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The best engine

  1. Oct 25, 2007 #1
    ok now my practicals are 15 days away and i n my friends constantly discuss about advantages and disadvantages of several combinations like 2-stroke SI engine with supercharging or 4stroke CI with CRDi etc etc. since people here are more experienced and have far more facilities than i do, i want to discuss it. so far we have picked out a 2stroke turbocharged CI engine. a 2 stroke obviously generates more power and therefore for same power output, ll be smaller. 2 stroke has a more smoky performance due to burning of lubricating oil, but with a turbocharger, air can be directly directed through a manifold to the cylinder and also crankcase can be wet. and many more things. then why dont we see this combination much in use??? what are the further advantages and disadvantages. also i am not much of an expert in this subject, i have the book knowledge and i do know the system pretty well, but still i want to discuss a lot about it. hope i can get a discussion going
  2. jcsd
  3. Oct 25, 2007 #2


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    It all depends on application. 2 strokes tend to win most of the performance/efficiency balances for very small (model aircraft, petrol hedgetrimmer etc) engines, and very large (marine propulsion, 8MW power generation etc) engines. Emissions don't matter so much on the small engines, where low cost and simplicity are more important. And very large (expensive) engines can afford to use clever control and combustion systems to optimise efficiency, and clean up the emissions afterwards.

    As you said, 2 strokes have smoky performance; this would be difficult to clean up in your average passenger car sufficiently well to pass modern emissions standards. Add to this the extra maintenance and noise you'd likely have to endure, and consider that you probably wouldn't be getting much more performance (and we don't struggle to get enough power for a car out of a 4 stroke anyway) and you'll see why 4 strokes are generally preferred.
  4. Oct 25, 2007 #3
    thats why i said we can turbocharge a CI engine, then smoke bcoz of the burning of lubricating oil ll be reduced
  5. Oct 25, 2007 #4
  6. Oct 26, 2007 #5
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