Cold air is supposed to increase the power  - I always thought this only would be of academical interest, but recent experience got me thinking.....

Can someone quantify or guesstimate the power gain, let's say twenties vs eighties?

The roads have been dry the last few days, so just to let her breathe and to hear the sound I've been riding a little.
Temperature is in the twenties and for the first time I get powerwheelies, on my S2R 800 - not very high and only in first, but nevertheless enjoyable!!!

For sureâ€"not sure how much, but it's probably negated by the higher wind resistance at speed.

Air density is roughly 12% greater at 20 degF versus 80 degF.

So, somewhere about that power increase, in an ideal world...

Quote from: Speeddog on November 17, 2008, 03:56:47 PM
Air density is roughly 12% greater at 20 degF versus 80 degF.

So, somewhere about that power increase, in an ideal world...

That's where my twisted mind usually thinks I live, so I'll settle for that [moto] Makes me think that a S4R might locate me there permanently

At Sea Level:
Air density at 70 *F, 29.9 inHg, and 65% R.H. = 1.1922 kg/m^3

Air density at 20 *F, 29.9 inHg, and 65% R.H. = 1.3234 kg/m^3

Air density at 20 *F, 29.9 inHg, and 30% R.H. = 1.3240 kg/m^3

Air density at 70 *F, 30.5 inHg, and 65% R.H. = 1.2155 kg/m^3

Air density at 20 *F, 30.5 inHg, and 65% R.H. = 1.3490 kg/m^3

Density % change, temperature only = ~11%

Density % change, temp + humidity = ~11%

Denstiy % change, temp + pressure = ~13%

Density % change, pressure only = ~2%

So humidity and pressure have less effect on air density than temperature.  One can make the extrapolation that to maintain the same A/F ratio, fuel must be increased by the same percentage.  I of course did not take into account the change in density of fuel if the fueling system supplies volumetrically rather than by weight.  I don't know of any fueling system that accounts for density or meters fuel by mass, so theoretically more fuel molecules enter the engine at every intake event and the real A/F ratio will slightly change.  Of course an O2 sensor and fuel heating by recirculation in an EFI system or in a carb throw wrenches into this line of reasoning.  Also we must take into account that an internal combustion engine is not 100% efficient, so the percentage increase in fuel does not necessarily equal the percentage increase in power output at the rear wheel.

Based on all that, I'd say a 5-7% increase is possible/likely

I was in the running for President of the Ducati Mathitista Club, but J3 is now IT  Knowledge and details are cool

One interesting part of my experience was that the 5, 7 or 12 % gain is what it takes to lift the wheel off the ground - can't do that when it's nice and warm.

Do I hear an InterCooler

2001 M900 74.5   hp/53.8 ft.lbs
S2R800      76.03 hp/ 53.5 ft.lbs

The m900 had no problems lifting the front in first. Work that wrist!!!

There is definitely more power in cold weather, especially on a Monster.  When I had my M900, I was able to do second gear power wheelies once the temperature got down to about 35 degrees, which were absolutely impossible above 60 degrees.  To me it felt like a 5-10% increase.

Quote from: wark on November 17, 2008, 03:36:05 PM
For sureâ€"not sure how much, but it's probably negated by the higher wind resistance at speed.

Something tells me that the average Monster rider is not as interested in top speed pursuits as they are interested in power wheelies in first  [moto]

Also the colder it is the less tire grip I would think there would be. Cold rubber. Cold Asphalt.

I know my Butt slids around on the seat easier when it's cold. I'm usually more concerned about the tires not getting good traction in the curves.

The tar snakes are more slippery !    At my age , there isn't much good that comes from riding when it is colder than 50 degrees.     Dolph

Quote from: He Man on November 17, 2008, 08:22:26 PM
2001 M900 74.5   hp/53.8 ft.lbs
S2R800      76.03 hp/ 53.5 ft.lbs

The m900 had no problems lifting the front in first. Work that wrist!!!

At what RPM?  The 900 made those numbers lower in the band.  It makes a difference.

My butt dyno 'confirms' this theory.  I definitely notice the old girls got more grunt when it's cooler out and feels a bit anemic when I've been forced to endure time on super-heated slab.

Well, either I'm producing but-loads more power, or my tires are just cold (yeah, I know thats it)... but when I start for a ride in the cold weather my monster just does a burnout instead of a wheelie!

Hows that for power increase?

Quote from: DoubleEagle on November 18, 2008, 12:13:31 AM
The tar snakes are more slippery ! 

My experience is that the tar snakes are MUCH more slippery when the temp is above 100 than below 50.

Quote from: Punx Clever on November 18, 2008, 07:31:09 PM
Well, either I'm producing but-loads more power, or my tires are just cold (yeah, I know thats it)... but when I start for a ride in the cold weather my monster just does a burnout instead of a wheelie!

Hows that for power increase?

I experienced the same thing a couple weekends ago, almost dumped the bike coming out of a gas station...

I am stunned .......... stunned.......... that nobody said, 11ty billion ........yet. [moto]

LA