5 ms·

They have a pretty narrow power band (produce efficient max power at a small range of RPMs) which always somewhat limited their use for normal ICE cars, but is

They have a pretty narrow power band (produce efficient max power at a small range of RPMs) which always somewhat limited their use for normal ICE cars, but is a pretty workable constraint for an electrical generator. So you have compact size, good power to weight ratio, and power limitations that don't really matter for range extender purposes. Lots of potential. I can't find the article right now, but I'd swear I remember discussion here a handful of months ago about a startup marketing a similar EV range extender engine design.

HPsquared 3y ago
They have low compression though, which really hurts the thermal efficiency.
coryrc 3y ago
Then you may as well use a gas turbine, which is pretty much better in every way that matters for generating purposes.
- iamthirsty 3y ago
  Except extremely complex and usually hard to repair and inefficiently sized for a consumer car.
  - userbinator 3y ago
    Actually far simpler than a piston engine; the fuel consumption and high production cost was what made them become extinct. https://en.wikipedia.org/wiki/Chrysler_Turbine_Car https://en.wikipedia.org/wiki/Chrysler_Turbine_Car
    - kyleee 3y ago
      Of course Jay Leno has one; not sure if he’s featured it on his youtube channel (I don’t recall seeing it). Awesome
      - 01HNNWZ0MV43FF 3y ago
        Yep I've seen it on his YouTube. The "EcoJet" https://www.youtube.com/watch?v=10q9_pB6unU https://www.youtube.com/watch?v=10q9_pB6unU He said that they had to put really big brakes on it. I guess for some reason you can't just have a clutch. Personally if I was going for eco I'd want something more clever than "bigger brakes" but maybe building something like a Hybrid Synergy Drive is harder than building a turbine.
        SoftTalker 3y ago
        > He said that they had to put really big brakes on it. There's no compression braking (engine braking) with a turbine engine.
        ssl-3 3y ago
        Also: While Leno seems to be very interested in restoration, he also is clearly very interested in staying alive. He's got a ton of old cars that have been modified to have very good, modern disc brakes. The EcoJet is just one of many examples of his cars that have been improved in this way.
      - jasonwatkinspdx 3y ago
        Here's his video on his 1960's one, which is worth watching and some neat animation footage from the period talking about the design: https://www.youtube.com/watch?v=b2A5ijU3Ivs https://www.youtube.com/watch?v=b2A5ijU3Ivs You can tell Jay genuinely loves cars and the history of the auto world. He's indulging his hobby interest in a way that will preserve these vehicles for future generations to see and learn about. As far as ways rich people can spend their money that's a pretty cool one in my book.
- WalterBright 3y ago
  Gas turbine cars have been built, but they tend to set anyone on fire if they walk behind the car. https://bandimere.com/previewing-the-brakes-plus-jet-car-nationals/ https://bandimere.com/previewing-the-brakes-plus-jet-car-nat...
  - JALTU 3y ago
    Oh! The Batmobile!
  - coryrc 3y ago
    You're probably being silly, but for anyone else, gas turbines as used for generators don't have jet exhausts on them, i.e. https://www.youtube.com/watch?v=yR5oVn-Fvvg https://www.youtube.com/watch?v=yR5oVn-Fvvg
    - philwelch 3y ago
      So what do they do with the exhaust?
      - elevatedastalt 3y ago
        The reason jet engines have that sort of exhaust is because the primary purpose of the gas turbine there is to dump all the excess energy into the exhaust to make it go fast (so that the plane can be pushed ahead by the reaction force). They produce very little power, just enough to power the Auxiliary Power Unit (that manages the plane electronics, air-conditioning etc.). If you want to use a gas turbine for producing power, you will set it up such that most of the energy goes into the work generated, rather than the exhaust, so it would be a cooler, slower exhaust, similar to an IC-engine.
        01HNNWZ0MV43FF 3y ago
        Depending on the plane and engine. Big jetliners have high-bypass turbines where they do intentionally produce a lot of torque, to spin a large compressor fan, but most of the fan air does not go through the combustion step, it's just used to react off of.
- fodkodrasz 3y ago
  Except for consumption, waste heat generated, size.
- mrighele 3y ago
