 Aero-Horsepower Calculator
Picture above are Mike Geokan's Bonneville Turbo Harleys. The #226 Blue bike has run with 104c.i. and 93 c.i, displacements. The new "Bullett" on the right will be running an new 132" Turbo ORCA motor. The newer Bullet is longer and has 16% less frontal area than does the older #226 bike. |
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RSR Bonneville Aero-Horsepower Calculator:
Calculate your horsepower requirements based on the physical limits of drag and frontal area. To get correct gearing for your top speed runs use our Gearspeed Calculator . Simply enter the four figures for your vehicle and see what you face horsepower-wise to meet your objectives. Keep in mind that you can never have enough horsepower. For shorter events like Maxton, which are essentially a mile long drag race on asphalt, you will need more horsepower for a higher rate of acceleration to achieve your peak velocity than is necessary to reach that velocity on a longer course. Coefficient of Drag: Street, faired motorcycles are notoriously inefficient aero-devices with Coefficient of Drag (Cd) figures in the .6 range. For example a Suzuki Hayabusa has a Cd of .561 whereas a Kawasaki ZX-12 has a Cd of .603. Modern cars often have paid close attention to aerodynamics and may have Cd figures of .3 . Streamliners may have Cd figures of under .2, perhaps as low as .15 or in some cases figures of .10 have been achieved. Frontal Area: Reducing frontal area is key to going fast as the horsepower requirements go up exponentially as you push that "barn door" through the air. You'll need a close approximation of your vehicle's frontal area in square feet to make this calculator entry. A Suzuki Hayabusa has a frontal area of 6.01 suare feet. A Kawasaki ZX-12 has a frontal area of 6.09 square feet. Vehicle Weight: On shorter courses like Maxton (1 mile) with asphalt surfaces and good traction weight is more of an issue than it is at Bonneville where weight can aid traction on the slippery salt surface. Short courses are more of a drag race and accelerating extra mass is not a good idea. At Bonneville the big dogs will be on the long course with over six miles of salt with the clocks at the 2 and 4 mile markers, so weight is not nearly as much of an issue. Speed: Miles per hour that is your objective. Remember when you set your gearing for Bonneville that you have to plan for wheelspin due to the slippery conditions. This can be factored into our Gearspeed Calculator. |
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