August 29th, 2012, 03:11 PM | #1 |
ninjette.org member
Name: Prescott
Location: Terrell, Texas
Join Date: Nov 2011 Motorcycle(s): 2007 BMW F800S; 2012 Ninja 250; 2013 Moto Guzzi V7 Stone, 2016 Triumph Street Triple Rx; 1996 Ducati 900 SS CR Posts: 77
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Ninjette: Horsepower and Speed
Was fooling around with an online horsepower/drag calculator, which I found very helpful in explaining the real world experience of riding the 250. I'm sure this is well known to the engineer types.
Based on my assumed variables, I get the following horsepower requirements for these speeds: 60 mph only requires 10 horsepower (30% of max) 65 takes 12.5 HP (41%) 70 needs 15.4 HP (51%) 75 takes 18.7 HP (62%) 80 takes 21 HP (70%) 85 takes 26.8 HP (89%) 90 takes 30 HP. (100%) This is presumably why I find the "sweet spot" for cruising to be 60-65 mph--still lots of HP in reserve, great fuel economy. 70-75 is ok too, but the engine is definitely reaching its limit. But if you are running 70 mph and hit a sudden gust of 15 mph headwind, you will suddenly need to go from 50% of max power output to 90%! That's probably why cruising more than 75 seems like a strain to me, because it is often pretty windy where I ride. Also of interest. Assuming my inputs are correct, if it takes a full 30 HP to run 90 mph, it would take an additional 7 horsepower just to increase speed to 95 mph. So even if your performance mods get you a few extra HP, it gains you very little in terms of top speed. (I assumed a CD of .5 and 12 square feet of frontal area. If anyone has more accurate data, I'm interested in seeing it) |
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August 29th, 2012, 03:40 PM | #2 |
not an actual panda
Name: dan
Location: philadelphia
Join Date: Aug 2012 Motorcycle(s): 2008 Ninja 250, 2009 CBR600RR (Sold) Posts: A lot.
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Out of curiosity how did you come up with the CD?
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August 29th, 2012, 03:52 PM | #3 |
Jigglin' your Jiglets
Name: Sean
Location: San Jose, Ca
Join Date: Jun 2011 Motorcycle(s): 2009 K1300S, 2013 Ninja 300, 2011 Ninja 250R, Faster than Unregistered's ninjette Posts: Too much.
Blog Entries: 1
MOTM - Apr '13
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Cool stuff though your numbers are quite a bit off. A stock ninjette on a good day will do 26hp and I believe stock will make it to 100mph indicated (~95mph)
Also 100% hp occurs at only 1 specific point, the rest of the time your power is already limited. In case you want to play around with some more accurate numbers heres a 2fiddy dyno
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If the Ninja 250 doesn't have enough power for you, then you don't know how to ride it. AFM #676 Supersports are for n00bs |
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August 29th, 2012, 04:39 PM | #4 |
ninjette.org member
Name: Prescott
Location: Terrell, Texas
Join Date: Nov 2011 Motorcycle(s): 2007 BMW F800S; 2012 Ninja 250; 2013 Moto Guzzi V7 Stone, 2016 Triumph Street Triple Rx; 1996 Ducati 900 SS CR Posts: 77
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For the CD I just used the low end of the suggested cd range for motorcycles. Seems like I read somewhere that the ninjette was pretty aerodynamic. Would be interested in knowing the actual figure.
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August 29th, 2012, 05:38 PM | #6 |
ninjette.org certified postwhore
Name: .
Location: .
Join Date: Feb 2011 Motorcycle(s): . Posts: Too much.
MOTM - Feb '13, Feb '14
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Maybe in a full tuck? Idk I think I have to take a fluids course next year. I'll get back to you more on that then.
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August 29th, 2012, 05:49 PM | #7 | |
Daily Ninjette rider
Name: Hernan
Location: Florida
Join Date: Mar 2011 Motorcycle(s): 2007 Ninja 250 Posts: A lot.
MOTY - 2016, MOTM - Dec '12, Jan '14, Jan '15, May '16
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Quote:
The exponential relation is only natural. A Hayabusa needs 280 HP's to reach 220 mph http://www.schultzengineering.us/aero.htm A pretty accurate Cd can be calculated this way: http://en.wikipedia.org/wiki/Drag_coefficient For force, use power/speed.
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Motofool .................................Never ride faster than your guardian angel can fly "Mankind is composed of two sorts of men — those who love and create, and those who hate and destroy. Love is the bond between men, the way to teach and the center of the world." - José Martí |
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August 29th, 2012, 06:09 PM | #8 |
ninjette.org member
Name: Prescott
Location: Terrell, Texas
Join Date: Nov 2011 Motorcycle(s): 2007 BMW F800S; 2012 Ninja 250; 2013 Moto Guzzi V7 Stone, 2016 Triumph Street Triple Rx; 1996 Ducati 900 SS CR Posts: 77
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I'm thinking my CD is probably too low, and the HP is too high at 30 for a stock bike. Guess you need to base the calculation on rear wheel HP, not at the crank.
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August 29th, 2012, 06:10 PM | #9 |
Jigglin' your Jiglets
Name: Sean
Location: San Jose, Ca
Join Date: Jun 2011 Motorcycle(s): 2009 K1300S, 2013 Ninja 300, 2011 Ninja 250R, Faster than Unregistered's ninjette Posts: Too much.
Blog Entries: 1
MOTM - Apr '13
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Yup
The applied force is generally the one that matters
__________________________________________________
If the Ninja 250 doesn't have enough power for you, then you don't know how to ride it. AFM #676 Supersports are for n00bs |
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August 29th, 2012, 08:21 PM | #10 |
not an actual panda
Name: dan
Location: philadelphia
Join Date: Aug 2012 Motorcycle(s): 2008 Ninja 250, 2009 CBR600RR (Sold) Posts: A lot.
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