I had my car at VIR Tuesday. My speedometer is broken and I was wondering if anyone might know how fast I was going? Stock OEM wheel and tire size and I was doing 8,000rpms in 4th gear entering the esses. Then I got up to 7,000 rpms in 5th gear on the back straight.

So what is the mph at 8,000rpms in 4th?
Then 7,000rpms in 5th?

Thanks and if anyone know the formula to figuring this out I could use it.

 

I'm going to say 115 in 4th and 130 in 5th.

I think the 4th gear ratio is 1.107 and 5th 0.848. Then I just googled gear speed calulator and plugged that along with FD 4.40 and tire data.

Of course, I could be way off.

 

I was thinking it was about 130 to 135 in 5th. I just don't know the math.

 

You are right! 115mph in 4th and 131mph in 5th. I googled the gear ratio also and found this.

http://fatboyraceworks.com/gears/ind...raph&Compare=1

I hope the helps someone else. Thanks for the help Scotty2H.