Do fat guys have to run less air pressure??
Sep 9, 2003 | 06:53 PM
#11
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Do fat guys have to run less air pressure??
Originally posted by: Redbaron
Lets say both the fat guy and the thin guy are on 400EXs. And lets say each 400EX weighs 400 pounds with fluids, and puts out 25 HP at the rear wheels. So the thin guy plus quad weighs 400 + 150 = 550 pounds. This gives him 550/ 25 = 22 pounds per horsepower. Fat guy plus quad; 400 + 250 =650 pounds. This gives him 650/ 25= 26 pounds per horsepower. So for the fat guy to get to 22 pounds per horsepower like the thin guy has, he would need 650/ 22 = 29.545 horsepower. To put it another way the fat guy would only need about 4.5 horsepower more in mods to equal the thin guy on the stock 400EX. Granted, in this example I have not included any increases for wind resistance or higher frictional loses and higher rolling resistance which the fat guy would also experience, but still no way near a 15 horsepower disadvantage.
Lets say both the fat guy and the thin guy are on 400EXs. And lets say each 400EX weighs 400 pounds with fluids, and puts out 25 HP at the rear wheels. So the thin guy plus quad weighs 400 + 150 = 550 pounds. This gives him 550/ 25 = 22 pounds per horsepower. Fat guy plus quad; 400 + 250 =650 pounds. This gives him 650/ 25= 26 pounds per horsepower. So for the fat guy to get to 22 pounds per horsepower like the thin guy has, he would need 650/ 22 = 29.545 horsepower. To put it another way the fat guy would only need about 4.5 horsepower more in mods to equal the thin guy on the stock 400EX. Granted, in this example I have not included any increases for wind resistance or higher frictional loses and higher rolling resistance which the fat guy would also experience, but still no way near a 15 horsepower disadvantage.
4.5hp doesn't sound like much but it really makes a difference
I weigh 250-255 and I raced a guy on a shee
I beat him by 2 lengths........and one of my friends that weighs 145/150 raced him on my back (we are both the same skill level, he is just lighter) and he beat the shee by 7 lengths.......
Sep 9, 2003 | 06:54 PM
#12
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Do fat guys have to run less air pressure??
Originally posted by: 14mins
I was wondering if a 350 pound guy sits on a quad if the air pressure goes up??
I was wondering if a 350 pound guy sits on a quad if the air pressure goes up??
Sep 9, 2003 | 07:20 PM
#13
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Do fat guys have to run less air pressure??
Zombie- I do not think your numbers are right. It would be like saying a stock raptor could beat you on a built 686.
I would say 30 pounds equals 1 HP, so go ahead and have another twinkie
Some of the DS guys i have seen have a combined weight close to 900 pounds. lol
I would say 30 pounds equals 1 HP, so go ahead and have another twinkie
Some of the DS guys i have seen have a combined weight close to 900 pounds. lol
Sep 9, 2003 | 07:33 PM
#14
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Do fat guys have to run less air pressure??
Hey Mark whats up. I race Mustangs. Everyone I know uses the formula 100lbs=10hp. This formula works quite well up to a certain point. If you have a car with minor bolt ons, this is a great formula to use. Now if you have a car with different heads/cam/intake etc etc, the formula changes. The faster the et of the car, the less correct the formula is. It is pretty much the same for the quad. But like I said, this only works for so long before it is null and void. Does that make any sense at all? LIke the stock quads could keep loosing weight and going faster until they reached a certain point A where now for every 10lbs they take off they are only gaining .5 hp then they reach point B and they are only gaining .25HP...etc etc. Does this make sense? THe faster a vehicle goes, the more resistance it encounters with the environment and the more power needed to propel the vehicle etc etc.
Sep 9, 2003 | 08:25 PM
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Do fat guys have to run less air pressure??
No 14 twinkies aren't what I like. I'm more of a beer guy. You comin to sandfest? I was thinkin we could race and test out the rider weight formula. If I'm right you might have a chance, if you are right you'll get smoked. I was hoping to get to race you at sandfest, but again I guess not.
Sep 9, 2003 | 08:31 PM
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Do fat guys have to run less air pressure??
[quote]
Originally posted by: 14mins
Fat guys should hook up better
I can honestly say, from personal experience, that being "skinny-azz challenged" helps me keep the quad on the ground and add's cushion in case of a bail-off....I'm 240....[img]i/expressions/face-icon-small-wink.gif[/img][img]i/expressions/face-icon-small-cool.gif[/img]
Originally posted by: 14mins
Fat guys should hook up better
I can honestly say, from personal experience, that being "skinny-azz challenged" helps me keep the quad on the ground and add's cushion in case of a bail-off....I'm 240....[img]i/expressions/face-icon-small-wink.gif[/img][img]i/expressions/face-icon-small-cool.gif[/img]
Sep 9, 2003 | 08:36 PM
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Do fat guys have to run less air pressure??
The only thing that really makes sense is condering power/weight ratio. The lb=hp estimation for a car will not work for a quad. If you consider translational kinetic energy
Power x time = 1/2 x mass x velocity^2 you can see a very direct relation between mass and power. But the velocity relation is not direct so you can see doubling power will not double the speed at a given time or acceleration for that matter.
For example if you needed 30hp to reach 50mph after 6 seconds
you would need... 120hp to reach 100mph in 6 seconds with the same mass. Not 60hp as might be supposed.
So mass and power have a direct relation but power and acceleration have a parabolic relation.
Of course once you get in the sand, or loose dirt, toss all this out the window becuse the traction is poor and there are new variables.
In conclusion, fat guys need more air pressure [img]i/expressions/face-icon-small-smile.gif[/img]
Power x time = 1/2 x mass x velocity^2 you can see a very direct relation between mass and power. But the velocity relation is not direct so you can see doubling power will not double the speed at a given time or acceleration for that matter.
For example if you needed 30hp to reach 50mph after 6 seconds
you would need... 120hp to reach 100mph in 6 seconds with the same mass. Not 60hp as might be supposed.
So mass and power have a direct relation but power and acceleration have a parabolic relation.
Of course once you get in the sand, or loose dirt, toss all this out the window becuse the traction is poor and there are new variables.
In conclusion, fat guys need more air pressure [img]i/expressions/face-icon-small-smile.gif[/img]
Sep 9, 2003 | 08:36 PM
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Do fat guys have to run less air pressure??
I did a test one day to see how much weight really did matter. We took 2 LS1 Z28's. Both cars were setup equal. With me in Car A, Car B would jump out ahead by a bit on the downshift when the race started and maintain his lead. With me in Car B, Car A would jump out. This is in a 320hp about 3700lbs or so vehicle me being about 190. So weight really does make a difference.
Sep 9, 2003 | 08:39 PM
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Do fat guys have to run less air pressure??
Green, exactly was I was saying. The formula (assumption might be a better word) works up to a given point but when you start going faster you need more power to continue accelerating. Glad someone agrees [img]i/expressions/face-icon-small-smile.gif[/img] [img]i/expressions/face-icon-small-smile.gif[/img]