supra5677
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posted January 10, 2006 10:11 AM
how much horsepower to go 210mph
To Board:
theoretically how much horsepower would it take to push a 12R to 210 mph.. looking a Doug M top speed runs with and without a pipe it appears that the ram air is working very well...
how much more rpm and horsepower would it actually take?
supra
   
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dougmeyer
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posted January 10, 2006 10:34 AM
SUpra,
That's easy to figure out. All you need to know is exactly how much hp your using to go a particular speed. Anybody on the board that's been on a good dyno and then taken that bike and run a particular speed can figure it out.
HP required to go speed X = hp1
Speed desired=S1 Speed achieved = S2
S2/S1= % of increase in speed desired or lets call that S3
S3xS3xS3= hp % increase required call that hp%
hp1xhp% = HP needed to go S1
so 200 195 hp, you want to go 210 thats 15 mph or a 7.69 % increase
7.69% cubed = 1.0769x1.0769x1.0769=24.88%
24.48%x195= 48.51 more hp or 243.51 hp required for THAT bike to go 210 (under the same conditions)
Doug
I did that in a hurry- I'm running to catch a plane- sorry if it's not clear enough...BFN
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Phantom Menace
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posted January 10, 2006 10:45 AM
Does that take into account the exponential increase in wind resistance as well?
From what I understand, as the wind resistance increases, so does the amount of power required to achieve more speed. Meaning, that if it took 3rwhp to gain 1mph at 190mph.... it would take more like 4-5rwhp to gain 1mph at 210mph.
Right?
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posted January 10, 2006 11:13 AM
quote:
Does that take into account the exponential increase in wind resistance as well?
From what I understand, as the wind resistance increases, so does the amount of power required to achieve more speed. Meaning, that if it took 3rwhp to gain 1mph at 190mph.... it would take more like 4-5rwhp to gain 1mph at 210mph.
Right?
7.69% cubed = 1.0769x1.0769x1.0769=24.88%
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Phantom Menace
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posted January 10, 2006 11:27 AM
ahhh.... thanks for pointing that part out. I get it now.
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TRNorBRN6001
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posted January 10, 2006 12:03 PM
Also depends on the rider and how big they are. Some fellas do it in a mile with about that much, but that is the exception. One mile, average person, I would guess about 280HP. Unlimited frontage then it would be like Slow Car says.
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dougmeyer
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posted January 10, 2006 03:07 PM
No it doesn't. Given the same vehicle shape (ona bike this includes the rider) and conditions it's ALWAYS drag goes up as a cube function of the speed increase. That's ALWAYS always.
D.
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Phantom Menace
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posted January 10, 2006 03:40 PM
You learn something new everyday!!!
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speedgene
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posted January 10, 2006 08:49 PM
That's why in '07, Suzuki is reverting back to spec '99, nip and tuck the fairing, and blow away anything Kaw introduces for this year.........
Just kidding.
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dougmeyer
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posted January 10, 2006 08:49 PM
Yeah, ain't it great.........
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trenace
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posted January 10, 2006 09:03 PM
 Edited By: trenace on 10 Jan 2006 21:57
Within a mile one does need more power increase than simply the cubed formula accounts for. It is applicable only to steady-state, true stop speed.
Within the standing mile, acceleration is also required and greater acceleration requires greater power on top of the greater power required to overcome the extra drag.
I wish I had more numbers to work with, but in the past I took various people's figures from Maxton and it seemed to me that each additional mph past 200 mph, in the regime close to 200 mph, required SEVEN additional hp, not merely the three additional needed when simply figuring drag. That figure may be rough. But adding just three hp does NOT seem to get an extra mph in the standing mile, though it would given enough room that acceleration didn't matter.
