Have you reached out to Guy (tiger racing)? If he doesn't have one yet I'm sure he can give you a time line when one may be available.
Top speed aerodynamics
- Thread starter outlawbusa
- Start date
Draco1340
Registered
Always amazed at how much power it takes to punch a hole in the wind. For the geeks out there (I'm one of them) this may be of interest. Sport Rider magazine did drag coefficient measurements on the GenI and GenII and they found very little difference between the two drag coeffients (Cd) and Frontal areas (A).
Cd = 0.561 (highly dependent on rider, technique and ride hight)
A = 6.01 ft^2
CdA = 3.37161
The force to punch a hole in the wind is expressed as:
F = 0.5 CdA *p*V^2
where
p is the fluid density of air at 0.075 lb/Ft^3
V is your speed in ft/sec
Lets say you get your Busa to go 200.000 MPH.
V= 200 mph = 293 ft/sec
F = .5CdA*p*V^2 (you also have to divide by gravity but thats a detail...)
Rear Tire force = 340 lbs force.
If tire has a 78 inch circumference, radius is 12.4 inches
Rear tire torque is 351 ft lbs.
Primary ratio is 52/82
6th gear ratio is 23/24
Final ratio is 18/40
Drivetrain efficiency = 90% ( a wild ass guess, but it factors out in end)
Crankshaft torque = 106 ft lbs
Since HP at any RPM is Torque * RPM/ 5252
Crank BHP @ 11,000 RPM is 222 HP.
Rolling Resistance at 200 mph = 15 HP (I calculated this out previously)
Total Gross HP is total of drag HP and rolling resistance
BHP gross = 237
BHP net = .90 * BHP gross = 210 HP net
A well tuned GenII busa on MR9 with perfect gearing, no head wind and full ram air makes "about" 210 BHP net, and on a perfect day with lots of rider technique, will get close to 200 MPH.
See you up at Loring in August
Cd = 0.561 (highly dependent on rider, technique and ride hight)
A = 6.01 ft^2
CdA = 3.37161
The force to punch a hole in the wind is expressed as:
F = 0.5 CdA *p*V^2
where
p is the fluid density of air at 0.075 lb/Ft^3
V is your speed in ft/sec
Lets say you get your Busa to go 200.000 MPH.
V= 200 mph = 293 ft/sec
F = .5CdA*p*V^2 (you also have to divide by gravity but thats a detail...)
Rear Tire force = 340 lbs force.
If tire has a 78 inch circumference, radius is 12.4 inches
Rear tire torque is 351 ft lbs.
Primary ratio is 52/82
6th gear ratio is 23/24
Final ratio is 18/40
Drivetrain efficiency = 90% ( a wild ass guess, but it factors out in end)
Crankshaft torque = 106 ft lbs
Since HP at any RPM is Torque * RPM/ 5252
Crank BHP @ 11,000 RPM is 222 HP.
Rolling Resistance at 200 mph = 15 HP (I calculated this out previously)
Total Gross HP is total of drag HP and rolling resistance
BHP gross = 237
BHP net = .90 * BHP gross = 210 HP net
A well tuned GenII busa on MR9 with perfect gearing, no head wind and full ram air makes "about" 210 BHP net, and on a perfect day with lots of rider technique, will get close to 200 MPH.
See you up at Loring in August
Always amazed at how much power it takes to punch a hole in the wind. For the geeks out there (I'm one of them) this may be of interest. Sport Rider magazine did drag coefficient measurements on the GenI and GenII and they found very little difference between the two drag coeffients (Cd) and Frontal areas (A).
Cd = 0.561 (highly dependent on rider, technique and ride hight)
A = 6.01 ft^2
CdA = 3.37161
The force to punch a hole in the wind is expressed as:
F = 0.5 CdA *p*V^2
where
p is the fluid density of air at 0.075 lb/Ft^3
V is your speed in ft/sec
Lets say you get your Busa to go 200.000 MPH.
V= 200 mph = 293 ft/sec
F = .5CdA*p*V^2 (you also have to divide by gravity but thats a detail...)
Rear Tire force = 340 lbs force.
If tire has a 78 inch circumference, radius is 12.4 inches
Rear tire torque is 351 ft lbs.
Primary ratio is 52/82
6th gear ratio is 23/24
Final ratio is 18/40
Drivetrain efficiency = 90% ( a wild ass guess, but it factors out in end)
Crankshaft torque = 106 ft lbs
Since HP at any RPM is Torque * RPM/ 5252
Crank BHP @ 11,000 RPM is 222 HP.
Rolling Resistance at 200 mph = 15 HP (I calculated this out previously)
Total Gross HP is total of drag HP and rolling resistance
BHP gross = 237
BHP net = .90 * BHP gross = 210 HP net
A well tuned GenII busa on MR9 with perfect gearing, no head wind and full ram air makes "about" 210 BHP net, and on a perfect day with lots of rider technique, will get close to 200 MPH.
See you up at Loring in August
Very nice info here for those looking to do LSR...
What issue did Sport Rider compare the Gen-I and Gen-II bikes, I'd like to pick up a copy...?
Remember some people claim my dyno numbers are high...
Keep up the good work Tom...
I actually did speak with Guy about a month ago, he's great and does sell them for the 2007 and down...he did not have one yet for the 2008-09 models. I figured he's be the first to get one in, but thought I'd just throw it out there to be sure.
Draco1340
Registered
What issue did Sport Rider compare the Gen-I and Gen-II bikes, I'd like to pick up a copy...?
Remember some people claim my dyno numbers are high...
