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Can supercharging of an engine ever lead to reduced power?

  1. Nov 16, 2011 #1

    I have decided to increase inlet T and P of a typical diesel engine (operatiing on dual air standard cycle).

    THeoretically if all other parameters r same, I have observed that t2 (temp at the end of compression) and p2 increases, but t3 (temp at the end of constant volume heating) and t4 (temp at the end of constant pressure heating) tend to decrease because of increased p2.

    This fall in temperatures result in reduced efficiency and power output.

    Can any1 confirm if this is really true? As Practically, supercharging is supposed to boost the power o/p..

    Thanks in advance
  2. jcsd
  3. Nov 16, 2011 #2


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    Gold Member

    Why would t3 and t4 decrease because of increased pressure?
  4. Nov 16, 2011 #3
    constant volume process.

    ratio of t3 to t2 = ratio of p3 to p2

    p2 increases = t3 decreases

    t4 is a function of t3..
  5. Nov 16, 2011 #4
    Sorry i forgot 2 mention

  6. Nov 17, 2011 #5
    Yes output can decrease, if you have poor inlet geometry or injectors that arent big enough, you'll be spending power compressing air that you then cant use for combustion.
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