  If all you need is power generation, use a nuclear reactor. Time to bring back the Ford Nucleon ! [1] Comes with daily free health checkup (in form of an X-Ray). [1] https://en.wikipedia.org/wiki/Ford_Nucleon https://en.wikipedia.org/wiki/Ford_Nucleon
  - xattt 3y ago
    Aaahktually, the radiation given off the reactor would be too “hard” and useless in soft-tissue imaging. Maybe neutrino imaging?
- user_7832 3y ago
  Apparently they really don't scale well. I found this reddit post explaining it better: > Gas turbines scale extremely poorly. They rely on small clearance between the rotating blades and the housings for efficiency. The smaller the turbine, the greater the relative clearance and the more energy is lost. Gas turbines, at least with established technology, make very little sense below 300ish HP. As a real life comparison: A Robinson R44 piston helicopter and an R66 turbine Helicopter have almost identical design, dimensions, and weights. Power is around 250 / 300hp. The former burns between 50-60L of gas per hour at cruise, the latter around 90-110L of Jet fuel. 1 - https://old.reddit.com/r/cars/comments/s8vkv8/are_wankel_engines_just_better_for_horsepower/htpvc6i/ https://old.reddit.com/r/cars/comments/s8vkv8/are_wankel_eng...
  - bob1029 3y ago
    300 HP = ~220 kW I believe a Tesla can charge its battery pack at approximately this rate.
    - avalys 3y ago
      What's your point? There's no reason to have a generator that charges the pack in a hurry. It really only needs to cover the maximum sustained average draw - driving up an extended grade at high speed. That's a lot less than 300 hp - it's probably not more than 80 hp or so at most.
      - Baeocystin 3y ago
        I remember back in the 90's in auto shop we calculated that you'd only need 15-25hp continuous to essentially power all of a car's needs if you could smooth demand for power from the peaks over the length of the trip. It stuck with me as a surprisingly small number, but it mathed out, even including heating and AC. Cars are both larger and more aerodynamic nowadays; I wonder if the amount would still be the same?
        DarmokJalad1701 3y ago
- alexose 3y ago
  Cosworth appears to have developed a microturbine for this purpose. And it (maybe?) has found a home in Ariel's latest insane car: https://www.carscoops.com/2022/09/ariel-hipercar-is-an-1180-hp-ev-with-a-gas-turbine-range-extender/ https://www.carscoops.com/2022/09/ariel-hipercar-is-an-1180-...
- cjbgkagh 3y ago
  AFAIK I think there is some difficulty in getting turbines to scale down efficiently with a need of a recouperator to maintain a higher core temperature for better efficiency. The recouperator is additionally expensive on top of the already expensive turbine cost. Having a rotary with a turbo should be able to work better at a lower scale for a pretty cheap production cost.
- cranky908canuck 3y ago
  Want to comment explicitly, though I upvoted a similar comment ... a gas turbine in a consumer car will be a maintainability nightmare (where do you find the technicians that can do anything with it?), at least in the current automotive ecosystem.
- simne 3y ago
  Gas turbines are economically effective when larger than about 300hp. This border with time slow lowered, but I don't know, when it will appear somewhere about 50Kw of most popular automobiles (Toyota Corolla, WV Golf, Ford Focus). When scaling down, gas turbines become much more expensive than ICE. For example on small planes market, exist many dual-powered models (in range 200-300hp), and with gas turbine it typically priced twice of ICU-powered with very similar parameters. Range of 1000hp+ on planes are near totally gas turbines.
- bluedino 3y ago
  Chrysler tried it in the 50's and 60's https://en.m.wikipedia.org/wiki/Chrysler_Turbine_Car https://en.m.wikipedia.org/wiki/Chrysler_Turbine_Car The ideas and innovations back then seemed amazing
eep_social 3y ago
Maybe you’re thinking of the Edison kits? They seem to be putting a genset into the truck bed to do EV conversions: https://news.ycombinator.com/item?id=38893567 https://news.ycombinator.com/item?id=38893567
seltzered_ 3y ago
> I'd swear I remember discussion here a handful of months ago about a startup marketing a similar EV range extender engine design. Possibly https://liquidpiston.com https://liquidpiston.com Prior discussions: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&query=Liquidpiston&sort=byPopularity&type=story https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...

