Japanese motorbike and marine engine manufacturer Yamaha will present at the next Miami Boat show in February 2024 a prototype of a 5.6 liter V8 outboard motor running on hydrogen. Specs are scarce, but Yamaha already developed a 5.0 liter V8 car engine on hydrogen for Toyota in 2021.
Yamaha is also working on fuel cells for marine applications but sees combustion engines burning hydrogen as a viable future solution for outboard engines for boats and recreational offroad vehicles or unmanned helicopter drones. Burning hydrogen has the advantage of releasing no CO2 but emits NOx, formed when air is heated to high temperatures.
Ten times more power is needed
One of the main problems for marine motors is that the density of water, compared to air, requires ten times more force than a land vehicle to move. So you can opt for batteries like in EVs today, but in theory, this would require ten times more battery power than on the road.
Unless you can reduce resistance significantly, like with hydrofoil boats, which are lifted a meter above the water once they reach a speed of approximately 17 knots (31 km/h), as only the torpedo-shaped propulsion pods stay underwater.
Like in Swedish Candela’s hydrofoil boats with a Polestar battery or the Frauscher x Porsche 850 eFantom Air that was presented in October. But even then, the range is limited to 50 nautical miles (92 km) at 20 knots, although the Candela C-7 set several world records for electric boats with that. With the Frauscher Porsche, you will get only 22 nautical miles (41 km) at a cruising speed of 22 knots or 45 km/hour, despite the vast 100 kWh battery.
140 liters of fuel per hour
So, an alternative is to convert proven internal combustion engine technology for outboards for burning hydrogen. Although Yamaha refrains from details on the hydrogen outboard it will present in Miami, it’s known it is an adaptation of the 5.6-liter XTO V8, which produces up to 450 hp on conventional gasoline fuels.
That one consumes already 3,5 liters per hour just running on idle and a whopping 140 liters per hour at wide open throttle (WOP). Even if hydrogen delivers about three times more energy than gasoline, you’ll need vast amounts of it in compressed form for this type of engine.
It remains to be seen what Yamaha USA, which is to develop the boat for the hydrogen engine to be shown in Miami, will propose as a solution. However, according to a Yamaha spokesperson, tests were carried out in the US at the Yamaha test center with American construction partners, and “this showed that it works”.
Converting V8 Lexus engine for Toyota
Yamaha already has some years of experience with hydrogen combustion engines as it converted a high-performance 5.0-liter 90° V8 DOHC 32-valve engine to use hydrogen for Toyota.
This one came from the Lexus RC F luxury sports coupé, with modifications made to the injectors, cylinder heads, intake manifold, and more, and delivered up to 450 hp at 6800 rpm and a maximum 540 Nm of torque at 3 600 rpm. For instance, the hydrogen version was used in the Toyota Corolla in the 2021 Super Taikyu endurance racing series.
Honda, Kawasaki, Suzuki, and Yamaha announced in October of this year they have agreed to develop hydrogen combustion engines to decarbonize two-wheelers and other compact vehicles. This consortium will focus mainly on the research for the viability of this type of powertrain, with no production plans quite yet.