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Post by prodigit on Sept 23, 2013 5:52:54 GMT -5
So, how does rain generally affect the AF ratio in a carburetor?
Imagine you're riding in 2 identical situations, except one has a totally dry environment, and the other has a 100% humidity, with the air filter scooping in a lot of rain.
I know that sometimes in fuel there's water in the tank, and the engine consumes it anyway.
But what would water damp do to the AF mixture MPG and performance wise?
Will it improve performance, or decrease it?
I know that water is denser than air, as you're sucking in liquids into the airfilter instead of gas, that after the combustion will become more like a gas. So let's say your airfilter is scooping in some water drops, what will it do to the engine?
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Post by carasdad on Sept 23, 2013 7:36:18 GMT -5
So, how does rain generally affect the AF ratio in a carburetor? Imagine you're riding in 2 identical situations, except one has a totally dry environment, and the other has a 100% humidity, with the air filter scooping in a lot of rain. I know that sometimes in fuel there's water in the tank, and the engine consumes it anyway. But what would water damp do to the AF mixture MPG and performance wise? Will it improve performance, or decrease it? I know that water is denser than air, as you're sucking in liquids into the airfilter instead of gas, that after the combustion will become more like a gas. So let's say your airfilter is scooping in some water drops, what will it do to the engine? Odd that you bring this up..but thank you. Sept is the cold rain season here in Michigan. yesterday I rode all day long in the cold rain..power and acceleration were up big time. ;D Then my stock foam airbox filter got soaked and it was too rich. I wrung the foam element out..put it back in...and the power was higher that it had been all summer! Maybe you can Google this..it was way before your time...but we old folks want to know what ever happened to it. In the 1970's during our fuel crisis.. a guy invented a water vapor injection system for his car. It was all over the news!! Because his invention increased his fuel economy..the engine ran cooler..and the introduction of unleaded fuel caused us pinging and detonation. But his invention took away spark knock for our old high compression Chevy 350's and Ford 351's. We waited for him to market this...but by some strange twist of fate he died in a house fire. We were all astonished...except...well the big oil companies. When questioned by reporters they failed to comment. When I was stationed in Italy..some of them use water vapor injection. A design they learned from the Germans...and now may countries use it.. EXCEPT the U.S. .gee Exxon..mind telling us why?..  prodigit you have a very valid question here..extremely insightful...I can't wait for answers.  |
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Post by gatekeeper on Sept 23, 2013 8:03:07 GMT -5
US Air Force used water injection systems in some of their older B-52's and KC-135's (the ones that used straight jet engines as opposed to turbo-fan engines) to provide more power during the takeoff roll. They would use them when the ambient temperature was above a certain degree. It made the air entering the engine intakes more dense. More dense = more oxygen by volume. That boosted the power output for takeoff. Of course the engines were able to pull more fuel through them when the systems were used to complement the denser air.
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Post by scootnwinn on Sept 23, 2013 8:41:44 GMT -5
Normally it seems like the bike will run a little better in the rain if I notice any difference at all. Your intake should not be scooping a lot of rain it should be pointed back... Motorcycles are waterproof and rain won't affect the performance all that much if at all. You shouldn't really care as you should be easing on the the throttle and generally not checking for peak performance...
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Post by sailracer on Sept 23, 2013 8:52:32 GMT -5
[replyingto=carasdad]carasdad[/replyingto]That was actually a wartime (ww2) invention. In the 80's, I was watching a neighbor fiddle around under his hood with a water bottle and some vacuum lines.He was an old ww2 vet. explained the whole thing to me. Has to do with water molecules making the combustion more efficient.
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Post by carasdad on Sept 23, 2013 8:58:24 GMT -5
US Air Force used water injection systems in some of their older B-52's and KC-135's (the ones that used straight jet engines as opposed to turbo-fan engines) to provide more power during the takeoff roll. They would use them when the ambient temperature was above a certain degree. It made the air entering the engine intakes more dense. More dense = more oxygen by volume. That boosted the power output for takeoff. Of course the engines were able to pull more fuel through them when the systems were used to complement the denser air. Our USMC C-130's and F/A 18's had to use it in Iraq...the air is hot and dry. Even our Hueys did..many suffered a 'flame out'..odd how we design aircraft to fly perfectly well in the U.S. environment..yet expect it to function properly in other climates.. @ Rob...I don't push my scoot to the max during rain..I just know it is 'snappier'...I keep the speed down...but for some reason if I crack throttle..it is more responsive..once our snow hits it is even better..makes me think I should ride my snowmobile instead...lol. Wanna flash from the past?.. My Snowmobile is a John Deere....1977 440 now all John Deere makes are Tractors in Moline Illinois... But then my John Deere was made by Ski-Doo anyway. It is mint condition..so I store it more than I ride it.. But where you live should be dry warm air..how does your Burgman run in that vs your cool wet season? |
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Post by prodigit on Sept 23, 2013 9:00:19 GMT -5
I actually noticed an improvement on my motorcycle (VT750) as I went through a rain storm last week!
I was on the I95, when all of a sudden it started pouring like you couldn't see a street width in front of you.
Of course, I hate this weather on a bike, so I tried hurrying up. The bike seemed to rev a lot better, have a lot more power than usual, despite the roads being full of water.
Usually you'd think water on the roads is friction for the bike to overcome.
Wasn't the case here, it revved faster than on a dry day.
How do I know this?
Because I overgeared my VT750 for better fuel economy. It doesn't have a lot of power at all in final gear, and takes nearly forever to go from 80-95MPH (I need to upshift to 4th to get to top speed of 103MPH).
I wasn't sure if it was my imagination, but I was almost sure it was working so much better.
Even if the air filter would not scoop solid rain drops in, the air filter could get sogged with water, from the water damp, and drops of water could enter the carburetor.
If not drops, at least tiny liquid water particles a fraction the size of a grain of sand or salt, that are floating in the air on the highways; that are not categorized as being in gas form.
Plenty of these in the air will cause the air density to increase.
Another aspect of water intake would be to see if it could actually damage the engine.
I suspect because the engine is so hot, most water entering it, will exit the exhaust, but what happens to the water vapor passing the cylinder seals, entering in the crankcase?
I suspect the oil is hot enough to keep it in a gas state, but as soon as you stop the engine, and it cools down, the water will become liquid?
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Post by scootnwinn on Sept 23, 2013 9:32:49 GMT -5
Wow seriously! The engineers who design engines assume it will rain. You will not get a measurable amount of water past the "cylinder seals" Water is a normal part of combustion. Change your oil regularly and you have nothing to worry about.
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Post by prodigit on Sept 23, 2013 14:01:28 GMT -5
Makes me wonder why AC water isn't routed to the air intake on cars?
It robs so much power to run an AC, only to let that water drop to the ground?
Instead use it to cool down the radiator, and then use it in the air intake.
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