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Featured Gen 6 Prius engine will be a “game changer,” achieve a 53% thermal efficiency

Discussion in 'Prius, Hybrid, EV and Alt-Fuel News' started by Gokhan, Jun 7, 2024.

  1. Trollbait

    Trollbait It's a D&D thing

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    Which is how I read the English, but was allowing for others to get creative.
    Such phrasing is used elsewhere in the English article
    There is too much faith in that direct efficiency to power relationship. The presentation graph for the 1.5 turbo has the 30% delta for power note, while it is less efficient than the comparison engine. The one for the 2.0 turbo also has it. The 1.5L one doesn't have it. If there is any meaning to the relative dot position on these graphs, the current 1.5L would see a lower power loss to meet regulations, while the new model sees the greatest efficiency gains of the set.

    I think it will have a high thermal efficiency too. It also has that mystery box that the drive shaft feeds into. I think it's a generator, and the high thermal efficiency will come from narrow operating range. Like the Nissan e-Power.
     
  2. Mr.Vanvandenburg

    Mr.Vanvandenburg Senior Member

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    You show a faded face clip of President Obama speaking before he was elected in 2008 that has been circulated to mean something from 2008 to 2024. You show a foundry going out of business article, and the electric rates on the graph were steady for the foundry during his two terms in office. Starting going up later, like everything else world wide has done.
     
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  3. Gokhan

    Gokhan Senior Member

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    There was confusion on your part because the English version implied that the 12% came both from improved combustion and aerodynamics:

    By contrast, the new engine retains output thanks to improved combustion technology. At the same time, its compact size allows for lower bonnet profiles, reducing aerodynamic drag. These changes are expected to yield 12% better fuel economy in sedan-class vehicles.

    They will all be hybrids. Claiming that it will be a series hybrid is speculation. Toyota's paper explicitly said that they didn't want a series hybrid. If you look at the presentation for the new engine by the Toyota CTO, there is a torque-vs.-rpm graph; so, the rpm is not limited.

    It's not clear why they have a dashed dot and a full dot. A wild guess is that the dashed dot represents a more powerful hybrid battery and electric motor for the current engine to produce a higher net power. To meet the carbon-dioxide emissions without reducing the power, they need to increase the thermal efficiency. I am guessing that the new regulations will be very strict; so, the increase in thermal efficiency will have to be substantial. However, the turbo engines don't seem to be very thermally efficient, but they seem to make up for the carbon efficiency by using more electrification (a larger hybrid battery and electric motor). Perhaps that 30% refers to 30% more electrification.
     
    #63 Gokhan, Jun 9, 2024
    Last edited: Jun 9, 2024
  4. mikefocke

    mikefocke Prius v Three 2012, Avalon 2011

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    Wonderful to see improvements promised. But I'd wait till independent reviews are here and several years of real world experience mounts to 8 digit miles and owner stories start to leak before considering buying. I want a minimum of today's reliability. I've been burned too many times with new models and technology even though I am addicted to the new.
     
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  5. Trollbait

    Trollbait It's a D&D thing

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    No, there wasn't. I was allowing for a counter claim that the 12% included the engine improvements if I had said 12% from aero. The post ceded that the 12% could be all aero.

    That graph is a visual representation of their strategy with these new engines, which is essentially further downsizing of the engine with more input from the electrical side. It isn't specific to any one of the three engines discussed, and I was only claiming the NA1.5L would be used in a series hybrid.
    Toyota said the current engines would lose power when made to meet upcoming regulations. It was the drive for developing these engines. Dashed white dot is labeled the current engine. The solid white dot is the current engine with added emission controls.
    And yet the new turbo1.5L is less efficient than the NA2.5L that it is compared too.

    "This new engine complies with regulations that would require the existing model’s power to be cut by 30%." - Toyota Times

    The SAE news article also cites Hiroki Nakajima, Toyota CTO, using the 30% in regards to power difference.
     
  6. Gokhan

    Gokhan Senior Member

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    OK, good, but again, gains will have to be more than 12%, and the Toyota news never ceded that it could all be aerodynamic. In fact, you can see that even their new turbo engines will have a thermal-efficiency gain over their current turbo engines.

