Question

The engine of a Lexus car has three cylinders with a total displacement of 770 cc. If the compression ratio is 8.7, then each cylinder has a clearance volume of 
1. 3.33 cc
2. 36.3 cc
3. 44.4 cc
4. 33.33 cc

Answer 1

Correct Answer - Option 4 : 33.33 cc

Concept:

Compression ratio:

Compression ratio is given by the ratio of volume before compression to volume after compression.

​\(Compression~ratio\left( r \right) = \frac{{{V_1}}}{{{V_2}}} = \frac{{{V_c}\; +\; {V_s}}}{{{V_c}}}\)

[NOTE: V_c and V_s are clearance and swept volume of single-cylinder only.]

Calculation:

Given:

Total displacement volume = 770 cc, Compression ratio r = 8.7, Number of cylinders = 3

Displacement or swept volume of one cylinder = \(\frac{Total\;displacemnet\;volume}{No.\;of\;cylinders}\)

∴  Swept volume (one cylinder) = \(\frac{770}{3}\) = 256.66 cc

\(Compression~ratio\left( r \right) = \frac{{{V_c}\; +\; {V_s}}}{{{V_c}}}\)

\(8.7 = \frac{{{V_c}\; +\; {256.66}}}{{{V_c}}}\)

∴ V_c = 33.246 cc