Aero-Horsepower & Drag Loss Calculator

Easyriders Harley

The double-engined Harley-Davidson streamliner of Easyriders Magazine's Joe Teresi. Piloted by Dave Campos it still holds the S-PF (Streamliner Pushrod Fuel) record at 322.149 mph. The design is by Bob George and the liner was originally the Jammer liner. It has an estimated Cd of .2, a frontal area of 5 square feet, and a weight of 2400 lbs. The two nitro burning engines were only putting out about a total of 380 hp. The engines were tired and the team was down to their last 5 gallons of nitro but Dave did the job and the record still stands. If it's slippery it doesn't take that much horsepower.

Lambky Vincent

Only four square feet of frontal area. Keeps breaking parts. Inspired by Bob George's successful design but on about a 7/8 scale. Teardrop tapered tail section.

Sam Wheeler

Sam Wheeler's ZX-11 powered streamliner next to a Kawasaki ZX-11. Bonneville is all about getting through the air. The shape for Sam's Liner was developed at The California Institute of Technology wind tunnel. In the 1997 wind tunnel document you can see Mike Geokan and his #226 Blue Bike in one of the pictures. The Cd is tested at .103. People ususally build something then test it. Here it was done correctly i.e. the shape was developed then the shell was made.

Mike Geokan

Picture above are Mike Geokan's Bonneville Turbo Harleys. The #226 Blue bike has run with 104c.i. and 93 c.i, displacements. Mike retired #226 and here has his prototype Bullett under construction. The new "Bullett" on the right is running an new 139" Turbo ORCA motor. The newer Bullet is longer and has 20% less frontal area than does the older #226 bike and about double the horsepower. The finished Bullett is pictured below during Bonneville licensing runs. 17 years after Mike started the project the new bike made it to the salt flats.

Bonneville Bullett

Mike Geokan's Bonneville Bullett with a 139" ORCA Turbo motor. Here pictured at the 2009 SCTA-BNI World Finals where it qualified for long course at 191 mph in 3rd gear. 1000 lbs and about 425 hp if the boost is turned up. It ran 191 with about 9 psi in 3rd gear. Cd is estimated at .476 and a frontal area of 5.5 feet. Rider and bike weigh 1250 lbs.

 RSR Bonneville Aero-Horsepower & Drag Loss 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. However, all the horsepower in the world won't help you if you are limited by a high Cd or traction on surfaces like Bonneville.

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. Some streamliners like the Lambky Vincent have only 4 square feet frontal area.

Vehicle Weight: On shorter courses 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 , 4, and 6 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. The biggest mistake you can make at Bonneville is to gear too close to your intended speed...

Coefficient of Drag (Cd):

Frontal area (sq. ft.):

Vehicle and Rider Weight (lbs):

Speed (mph):

   
 

Horsepower Needed:

Horsepower Lost to Drag: