Do lower temps. increase HP?
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Outstanding HDF Member
Joined: Sep 2007
Posts: 2,210
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From: Elk Grove Village,Il.
Do lower temps. increase HP?
I wonder if any significant ponies arise from lower temps? I know turbo's with inner coolers boast about more HP.But yesterday I was riding,it was about 35F and sometimes it feels like a little extra boost is there,but I could easily be fooling myself.Any idea's?
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Tourer
Joined: Mar 2007
Posts: 368
Likes: 2
From: Salina, KS
RE: Do lower temps. increase HP?
Not to be contrary, but cold air is more dense (thicker) than hot air. When gliders fly over flatland, they will look for plowed fields, because the warmth causes an updraft, and they will try to avoid green fields or irrigated land, because cool air sinks--it is heavier and more dense.
Cold air has more oxygen per cubic foot, so, if your bike was a little rich when it was warmer, then it is entirely possible that you could extract more power when it is colder. The extra fuel will burn more completely with cold air. In fact, if the tuning is right on at 90 degrees, and it drops to 30, the idle air mix may have to be opened a bit to keep the bike from getting the lean farts when the throttle is popped open.
However, I don't know how significant the change is.
Cold air has more oxygen per cubic foot, so, if your bike was a little rich when it was warmer, then it is entirely possible that you could extract more power when it is colder. The extra fuel will burn more completely with cold air. In fact, if the tuning is right on at 90 degrees, and it drops to 30, the idle air mix may have to be opened a bit to keep the bike from getting the lean farts when the throttle is popped open.
However, I don't know how significant the change is.
Club Member
Joined: Feb 2007
Posts: 16,320
Likes: 306
From: Boynton Beach, FloriDuh
RE: Do lower temps. increase HP?
rfranz1952 is correct. Unfornunately, based on some recent posts here, the newer Sporty's with EFI may not be doing a great job of compensating. If you have a carbed bike, it's usually a matter of backing the mixture adj. screw out about a 1/4 turn during the cold months.
Outstanding HDF Member
Joined: Aug 2007
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From: fegfsg
RE: Do lower temps. increase HP?
ORIGINAL: rfranz1952
Not to be contrary, but cold air is more dense (thicker) than hot air. When gliders fly over flatland, they will look for plowed fields, because the warmth causes an updraft, and they will try to avoid green fields or irrigated land, because cool air sinks--it is heavier and more dense.
Cold air has more oxygen per cubic foot, so, if your bike was a little rich when it was warmer, then it is entirely possible that you could extract more power when it is colder. The extra fuel will burn more completely with cold air. In fact, if the tuning is right on at 90 degrees, and it drops to 30, the idle air mix may have to be opened a bit to keep the bike from getting the lean farts when the throttle is popped open.
However, I don't know how significant the change is.
Not to be contrary, but cold air is more dense (thicker) than hot air. When gliders fly over flatland, they will look for plowed fields, because the warmth causes an updraft, and they will try to avoid green fields or irrigated land, because cool air sinks--it is heavier and more dense.
Cold air has more oxygen per cubic foot, so, if your bike was a little rich when it was warmer, then it is entirely possible that you could extract more power when it is colder. The extra fuel will burn more completely with cold air. In fact, if the tuning is right on at 90 degrees, and it drops to 30, the idle air mix may have to be opened a bit to keep the bike from getting the lean farts when the throttle is popped open.
However, I don't know how significant the change is.
i dont know where he came up with "cold air is thinner"
maybe thinner cold air at a higher altitude, but if you focus on the change of seasons in the particular place a bike is ridden then it is thicker usually
Seasoned HDF Member
Joined: Feb 2007
Posts: 5,067
Likes: 394
From: Edmonton Alberta Canada
RE: Do lower temps. increase HP?
I agree with most of the above but it is true that cold air produces more horsepower, that's the whole point of an intercooler. Also cold gas does the same, many dragsters cool the fuel before the run or have onboard dry ice tanks to cool the fuel just before it goes into the engine.
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Road Warrior
Joined: Aug 2006
Posts: 1,269
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From: St. Albans, West Virginia
RE: Do lower temps. increase HP?
I can tell a difference in how mine sounds and runs when it is cooler. That is why I love the cooler weather in the Phoenix area.
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From: Nashville, TN
RE: Do lower temps. increase HP?
ORIGINAL: rfranz1952
However, I don't know how significant the change is.
However, I don't know how significant the change is.