HPsquared 3y ago

They have low compression though, which really hurts the thermal efficiency.

coryrc 3y ago

Then you may as well use a gas turbine, which is pretty much better in every way that matters for generating purposes.

iamthirsty 3y ago
Except extremely complex and usually hard to repair and inefficiently sized for a consumer car.
- userbinator 3y ago
  Actually far simpler than a piston engine; the fuel consumption and high production cost was what made them become extinct. https://en.wikipedia.org/wiki/Chrysler_Turbine_Car https://en.wikipedia.org/wiki/Chrysler_Turbine_Car
  - kyleee 3y ago
    Of course Jay Leno has one; not sure if he’s featured it on his youtube channel (I don’t recall seeing it). Awesome
    - 01HNNWZ0MV43FF 3y ago
      Yep I've seen it on his YouTube. The "EcoJet" https://www.youtube.com/watch?v=10q9_pB6unU https://www.youtube.com/watch?v=10q9_pB6unU He said that they had to put really big brakes on it. I guess for some reason you can't just have a clutch. Personally if I was going for eco I'd want something more clever than "bigger brakes" but maybe building something like a Hybrid Synergy Drive is harder than building a turbine.
      - SoftTalker 3y ago
        > He said that they had to put really big brakes on it. There's no compression braking (engine braking) with a turbine engine.
        ssl-3 3y ago
        Also: While Leno seems to be very interested in restoration, he also is clearly very interested in staying alive. He's got a ton of old cars that have been modified to have very good, modern disc brakes. The EcoJet is just one of many examples of his cars that have been improved in this way.
    - jasonwatkinspdx 3y ago
      Here's his video on his 1960's one, which is worth watching and some neat animation footage from the period talking about the design: https://www.youtube.com/watch?v=b2A5ijU3Ivs https://www.youtube.com/watch?v=b2A5ijU3Ivs You can tell Jay genuinely loves cars and the history of the auto world. He's indulging his hobby interest in a way that will preserve these vehicles for future generations to see and learn about. As far as ways rich people can spend their money that's a pretty cool one in my book.
WalterBright 3y ago
Gas turbine cars have been built, but they tend to set anyone on fire if they walk behind the car. https://bandimere.com/previewing-the-brakes-plus-jet-car-nationals/ https://bandimere.com/previewing-the-brakes-plus-jet-car-nat...
- JALTU 3y ago
  Oh! The Batmobile!
- coryrc 3y ago
  You're probably being silly, but for anyone else, gas turbines as used for generators don't have jet exhausts on them, i.e. https://www.youtube.com/watch?v=yR5oVn-Fvvg https://www.youtube.com/watch?v=yR5oVn-Fvvg
  - philwelch 3y ago
    So what do they do with the exhaust?
    - elevatedastalt 3y ago
      The reason jet engines have that sort of exhaust is because the primary purpose of the gas turbine there is to dump all the excess energy into the exhaust to make it go fast (so that the plane can be pushed ahead by the reaction force). They produce very little power, just enough to power the Auxiliary Power Unit (that manages the plane electronics, air-conditioning etc.). If you want to use a gas turbine for producing power, you will set it up such that most of the energy goes into the work generated, rather than the exhaust, so it would be a cooler, slower exhaust, similar to an IC-engine.
      - 01HNNWZ0MV43FF 3y ago
        Depending on the plane and engine. Big jetliners have high-bypass turbines where they do intentionally produce a lot of torque, to spin a large compressor fan, but most of the fan air does not go through the combustion step, it's just used to react off of.
fodkodrasz 3y ago
Except for consumption, waste heat generated, size.
mrighele 3y ago
If all you need is power generation, use a nuclear reactor. Time to bring back the Ford Nucleon ! [1] Comes with daily free health checkup (in form of an X-Ray). [1] https://en.wikipedia.org/wiki/Ford_Nucleon https://en.wikipedia.org/wiki/Ford_Nucleon
- xattt 3y ago
  Aaahktually, the radiation given off the reactor would be too “hard” and useless in soft-tissue imaging. Maybe neutrino imaging?
