SuperHatch

iTrader: (23)

This is a little something I put together in Excel to help Evo owners determine what effects on vehicle speed changing tire size and gear will have.

If you look at the sheet selection area at the bottom of the page, there are multiple tabs for different sheets. The first 4 tabs show graphs of vehicle speed versus RPM for each transmission option, the Evo VIII stock ratios, the Evo IX Stock ratios, the MR Stock ratios, and the Evo VIII/IX Hybrid 5-speed ratios.

If you go to the Data tab and change the value in the Red Box under "Selected Final Drive" to any of the values in the three boxes to the right (those are the available options) it will automatically update the graphs to account for the gear changes.

The same goes for tire size, it will update your speed for the changes in tire size. The graphs show ACTUAL VEHICLE SPEED, not what will be displayed on your speedometer. The speedometer will read correctly if you change final drive in your car, but it will not read correctly if you change tire size.

There is a box next to the tire size window that shows the percent error for a given tire size change from stock, and what your speedometer will say when you are actually going 65MPH.

Hope this is found to be useful by some of you folks...

Gear / Tire Calculator, click here

**Yes, this is hotlinked to another site, but the info is good and I wanted to share.

recompile

iTrader: (38)

Very nice!

Now, I've been playing with my new Beltronics Vector G-Meter... based on this chart, if I want to get a good "dyno" rating using the G-Meter, I should do a 3rd gear pull from 35mph (3000rpm) to 80mph (7000rpm). Sound good?

SuperHatch

iTrader: (23)

That sounds good, but the most important thing is to make sure you're on a flat straight road and there is no wind. When you make tuning changes and want to record differences, always travel in the same direction on the same stretch of road. You want to keep variables to an absolute minimum.

KevinD

iTrader: (56)

holy crap, that is almost identical to a excel worksheet i made a friend a year ago. like seriously... i had tire size entry, gear ratio entry, final drive entry, the speed in gear plots and the delta speedometer values.

if i had copyrighted mine i'd be suing you hahahaha j/k. i know he posted it up on his f-body forums, and maybe even into his subaru forums or even the supercars.net. anywho, great minds must think alike, cause well damn, we are the same

SuperHatch

iTrader: (23)

Haha, well I definately didn't copy that off of anyone, but great minds do usually think alike.

9sec9

iTrader: (2)

I've been using a program to do this and 1/4 mile times. This is a great tool you've posted. thanks

SuperHatch

iTrader: (23)

no problem