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The word "turbocharger" was introduced to shorten the phrase "turbine supercharger", whether driven by the crankshaft or by the exhaust. Later, it came to mean

The word "turbocharger" was introduced to shorten the phrase "turbine supercharger", whether driven by the crankshaft or by the exhaust. Later, it came to mean "exhaust driven turbine supercharger" pretty much exclusively. I don't have any dates for these usages. Edit: that p-47 powertrain is an absolute beast!

diarrhea 6y ago
So when you have such a turbine supercharger driven by the crankshaft, what does the turbine do at all?
- usrusr 6y ago
  A crankshaft driven charger would haven been called just a supercharger, exactly like we do today. But we don't call turbine driven chargers "turbine supercharger" anymore, we call that a turbocharger.
  - diarrhea 6y ago
    Exactly, but GP's > "turbine supercharger", whether driven by the crankshaft or by the exhaust. made it sound like there's "crankshaft-driven turbine superchargers", which I stumbled over.
    - agurk 6y ago
      What we call a turbocharger today has two turbines in it - one that is spun by the exhaust gasses and a second one that compresses the incoming air. These two turbines are directly connected. If you look at super chargers they're all some kind of pump driven by the mechanical energy directly from the crank. If this pump was a turbine, then you'd have a crankshaft driven turbine super charger. So this is half of a modern turbocharger (the compressor) being driven by the crank rather than the exhaust gasses.
      - diarrhea 6y ago
        > What we call a turbocharger today has two turbines in it - one that is spun by the exhaust gasses and a second one that compresses the incoming air. These two turbines are directly connected. That's incorrect, a turbocharger has one turbine, and its driving counterpart is the impeller. That impeller/compressor is never referred to as a turbine. Turbines can only ever extract work from a fluid. Superchargers as well as turbochargers also don't have pumps, those are machines for which the working medium is incompressible (water, ...; density is not a function of pressure, in "engineering precision"). If it is compressible, it's a compressor: it affects not only an increase in pressure but also in density. A fan also works on compressible media but is only supposed to impose some velocity. For this, it necessarily also increases the medium's pressure, but to a low degree, such that (IIRC) changes in density are negligible.
        agurk 6y ago
        You're right I did misspeak about the definition of a impeller/turbine. Never is a strong word though and there are such things as turbine pumps which are not true turbines[0]. As far as I can tell they've never been used for engine applications. Regarding pumps they operate on a fluid, of which air is definitely classed as. [1] [0] https://www.globalspec.com/learnmore/flow_transfer_control/pumps/turbine_pumps https://www.globalspec.com/learnmore/flow_transfer_control/p... [1] https://en.m.wikipedia.org/wiki/Pump https://en.m.wikipedia.org/wiki/Pump
        usrusr 6y ago
        Well, you can find the term "bike pump" even on newyorktimes.com and that's not about hydraulic brake levers, so there might be some difference between technical language and common usage even in English. But I'm posting this to say thank you, I was completely unaware of this detail. In my mind, and likely in GP's mind, the term pump was characterized by the piston principle, not by the medium. And I realize now that the "pumps for air" incorrectness is much less common in English than in German (my home language). Apparently in engineering German the distinction is exactly the same as in English, but it's completely absent from common usage. German never even adopted a verb for high pressure inflation that is not derived from pump. Other than that, the terms pump and Pumpe are extremely similar in English and in German, which is unlikely due to common Germanic roots but because of something much more recent. I suspect nautical terminology which must have been a strong language unifier before navies became a key element of national separation.
- sk5t 6y ago
  I think what you’re getting at is that there is no turbine (only an impeller) in the case of crank/belt driven units.
- Toutouxc 6y ago
  I don't get the downvotes, you're right. A crankshaft driven supercharger doesn't need a turbine (a device that extracts power from a fluid), only an impeller (the opposite).
jandrese 6y ago
The crazy part is that by modern standards they aren't really developing that much power. Sure this thing puts out 2,100 HP (using 130 octane gas), but it needs a whopping 46 liters of displacement to get that. A Veyron engine puts out about half the HP using 17% of the displacement on worse gas. You can't even buy 130 octane gas anymore. The Veyron is a notorious fuel hog, but it has nothing on a twin Wasp radial.
- czch 6y ago
  But the P-47 is on fairly high power the whole time it’s running. Most Veyrons will never use 50% of their rated power. That being said, modern metallurgy really revolutionized ICEs. Followed by computerized control.
  - Gibbon1 6y ago
    Not my field but the other difference is 1500 hp at 2,400 rpm. The low max rpm is because it needs to match the propeller design speed and needs to be efficient at near full power.
    - lovecg 6y ago
      Couldn’t you gear down? This whole discussion makes me think what would a modern maxed out aircraft piston engine be like!
      - Merad 6y ago
        If you're really interested in the topic look up the YouTube channel Greg's Planes and Automobiles. In addition to a deep dive series on the P-47 just a few weeks ago he made a video about late WW2 "super prop" fighters. They were the pinnacle of piston engine fighter performance, but they were all canceled because they weren't needed to win the war and everyone could see that jets were the future. We'd probably struggle to beat them even with modern technology TBH.
        6y ago

diarrhea 6y ago

So when you have such a turbine supercharger driven by the crankshaft, what does the turbine do at all?

