Toyota's WTF development of the month. But it make cool noise and kept the engineers entertained. Personally, I prefer the lack of noise from BEVs and would rather see the engineers doing something more useful.

Hydrogen ICEs might make some sense if there was a low cost supply of clean hydrogen but, at the moment, it does not exist. The best possibility for reasonable cost clean hydrogen is high temperature thermal chemical reactions using Gen 4 high temperature nuclear reactors. However, Japan shut down most of their existing nuclear reactors so they can not even do high electrolysis. Even if you had a low cost source of clean hydrogen, fuel cells are more efficient although they probably cost more. Also, even if we had reasonable cost hydrogen, the first use should be to replace the steam reformed hydrogen that is currently used in industrial chemicals.

Carbon-neutral synthetic fuels make a lot more sense if you want to continue with internal combustion engines. Make a gasoline or diesel drop-in replacement that uses existing fueling infrastructure. Of course that doesn't require you to make cool new engines.

With intake manifold on the outside, and exhaust manifold on the inside of the V, that motor only makes sense as a speed boat motor. It is too high profile to fit under the hood of a land transport vehicle and even if you did (truck) the rest of the exhaust plumbing would be nightmarish.

A boat is also the only vehicle that could carry enough fuel to power a 450 hp motor motor more than very short distances between refueling.

H2 is gravimetrically more energy dense than gasoline, but much worse volumetrically.

This is an engineers implementation of a fantasy that will appeal to fans of Ed "Big Daddy" Roth‘s illustrations.

Those old codgers who trailer their lovingly maintained or restored classics to “Cruisin the Coast” on the Mississippi Gulf Coast every year to slowly drive by other old codgers slouched in beach chairs along the roadside who cheer the occasional massive burnout made possible by applying the front brake line locks.

Fun times, fun times.

Well, at least they will be able to turn their beach chairs around and watch this new fangled technology cruise by on the water without choking on the raw hydrocarbons flowing unrestricted from those muscle car and rat rod exhoust pipes. That’s bad for the COPD.

Inside-the-V exhausts are used on diesels these days; it reduces the amount of plumbing required between the head and a single turbocharger.  Of course, they don't use outlandish tuned manifolds like the one shown.

Cast exhaust equalizes temperature between the banks

EP the lunatic insulter

If this H2 engine can develop 450 hp on H2 fuel without melting, it would be a great accomplishment, because H2 burns hotter than gasoline. I suppose direct injection and generous H2 fuel enrichment would be necessary to put out this kind of power!

What H2 engine really shine is high-efficiency and low emission at mid to low power range, when H2 's very rapid combustion permits very high EGR ratio and still burns rapid and complete enough to permit higher efficiency and lower emission than comparable gasoline engines. Toyota's gasoline engine now is capable of 41% thermal efficiency, and with H2 combustion characteristic permitting high EGR for high thermal dilution hence lower heat loss and lower pumping loss at part-load, ...can achieve 45-50% efficiency?...Almost on par with FC? Don't write off H2-ICE just yet!!!

Hydrogen certainly has its justification as a rocket propellant or as a chemical component in some other chemistries but not as a propellant for mobility via land, air, or sea. It is, however, unbeatable as a fuel for aneutronic fusion. What development potential does H2 have? None! H2-ICEs underline the peak of stupidity. Life is difficult, “it is the most difficult of all” especially for the stupid.
Solid state batteries document the SOA. Quantumscape has the lead worldwide not only in their anodeless battery chemistry but in their specific technological platform as well. Once the transition “from lab to fab” has succeeded, there surely is still potential for further improvement. As far as battery development is concerned, we’ve experienced an unparalleled surge in a relatively short period of time. There is a long road of technical potential ahead of us before we reach its end. That definitely cannot be said for H2.

It would be very unconventional to mount fuel injectors on the inside of the V next to the exhaust manifold, but variations of the UR family V8 this engine is based on came with conventional manifold injection, direct injection and both manifold and direct injection.

I don’t see any plumbing for direct injection, and running fuel, even gaseous hydrogen, alongside those exhaust pipes would be extremely problematic. It’s not impossible that this engine has direct injection in addition to the manifold injection we see slots for.

I’ll give Roger credit for having a better imagination than mine.