user_7832 3y ago
Apparently they really don't scale well. I found this reddit post explaining it better: > Gas turbines scale extremely poorly. They rely on small clearance between the rotating blades and the housings for efficiency. The smaller the turbine, the greater the relative clearance and the more energy is lost. Gas turbines, at least with established technology, make very little sense below 300ish HP. As a real life comparison: A Robinson R44 piston helicopter and an R66 turbine Helicopter have almost identical design, dimensions, and weights. Power is around 250 / 300hp. The former burns between 50-60L of gas per hour at cruise, the latter around 90-110L of Jet fuel. 1 - https://old.reddit.com/r/cars/comments/s8vkv8/are_wankel_engines_just_better_for_horsepower/htpvc6i/ https://old.reddit.com/r/cars/comments/s8vkv8/are_wankel_eng...
- bob1029 3y ago
  300 HP = ~220 kW I believe a Tesla can charge its battery pack at approximately this rate.
  - avalys 3y ago
    What's your point? There's no reason to have a generator that charges the pack in a hurry. It really only needs to cover the maximum sustained average draw - driving up an extended grade at high speed. That's a lot less than 300 hp - it's probably not more than 80 hp or so at most.
    - Baeocystin 3y ago
      I remember back in the 90's in auto shop we calculated that you'd only need 15-25hp continuous to essentially power all of a car's needs if you could smooth demand for power from the peaks over the length of the trip. It stuck with me as a surprisingly small number, but it mathed out, even including heating and AC. Cars are both larger and more aerodynamic nowadays; I wonder if the amount would still be the same?
      - DarmokJalad1701 3y ago
alexose 3y ago
Cosworth appears to have developed a microturbine for this purpose. And it (maybe?) has found a home in Ariel's latest insane car: https://www.carscoops.com/2022/09/ariel-hipercar-is-an-1180-hp-ev-with-a-gas-turbine-range-extender/ https://www.carscoops.com/2022/09/ariel-hipercar-is-an-1180-...
cjbgkagh 3y ago
AFAIK I think there is some difficulty in getting turbines to scale down efficiently with a need of a recouperator to maintain a higher core temperature for better efficiency. The recouperator is additionally expensive on top of the already expensive turbine cost. Having a rotary with a turbo should be able to work better at a lower scale for a pretty cheap production cost.
cranky908canuck 3y ago
Want to comment explicitly, though I upvoted a similar comment ... a gas turbine in a consumer car will be a maintainability nightmare (where do you find the technicians that can do anything with it?), at least in the current automotive ecosystem.
simne 3y ago
Gas turbines are economically effective when larger than about 300hp. This border with time slow lowered, but I don't know, when it will appear somewhere about 50Kw of most popular automobiles (Toyota Corolla, WV Golf, Ford Focus). When scaling down, gas turbines become much more expensive than ICE. For example on small planes market, exist many dual-powered models (in range 200-300hp), and with gas turbine it typically priced twice of ICU-powered with very similar parameters. Range of 1000hp+ on planes are near totally gas turbines.
bluedino 3y ago
Chrysler tried it in the 50's and 60's https://en.m.wikipedia.org/wiki/Chrysler_Turbine_Car https://en.m.wikipedia.org/wiki/Chrysler_Turbine_Car The ideas and innovations back then seemed amazing

eep_social 3y ago

Maybe you’re thinking of the Edison kits? They seem to be putting a genset into the truck bed to do EV conversions: https://news.ycombinator.com/item?id=38893567 https://news.ycombinator.com/item?id=38893567

seltzered_ 3y ago

> I'd swear I remember discussion here a handful of months ago about a startup marketing a similar EV range extender engine design. Possibly https://liquidpiston.com https://liquidpiston.com Prior discussions: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&query=Liquidpiston&sort=byPopularity&type=story https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...