The larger the turbo, the later the boost comes on. This GT30 will certainly be a handful on the street.
All of the turbo kit's electronics are housed cleanly on a Tiger Tail that replaces the stock undertray.
Secondary injectors will mount on top of the plenum and provide the extra fuel needed under high boost conditions.
The side mounted dump pipes and a shortened oil pan will allow the bike to get as close to the ground as possible.
While there are many paths to making big power, it’s a turbocharger that will ultimately produce the most impressive horsepower figures. There are several renowned companies that produce turbo systems, and while they all operate on the basic principle of forced induction they take different configurations in their design. Furthermore, there are different levels of intricacy, from a bolt-on turbo kit to a top level, race only design that’s not only extremely elaborate but also very expensive.
We opted for a middle of the road, do-it-all turbo system from Velocity Racing. The Stage 2 kit includes everything necessary to make upwards of 400 horsepower (with a properly reinforced engine) while still remaining streetable and user friendly. Our objective was to create a daily rider that the average guy could own without too much grief, but it’s still a good idea to have a firm grasp of how a turbo system functions so you can maintain it properly and make minor adjustments when needed. For the most part, the ownership experience should be turnkey and problem free if a reputable shop performs the installation and tuning though.
The general biking public shares a negative view toward turbocharged bikes. Turbos have gotten a bad rap over the years as being unreliable, but most of the issues eventually point to user error, not mechanical failure. The situation that the Japanese manufacturers created in the early 1980s with their poor attempts at creating mass produced turbo bikes certainly didn’t help the perception that turbos can be safe and reliable, and fly-by-night tuners have also left some sour sentiments within the industry.
Building a turbo bike shouldn’t be done on a whim, nor should it be pieced together in your garage for the lowest price possible. Cheap kits (purchased on eBay) are inferior and will lead to problems due to poor fitment, leaking seals and knock-off turbos. To avoid the inevitable problems associated with DIY kits we handed our Hayabusa over to RPM Cycle Performance, who also owns Velocity Racing and let them have at it. RPM handled the entire operation, from the internal engine build to the turbo installation and tune. The shop also supplemented the project with some of its own products to help reach the highest performance figures possible.
Garrett GT30 Turbo
The heart of the turbo system is, of course, the turbine that compresses the air, in this case a Garrett GT30. Different turbo sizes are used with different goals in mind, and for our application the GT30 was the best bet. It spools up quick for use on the street and can make plenty of power when really pushed for land speed racing or drag strip laps.
RPM Cycle Performance sources the turbo from Garrett, then builds the manifold, plenum, exhaust and dump pipe and all other fittings necessary to make it function properly. Note the stylish bends in the exhaust and dump pipe that are far more aesthetically appealing than many other styles of straight pipes.
Water Injection, NLR AMS-1000, Bazzaz Z-Fi TC
The trunk space is generally the location for all of the electronic gadgets to reside as there is lots of room and it’s away from the engine’s heat. But because the Stage 2 system is more advanced than the Stage 1, it requires more electronics, and this is where the aluminum Tiger Tail saves the day. It’s designed to efficiently hold items that otherwise may not fit properly using the stock plastic undertray.
Bazzaz Z-Fi TC
Fueling for the primary injectors is being controlled with the stock ECU, while the secondary injectors utilize a specialized fueling computer designed specifically for Velocity Racing turbo kits.
We opted to use a Bazzaz Z-FI TC system not for its fuel control capabilities, but because it offers traction control alongside its quickshifter option. Call it an experiment if you like, because we believe the traction control could be beneficial when matched with the proper boost level.
Turbo systems compress an engine’s intake air, but compressing air also heats it up. This raises the combustion chamber temperature, which in turn increases the chance of detonation (a bad thing). We opted for a water (and alcohol) injection system to cool the charge of compressed air, and the reservoir in the tail is controlled by a two-pound air bottle mounted on the swingarm. It mists a fine spray into the plenum to cool the charge, thus reducing the chances of detonation and increasing horsepower with cooler, denser air.
The AMS-1000 is an ingenious device that controls the boost pressure when programmed to do so. During street riding conditions (running pump gas) the AMS-1000 will operate at a specific PSI (to be determined during the tune), but because we’ve built the motor iternally we can exceed the standard six-PSI spring in the wastegate.
When the VP C16 race gas is added we’ll be looking to maximize the power, and the AMS-1000 will override the six-pound spring and control boost as programmedin this case 24 PSI (or more).
RPM Cycle Performance has developed a new, smaller plenum than the ones seen on older kits. Because the turbo is forcing compressed air into the motor, a stock plastic airbox would simply burst. The aluminum plenum withstands the high pressure and also hosts a blow-off valve (BOV) to keep the compressed air from backing up and damaging the turbo during off throttle situations.
RPM Oil Pan
A reduced height oil pan is critical when it’s time to slam the bike to the max for the drag strip. RPM’s one-inch oil pan allows the bike to get as close to the ground as possible without the risk of cracking or other damage (stock oil pans are frequently destroyed this way).
Velocity Racing Stage 2 Turbo Kit
Bazzaz Z-Fi TC
RPM Cycle Performance
Next Month: Paint and finishing touches