ABE TUTORIALS

PROBLEM 15:

YOU ARE GIVEN THE SPECIFICATIONS FOR AN ENGINE:
4 cylinder, 4 cycle; Bore = 10.16 cm; Stroke = 20.32 cm; MEP = 4.23 kg/cm²; RPM = 1000.
Dynamometer test: Lever arm = 45.72 cm; Scale reading = 40.91 kg; Speed = 1000 rpm.

---

1. Calculate the IHP:

a. 15 hp | b. 11 kW | c. 22.7 kW | d. 30.5 Btu/hr | e. 60.92 hp

View Solution

IHP = (P L A N n) / 450,000
IHP = (4.23 × 20.32 × 81.07 × 500 × 4) / 450,000 = 30.46 hp
Convert to kW: 30.46 hp × 0.746 = 22.7 kW

Result: c. 22.7 kW

2. Calculate the BHP:

a. 12.8 hp | b. 51.4 hp | c. 9.59 kW | d. 19.2 kW | e. 25.7 Btu/hr

View Solution

BHP = (2π R F N) / 4500
BHP = (2 × 3.1416 × 0.4572 × 40.91 × 1000) / 4500 = 26.1 hp
Convert to kW: 26.1 hp × 0.7355 = 19.2 kW

Result: d. 19.2 kW

3. Calculate the mechanical efficiency:

a. 15.6% | b. 70.3% | c. 31.2% | d. 85% | e. 60.4%

View Solution

Mech Eff = (BHP / IHP) × 100
Eff = (19.2 kW / 22.7 kW) × 100 = 84.5% (Rounded to 85%)

Result: d. 85%