V12 Diesel

Discussion in 'Volkswagen' started by gofastclint, Jan 2, 2009.

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  1. Jan 4, 2009 #21

    PTAirco

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    Yes, basically it is stroke length that makes the difference. Torque might as well be called "leverage" and a crank with more stroke produces more leverage. Of course, cams and valve timing etc would be tailored to that particular rpm, but that makes only a comparatively minor difference.

    If you took at 0-360 Lycoming and a 350 Chevy V8, and played with cams a little they would show a very similar power curve up to 2700 rpm, both being fairly 'square' bore and stroke ratio engines.

    If you look engines from WW1 to the 1920s you see engines swinging enormous propellers at extremely low rpm - all these engines had extremely long strokes compared to their bores. Far more efficient for aero engines. Even back then they felt if an engine had to go much over 1800rpm, they really ought to gear down the propeller. The engineers back then would probably cringe at at our 2700 toothpick-props whizzing around.
     
  2. Jan 4, 2009 #22

    Midniteoyl

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    Technically speaking, this is not true any more... OEM engines in the last 10 years or so have been in the 'under .4' range, not .45 or more commonly quoted '.5'. 'Crate' engines are higher, but not always. In fact, there was a Vortech based motor just built that was in the .34-.4 range during its entire RPM range... and it made over 450hp. Nascar engines are routinly in the .3's.
     
  3. Jan 4, 2009 #23

    PTAirco

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    Interesting - it would be nice if car manufacturers published more SFC figures, without having to dig around for them. But I guess they believe the car buying public to be a pretty ignorant bunch (correctly...?) and maybe they consider this kind of info just too far above our heads.
     
  4. Mar 13, 2015 #24

    B100

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    Hi all! The V12 is nice, but there are other options that might be a better fit for your requirements , so here is the full list ;

    List of Volkswagen Group diesel engines - Wikipedia, the free encyclopedia

    And let me remind you that these engines respond very well to chip tuning, increasing power and torque, while bringing down fuel consumption!
    The V 12 can be made to produce around or over 600 hp !
    But don't take my word for it, see for yourselves ;

    Audi Q7 6.0 V12 TDI Quattro 500PS/368kW

    My personal home "fleet" is powered by two of these engines on the list ( 1,9 TDI) and they are great engines, and can even run on 100% home made Biodiesel!:)

    So consider .....lower fuel consumption , and home made fuel ! :gig:
     
  5. Mar 13, 2015 #25

    JamesG

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    Yes, marketing types hear engineers as, "blah, blah, blah, blah". and then do what they think will sell the most units.

    Peak torque and rpm can occur at different points. It all depends on what you want/need the engine to do. Spin a shaft with lots of power or lots of speed.
     
  6. Mar 16, 2015 #26

    B100

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    Hi James, I honestly dont get what you mean with your post! could you please clarify?
     
  7. Mar 16, 2015 #27

    JamesG

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    Sorry, that was a post that was related/should be benieth another post but got shuffled back out of context.
     
  8. Mar 16, 2015 #28

    B100

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    No problem! Don´t know if you have come across this before, but while some talk about what if? regarding diesel conversions and the endless bla bla bla about weight & power, some folks here across the pond have actually done it!
    so check out these links !

    http://gazaile2.free.fr/caracteristiqu
    http://gazaile2.free.fr/englishInformations.pdf

    Now imagine what could be done with bigger more powerful engines! Granted the best options are here in Europe, as 60% of all motor vehicles on the road are diesels , so we are spoilt for choice :).
     
  9. Mar 16, 2015 #29

    Bin31

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    Last edited: Mar 16, 2015
  10. Mar 17, 2015 #30

    B100

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    Wow! you made my day...lol....night! Its good to know that myths are being broken! I always questioned the fact that a reduction drive was needed for a diesel!
    Why? because it didnt make sense to me that if the "ideal" rpm for prop eficiency is in the 2000 t 2700 rpm range, (depending on the variables) that wasn´t taken into consideration when applied to diesel engines.
    Most current automotive diesels achieve their max torque, and retain that flat torque curve, from as low as 1600 rpm to 3000 rpm ! Max hp is achieved at 4000 rpm or lower !
    So best torque coincides with best prop rpm regimes! The result is you dont need a heavy complex reduction system, but a lighter simpler means of bolting on the prop!
    A lot of the perceived dificulties, are due to a mentality based on either certified engines, or gasoline automotive conversions, and the comparisons made! But as the article by mr. DuCros states if you aproach the technical issues by embracing and working with the specifics of a diesel engine, then the perceived limitations are overcome, and one reaps the benefits of diesel power that translate into, fuel economy, reliability , and long engine life !

    Another benefit that the article also mentions, and I can atest to is the availability of these engines new or used, as well as cheap spares!