To get an illustration of this,while of course the quarter mile is shorter than the full mile, still we're talking about the need to accelerate to a speed at the end of the distance. Hp can be calculated from the trap speed and weight. For example, using that calculator, if trap speed is 160 mph and the bike plus rider weighs 700 lb, the rear wheel hp is probably about 224 hp. The value corresponding to 161 mph is 228 hp, to 162 mph 232 hp, and so on while remaining close to that speed. And that's before aero drag starts leaving the acceleration only with the "leftovers" as is the case around and past 200 mph.
As a really rough illustration, 250 mph has been achieved in the standing mile. On the cube formula, that would be, relative to 200 mph, 1.95 times the power, or if 1.95 times 200 hp, then 400 hp. While enough to do it given sufficient room, it's not enough to do it while having only those few seconds and limited space to accelerate. On the other hand, the "7 mph per additional hp" model would demand 350 hp extra, and that's more like the actual output of the bike.
If more and better data can be provided allowing better estimation of this that would be great. I had only five or six different figures to use (and did not use the above turbo-bike run.)
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wedrivezs
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posted January 10, 2006 09:20 PM
Edited By: wedrivezs on 10 Jan 2006 21:21
If you're talking Bonneville
350+ HP = 250 MPH  proven on the salt
JoeA is geared for 270+ MPH and just threw down a HUGE amount on the dyno, time will tell what happens
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dougmeyer
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posted January 10, 2006 10:09 PM
Trenace,
Huh?
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trenace
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posted January 10, 2006 10:43 PM
Edited By: trenace on 10 Jan 2006 22:59
Hopefully better put --
If acceleration is no issue, there's miles to run, then all the motor needs to do is overcome rolling resistance (relatively minor) and aero drag.
As you pointed out, the power needed to overcome aero drag increases with the cube of the speed.
So to go 10% faster, you need 1.1 x 1.1 x 1.1 the power.
However, to go 10% faster within a quite limited space, you also need to ACCELERATE harder, totally independent of aero drag.
So for example, say for a given bike at 200 mph, 200 hp matches the drag, and 200 hp is all the bike has got, and so that's its true top speed.
Say you retune it and now have 203 hp.
By the cube rule, top speed should now be about 201 mph.
However, once the bike is up to 200, there's only 3 hp left over.
How much distance does it take for those remaining 3 hp to accelerate from 200 to 201?
More than you've got left in the standing mile, if you reached the 200 only just before getting to the end.
To get that 201, the bike has got to accelerate harder, it's got to reach 200 at an earlier point, so it has room for yet further acceleration. And that means yet additional power is required.
Example, look at the quarter mile: to get higher trap speed, you need quite a bit more hp, even though you're not eating distance quite as fast as you are at the end of the standing mile.
The cube rule takes into account the aero factor, but not the need for greater acceleration. Combine the two needs, and the total increased power is more than predicted from just the cube equation. E.g., you might do 200 in the standing mile with 180 rear wheel hp, but if you want 210 in the standing mile, I would recommend one not figure that 208 rear wheel hp (the value from the cube equation) would be enough.
But if one is talking pure top speed then it's as you provided the calculation for.
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trenace
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posted January 10, 2006 10:50 PM
Edited By: trenace on 10 Jan 2006 23:00
Or, this might be a simpler way of looking at it:
Pretend the job is to accelerate to the best speed in the QUARTER mile.
If so, a calculator that's pretty accurate shows you'd need about 375 hp to get 200 mph.
To get 210 mph, you'd need about 434 hp.
Though of course the mile is longer, accelerating to a greater speed in the same distance still in the exact same way requires more power, above and beyond considerations of overcoming aero drag. Combine the two considerations, and the requirement in the standing mile is greater than the cube formula says, which accounts only for the aero drag consideration.
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speedgene
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posted January 11, 2006 12:05 AM
Edited By: speedgene on 11 Jan 2006 00:45
Trenace says, "To get 210 mph, you'd need about 434 hp." Are you saying it will take almost 250 more horses to go 8 or 9 more mph? If a stock '99 went 201, it will take over 200hp more to achieve 9 more mph? NFW.
