Most of the production engines still use tumble flow combustion

For reference: Nissan e-power with recuperation ~50%: https://www.nissan-global.com/EN/INNOVATION/TECHNOLOGY/ARCHI...

Mahle ~45% with pre-chamber: https://www.mobilityengineeringtech.com/component/content/ar...

Toyota dynamic force engines ~40% : https://www.thedrive.com/tech/18919/toyota-develops-worlds-m...

Toyota's newest engines claim even more: https://global.toyota/en/newsroom/corporate/40850156.html

Honda hybrid ~40%: https://hondanews.com/en-US/honda-automobiles/releases/relea...

Startup Carnot engines claim 70% efficiency: https://carnotengines.com/technology/

>Mahle ~45% with pre-chamber

That looks deceptively simple and counterintuitive. Mentioned Honda CVCC injects fresh air/fuel mixture into pre chamber. Mahle passive doesnt at all. How does it accomplish detonation in the first place? How does the fresh air/fuel get into the chamber thru those tiny nozzle openings? there must be something they arent showing like additional channel leading close to intake valve.

What’s the catch with the Carnot engine? If if’s real then surely this would be a global news worthy breakthrough?

> Carnot is targeting the hardest to abate sectors including [long haul] marine [transportation], heavy-duty vehicles and primary off grid power.

Even if great advances were being made, these are not very interesting sectors to the vast majority of people and the industries have massive inertia. Presumably Carnot's therefore unlikely to be grabbing headlines.

But such an improvement in efficiency would surely reduce fuel costs, which matter a lot to consumers, though maybe not in the US where it’s cheap.

The power unit in F1 generally refers to the ICE and the MGU-H & MGU-K. This article doesn't mention nor specify the actual numbers.

Mahle / Ferrari were getting 45% or so out of the ICE a few years ago with pre-chamber ignition.

The only manufacturer to release any details about their powertrain technology.

They've detailed their work on engine/MGU-K/MGU-H/ESS here: https://global.honda/en/tech/motorsports/Formula-1/

UMmmmm, actualy there are no details, it's more like bait, layed out in front of the rabbit hole. What it does outline/hint at is the methodology of there thinking about engine development, within the arbitrary rules of F1. And what they, and everybody else leaves out, is that limitations in material sciences is the reason for the engineering heroics, and that access to say, the single crystal materials used for jet turbine hot section blades, would allow higher combustion temps and pressures, and greater efficiency, in NA engine, that would outperform anything built yet. The reason that F1 cant do that is money, and compared to true airospace development,F1 has lint in there pockets, and have falken back onto 1940's turbocompound aircraft engine technology.

what are you even talking about? A lot of stuff is clearly laid out on how they achieved better efficiency.

You can get more power out of NA with better materials you've stated but not efficiency.

F1 wanted more road relevancy and hence ended up with turbo-charging and Fuel limits

zero mechanical details, nothing verifiable is zero information, plus there is a long venerable tradition of lying like hell whenever you talk about competitive advantages :) efficiency goes with materials, as a higher temperature and shock loading, will permit higher compression ratios, and that is as far as I know the only way to exract energy from a piston engine well unless the piston part is just viewed as a gas generator, but whoa betsy, the rabbit hole is looming before us, and having listened to folks involved in engine development (including F1), I am just a spectator,engines are hard, and these days anyone who could do ICE, is looking at other stuff, or retirement ceramics have come close, but dont have the reiability when produced at the scale needed for mass market

Engines are hard, but Honda's problem always was the gearbox, which is much harder. And it's not simulatable.

But I like Honda. They have the very best company leader.

What are the NOx emissions?

Given that they weren't optimizing around them, I'm guessing not-so-good. But maybe I'm wrong.

Likely high, other posters say the operating temperature is higher than a traditional gasoline engine, and NOx is formed when N and O2 from the atmosphere are heated. I wouldn't expect exhaust treatment on an F1 engine.

Nitrogen oxides, NO2, NO3.

They're generally toxic in large concentrations and I think a greenhouse pollutant.

If they cared they could probably use a DEF system to reduce them.

This sounds like a game changer, can it be adapted to low power engines at some point?

Ferrari's partner MAHLE has pre-chamber ignition productized for OEMs: https://www.mahle-powertrain.com/en/experience/mahle-jet-ign...

I think, Maserati MC20 has this tech.

This is misleading. The article doesn't claim a specific thermal efficiency anywhere. Not sure why the title of this post says >50%.

Also, the engine itself is not achieving >50% thermal efficiency. The propulsion system is a hybrid electric / ICE unit that is designed inside and out to be able to recover potential energy in a variety of ways, and then turn that back into kinetic energy that propels the car.

So to say that the "engine" technology enables ">50% thermal efficiency" is completely untrue.

Now, to look at the merits of the article. The specific technology that they are claiming to have advanced here is "Rapid Combusion" and "Lean Boost." Rapid combustion refers to the layout of the fuel injectors in relation to the spark plug and the fuel injector timing. In early SPFI (Squential port fuel injection) vehicles and earlier, air was pre-prepared and fully mixed with an adequate amount fuel before it entered the combustion chamber. This mixture enters the combustion chamber and is ignited by the spark plug. The flame front propagates away from the spark plug until the (air within the ) mixture is consumed.

What Honda is doing now is injecting only a small amount of fuel into the combustion chamber up front. This small amount of fuel is ignited by the spark plug, and then the rest of the fuel is injected into the cylinder. This enables Honda to use another technique called "lean boost" that has been around in diesel engine technology for decades.

By initiating combustion with a small amount of fuel, the flame front propagates faster and burns hotter. The added intensity of the burn means that subsequent fuel injected into the cylinder will self-ignite without any further spark from the spark plug. These two flame fronts essentially "meet in the middle" of the combustion chamber. Tech geeks can think of the performance improvement of having two concurrent flame fronts propagating simultaneously as an improvement similar to the data transfering out of a RAID 0 array vs a single drive.

Because the fuel mixture is injected directly into the combustion chamber, (instead of being mixed outside and then pushed in like SPFI) pre-detonation is virtually impossible. Pre-detonation is avoided in passenger cars by injecting more fuel into the combustion chamber than what is required. This additional fuel doesn't carry additional power, but it makes the mixture robust enough to withstand high temperature and pressure long enough for the spark plug to ignite the mixture in a controlled way. In an F1 car, wasting fuel for this purpose is not acceptable. This is where "lean boost" comes into play.

In a passenger car, the fuel mixture is already in the combustion chamber when the piston begins it's compression stroke. So the mixture must be robust enough to withstand being compressed by the piston. In an F1 car, the fuel is absent until the piston has reached the very top of it's compression stroke. So in an F1 car, the fuel mixture isn't exposed to high temperature or pressure until the very moment it is expected to burn. As a result it is possible to inject a lesser amount of fuel than what is ideal. The ideal mixture of air:fuel for petrol is 14.7:1. In a passenger car this is a little bit lighter, say 13.5:1 to avoid pre-detonation. In an F1 car they go the other way say 15.5:1, because it saves fuel and there is no risk of pre-detonation due to other design factors.

Mercedes crossed 50% thermal efficiency in 2018 with their F1 engine: https://www.roadandtrack.com/motorsports/a15049580/mercedes-... Their recent interviews suggest they are up by 2 to 3% on that

Honda did too but they never marketed the explicit number.

The geometric compression limit for F1 is 18:1. They make it sound like they can go farther.