Yamaha Jet Watercraft Engines - SVHO
This CAD image shows the new forged pistons at the heart of the SVHO engine. They connect to the crankshaft, then the drive shaft and the new impellor in the redesigned jet-pump unit.
Pistons: Taking what they have learned from their racing teams, Yamaha has redesigned the pistons in the SVHO in addition to now manufacturing them from forged steel. The result has created pistons that are 30% stronger, which will help to increase performance and add to the already excellent reliability.
This CAD image shows the new supercharger on the forward end of the SVHO engine running off the main crank shaft, forcing compressed air through the intercooler.
Supercharger: One of the ways that all watercraft engines have been able to provide higher horsepower is through the use of superchargers and the SVHO is no different. Knowing the potential for this component to be a weak point, Yamaha has redesigned its supercharger, which many considered the best in the market, and made it even better. They have taken another cue from its racing teams and added a seven blade, 86mm impeller with the result of increasing the boost by 22%. This, in conjunction with all of the other changes to this engine, has increased the total boost of the engine by 60%.
Yamaha’s new larger intercooler.
Larger Intercooler: The power or energy for an internal combustion engine comes from the expansion of gases when igniting the fuel air mixture. Air that is hot is already expanded to some degree, so the cooler the air feed into an engine, the greater expansion of gases is achieved, resulting in more power and reducing the amount of fuel required. Yamaha has added a new, larger, more efficient intercooler, which by its testing shows an improved efficiency of 25%. Our testing of the SHO engine over the years has shown a consistent level of fuel efficiency, so we look forward to testing the SVHO to see if this still holds true.
The oil filter is mounted to a two-part oil cooler which is larger and a more efficient design.
Oil Cooler: Because this engine utilizes a wet-sump for the oil system, keeping the oil cool is important for the efficiency as well as the longevity of the engine. Yamaha has redesigned the oil cooler choosing a larger, more efficient design which is able to dissipate heat up to 110% more effectively.
Here you can see the fuel injector mounted through the intake manifold leading into one of the cylinders.
Fuel System: Being able to regulate the amount and flow of fuel into each cylinder is reliant on many factors, one of these being the availability of fuel. The SVHO has larger fuel injectors to ensure better fuel flow. This does not mean the engine will burn more fuel. Fuel burn is dependent on fuel air mixture, how efficiently the fuel was atomized before being injected into the cylinder and the pressure that the system is running on.
The fuel delivery rail is located on the starboard side of the SVHO engine and feeds fuel to the new larger injectors.
Power and Torque: Yamaha has spent years on research and development on its engine design and has taken full advantage of engineering technology and experience from racing. All of these developments comes together in the SVHO to create in an impressive new engine. The team at Yamaha tells us its dyno testing shows the SVHO is delivering 20% more power and torque than its predecessor, the SHO engine.
This CAD image show the marriage of the SVHO engine package with the new jet-pump unit as installed in the Yamaha FZ Series.
New Pump: Anyone who has been riding or racing PWCs for many years knows, having a great engine package is only part of the performance equation. Effectively utilizing the power and transferring it to the water is a critical factor. Yamaha has paired the SVHO with an entirely new jet-pump unit for the 2014 FZ Series. The most notable design change is the addition of an 8 vein impeller. Many who ride have been purchasing aftermarket impellers for years, experimenting with all kinds of combinations. Yamaha has optimized the transfer of power by increasing the surface area in contact with the water with five more blades. In addition, they have redesigned the shape and size of the jet-pump and nozzle which now measures 160mm. Just as on the engines of a fighter jet, the shape and size of the jet nozzle has an impact on performance and we fully support this design change.
On the left is the standard 155MM 3 blade system with a 75MM hub, while on the right is the new design, 160MM 5 blade system with a 75MM hub. Note the addition of a fourth retaining bolt.
This CAD image shows the new intake grate (mustard colored) at left as it attaches to the jet-pump unit.
Intake Grate: Feeding water to the new jet-pump also required great consideration and eventually a new design. Again, inspired by experience on the racing circuit, Yamaha redesigned the intake grate to make it larger with the addition of what Yamaha calls a “top loader” design. Essentially, this is a direction scoop helping to channel the flow of water into the jet-pump unit.
This is the Yamaha 2014 top loader intake grate for the new jet-pump unit.
Conclusions: Over the last seven years we have tested every watercraft that Yamaha has brought to the market. We have found them to be well designed, very well built, and perform at or above expectation. As experienced watercraft enthusiasts and owners, we fully agree with the design changes and improvements that Yamaha has made to both the new SVHO engine, the intake and jet-pump unit. When we compare the overall weight of the FZ Series with the new power package, we see an optimum power-to-weight ratio.