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I am working though a question which states that the compression ratio of a diesel engine is 20/1 . This allows me to find the first 3 temperatures until the constant pressure stage. I do this using the formula :
T2 = T1 * (Compression ratio)^1-k where k is 1.4 .

However, after T3, the cutoff ratio must be used instead of the compression ratio in a similar formula which writes as follows:

T4 = T3 * (cutoff ratio)^1-k where k is again 1.4 .

The cutoff ratio is the ratio of the volume of air when fuel is added over the volume of air once the fuel and air mixture has stopped burning.

The question states that the piston moves 7% of the swept volume during that time (between fuel being added to end of burning).

To get a better idea, the compression ratio is defined as
clearence volume + swept volume / clearance volume

so I assumed the cuttoff ratio would be 0.07 x 19 = 1.33 but I am not sure this is the right way to go.
The reason I did this is because compression ratios are generally given as a number and not a fraction.

Any input or thoughts would be much appreciated.

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