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Old May 10, 2012 | 11:22 AM
  #27106  
jakbob's Avatar
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From: Pasadena, MD
Year: 1987
Model: Wagoneer
Engine: Renix 4.0
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Originally Posted by nowhres
I have the Rustys Airtube with a 9" K&N conical in place of the factory airbox.
There was a noticeable difference in mpg and hp. But this is coming from someone that has one installed.
and not trying to be a dick... but how do you know your mileage went up? were you running 32s? do you know the difference in rolling distance between stock wheels and 32's (if you didnt adjust your speedo gear) etc...

without data there is only opinion.
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Old May 10, 2012 | 11:26 AM
  #27107  
nowhres's Avatar
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From: Crofton, MD
Year: 1992
Model: Cherokee
Engine: 4.0 I6, 62mm BBK Throttle Body w/ 1" Spacer, Rusty's Airtube w/ 9" K&N Conical
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Originally Posted by jakbob
and not trying to be a dick... but how do you know your mileage went up? were you running 32s? do you know the difference in rolling distance between stock wheels and 32's (if you didnt adjust your speedo gear) etc...

without data there is only opinion.

MPG is not difficult to figure out. No matter the tire size, the equation remains the same.

20 gallon gas tank / distance driven

The airtube and filter gained about 50 miles per tank

Not opinion
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Old May 10, 2012 | 11:27 AM
  #27108  
Green2000's Avatar
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From: Sykesville, Md
Year: 2000
Model: Cherokee
Engine: 4.0
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Originally Posted by nowhres
Okay, I'll make a trip up and bring that inverter
Ill keep you posted
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Old May 10, 2012 | 11:29 AM
  #27109  
NewKindOfClown's Avatar
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From: Frederick, MD from Cleveland, OH
Year: 1993 YJ Wrangler
Engine: 4.0 I6
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Originally Posted by nowhres
MPG is not difficult to figure out. No matter the tire size, the equation remains the same.

20 gallon gas tank / distance driven

The airtube and filter gained about 50 miles per tank

Not opinion
But if you change your tire size without correcting speedo gear, you need to compensate for distance driven. If you've done that, great. If not, your numbers are off (as well as your odometer).
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Old May 10, 2012 | 11:30 AM
  #27110  
nowhres's Avatar
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From: Crofton, MD
Year: 1992
Model: Cherokee
Engine: 4.0 I6, 62mm BBK Throttle Body w/ 1" Spacer, Rusty's Airtube w/ 9" K&N Conical
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http://www.youtube.com/watch?feature...v=jlSF0dtDRD8#!
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Old May 10, 2012 | 11:34 AM
  #27111  
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From: Frederick, MD from Cleveland, OH
Year: 1993 YJ Wrangler
Engine: 4.0 I6
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Old May 10, 2012 | 11:34 AM
  #27112  
nowhres's Avatar
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From: Crofton, MD
Year: 1992
Model: Cherokee
Engine: 4.0 I6, 62mm BBK Throttle Body w/ 1" Spacer, Rusty's Airtube w/ 9" K&N Conical
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Originally Posted by NewKindOfClown
But if you change your tire size without correcting speedo gear, you need to compensate for distance driven. If you've done that, great. If not, your numbers are off (as well as your odometer).

Okay, I changed my tires over a year ago. When changing tires, I had factory airbox. After changing, I drove my Jeep. 6 months later, I changed my air filter. Equation remains the same
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Old May 10, 2012 | 11:36 AM
  #27113  
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From: Frederick, MD from Cleveland, OH
Year: 1993 YJ Wrangler
Engine: 4.0 I6
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Originally Posted by nowhres
Okay, I changed my tires over a year ago. When changing tires, I had factory airbox. After changing, I drove my Jeep. 6 months later, I changed my air filter. Equation remains the same
Calm down, I'm just trying to prevent 3 pages of tech questions from the youngins
So whether the numbers are right or wrong doesn't matter; the ratio still shows improvement.
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Old May 10, 2012 | 11:41 AM
  #27114  
nowhres's Avatar
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From: Crofton, MD
Year: 1992
Model: Cherokee
Engine: 4.0 I6, 62mm BBK Throttle Body w/ 1" Spacer, Rusty's Airtube w/ 9" K&N Conical
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Originally Posted by NewKindOfClown
Calm down, I'm just trying to prevent 3 pages of tech questions from the youngins
So whether the numbers are right or wrong doesn't matter; the ratio still shows improvement.

