Generating the levels of boost necessary to propel today’s race-level, hyper-competitive machines takes a degree of mechanical understanding and a level of precision that few speed shops can generate. Industry-leader RIVA Racing has proven its commitment to developing, testing and delivering repeatable performance gains since 1991, and maintains that promise today with two brand new impeller wheels for the SVHO (Super Vortex High Output) Yamaha Marine Engine, as well as an all-new XX-Charger Kit for the 300 ACE-powered Sea-Doo.
All three impeller designs began as “clean sheet” designs despite years of offering impeller wheels for these two platforms since their respective introductions. The intent behind each entry was to maximize the total boost or psi (pounds per square inch) throughout the engine’s powerband. Previous iterations build boost in a gradual curve, increasing the positive atmosphere progressively; the new impeller designs by RIVA provide greater boost earlier in the curve, continuing to increase throughout the band.
For Yamaha applications, RIVA Racing designed two impeller wheels for the SVHO that do not require any milling or modifications to the factory housing itself. Although part of the Stage 3 and higher levels of modified engines, removing the need to machine the housing saves engine builders a major step. Rather, the new R3 and R4 impellers ($499.95 each) generate increased boost pressures earlier and continually, delivering increased horsepower and torque throughout the RPM curve without permanent modification.
These gains are achieved via two methods: Radical new blade designs that maximize internal volumetric efficiency and optimized precision machining. Each impeller wheel is machined within exact tolerances, resulting in an impeller wheel without the telltale “bite marks” taken out of the leading edge – the result of post-production balancing. Made from 2618 US forged aluminum and machined in North America, each impeller is anodized to prevent corrosion, and labeled with RIVA’s logo via laser etching.
Although not visually significant, the differences between the RIVA Racing Yamaha SVHO R3 and R4 supercharger impellers are significant when comparing the boost pressures throughout the acceleration curve (particularly when reaching revolutions above 8,000rpm). Each requires an engine management tune and supercharger shaft upgrade kit to handle the radically increased boost pressures:
Yamaha R3 Impeller Boost Performance
• 8psi@ 6,000rpm
• 11psi @ 7,000rpm
• 15.5psi @ 8,000rpm
• 17.5psi @ 8,500rpm
• 20psi @ 9,000rpm
• 22psi @ 9,500rpm
Yamaha R4 Impeller Boost Performance
• 8.5psi @ 6,000rpm
• 11.75psi @ 7,000rpm
• 16psi @8,000rpm
• 19.5psi @ 8,500rpm
• 22psi @ 9,000rpm
• 25psi @ 9,500rpm
For Sea-Doo enthusiasts, RIVA Racing offers an all-new XX-Charger Upgrade Kit ($649.95) for all 300 ACE 1630 applications. Unlike the two Yamaha SVHO applications, to best maximize the efficacy of the new XX-Charger impeller wheel, RIVA includes a billet spacer made from the same 2618 US forged aluminum as the impeller itself. This 3mm spacer fits between the front and rear housing of the factory supercharger, increasing the housing’s total volume, permitting RIVA to design a taller, more aggressive blade design for wheel.
Due to the superior materials used, RIVA is able to shave 22 grams off of the impeller’s wheel (168 grams) over stock (190grams), meaning although taller and more aggressive, the XX-Charger wheel is lighter and better balanced. This also means less wear on the clutch and bearings. Similar to the aforementioned Yamaha R3 and R4 impellers, the XX-Charger impeller is precision machined so there’s no need for re-balancing after final machining.
Equally, the XX-Charger is anodized for corrosion resistance and is made entirely in North America – so no waiting for a container ship from overseas. For those professional racers, the new XX-Charger Kit is also IJSBA Limited Class legal; otherwise, the impeller upgrade is designed for dedicated performance enthusiast running the Stage 3 or Stage 3+ kit with an upgraded engine management tune and fuel delivery system, as the XX-Charger produces a peak 17.5 psi at 8,700rpm – nearly double the peak psi of the stock impeller wheel.
Sea-Doo 300 ACE XX-Charger Boost Performance
• 12psi @ 8,000rpm
• 15psi @ 8,400rpm
• 17.5psi @ 8,700rpm
As RIVA Racing remains unrivaled in its ability to design, prototype, test and manufacture some of the industry’s most successful performance products, it’s also the tip of the spear when it comes to customer assistance and troubleshooting.
RIVA has a full technical support team dedicated to answering emails and phone calls if you’ve got questions regarding your particular application or deviations from RIVA’s prescribed packages. As RIVA Racing president, Dave Bamdas stated, “Even if you’ve got a somebody else’s camshaft, we can work with you to get that calibration – through MaptunerX – to get that to work with your package.”
Superior performance has never been this easy, and RIVA Racing remains at the forefront of this effort. If you haven’t already, visit www.rivaracing.com, enter in your personal watercraft into the search function and begin perusing the pre-packaged Stage Kits or scour the catalog of parts to begin building your ideal performance package.