    But that rectangular inverter housing is also found in Gen 4 and Gen 5, isn't it? I can't imagine Toyota changing its hybrid design completely. That would be an unwise engineering move, especially given how conservative Toyota is. Moreover, a series hybrid would require a much larger electric motor than that rectangular box can contain.

    So, if the power would have to be cut by 30% in the current engine, than the carbon emissions would have to be reduced by 30% in the new engine. That requires a combination of thermal-efficiency gains and other tricks, possibly including alternative fuels. Both their current and new turbo engines are less thermally efficient than their current and new naturally aspirated engines. Moreover, the thermal-efficiency gains in their naturally aspirated engines will be a lot higher than in their turbo engines according to the plots they provided. I don't think it has anything to do with a potential series hybrid. They are using turbo to avoid large and heavy engines at the cost of thermal efficiency.
     
  7. austingreen

    austingreen Senior Member

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    Is it though, that's the one they seem to be claiming the 53% efficiency for in other places.

    https://www.motor1.com/news/721489/new-toyota-engines-details/
    30% increase in efficiency would make it around 53% efficient. The only way to do that in an aluminum block gasoline engine would be using the waste heat - a turbo does this. This likely is a turbo tuned for efficiency, while most turbos today are tuned for power.

    This one will be tuned for power and efficiency if correct. It won't be as efficient as the 1.5 liter as the 2.4 turbo is less efficient than the current 2.5 Atkinson. The highlander with the 2.5 hybrid is much more efficient than the 2.4 turbo even on the highway where the hybrid doesn't help much

    Compare Side-by-Side



    we should be able to see what real efficiencies are sometime in 2026 if these are going in real cars.
     
  8. Trollbait

    Trollbait It's a D&D thing

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    The quote from Motor1 is the one I believe was the result of a telephone game error. Someone made an error in switching power to efficiency, and other sources simply 'copy and pasted' it without checking the primary ones.

    Here is the Toyota CTO's presentation graph comparing the new 1.5L turbo to the current 2.5L.
    upload_2024-6-10_16-36-33.jpeg
    https://www.subaru.co.jp/news/2024_05_28_184137/TOYOTA_CTO.pdf

    Toyota has said that getting the current engines to meet Euro7 and other upcoming regulations will result in power loss. I believe the solid white circle on the graph represents this modified current engine. The Toyota Times even reported this loss for the 2.5L was 30% (The Engine Reborn--Three Companies Develop ICEs for Decarbonization).

    This is how the SAE reported it, "The new 1.5-L turbo engine would be similarly smaller (a 20% volume reduction and a 15% height reduction) compared to the current 2.5-naturally aspirated engine and will trade slightly worst fuel-efficiency for a 30% improvement in horsepower." - Toyota, Mazda, Subaru agree carbon is ‘enemy' with internal combustion engine announcement. They missed the part about the power and efficiency differences being to a modified version of the current engines.

    I haven't seen 30% and efficiency used in conjunction in any of the Toyota sources. Only at Motor1, though I noted others had copy & pasted from the source they had used upon skimming.

    From that graph, it doesn't look like Toyota has done anything new from others using a turbo down sizing for economy. While the 1.5L turbo's peak efficiency is less, under the lighter loads of emission and economy testing, a car with it will get better ratings than the 2.5L. The new part is in making the engine smaller, and using a greater degree of electrification to offset reduced torque from that. Simply put, an engine for a hybrid only.
     
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  9. hill

    hill High Fiber Member

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    As we dialogue whether a Prius will or won't ever have this new type of engine, it might be noteworthy to address how sedans in general are going away in favor of pickups & SUVs, electric or not. Maybe the question isn't whether or not a future prius engine will ever come to be, but whether there will be a next Prius at all - since the very features Prius used to stand alone with are now becoming available in all other Toyotas. All manufacturers tend to develop the lien & mean build philosophy. Long gone are the days where you could get 3 or 4 similar models that differed primarily by chrome moldings on sides & back.
    .
     
