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Posts: 18 
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Joined: Jun 9, 2015 21:36:31 GMT -5
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Post by elektrey on Jun 14, 2015 20:41:43 GMT -5
I think when the air fuel mixture gets sucked into the engine its pressurized right?
this would alter the air density then
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Post by geh3333 on Jun 15, 2015 9:46:52 GMT -5
I think when the air fuel mixture gets sucked into the engine its pressurized right? this would alter the air density then What happens is on the downstroke the air and fuel is sucked into the chamber by the " downstroke of the piston in the cylinder" . same thing if you would suck something into a syringe . its not pressurized as its sucked in . then on the upstroke , both valves are closed Anthe the piston compresses the air and the gas , then around tdc the plug fires and ignites the compressed mixture which forces the piston back down . the piston then rises as the exhaust valve opens letting The gasses escape through the exhaust. |
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Post by geh3333 on Jun 15, 2015 10:29:42 GMT -5
The more I think about these calculations , the more I have issues with them . well at least some parts. Like , shouldn't the piston pull in at least the amount of air and fuel to equal the cc of the bore ? Well considering the rings are sealed good , I would expect yes. The more I look at my calculations I come to understand that when it comes to my setup , I am pulling in the perfect amount of fuel to match the amount of air in my chamber. When it comes to a stock setup with  mpg . the amount of fuel the setup is pulling into the chamber only needs 77cc's of air to burn it. So this would be a lean condition. The part that really gets me is , how then is someone with a stock bore able to not run lean and still get or even 80 mpg ? I did these calculations not having a clue how they would turn out , and when it comes to my setup , it seems I'm running the perfect mixture . when I say perfect mixture , I mean I'm pulling in the perfect amount of fuel to match the amount of air pulled in by the 58.5 top end. I do have a question . when it comes to the cc's of the chamber . does the 155cc count the head chamber also ? When it comes to the amount of air and fuel being pulled into the top end , a bigger head size would allow in more air and fuel . I'm thinking it only counts the cylinder space . does anyone have the answer to this ? |
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Post by geh3333 on Jun 15, 2015 10:47:57 GMT -5
Well from what I read , the head is not considered into the cc's of the engine. The cc of the combustion chamber however , is used for compression ratio. It only makes sense that the bigger the combustion chamber the more air and fuel can enter on downstroke. May not be much more but it still would be more . so everyone who is running a stock head with a bbk , your loosing out on performance. Not only with better quality but a smaller combustion chamber which would cause you to not be able to burn as much fuel .
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Post by geh3333 on Jun 15, 2015 10:53:47 GMT -5
Actually , since the piston does not rise into the combustion chamber , the piston would only suck from tdc of the cylinder , to the bottom of the stroke in the cylinder . however , the combustion chamber would still be filled with extra air . so this means the air to fuel ratio being sucked in by the piston can be a little richer , because of the extra in the combustion chamber . I hope I didn't confuse anyone , lol
Then again it would be exhaust gasses left in the combustion chamber . sooo , hmmm
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Post by dmartin95 on Jun 15, 2015 14:09:24 GMT -5
The more I think about these calculations , the more I have issues with them . well at least some parts. Like , shouldn't the piston pull in at least the amount of air and fuel to equal the cc of the bore ? Well considering the rings are sealed good , I would expect yes. The more I look at my calculations I come to understand that when it comes to my setup , I am pulling in the perfect amount of fuel to match the amount of air in my chamber. When it comes to a stock setup with mpg . the amount of fuel the setup is pulling into the chamber only needs 77cc's of air to burn it. So this would be a lean condition. The part that really gets me is , how then is someone with a stock bore able to not run lean and still get or even 80 mpg ? I did these calculations not having a clue how they would turn out , and when it comes to my setup , it seems I'm running the perfect mixture . when I say perfect mixture , I mean I'm pulling in the perfect amount of fuel to match the amount of air pulled in by the 58.5 top end. I do have a question . when it comes to the cc's of the chamber . does the 155cc count the head chamber also ? When it comes to the amount of air and fuel being pulled into the top end , a bigger head