I've been looking at the sulfur-iodine process for thermochemical separation of water, and I realized that the use of hydrogen as a medium- to long-term (days to months) energy buffer fills a gap in the capabilities required to fully decarbonize energy supplies.  If we can get 52% heat-to-H2 efficiency in H2 generation and 50% in consumption, it's not too much worse than stored H2 run through CCGTs to charge batteries and the downtime for refills is less than charging.  Aside from the thermochemical stuff, the technology is already here and no scarce or precious materials are required.

Aside from the thermochemical plant (which i figure may cost about $1.00/kgH2 while amortizing and about $0.25/kgH2 afterward on top of the heat input) we'd need nuclear reactors running at about 1000°C.  We've already gotten close to this, so it has to be considered within reach.

This Yamaha Hydrogen engine is very intriguing!
Not only are the exhausts in the Vee but they are also 8 into one. The engine is based on the Toyota 2UR-GSE v-8 used in the Lexus IS-F and RC-F, this engine has both Port and Direct Fuel Injection, Variable Valve Actuation, and combined Atkinson/Otto Cycles. The Hydrogen engine also has almost the same power as the gasoline engine - 450hp.
Not much else is known. Definitely a design exercise (it might fit in a race car, not a front engine car like the Lexus IS-F). Many questions: Are the exhausts used for scavenging purposes? Does the Port Injection add a dilute H2 or water injection for cooling purposes? What is the thermal efficiency? Hybrid Application?
Yamaha is a R&D company (originally developed the 2UR-GSE) and are also into electric motor design, e.g. the Hyper EV electric motor in the Subaru STI E-RA EV.
Additional information would be interesting.

Agree with E-P's assessment about using nuclear energy for transportation. It seems that molten-salt Thorum reactors are most promising, safe, and very abundant source of energy to complement Renewable Energy. Countries that are low in RE potential like Japan, Korea, and Western Europe should invest heavily in new nuclear energy techs in order to become energy independent. We can make PHEV's instead of BEV's, that requires only 1/5-1/8 the battery capacity of a long-range BEV, and use grid electricity to drive in Springs and Falls when power consumption is low, while use H2 to drive in Summers and Winters when power consumption is high.

@Thomas,
If you already have H2, then why not use it directly on board vehicles instead of using power plants to make electricity and use it to charge batteries. This is because Summers and Winters have the Electricity Grid heavily utilized, and if adding more power consumption to charge BEV's will need expensive Grid upgrade, PLUS massive investments in battery-making plants to the tune of $5 Billion USD per GigaFactory to make 500,000 BEV's per year. Why not make PHEV's instead, that requires only 1/5-1/8 the battery capacity of a long-range BEV, and use grid electricity to drive in Springs and Falls when power consumption is low, while use H2 to drive in Summers and Winters when power consumption is high?

@Gryf,
Yes, port injection with water at high engine load can be used to reduce combustion temperature to lower NOx emission and to ensure engine durability, and to avoid fuel enrichment to improve fuel efficiency at high load. The water can be obtained from condensing exhaust gas, which contains high water vapor concentration, being the sole end product of combustion. One can look at water injection as another method of EGR, and in liquid form, permits full-volume Oxygen intake to permit maximum power WITHOUT fuel enrichment, as well as raising maximum power output due to evaporative cooling of intake air, as well as washing the intake valve from the carbon built-up from the gaseous EGR process and PCV process.

@ECI,
Why not use this engine in land-based Motorsport application? Motorsport carries only the driver and zero luggage space, thus plenty of space for fuel. Why not use Liquid H2, that is much lighter than petroleum fuel or methanol, thus permitting even better performance? The larger fuel tank size to carry H2 is of no problem in Motorsport.
Remember that BEV's have WORSE problem than H2-vehicles with energy storage density, BOTH volumetric and gravimetric wise.
Remember that the H2-ICE can have water injection for high-load cooling instead of using very rich fuel mixture in racing engines, thus making it more efficiency at racing power regimes when compared to gasoline or methanol racing engines.
Remember that Toyota gasoline engines are now capable of 41% thermal efficiency, with Toyota H2-ICE to be capable of nearly 50% thermal efficiency, which should stretch the fuel supply pretty far in comparison to previous gasoline racing engines.