The first article / data I saw was in the June 2001 Sport Rider wind tunnel tests. Sport Rider-Testing Suzuki Hayabusa and Kawasaki ZX-12R aerodynamics in the wind tunnel
They compared the GenI against the ZX12 and a bunch of other bikes.
The article was later "redone" I think 3 years ago with Lee S. and Dave O. (RIP) as the riders, and Dave's copperhead 99, among other bikes. Many people oringinaly thought Dave had spray hiding on his bike to go 215 - 220 on all motor.
Remember at the time that was faster than many of the turbo and nitrous records at Maxton. Dave just knew the numbers and had a very unique tuck (terrifying to watch) and a very slippery busa. Dave was a much bigger guy than Lee (by 50 lbs?), but Daves CdA was lower because of his tuck and his flatter back. I don't remember the actual date of these tests.Then I think I remember in May 08 Motorcyclist did a comparo between GenI and GenII and mentioned (but did not offer data) that the CdA were comparable. I only have hard data on the GenI.
That is some really interesting reading, thank you. I was going to post some highlights out of it but I would end up with an entire book report out of that article, LoL.
I did see this though:
"The most immediate way to decrease drag on a motorcycle is for the rider to adopt a crouched position. A smaller rider can produce a 15 percent reduction in drag; tight clothing, which reduces the "balloon effect," can provide another 15 percent reduction."
I know that is something I can work on a little more...the 199mph run, I felt the wind remind me to go lower twice on the top of my helmet. It's like hitting a bump and staying an inch up...oh yeah~!~ Gotta get back down~!~
I am actually able to tuck in much better now after removing the seat and sitting on a paper plate...I know it sounds funny, but it works. I can wrap around the gas tank and actually tuck right in easier now.
I am looking for a used seat so I can take the padding out and make myself a lower seat. I have seen the drag seats, but I am too tall for them, My a$$ has to scoot back to the hump for me to get under the screen.
I did see this though:
"The most immediate way to decrease drag on a motorcycle is for the rider to adopt a crouched position. A smaller rider can produce a 15 percent reduction in drag; tight clothing, which reduces the "balloon effect," can provide another 15 percent reduction."
I know that is something I can work on a little more...the 199mph run, I felt the wind remind me to go lower twice on the top of my helmet. It's like hitting a bump and staying an inch up...oh yeah~!~ Gotta get back down~!~
I am actually able to tuck in much better now after removing the seat and sitting on a paper plate...I know it sounds funny, but it works. I can wrap around the gas tank and actually tuck right in easier now.
I am looking for a used seat so I can take the padding out and make myself a lower seat. I have seen the drag seats, but I am too tall for them, My a$$ has to scoot back to the hump for me to get under the screen.
We've tested this and it's works. My buddy was make consistant speeds then we taped him up to the point he could barley breath. He went +5mph on the next two runs. 
We had to take the tape off after that because he was starting to turn different colors 
Tight fitting leathers improve your aero's alot. You don't want anything that flaps in the wind.
We had to take the tape off after that because he was starting to turn different colors Tight fitting leathers improve your aero's alot. You don't want anything that flaps in the wind.
Sent you a PM so this aero thread doesn't start going side ways.
Draco1340
Registered
I don't consider myself an expert in anything in life but...
Getting your butt low is not always the best form. Have someone take a video or photo of you to take a look at what you are doing. I have a two step seat on my busa (and on this older picture of my ZX12R) to try to get my butt high and back, back as flat as possible, and helmet as flat on tank as possible. Without going into a treatise on aero, you want to create a smooth transition. Getting the bike low makes the lower wing aero much less important.
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Getting your butt low is not always the best form. Have someone take a video or photo of you to take a look at what you are doing. I have a two step seat on my busa (and on this older picture of my ZX12R) to try to get my butt high and back, back as flat as possible, and helmet as flat on tank as possible. Without going into a treatise on aero, you want to create a smooth transition. Getting the bike low makes the lower wing aero much less important.
ImageShack Links Do Not Work
I agree about the back and the butt. There a problem though...I'm 6.1, 205 lbs and my tuck just isn't as good as it could be. My wifes having the baby (due in August) but I think I am the one gaining the weight, LoL. Anyway, with a stock seat I can not tuck my neck and head in as low as I need to because of my chest (yeah, that's it). If I remove the seat I can lower my entire body and hug the gas tank better and get my neck and helmet all under the wind screen.
I know there's gonna be a drawback to that, my butt may be under the cowl and disrupt the air there. I am looking for a used front seat to just cover the plastic. That way it may be a compromise and not be quite so low on my rear end and flow better over the cowl, yet still give me some tuck room on the upper end.
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When I say cover teh plastic, I mean take all the foam out and just use the plastic part of the seat...
Double Bubble Windscreen
Got that, they say the double bubble hurts on the gen 1 Busa, I found it helped me quite a bit on the gen II...picked up quite a few mph. Last OCT I only ran 189. Stuck the double bubble and went two down on the rear sprocket in April and ran the 199.2
Thanks for the info Guy. I didn't get to see you last meet...but I think you met Kevin on the dark 08 Busa. We're the guys from Roanoke that helped out with the chain guard fitting.
"""went two down on the rear sprocket in April and ran the 199.2"""
Don't take that gearing to heart (whoever's writing this down, LoL)...I'm just saying what I ran with that gear. Kevin is not hitting the rev limiter on the stock gear until 200mph on the mark. He ran 202.7 with 2 down. I'm going back to 1 down next meet.
Don't take that gearing to heart (whoever's writing this down, LoL)...I'm just saying what I ran with that gear. Kevin is not hitting the rev limiter on the stock gear until 200mph on the mark. He ran 202.7 with 2 down. I'm going back to 1 down next meet.
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