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  1. Join Date
    May 2008
    Posts
    329
    #1
    Mga experts ask ko lang kung anong mas magandang configuration ng diesel engine let say parehong 2.5 Liter diesel engine

    1.ano kaya mas malakas sa akyatan,mas mabilis sa acceleration at mas mabilis sa rektahan
    2.ano mas matipid

  2. Join Date
    Jun 2011
    Posts
    130
    #2
    Also consider the differential gear or final drive ratio. With high differential ratio 4.1 and
    higher, malakas sa akyatan at mabilis sa acceleration. Below 4.1 mabilis sa recta
    matipid sa gas kasi mas mababa RPM at the same speed.

  3. Join Date
    Jul 2006
    Posts
    8,494
    #3
    Stroke ratio - Wikipedia, the free encyclopedia

    TS: For your better understanding.

  4. Join Date
    Feb 2009
    Posts
    5,010
    #4
    Quote Originally Posted by HUMABOL KA View Post
    Mga experts ask ko lang kung anong mas magandang configuration ng diesel engine let say parehong 2.5 Liter diesel engine

    1.ano kaya mas malakas sa akyatan,mas mabilis sa acceleration at mas mabilis sa rektahan
    2.ano mas matipid

    assuming all factors the same:
    altitude
    air temperature
    load
    speed
    fuel quality
    ambient atmospheric pressure
    designed compression ratio
    the difference in fuel economy would not be noticeable. however, the torque for the longer stroke (longer crank throw or over square engine) would be higher since it will have more leverage.
    but the engine with shorter crank throw (under square engine) can compensate this with a higher redline or rpm range. what matters now will be the volumetric efficiency specially the intake valve opening time is shortened by the increased speed

  5. Join Date
    May 2008
    Posts
    329
    #5
    Quote Originally Posted by perrydel View Post
    Also consider the differential gear or final drive ratio. With high differential ratio 4.1 and
    higher, malakas sa akyatan at mabilis sa acceleration. Below 4.1 mabilis sa recta
    matipid sa gas kasi mas mababa RPM at the same speed.
    Yes sir, but when it comes to the configuration of Diesel engines sir totoo bang mas maganda ang performance sa rekta ng mga long stroke diesel engines kesa short stroke diesel engine, let say pareho clang may 4.1 or 3.9 final gear ratio

  6. Join Date
    Oct 2002
    Posts
    10,783
    #6
    pag sinabi mong short stroke engine then i take it that piston stroke length < cylinder bore diameter. so, meron bang "short stroke" diesel engine? by requirements of the ignition system (compression ignition so it has to have a high compression ratio) e medyo mahirap yata gawin yan. true na mas mababa na ang compression ratios of new diesel engines now but that is a development due to crdi. because of the higher injection pressures the atomization of fuel is better leading to easier ignition.

    but, theoretically, in case in the future they develop a diesel engine fuel than ignites at lower compression ratios...

    small bore, long stroke = high compression ratio, high torque (kasi mas malaki ang moment arm. moment arm = 1/2 of the stroke).
    large bore, short stroke = lower compression ratio, lower torque (as above, smaller moment arm).

    this is why diesels have inherently higher torque output than gasoline engines because the piston stroke > cylinder bore. and this is also why the favorite "btek yo!" of our fav fanbois have the lowest torque of all, because they have engines where bore > stroke. the engine design sacrifices torque for the ability of the engine to rev up faster.

  7. Join Date
    May 2008
    Posts
    329
    #7
    Quote Originally Posted by jick.cejoco View Post
    assuming all factors the same:
    altitude
    air temperature
    load
    speed
    fuel quality
    ambient atmospheric pressure
    designed compression ratio
    the difference in fuel economy would not be noticeable. however, the torque for the longer stroke (longer crank throw or over square engine) would be higher since it will have more leverage.
    but the engine with shorter crank throw (under square engine) can compensate this with a higher redline or rpm range. what matters now will be the volumetric efficiency specially the intake valve opening time is shortened by the increased speed
    Gud aftie sir, for example both engine are 2.5 liter pero ung isa is Bore: 91 x Stroke: 96, then the other one Bore:92 X Stroke:93 meron ba talagang effect yan sa acceleration and rekta and kung meron which one has the advantage assuming nga sir na the rest is equal na

  8. Join Date
    Jul 2006
    Posts
    8,494
    #8
    A general rule, (but very subjective)

    Long stroke, small bore engines (undersquare) = high torque
    Short stroke, big bore engines (oversquare) = high horsepower

  9. Join Date
    May 2008
    Posts
    329
    #9
    Quote Originally Posted by yebo View Post
    pag sinabi mong short stroke engine then i take it that piston stroke length < cylinder bore diameter. so, meron bang "short stroke" diesel engine? by requirements of the ignition system (compression ignition so it has to have a high compression ratio) e medyo mahirap yata gawin yan. true na mas mababa na ang compression ratios of new diesel engines now but that is a development due to crdi. because of the higher injection pressures the atomization of fuel is better leading to easier ignition.

    but, theoretically, in case in the future they develop a diesel engine fuel than ignites at lower compression ratios...

    small bore, long stroke = high compression ratio, high torque (kasi mas malaki ang moment arm. moment arm = 1/2 of the stroke).
    large bore, short stroke = lower compression ratio, lower torque (as above, smaller moment arm).

    this is why diesels have inherently higher torque output than gasoline engines because the piston stroke > cylinder bore. and this is also why the favorite "btek yo!" of our fav fanbois have the lowest torque of all, because they have engines where bore > stroke. the engine design sacrifices torque for the ability of the engine to rev up faster.
    hehe sori sir mali pala ung term i know na long stoke pala talaga ang diesel engines but what i mean is pag mas longer ba ang stroke mas may advantage ito kesa sa average stroke ng diesel engine

  10. Join Date
    May 2008
    Posts
    329
    #10
    Quote Originally Posted by lowslowbenz View Post
    A general rule, (but very subjective)

    Long stroke, small bore engines (undersquare) = high torque
    Short stroke, big bore engines (oversquare) = high horsepower
    so sa diesel engines sir is it better to have longer stroke?

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