12/1 and the volumetric efficiency at this speed is 69%. If the stroke to bore ratio is 0.8, determine the engine displacement required and the dimensions of the bore and stroke. The Qnet,v of the fuel is 44 200 kJ/kg, and the free air conditions are 1.013 bar and 15 ?C.

ANSWERS (5.1 litres; 100.5mm; 80.4 mm)

Answer 1

Given,

output power, brake power=186.55 kW

speed=4400 rev/min

brake thermal efficiency = 32%

compression ratio = 9/1.

The air-fuel ratio= 12/1volumetric efficiency at this speed=69%.

stroke to bore ratio = 0.8,

Cv of the fuel is 44 200 kJ/kg,

P= 1.013 bar

T=15 degree c.

determine,

the engine displacement =?

the dimensions of the bore and stroke.=?

we know,