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speedgene
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posted January 11, 2006 12:07 AM
Formulas aside, It's not the 210 you want. It's the back door you receive from the factory to bust through 209. Some/Most don't want to go near 210 if this was offered to the public. But they sure would play with the back (HP/TQ) door, opening and closing the ..... till the hinges fall off.
That's why 210 is way overdue. Is it Montana that has the politically correct speed limits? Maybe I'll wait for that Special Edition "Montana ZX12."
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tuusinii
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posted January 11, 2006 04:25 AM
F=ma, v=at, s=1/2at^2 That's all You need with a model to the drag taking acount both aero and rolling allthough the aero drag is much greater. To get to some speed You have to all so take in to count that the high HP figure isin't everything You have to have enough HP:s at the right RPM:s and wide enough HP curve to give You the max HP:s at the max speed. But anyway to get to the 210MPH You're going to need lot of horses! 
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zx23rr
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posted January 11, 2006 08:25 AM
I wrote this article on Jereon site years ago (1998) just from the top of my head. I think it will give you a better visual.........................
For more stuff check out < http://www.zx11.info/zx11/home.htm > under articles.
==============================================================
Aerodynamics, Horsepower, and Speed
- Double The Speed, Need Four Times The Power -
By: Frank Hartung, March 1998
My hope is to shed some, if not a lot of light in the simplest terms, how aerodynamics and horsepower affects speed. I'll also cover briefly the areas covering temperature, humidity, wind, weight, and their effects on speed.
I will make some assumptions that will carry throughout, except where noted. This is all approximate, so don't hold me to this.
1. Bike is a Zx-11 C - model.
2. The Zx-11 motor is producing *160 crank horsepower.
3. There will be no mechanical or frictional losses accounted for.
4. There is no "Wind".
5. Conditions are the "Standard" - Sea Level, 59' F, and 29.92" of Mercury.
6. With the above in mind. this Zx-11's Top Speed is 176 Mph.
* Zx-11 produces 149 crank hp at 10,500 rpm. With ram air this will increase it to the said 160 hp. The losses in the driveline for simplicity reasons, ( #3.) will be said to be the same percentage as the power is increased.(in real life this might not be the case).
What effect does Aerodynamics have on Horsepower requirements?
To double the speed, the engine needs to produce four times more power.
At 22 mph, engine needs to produce 2.5 Hp
At 44 mph, engine needs to produce 10 Hp
At 88 mph, engine needs to produce 40 Hp
At 176 mph, engine needs to produce 160 Hp
At 352 mph, engine needs to produce 640 Hp
If top speed and horsepower numbers are known, calculate the percentage increase in speed wanted. Square this percentage and add to the known horsepower
Example:
Everyone has gone 180 Mph! So how much power is the engine making?
176 plus 2.3% = 180, So, 1.023 x 1.023 = 1.0465 or 4.65%.
160(hp) + 4.65% = 167 hp. needed
Everyone wants to go 200 miles per hour.
176 + 13.7% = 200, So 1.137 x 1.137 = 1.293 or 29.3%
160(hp) + 29.3% = 207 hp. needed
Mr. Turbo's 1992 Zx-11 C - Model top speed of 215 mph.
176 + 22.2% = 215, So 1.222 x 1.222 = 1.493 or 49.3%
160(hp) + 49.3% = 239 hp needed
Mr. Turbo's 1993 Zx-11 D - Model top speed of 231 mph.
(note: does not take aerodynamical differences of the D-model into account)
176 + 31.3% = 231, So 1.313 x 1.313 = 1.724 or 72.4%
160(hp) + 72.4% = 275.8 hp needed
In summary:
88 mph requires 40 hp
176 mph requires 160 hp
180 mph requires 167 hp
185 mph requires 177 hp
190 mph requires 186 hp
195 mph requires 196.5 hp
200 mph requires 207 hp
Temperature: How does it effect Horsepower?