usrusr 6y ago
A crankshaft driven charger would haven been called just a supercharger, exactly like we do today. But we don't call turbine driven chargers "turbine supercharger" anymore, we call that a turbocharger.
- diarrhea 6y ago
  Exactly, but GP's > "turbine supercharger", whether driven by the crankshaft or by the exhaust. made it sound like there's "crankshaft-driven turbine superchargers", which I stumbled over.
  - agurk 6y ago
    What we call a turbocharger today has two turbines in it - one that is spun by the exhaust gasses and a second one that compresses the incoming air. These two turbines are directly connected. If you look at super chargers they're all some kind of pump driven by the mechanical energy directly from the crank. If this pump was a turbine, then you'd have a crankshaft driven turbine super charger. So this is half of a modern turbocharger (the compressor) being driven by the crank rather than the exhaust gasses.
    - diarrhea 6y ago
      > What we call a turbocharger today has two turbines in it - one that is spun by the exhaust gasses and a second one that compresses the incoming air. These two turbines are directly connected. That's incorrect, a turbocharger has one turbine, and its driving counterpart is the impeller. That impeller/compressor is never referred to as a turbine. Turbines can only ever extract work from a fluid. Superchargers as well as turbochargers also don't have pumps, those are machines for which the working medium is incompressible (water, ...; density is not a function of pressure, in "engineering precision"). If it is compressible, it's a compressor: it affects not only an increase in pressure but also in density. A fan also works on compressible media but is only supposed to impose some velocity. For this, it necessarily also increases the medium's pressure, but to a low degree, such that (IIRC) changes in density are negligible.
      - agurk 6y ago
        You're right I did misspeak about the definition of a impeller/turbine. Never is a strong word though and there are such things as turbine pumps which are not true turbines[0]. As far as I can tell they've never been used for engine applications. Regarding pumps they operate on a fluid, of which air is definitely classed as. [1] [0] https://www.globalspec.com/learnmore/flow_transfer_control/pumps/turbine_pumps https://www.globalspec.com/learnmore/flow_transfer_control/p... [1] https://en.m.wikipedia.org/wiki/Pump https://en.m.wikipedia.org/wiki/Pump
      - usrusr 6y ago
        Well, you can find the term "bike pump" even on newyorktimes.com and that's not about hydraulic brake levers, so there might be some difference between technical language and common usage even in English. But I'm posting this to say thank you, I was completely unaware of this detail. In my mind, and likely in GP's mind, the term pump was characterized by the piston principle, not by the medium. And I realize now that the "pumps for air" incorrectness is much less common in English than in German (my home language). Apparently in engineering German the distinction is exactly the same as in English, but it's completely absent from common usage. German never even adopted a verb for high pressure inflation that is not derived from pump. Other than that, the terms pump and Pumpe are extremely similar in English and in German, which is unlikely due to common Germanic roots but because of something much more recent. I suspect nautical terminology which must have been a strong language unifier before navies became a key element of national separation.
sk5t 6y ago
I think what you’re getting at is that there is no turbine (only an impeller) in the case of crank/belt driven units.
Toutouxc 6y ago
I don't get the downvotes, you're right. A crankshaft driven supercharger doesn't need a turbine (a device that extracts power from a fluid), only an impeller (the opposite).

jandrese 6y ago

The crazy part is that by modern standards they aren't really developing that much power. Sure this thing puts out 2,100 HP (using 130 octane gas), but it needs a whopping 46 liters of displacement to get that. A Veyron engine puts out about half the HP using 17% of the displacement on worse gas. You can't even buy 130 octane gas anymore. The Veyron is a notorious fuel hog, but it has nothing on a twin Wasp radial.

czch 6y ago
But the P-47 is on fairly high power the whole time it’s running. Most Veyrons will never use 50% of their rated power. That being said, modern metallurgy really revolutionized ICEs. Followed by computerized control.
- Gibbon1 6y ago
  Not my field but the other difference is 1500 hp at 2,400 rpm. The low max rpm is because it needs to match the propeller design speed and needs to be efficient at near full power.
  - lovecg 6y ago
    Couldn’t you gear down? This whole discussion makes me think what would a modern maxed out aircraft piston engine be like!
    - Merad 6y ago
      If you're really interested in the topic look up the YouTube channel Greg's Planes and Automobiles. In addition to a deep dive series on the P-47 just a few weeks ago he made a video about late WW2 "super prop" fighters. They were the pinnacle of piston engine fighter performance, but they were all canceled because they weren't needed to win the war and everyone could see that jets were the future. We'd probably struggle to beat them even with modern technology TBH.
      - 6y ago