Originally Posted by jimmy21669

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




TWSS!

Originally Posted by jakbob

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.

Originally Posted by jakbob

no. it is invalid data. if you dont know how off you are, none of the data is sound. all you have is that feeling that you are saving... like the "zomg i put on a CAI and i feel the HP" feeling people get. go by hard math. thats how you know. same way i found out im getting better mpg putting on 31s, and the way i modified my exhaust. hard numbers.

what is TWSS?

Originally Posted by nowhres

Don't always need hard math, common sense works well also.

That's what she said

Originally Posted by Veeb0rg

https://docs.google.com/spreadsheet/...NSzFYWGc#gid=0

I use this to calculate for MPG. I made it editable by yall, feel free to use it. Its just something I found on the web.

Originally Posted by jimmy21669

The scientific method proves MY point. Equal conditions yielding a different result. Are rhe numbers reliable? No. Is the conclusion reliable? Yes.

Originally Posted by jakbob

what conditions are you relying your thesis on?

Originally Posted by jimmy21669

That in Scott's example...tire size was the same before AND after installing the CAI. The only variable was the intake. So yes...you are not reading correct MPG...but can you draw the conclusion that MPG got better from that DATA? YES!