For every 11 degrees Fahrenheit or 6 degrees Celsius change at the carburetors, a 1 percents change in horsepower can be realize if jetting is also corrected for that temperature. Cooler air is more dense and therefore has more oxygen per cubic foot than warmer air. More oxygen allows for more fuel to be burnt, and therefore more power to be produced.
Example:
If the air ingested by the engine is 66 degrees Fahrenheit cooler than the surrounding air, (engine heat!?!) then a 6 percent increase in power can be realized with proper jetting.
Aerodynamics and Horsepower: How does Ram-air fit in?
Atmosphere pressure is 14.7 pounds per square inch. This is equal to 29.92 inches of Mercury. At 170 miles per hour, the pressure created at the front of an object that is moving through clean air, and causes that air to stop or become stagnant, will increase the pressure by 0.5 pounds per square inch.(in that immediate area) This translates into an increase of 3.2 percent in air pressure. Hence, a 3.2 percent increase in Horsepower.
Again, there is a square root effect that comes into play. At 100 miles per hour, the increase in pressure is only 0.17 pounds per inch or 1.2 percent.
Air that is moving from the front towards the side is less stagnant air and will lose some of this effect. It's pressure will be closer to atmosphere pressure as it speeds up.
Air that is moving along side of the fairing will be at surrounding atmospheric pressure.
The air passing at right angles by the fairing may actually cause it to create a vacuum by the carburetors / airbox. A pressure drop at the carburetors will cause a loss of power.
Humidity: How does it effect Horsepower?
Humidity is the amount of water vapor in the air. Relative humidity is the amount of water vapor in the air compared with the amount of vapor needed to make the air saturated at the air's current temperature.
The dewpoint temperature gives a much better estimate of the amount of moisture actually present in the air, which is very important in determining precipitation amounts and even how comfortable you feel. Very cold, 10 degrees Fahrenheit air with a relative humidity of 100% with 72-degree tropical air, also with 100% relative humidity. In both cases, the relative humidity is 100%, but the cold air's dewpoint is 10 degrees and the warm air's dewpoint is 72 degrees. The higher the dewpoint temperature, the more moisture in the air.
As the temperature goes up, so does the ability of the air to hold more Water vapour before it reaches 100 percent humidity.
At 32 degrees Fahrenheit and 100 percent humidity, the water content is approximately 1 percent (this is not the correct percentage. I am still trying to find the correct number. For demonstration purpose, I have used 1%. This is in the ball park. If anyone knows the exact figure, e-mail me) So there will be 1 percent less air available to the engine.
At 100 degrees Fahrenheit and 100 percent humidity, the water content is approximately 6 percent. So to make better sense of it, at 32 degrees with 100 percent humidity, power loss will be 1 percent at that temperature. While at 100 degrees with 100 percent humidity, power loss will be 6 percent at that temperature.
This is on top of the power loss or gain due to temperature change.
Air temperature in degrees F Amount of water vapor air can hold at this temperature
(100 percent relative humidity)
86 degrees 30 grams of water per cubic meter of air
68 degrees 17 grams of water per cubic meter of air
50 degrees 9 grams of water per cubic meter of air
To some it all up. Humidity is less of a factor in cooler weather than in warmer weather. If the air temperature is around 40-50 degrees Fahrenheit, its 100 percent humidity (raining), and you experience power loss or poor throttle response, chances are you are suffering from Carburetor Icing.
Weight: How does it effect Horsepower and Speed?
These rules assume there are no Aerodynamic forces (drag) coming into play.
Rule #1 : If you double the weight, it will require double the power to accelerate a weight at the same speed.
Example:
It takes a known amount of power and time to accelerate 500 lbs to 50 mph. If this weight is increased to 1000 lbs, it will take twice as long to accelerate to 50 mph, or the power will have to be doubled to maintain the same time.
Rule #2 : If the Power to Weight ratio is known, then removing that amount of weight will accelerate the bike as if the engine has gain 1 Horsepower. (that's why the bike is more fun with an empty fuel tank). Adding weight is like losing power.
