4 stroke, 6 cylinders engine running at speed of 2400 rpm. Given that the engine bore is 90 mm, stroke is 120 mm, IMEP is 560 kPa and engine torque is 120 Nm. Find:

a) Brake power,

b) Indicated power,

c) Friction power,

d) Efficiency of engine.

Answer:

a) Brake power : Answer 1 Question 25
watt (whole number)

b) Indicated power : Answer 2 Question 25
watt (1 decimal)

c) Friction power : Answer 3 Question 25
watt (1 decimal)

d) Efficiency of engine : Answer 4 Question 25
% (whole number)

Let's calculate each of the required values step by step.

### Given:
- Number of cylinders (\(n\)) = 6
- Engine speed (\(N\)) = 2400 rpm
- Bore (\(D\)) = 90 mm = 0.09 m
- Stroke (\(L\)) = 120 mm = 0.12 m
- Indicated Mean Effective Pressure (IMEP) = 560 kPa = 560,000 Pa
- Torque (\(T\)) = 120 Nm

### Formulas:
1. **Brake Power (\(P_b\))**: 
   \[
   P_b = \frac{2 \pi N T}{60}
   \]
   where \(N\) is in rpm and \(T\) is in Nm.

2. **Indicated Power (\(P_i\))**:
   \[
   P_i = \frac{n \times P_m \times L \times A \times N}{2}
   \]
   where:
   - \(P_m\) is the IMEP
   - \(A\) is the area of the piston = \(\frac{\pi D^2}{4}\)

3. **Friction Power (\(P_f\))**:
   \[
   P_f = P_i - P_b
   \]

4. **Efficiency of Engine (\(\eta\))**:
   \[
   \eta = \frac{P_b}{P_i} \times 100
   \]

### Calculations:

#### a) Brake Power (\(P_b\)):
\[
P_b = \frac{2 \pi \times 2400 \times 120}{60} \, \text{Watt}
\]

Let's calculate this:

\[
P_b = \frac{2 \times 3.1416 \times 2400 \times 120}{60}
\]

\[
P_b \approx 30159.29 \, \text{Watt} \approx 30159 \, \text{Watt}
\]

**Answer 1**: 30159 Watt

#### b) Indicated Power (\(P_i\)):
\[
A = \frac{\pi \times (0.09)^2}{4}
\]
\[
A \approx 0.00636 \, \text{m}^2
\]

Now,

\[
P_i = \frac{6 \times 560000 \times 0.12 \times 0.00636 \times 2400}{2}
\]

Let's calculate this:

\[
P_i \approx 30829.82 \, \text{Watt}
\]

**Answer 2**: 30829.8 Watt

#### c) Friction Power (\(P_f\)):
\[
P_f = P_i - P_b = 30829.8 - 30159
\]

Let's calculate this:

\[
P_f \approx 670.8 \, \text{Watt}
\]

**Answer 3**: 670.8 Watt

#### d) Efficiency of Engine (\(\eta\)):
\[
\eta = \frac{P_b}{P_i} \times 100 = \frac{30159}{30829.8} \times 100
\]

Let's calculate this:

\[
\eta \approx 97.8 \%
\]

**Answer 4**: 98 %

---

Would you like more details or have any questions?

### Related Questions:
1. What are the implications of a high friction power in an engine?
2. How does the IMEP affect the indicated power in an engine?
3. Why is the efficiency of a 4-stroke engine typically lower than 100%?
4. What is the relationship between engine torque and brake power?
5. How would increasing the engine bore affect the engine’s power output?

### Tip:
Regular maintenance, such as proper lubrication, can reduce friction power and improve engine efficiency.

Learn how to calculate Brake Power, Indicated Power, Friction Power, and Efficiency for a 6-cylinder engine running at 2400 rpm with specific dimensions and parameters. Detailed step-by-step solutions provided.

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