    In the 300 pound range 2 liter engines can be had for as low as 700 euro! these engines put out between 110 to 180 hp, and can even be made to produce more! Now that not mght not sound so good in aero engine terms, but when you factor in lower fuel burn, it does narrow or even eleminate it completely !

    When Lyc 540 power level territory ir reached then automotive diesels equal and mostly beat the aero engines!
    waiting to see who is the first to take the plunge, and hang one of these on a decent airframe :)
     
  11. Mar 17, 2015 #31

    rv6ejguy

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    There are no 4 stroke diesels out there flying which beat the power to weight ratios of traditional aircraft engines and especially turbocharged ones (let's remember to compare apples to apples here). Let's also compare certified aero diesels to certified SI engines. Cost wise, the current crop of certified aero diesels are all way more expensive to buy in the first place.

    The only way for a diesel to even approach these levels is with massive boost pressures, limiting both engine life and altitude performance with single stage turbos. No free ride here.
     
  12. Mar 17, 2015 #32

    B100

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  13. Mar 17, 2015 #33

    BJC

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    For comparison purposes, can you provide estimated weights of the total propulsion systems for each of there two engines? Including fuel pumps, cooling systems, coolant, PSRU if needed, propeller, propeller RPM controller, exhaust system, mounts, etc.?

    Thanks,


    BJC
     
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  14. Mar 17, 2015 #34

    rv6ejguy

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    Last edited: Mar 17, 2015
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  15. Mar 18, 2015 #35

    B100

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    BJC[/QUOTE]
    Hi BJC ! I have no idea in regards to the Lyc 540, but I´m sure there will be a lot of people on HBA that would know! In fact I would like to know myself!
    As for the Audi, I have seen them in Audi and VW vehicles , and coolant and rad would amount to around 26 lbs, depending on the version no extra fuel pump is needed. The exaust I have no idea, but as with most auto conversions, a lighter custom exaust manifold would shave some weight off by replacing the heavy stock one. Mounts? No idea, cause ithasnt been done yet!
    Psru if needed might amount to around another 80 Lbs!( Just very rough guess based on the automotive gear box)

    The point is yes! it would weigh more ready to fly then the 540, but the added weight would be compensated by lower fuel burn and cost , as well as lower aquisition and maitenance costs ! I am also sure that TBO would be double, and cheaper too!

    Now this discussion is academic, after all that is part of the point and fun of being on HBA right! some of us on HBA are luky enough to have build, or are building an aircraft, and others like me intend to, at some time in the future (when kids are out and supporting themselves) lol.....but not there yet !
    I have been learning a lot for some years on HBA and other related sites, recently I signed up to take part , and have no problem asking when I dont know something, but I do feel that there are too many people focusing on problems and reasons not to do something, instead of focusing on how to get around them!

    Here is an example of what I mean : If somebody proposed puting a engine on a plane that only produces 55 hp and a ready to fly installed weight of 242 lbs, most would say, its too heavy!
    But consider the said engine, passinger, pilot, and 4 hours + reserve doing 200kmh or 124mph at a MTOW of 450 kg or 990 lbs! Possible? yes its been done
    works well and is very eficient!

    The same aircraft flown solo did a 845 mile trip in 7,5 hours on just under 2 galons an hour! these figures are only atainable with a diesel!

    So my question in regards to my comparison, is what can we achieve with a engine that has a better power to weight ratio, and better sfc numbers ?

    Just food for thought ! Isnt that what progress is? daring to ask ? daring to question! [​IMG]
     
  16. Mar 18, 2015 #36

    B100

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  17. Mar 18, 2015 #37

    cheapracer

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    Not true at all. For less effort you could install a current direct injection SI engine for a better result. There are other options also.


    You're ignoring the answers.
     
  18. Mar 18, 2015 #38

    rv6ejguy

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  19. Mar 18, 2015 #39

    Bin31

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  20. Mar 19, 2015 #40

    B100

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    Really! then do a fact check , because you are ignoring the facts !

    My main point is simple ! Successful conversions have been done and are flying, using less then ideal power to weight ratios that would have precluded any use of those engines! Yet it has been made to work and some are close to a 1000 hours (Dieselis and Gazaile ) with no apparent problems. Will there be some? Sure there will, that's why the aircraft are classed or termed as experimental. But even certified well established aero engines fail so..... its only question of time and more aircraft flying to build up knowledge and establish some parameters!

    With these facts in mind , my question regards the fact that there are some stock auto diesel engines with power to weight ratios that can rival or get pretty close to current certified aero engines , so if its been done with the other ones why not with these?

    People on HBA keep asking and wishing for a decently powered and priced diesel to hang on a plane all I did was list some candidates, so if want sue me for that go ahead, but don't confuse opinions with facts!
     

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