size would allow in more air and fuel . I'm thinking it only counts the cylinder space . does anyone have the answer to this ? There's a lot of issues with these equations. Environmental effects come into play with the way fuel is burned, like for example in the mountains or at sea level. In addition, rider weight, scooter weight, speed etc etc... How much fuel are you using at 25MPH, how 'bout 60MPH? etc etc... Can you provide a link to where you're getting your source material at? ------------------------------ If you're wanting to measure your actual fuel consumption, I suggest getting a digital flow meter and installing it inline on your fuel line. (I'm not recommending any of these products, as I have never used them for this application. Just providing a link to illustrate what type of device I think you could use.) I'm a big fan of math, but in this instance, there's a lot of variables. |
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Post by geh3333 on Jun 15, 2015 14:22:13 GMT -5
The more I think about these calculations , the more I have issues with them . well at least some parts. Like , shouldn't the piston pull in at least the amount of air and fuel to equal the cc of the bore ? Well considering the rings are sealed good , I would expect yes. The more I look at my calculations I come to understand that when it comes to my setup , I am pulling in the perfect amount of fuel to match the amount of air in my chamber. When it comes to a stock setup with mpg . the amount of fuel the setup is pulling into the chamber only needs 77cc's of air to burn it. So this would be a lean condition. The part that really gets me is , how then is someone with a stock bore able to not run lean and still get or even 80 mpg ? I did these calculations not having a clue how they would turn out , and when it comes to my setup , it seems I'm running the perfect mixture . when I say perfect mixture , I mean I'm pulling in the perfect amount of fuel to match the amount of air pulled in by the 58.5 top end. I do have a question . when it comes to the cc's of the chamber . does the 155cc count the head chamber also ? When it comes to the amount of air and fuel being pulled into the top end , a bigger head size would allow in more air and fuel . I'm thinking it only counts the cylinder space . does anyone have the answer to this ? There's a lot of issues with these equations. Environmental effects come into play with the way fuel is burned, like for example in the mountains or at sea level. In addition, rider weight, scooter weight, speed etc etc... How much fuel are you using at 25MPH, how 'bout 60MPH? etc etc... Can you provide a link to where you're getting your source material at? ------------------------------ If you're wanting to measure your actual fuel consumption, I suggest getting a digital flow meter and installing it inline on your fuel line. (I'm not recommending any of these products, as I have never used them for this application. Just providing a link to illustrate what type of device I think you could use.) I'm a big fan of math, but in this instance, there's a lot of variables. I understand completely . many different variables for how many mpg I'm getting. On average while running the scoot a little harder I get about 60mpg. Its def not 100% accurate , but I tried to make it as accurate as possible by using a relatively average rpm , considering even while running hard , there are stop signs and stop lights we have to consider . to me running her hard , is around 7000 rpms , but taking into consideration the stop signs and stop lights I came up with an average of around 5500 rpms. I'll find the site I got the 9,000 lbs of air to burn 1 gallon of fuel from and post it. Other than that its all math based on an average I got from my setup. But yes im sure its not 100% accurate but I believe it is in the ballpark. |
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Post by geh3333 on Jun 15, 2015 14:27:59 GMT -5
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Post by geh3333 on Jun 15, 2015 14:33:39 GMT -5
9000 gallons of air to 1gallon of gas is a 15:1 ratio of air to 17.1 is slightly lean , and 11.1 is very rich. 9000 gal of air weighs  lbs and 1 gal of gas weighs about 6 lbs . that's where the ratio comes in. |
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Post by geh3333 on Jun 15, 2015 14:46:49 GMT -5
Let's consider my averages are close , and it seems as if the book used for the my information on air to fuel is a good source . we are looking at some crazy stock numbers . I used the stock number from what I feel is an average number of mpg that many of these stock scoots get. I've heard of some getting nearly 100mpg . my scoot got around mpg stock. |
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mpg . the amount of fuel the setup is pulling into the chamber only needs 77cc's of air to burn it. So this would be a lean condition. The part that really gets me is , how then is someone with a stock bore able to not run lean and still get 
lbs and 1 gal of gas weighs about 6 lbs . that's where the ratio comes in.