The formula for acceleration times/temperature

[KingCast 650R]

I posted this on a Gixxer Board and was curious. I'm trying to figure out concrete examples of how heat (ambient, not engine) affects acceleration. What, is it as much as .3 seconds in a quarter? More? Less? Do our bikes just FEEL that much slower in hot humid air? What is the formula the experts use to "correct" acceleration times to 59 degrees F and blah blah blah.... how much faster are our bikes at 48 degrees F instead of the 59 I see them use?????

Because I ride all year round in Boston I can tell you that little 650R is real pocket rocket in the winter.... in a straight line of course and never right off the line, so it's of limited use but still... OMG the difference.....

Anyway, here is part of the thread:

The problem is that you're then adding in more variables like traction, human control, etc Finding the relationship between temp and acceleration amoungst all the other variables will be difficult. You would need numerous runs and still may lose the data in the noise.
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True, true it would take several runs with the same rider on different days on the same exact stretch of road and there are several variables including traction.

Is there a point at which it being hotter gives more traction initially but then becomes a hindrance throughout the run?

All of which fascinates me to wonder how the experts in the field use their formulas and data to "correct" test results...

[Kitt]

F = ma
The temp and humidity don't affect acceleration at all. It will however, affect your HP (force).

HP is a result of energy, from combusted fuel, at a given air:fuel ratio. Temp and humidity affects the mass of air in the same given volume (temp/saturation affects density of air).

This is a basic idea behind the main affects of heat and humidity on the butt dyno.

[KingCast 650R]

F = ma
The temp and humidity don't affect acceleration at all. It will however, affect your HP (force).

HP is a result of energy, from combusted fuel, at a given air:fuel ratio. Temp and humidity affects the mass of air in the same given volume (temp/saturation affects density of air).

This is a basic idea behind the main affects of heat and humidity on the butt dyno.

So what you're saying is that because there is less air to explode with higher temp because it is less dense, you get less HP, I got that.

Same principle behind the lovely intercoolers on my old SAAB Turbos

I guess I'm just trying to figure out the formula the magazines use.... F = ma is a little cryptic for me, my Dad was an chemist, I'm a Civil Rights lawyer, that shit is Greek to me LOL.

[DesmoTull]

Force = Mass * Acceleration

[obsolete]

I don't know the math behind it but there are weather stations that I've seen bracket racers use to adjust dial-in for weather changes. http://www.summitracing.com/parts/TAG-WSC-2/

As stated before temp and humidity effect the power out put of the car which will have a direct effect on acceleration. There is a formula that the SAE came out with takes the temp and humidity and comes out with a corrected density altitude. I also believe there is an accepted table that corrects quarter mile times based on DA. The only issue is of course the amount of variables that come into play with drag times. Also, from what I’ve seen, use of power adders really throws things off.

[KingCast 650R]

Wow I'll take a look at that later.... the science is fascinating. While I'm sure I'm not an elder here, at 45 I've seen it all come up since the days when computers took up half a room, saw Forumula One and Indy cars get wired, and of course we were all mesmerized by the Dire Straits' Money for Nothing video (Cray Supercomputer, whoo-hoo.....) what like anybody could do that now, LOL.

http://en.wikipedia.org/wiki/Money_for_Nothing_(song)

[Woodsy]

for a ten degree rise in intake temperature you can expect roughly a one percent decrease in hp. if you have a CAI than ambient temperature works pretty good for this equation. however most sportbikes have the air box shielded and above the engine. this heats the charge as it enters the airbox. so to properly know the real intake temp you would have to take into acount ambient temp, the specific heat capacity of air, the specific heat capacity of the material the airbox is made of and the volumetric flow rate of the air entering the engine. in simpler terms, how fast is the engine heating the airbox and how long is the air susceptible to that heating. one you get that worked out you can apply it to the horsepower figure and determine the net loss

after this you can find out the theoretical acceleration by converting hp to ft-lbs-sec. One hp is equal to 550 ft-lbs-sec. so for example:

if you have a 100hp bike that weighs 400lbs with a 180lbs rider you have 5500ft-lbs-sec being applied to a 580lbs mass

to find acceleration you would simply divide force by mass and determine acceleration.

5550/580= approx 9.5 ft/sec^2

now just drop the hp and run it again for the difference in acceleration

this also assumes that there is no drag on the system which there is but for simplicity i have decided to leave it out

[ɹǝʍoןandɹǝʍoן]

this also assumes that there is no drag on the system which there is but for simplicity i have decided to leave it out

just like physics class!

[Woodsy]

just like physics class!

when you start incorperating CD it get way messy and there are just too many variables to adiquately explain. everything is easier in a vaccum but the irony is a motorcycle would fail to function in such an enviorment .