Dramatic acceleration difference with weight - Ford Mustang Forum
 
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post #1 of 14 (permalink) Old 03-17-2007 Thread Starter
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Dramatic acceleration difference with weight

Anyone else notice a dramatic difference, in acceleration and tire spin, between a full tank and an almost MT tank?

In second gear, I get squirrley putting the pedal down, clutch out, between 3K and 5K RPM, but only with less than a 1/4 tank.

At about 7.6 pounds per gallon, those 14 missing gallons weigh 106 pounds. And that's behind the rear wheels so those pounds are like little levers... if the CG of the tank is two feet behind the axle, does that make a difference? Is it like twice the foot pounds, at that point? Any engineers out there? I would think yes, because if I imagine puting the 200 pounds out on a ten foot lever, I could lift the front of my car every time I hit the gas, therefore I am able to put a lot more force on the rears by putting the weight farther back so 106 pounds of fuel centered 2 feet back (I think it's actually farther back than that) puts the eqivalent of 212 pounds on the back tires. I see why weight placement would be very important in a serious drag racer. 100 pounds, three feet back only adds 100 pounds but would shift 300 pounds onto the back tires for traction and pulling a percentage of that, off the fronts. Seven feet back and they become like "dog pounds".

Did I hear that 100 pounds of weight loss is equal to about 0.1 second in the 1/4 mile? Diet time.

Ah, I'm probably way off on this... weigh off too. Geek humor.


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post #2 of 14 (permalink) Old 03-17-2007
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I've noticed that years ago with my 64 fairlane. With that exact weight of fuel at 7.6 you must have been in the military? I guess Gas is heaver then JP-8 jet fuel which is 6.7.



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post #3 of 14 (permalink) Old 03-17-2007
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Isn't the tank in front of the rear wheels?

Sure, more fuel= weight=pressure=traction. and the power to weight ratio goes down. definitely less tire spin.
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post #4 of 14 (permalink) Old 03-17-2007
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Quote:
Originally Posted by Kohaku View Post
Isn't the tank in front of the rear wheels?
But it is correct that weight=pressure=traction.
.
Yes it is and if it was behind the rear it would have a higher pressure per the same weight because of mechanical advantage.


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post #5 of 14 (permalink) Old 03-17-2007
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I too notice a difference. If I am not mistaken, when the mags do the quarter and zero to sixty thing the standard is a quarter tank... To keep it uniform in some way...

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post #6 of 14 (permalink) Old 03-17-2007
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Quote:
Originally Posted by Nyt_Muves View Post
I too notice a difference. If I am not mistaken, when the mags do the quarter and zero to sixty thing the standard is a quarter tank... To keep it uniform in some way...
Yeah, I've read that too...also gets a better time because of less weight. I you watch any NASCAR they mention quite a bit that the cars handle differently once they start burning off the fuel load.

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post #7 of 14 (permalink) Old 03-17-2007
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Quote:
Originally Posted by travelers View Post
...if it was behind the rear it would have a higher pressure per the same weight because of mechanical advantage.
duh. theater of the obvious.

lol, I'm picturing a gigantic penny on the rear bumper

.

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post #8 of 14 (permalink) Old 03-17-2007
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When i am out messing around, i like to have atleast 3/4(yes 3/4) in the tank just so i dont lose fuel. Also with the weight thing, i was going to lunch with 2 friends that equat to just about 400 pounds and i see a gray gt500 going the other way. needless to say i swung it around at the next intersection caught up to him and he wouldn't run me at first but them from 50-85 all in 3rd he got me by 3/4 of a car. I was pissed, then he told me hed rip me a new one. I told him to let me drop them off on the side of the road and well go again. He said ok as were pulling off the road he takes off. ****, he knew what was gonna happen if he let me drop them off. BTW I had 7/8's of a tank.
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post #9 of 14 (permalink) Old 03-18-2007
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Perhaps he decided he didnt want to street race some some punk kid who thinks he knows it all?

There's a difference between a momentary "punching the throttle" and a semi-organized street race. Just because the other guy chose not to participate doesn't mean you win by default or that the other guy is a *insert phallic symbol here.* I don't reckon you'll understand this now... but give yourself some time, you'll be the fellah in the gt500 and perhaps then you'll understand.

Then again, perhaps it was being driven by another kid that goes to your school... in which case he was perhaps of the avarian persuasion, I don't know... I don't run in your circles.
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I too notice a difference with less gas in the tank. Just the other day I was surprised how easy my tires were breaking loose from the line at stops even at a low MPH roll. I then realized how low on gas I was.
I usually keep it full to 3/4 full.
I have an automatic, and it usually takes just a slight "power brake" to get the rpms up a bit to break loose or else the car just hooks up (which I know...is what it is suppose to do)
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eyelleye did i ever say i won by default, or that i won at all. I would love to say something rude to you but i dont want anymore infraction points
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Quote:
Originally Posted by KILLER06MUSTANG View Post
eyelleye did i ever say i won by default, or that i won at all. I would love to say something rude to you but i dont want anymore infraction points

OFFTOPIC: What are infraction points?

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ya gotta be careful on what ya say or they will get ya

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Remove the mufflers,go with straight pipes ,dont worry about how much gas you have (right jet-black?)

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