That's the same thing I was trying to prevent, lol

And brb, gotta order myself a Sticky Buddy
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Old May 10, 2012 | 11:46 AM
  #27115  
zwhiz's Avatar
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From: Alaska
Model: Cherokee
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Originally Posted by dukie564
this spot?
Originally Posted by NewKindOfClown
I didn't see him cross, but mine went over the hood twice. Look at how much of the front end is wet after I got out.

Sweet pics...whoever took those is a bamf
a couple weeks ago I took my buddy out to bowie state with his wrangler and we accidentally went through that deep spot in the river....he got stuck in it lol
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Old May 10, 2012 | 11:47 AM
  #27116  
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From: Frederick, MD from Cleveland, OH
Year: 1993 YJ Wrangler
Engine: 4.0 I6
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Originally Posted by nowhres
That's the same thing I was trying to prevent, lol

And brb, gotta order myself a Sticky Buddy
Suggestively sized?
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Old May 10, 2012 | 11:48 AM
  #27117  
nowhres's Avatar
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Joined: Feb 2012
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From: Crofton, MD
Year: 1992
Model: Cherokee
Engine: 4.0 I6, 62mm BBK Throttle Body w/ 1" Spacer, Rusty's Airtube w/ 9" K&N Conical
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Originally Posted by NewKindOfClown
Suggestively sized?
I want them rubber fingers.
While I am at it, may also order one of these
http://www.youtube.com/watch?feature...&v=h5qMbk5mL24
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Old May 10, 2012 | 11:52 AM
  #27118  
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From: Frederick, MD from Cleveland, OH
Year: 1993 YJ Wrangler
Engine: 4.0 I6
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Originally Posted by nowhres
I want them rubber fingers.
While I am at it, may also order one of these
http://www.youtube.com/watch?feature...&v=h5qMbk5mL24
I love this guy.


The dub guy...not the guy who posted above me.
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Old May 10, 2012 | 12:33 PM
  #27119  
jakbob's Avatar
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Joined: Dec 2011
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From: Pasadena, MD
Year: 1987
Model: Wagoneer
Engine: Renix 4.0
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Originally Posted by nowhres
MPG is not difficult to figure out. No matter the tire size, the equation remains the same.

20 gallon gas tank / distance driven

The airtube and filter gained about 50 miles per tank

Not opinion
i cant see the youtube vids at work but...

if you dont correct your speedo gear but increase the size of the tires, the odometer is off. for example (i worked out all this math a while ago, ill give the condensed version)

a 31 inch tire is 109% larger than a stock tire. Therefore, whatever my trip odometer says, i multiply it by 109% to get a better idea of where i am. its all about circumfrence.

which is why my speedo is off (roughly) 5 mph at 55 mph, 6 at 60, but the lower the speed, the lower the difference. its all math. now if my speedo says 120, im actually going about 131-132...

and no, the equation doesnt remain the same. when you change your tire size, you actually insert a variable. and that variable is the difference in distance that one revolution of the tire will net you. since the speedo reads the output shaft of the transfercase, it will always see the same data. so lets say for ****s and giggles, four rotations of the driveshaft equals 1 revolution of the wheel. this wheel is 29 inches long (and we can find the circumference by 3.14(diameter)) so 3.14(29)=91.06 inches. so now we have figured out this:

4 revolutions of the driveshaft = 91.06 inches traveled.

now we increase the tire size to 31 inches.

3.14(31)=97.34

so...

4 revolutions of the driveshaft = 97.34 inches traveled.

so you divide 97.34 by 91.06 to get the percentage increase which is

97.34/91.06=1.068965.

so by increasing the tire size diameter by 2 inches has changed your actual distance per revolution 106.8965%.

this is why your speedo is wrong.

Last edited by jakbob; May 10, 2012 at 12:40 PM.
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Old May 10, 2012 | 12:36 PM
  #27120  
jimmy21669's Avatar
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Joined: Mar 2009
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From: Berea, OH
Year: 1998
Model: Cherokee
Engine: 4.0
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Originally Posted by jakbob
i cant see the youtube vids at work but...

if you dont correct your speedo gear but increase the size of the tires, the odometer is off. for example (i worked out all this math a while ago, ill give the condensed version)

a 31 inch tire is 109% larger than a stock tire. Therefore, whatever my trip odometer says, i multiply it by 109% to get a better idea of where i am. its all about circumfrence.

which is why my speedo is off (roughly) 5 mph at 55 mph, 6 at 60, but the lower the speed, the lower the difference. its all math. now if my speedo says 120, im actually going about 131-132...

Yes we get it.

BUT....if my speedo is off with one tank, and off by the same amount the next tank...I can tell if I am saving.


AND

Originally Posted by jakbob
its all about circumfrence.

TWSS!
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