Merlin turbocharger?

Discussion in 'Technical' started by Negative Creep, Jan 12, 2008.

  1. Negative Creep

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    Please help settle a discussion I was having with someone on another forum. Regarding the forced induction of the Merlins, it is my understanding that they are essentially the same as turbochargers fitted to modern engines. However, I've always been under the impression that the contemporary name for them was a turbo-supercharger, hence I would be correct in saying the Merlin was supercharged. He disagrees and thinks it was always referred to as a turbo. So basically, who's right?
     
  2. Micdrow

    Micdrow “Archive”
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  3. Negative Creep

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    Cheers for the link, interesting read and seems I'm vindicated. So while it is a turbo, referring to it as supercharged is technically correct
     
  4. Micdrow

    Micdrow “Archive”
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    That's the way I read into it.
     
  5. antoni

    antoni Banned

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    The Merlin engine was not turbo-supercharged, that option was rejected. (See Rolls-Royce Merlin and Griffon
    ) The supercharger was driven mechanically. That is by the engine via a shaft and gearing. A turbocharger, like those fitted to modern cars, is driven by the exhaust gases turning a turbine. So a turbocharger is a type of supercharger, hence turbo-supercharger, but not all superchargers are turbo-superchargers. I think there may even have been electrically driven superchargers in the past. Superchargers require much more exact engineering and so are more expensive to manufacture. Turbochargers suffer from turbo-lag. There is a delay between the engine increasing speed and the extra power being produced. However, they are easier and cheaper to manufacture so are most often used in modern car engines. VW were the only volume car manufacturer to use superchargers and they seem to have abandoned them now.

    Mechanically driven superchargers require power from the engine, in the case of the Merlin several hundred hp. This is not the case with a turbocharger as the energy comes from the waste heat of the exhaust gases. However mechanically driven superchargers are able to produce much more extra hp than a turbocharger and so overall they are more powerful engines.
     
  6. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    And I could tell you as a maintainer "turbocharger" and "supercharger" are used interchangeably...
     
  7. Negative Creep

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    After a bit of reading it would actually seem I'm in the wrong! A turbo can be referred to as supercharged but not vice-versa. All very confusing! Although I'm certain I've read sources that describe the Merlin as being turbo-supercharged
     
  8. red admiral

    red admiral Member

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    A turbosupercharger utilises a turbine to extract work from the exhaust gas stream. That is why it is called a "turbo".

    A supercharger is the term used for a device used to increase the inlet charge density so that the engine can develop more power. It usually consists of a centrigual pump.

    For boosts of below one atmosphere, the term "blower" is used as well as supercharger.
     
  9. HoHun

    HoHun Active Member

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    Hi Red,

    >For boosts of below one atmosphere, the term "blower" is used as well as supercharger.

    Allow me to add that historically, "blower" was used as a synonym for "supercharger", or even "supercharger speed" (in the combination "high blower" or "low blower"), for example in the "Pilot Training Manual for the P-51 Mustang". The V-1650's supercharger of course was capable of producing boosts far exceeding one atmosphere.

    Modern terminology might be different, of course!

    Regards,

    Henning (HoHun)
     
  10. seesul

    seesul Active Member

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    Never heard about VW using supercharger, at least here in Europe. They always use a turbocharger with waste gate or turbocharger with variable geometry control. The only one producer here that still uses supercharger (and they call it compressor) is Mercedes.
    Also Mazda used to use compressor on Xedos model, guess on ´97 and ´98 production year, but not anymore, at least here.
     
  11. HoHun

    HoHun Active Member

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  12. antoni

    antoni Banned

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    It was called the G60 G-lader, named after its spiral displacer. All the VW models had a G60 version apart from the Polo that had a smaller supercharger G40. They were first available in the late 1980’s I think. They earned a reputation for unreliability needing rebuilding after 45,000 miles but I think later improved versions last 100,000 miles. I haven’t owned a VW for over ten years and I am out of touch with what bthey are up to these days. I had five or six in the 1980’s and early 1990’s. From what I remember at the time VW and Audi had different engines and separate design and development establishments. Audi had turbocharged engines but WV did not like turbochargers apart from diesels. So they developed a supercharger that could be produced at a cost that allowed them to be used in mass produced cars. I don’t think they have any supercharged model anymore probably because the unreliability problems put people off buying them. So, no doubt, they have had to follow the pack and move to turbochargers. I think you will find the turbocharged VWs, like my Seat, actually have Audi engines.


    Polo G40 History
     
  13. Negative Creep

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    The older BMW Mini used a supercharger but it's now a turbo. VW also make the TSI engine which is both turbo and supercharged
     
  14. seesul

    seesul Active Member

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    Thank you guys for those interesting informations! When i was in the school one teacher told me that there was one russian combine (harvester), that used to use both supercharger and turbocharger which logicaly gave a very flat curve of the torque in both low and high RPM. Think the supercharger and turbocharger control system had to be pretty difficult.
    But really I don´t know why did they use it on combine as such a kind of machine works mostly with high RPM and doesn´t change the RPM setting during the work:rolleyes:
     
  15. Philgé

    Philgé New Member

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    Hi every body,
    You could have also a self sustain turbocharger (SST), like on the french battle tank Leclerc (french army). This is a big turbocharger with a main burner and a valve to manage the difference of pressure between exhaust gas and air pressure after compression . It is the system SURALMO HYPERBAR.
     
  16. HoHun

    HoHun Active Member

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    Hi Philgé,

    >This is a big turbocharger with a main burner and a valve to manage the difference of pressure between exhaust gas and air pressure after compression .

    Very interesting! Is my impression correct that this is almost a turbine engine in itself?

    (In the sense that if no exhaust gases were present, it would just burn some fuel with the compressed air to generate enough to drive itself like a true turbine engine :)

    Regards,

    Henning (HoHun)
     
  17. Philgé

    Philgé New Member

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    Hi,

    yes it is like that, you could start only the turbocharger to use it like an APU,to have nine kW of electrical power.

    Regards
     
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