Example:
Bike weighs 550lbs. plus 200 lbs. rider total = 750 lbs.
Horsepower is 150. Power / Weight ratio is 5 / 1.
Remove 5 lbs is same as 1 Hp increase.
Wind: How does it effect Horsepower requirements and Speed?
The Zx-11 needs 160 horsepower to achieve 176 mph in still wind conditions. With a 20 mph tail wind, the Zx-11 would / could theoretically obtain 187 mph. This is due to the fact that at 176 mph the Zx-11 is actually moving through the air at 156 mph. This leaves 40 extra horsepower to accelerate the Zx-11 to the 187 mph.
With a dreaded 20 mph head wind, the Zx-11 would only be able to theoretically obtain amazingly enough, 163 mph. Because at that speed, the bike would be moving though the air at 176 mph. And we know that it takes 160 horsepower to go that fast. The only difference is that the bike would be in top of 5th gear instead of 6th because the ground speed is 163 mph. With a 42 tooth rear sprocket and a 17 tooth front, plus a 35 mile per hour tailwind, the bike would go a true 200 mph!
Brakes: How weight and speed effects them!
At any speed:
Double the weight, need double the braking power
Double the speed, need quadruple the braking power
Double the weight and the speed, need Eight Times the braking power!
In Conclusion:
The most important piece of equipment on a bike is ..... the brakes! If anyone out there has ever reached for the lever only to have it go to the bars, knows what I mean! The biggest diaper will not be enough!
Temperature, ram-air, humidity, weight, all play a part in how much horsepower an engine will ultimately produce. But, aerodynamics and wind direction play a major (understatement) role in what the top speed of any bike is. Magazine's that do two way averaging is not an accurate way of measuring the top speed. So is the CBR-1100 the World's Fastest Production bike. Maybe. It has less weight to accelerate and therefore will most likely get to top speed quicker. For true comparison, it must be tested at the same time with no wind, (zero) a standard day, (29.92, 59 degrees, 0 % humidity) and identical riders (twins). Then the truth shall be known!.
By Frank Hartung
====================================================================
PS, where did the 8 years go? lol
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trenace
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posted January 11, 2006 08:44 AM
quote:
What effect does Aerodynamics have on Horsepower requirements?
To double the speed, the engine needs to produce four times more power.
At 22 mph, engine needs to produce 2.5 Hp
At 44 mph, engine needs to produce 10 Hp
At 88 mph, engine needs to produce 40 Hp
At 176 mph, engine needs to produce 160 Hp
At 352 mph, engine needs to produce 640 Hp
That author is incorrect.
Mr Meyer stated it correctly.
The force required is according to the square, e.g. at twice the speed four times the force is needed to overcome aero drag.
But since power is force through distance per unit time and distance is being covered twice as rapidly, this results in an additional factor of two -- thus the cube formula, or 8 times the power needed to overcome aero drag at twice the speed.
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zx23rr
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posted January 11, 2006 08:54 AM
horse power is force and not taking mechanical lose into the equation..., but you have stuffed a red hearing in there with the time distance part. If you want to go 352 miles per hour from a stand still, 640 hp is not going to cut it. What is stated above is to maintain a constant 352 mph (with everything being equal in this example) you would require 640 hp to overcome the drag. Change any variable, you will either require more or less hp.
and that all I have to say about that...........
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trenace
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posted January 11, 2006 09:32 AM
No.
Look up the definition of hp.
It is not a matter to argue, it is a matter of definition.
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tuusinii
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posted January 11, 2006 11:43 AM
And that wind equation dosen't look good either if you assumme that You have the max hp on every RPM (- like the author is thinking)
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kram
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posted January 11, 2006 12:02 PM
Assuming no lost traction, I calculate it would take approximately 225 rear wheel hp to reach 210mph on level ground with no head/tail wind.
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TRNorBRN6001
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posted January 11, 2006 12:41 PM
Would that be at sea level? You guys are kill'n me.
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