  10. Gokhan

    Gokhan Senior Member

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    Toyota Times said that:

    By contrast, the new engine retains output thanks to improved combustion technology.

    To me, this reads like they have increased the thermal efficiency to reduce the carbon dioxide so that they could have the same power output while still meeting the new emissions regulations. I wouldn't be surprised if the new 1.5-L naturally aspirated engine actually has a thermal efficiency of 53%. Specifically, the improved combustion technology refers to the turbulent combustion used to achieve super lean burn at or close to a stoichiometric ratio λ = 2.5, similar to what is in the Toyota paper I posted here. Perhaps they are doing this only for the naturally aspirated engines, as it could not be possible to have super lean burn in a turbo with a very high BMEP.
     
  11. Trollbait

    Trollbait It's a D&D thing

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    My comment was to the graph for the 1.5 turbo; the only graph in the post.

    There is a lot of unknowns with the 1.5L NA. It has that black box. What is it; generator, built in transaxle, something completely different? Don't know if the 1.5 turbo has it, but the 2.0L turbo doesn't.
     
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  12. Numtini

    Numtini Member

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    It's already cheaper for me to run my Prime in EV than HV mode.
     
  13. telmo744

    telmo744 HSD fanatic

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    I simply do no believe such high figures in a wide range of the bmep-rpm map.
    Been here long enough to study ICE technologies in the 90's, and watch the extended expansion cycle being wide spread for the past 10 years...
     
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  14. Trollbait

    Trollbait It's a D&D thing

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    It also overlooks the fact that engines reaching 50% thermal efficiency do so with the use of some waste heat recovery tactic. The car engines use some form of turbo charging, and ccgt power plants have a second turbine generator in the exhaust stream. Even the Toyota paper referenced involved work with a turbocharged engine.

    Maybe the box has some new heat recovery system in it. Reaching 50% efficiency doesn't mean the car can make regular use of it though.
     
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  15. hill

    hill High Fiber Member

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    people presume, then do it as Authority. Cost for fuel is spread over quite a wide spectrum. SoCal Edison (SCE - different rates varrying via time of day, season & amts used) while using juice at tier 3 (easy amt to reach - car charging)
    may run you 42¢/kWh. That equivalent amount of gas might be around $5/gallon. That's almost what regular is going for currently - today.
    If you're running fully amortized rooftop solar? You can't match that - fueling on gasoline.
    But all of that turns on a hypothetical engine & hypothetical fuel prices "if" that ever even happens. Will check back if this ever becomes a future reality.
    Is this ICE coming sooner than Toyota's promised ubiquitous hydrogen cars? Solid state batteries?
    .
     
  16. Trollbait

    Trollbait It's a D&D thing

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    This ICE may be part of their hydrogen car push. The claims being made for Toyota may require hydrogen injection to reach with gasoline. Hydrogen was also mentioned for a carbon neutral fuel.

    Looks like Euro7 for new car types goes into effect sometime during 2027. The engines need to be ready by then.
     
  17. Gokhan

    Gokhan Senior Member

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    No… I don't know why you keep repeating this despite I having explained it to you.

    As I tried to explain you before, the hydrogen injection was only done to study a high stoichiometric ratio λ in existing engines to see what happened before developing the all-new engine, which did not use hydrogen at all. They had to see what happened at a higher λ before they could design the all-new engine.
     
  18. Gokhan

    Gokhan Senior Member

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    Yeah, the electricity is expensive here, and it will probably get even more expensive with the increasing usage with the increasing number of BEVs. They will also start giving free electricity to low-income families here, which will not only make the rates even higher but also increase wasteful usage. I don't know why it is so difficult to realize that if you give something for free, it is wasted.
     
  19. Gokhan

    Gokhan Senior Member

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    I don't think there is any new magic in that rectangular box. The Turquoise Jewel (my 2021 Prius Prime Limited) has the same rectangular box, except it is painted in black as the Rolling Stones would say. Perhaps Toyota hasn't had a chance to paint the new box yet and that's all. ;)

    [​IMG]
     
  20. Trollbait

    Trollbait It's a D&D thing

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