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Old 11-10-2014, 02:27 PM   #1
Iranian OP
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wieght vs topspeed

Hi,

Is there anybody among us that are mecanical engineer and who can tell me how much horsepower a engine must for being able to pull a 450 kg cruiser inclusive drive to a top speed of 220 km/h? The drivers weight is 72 kg.


Regards,

Iranian
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Old 11-10-2014, 04:00 PM   #2
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Originally Posted by Iranian View Post
Hi,

Is there anybody among us that are mecanical engineer and who can tell me how much horsepower a engine must for being able to pull a 450 kg cruiser inclusive drive to a top speed of 220 km/h? The drivers weight is 72 kg.


Regards,

Iranian
Weight is an issue with rates of acceleration, not top speed. Top speed limits are set by aerodynamic drag & horsepower.
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Old 11-10-2014, 04:45 PM   #3
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While the above is somewhat true when distance is unlimited if the distance available is short (say a mile) acceleration plays a large role.
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Old 11-10-2014, 05:39 PM   #4
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Quote:
Originally Posted by Iranian View Post
Hi,

Is there anybody among us that are mecanical engineer and who can tell me how much horsepower a engine must for being able to pull a 450 kg cruiser inclusive drive to a top speed of 220 km/h? The drivers weight is 72 kg.


Regards,

Iranian
That isn't an issue of horsepower, you never ride in a vaccum, and your average Honda Accord has a HELL of a lot better aerodynamics than a Pangiale. Bikes, even full-faired super sports are bricks in the wind.
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Old 11-10-2014, 06:30 PM   #5
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That isn't an issue of horsepower, you never ride in a vaccum, and your average Honda Accord has a HELL of a lot better aerodynamics than a Pangiale. Bikes, even full-faired super sports are bricks in the wind.
They still require less horsepower to go the same speed as most cars. Cd coeficient is worse but they aren't as big as 4 wheelers.

I imagine there is a crossover point when going very, very, fast.
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Old 11-10-2014, 06:40 PM   #6
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220 kph equals 136 mph.

131 mph happens to be the TESTED top speed of the 2010 kawasaki concours.

http://www.policemag.com/blog/vehicl...torcycles.aspx

Bike has appx 155 horsepower. So maybe 162 horsepower to get your theoretical machine to 136 mph.

162 hp, DEPENDING on aerodynamics, fairing, windscreen, saddlebags, size of rider....

That's my final answer and I'm sticking to it.
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Old 11-10-2014, 06:57 PM   #7
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there are so many variables in this. you may as well attempt to calculate how many angels will fit on the head of a pin.
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Old 11-10-2014, 08:22 PM   #8
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Originally Posted by DFH View Post
Weight is an issue with rates of acceleration, not top speed. Top speed limits are set by aerodynamic drag & horsepower.
Correct. The issue is the ratio of power-to-aerodynamic drag. Cars, motorcycles, aircraft, it doesn't matter (as long as the tires don't slip and we are not talking about super-sonic speeds).

A 1/4 mile or one-mile drag race has nothing to do with top speed. They are two different measures of performance. This is the difference between a drag strip (or stoplights on the way to Starbucks) and the Bonneville salt flats.
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Old 11-10-2014, 09:09 PM   #9
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Keep in mind that a lot of the FI bikes now day's will not pull down full power in the top 2 (or 3 gears in some cases) so rated horsepower in the magazine is going to be skewed a great degree and that is also going to affect your tops speeds. Yamaha is particularly notorious for this. I was taking note of a tuner friend and he was recently dynoing the FZ-09. He already expected it due to the fact that he had done some dyno work on a Vmax previously. The fz-09 has ECU restrictions in every mode in 4th, 5th and 6th.... (yes, even the highly touted A mode). Not only does it restrict the power but it pulls the redline back for each gear you go higher.

Pretty profound limits too as the dyno chart will display, Personally I am pretty excited to see what happens once he gets the ECU back and it has been excised of the factory imposed limits.

It revs to 11,300 in 4th gear, 10,100 in 5th gear, and 8700 in 6th gear. Power in STD and A mode is similar. In B mode it has less top end.

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Old 11-10-2014, 11:06 PM   #10
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Originally Posted by Tripped1 View Post
That isn't an issue of horsepower, you never ride in a vaccum, and your average Honda Accord has a HELL of a lot better aerodynamics than a Pangiale. Bikes, even full-faired super sports are bricks in the wind.
Not quite. Horsepower is what you fight wind resistance with. The Panigale definitely has a much worse Cd figure than the Accord, but once frontal area is taken into account (CdA) the Accord has much higher aerodynamic drag.
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Old 11-10-2014, 11:18 PM   #11
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Quote:
Originally Posted by Iranian View Post
Hi,

Is there anybody among us that are mecanical engineer and who can tell me how much horsepower a engine must for being able to pull a 450 kg cruiser inclusive drive to a top speed of 220 km/h? The drivers weight is 72 kg.


Regards,

Iranian
Give us a figure of a top speed for given bike with given power and will tell you how much more it takes to do 220km/hr
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Old 11-10-2014, 11:29 PM   #12
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road king, midnightstar 1300, vn 900 classic, vstar 1100 classin and all of them with windshield and side carriers.
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Old 11-10-2014, 11:55 PM   #13
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The power needed to overcome aerodynamic resistance grows with velocity cubed.
So if for example a bike with 80hp does a max speed of 180 km/hr then the same bike in order to do 220 km/hr will need power:

P = (220/180)^3 * 80 = 146 hp

Fill in your numbers in the above equation and you will have your answer.
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Old 11-11-2014, 01:16 AM   #14
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road king, midnightstar 1300, vn 900 classic, vstar 1100 classin and all of them with windshield and side carriers.
These bikes would not be my first choice if top speed is a consideration. Firstly their design is as un-aerodynamic as you can get, even by motorcycle standards. Secondly their rearward weight balance, short travel & underdamped suspension plus flexible frames are not the best choice for stability at speed. Thirdly their powerbands are so narrow that they require more gear ratios with tighter steps than the usual cruiser 5 speed gearbox.
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Old 11-11-2014, 05:22 AM   #15
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Laugh Ding! Ding! Ding!

Mousitsas wins a cookie! Correct answer.

Ask any Bonneville racer what role weight plays in top speed. In fact, they often weight the bike to gain traction.

If all forms of drag could be eliminated, and the course was perfectly flat, a Z-50 would have unlimited speed, given enough distance to accelerate.
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