Jump to content
Sign in to follow this  

Engine Speed Calculation

Recommended Posts

Found this cool Excel spreadsheet on Triumph Rat (set up for Triumph Thunderbird Sport) which gives you your rpms for various speeds in each gear and your speed in each gear for various RPMS.

http://www.triumphrat.net/modules.php?op=modload&name=Downloads&file=index&req=getit&lid=52

You have to plug DRZ data into it.

I got the raw DRZ data from this thread -

https://thumpertalk.com/forum/showthread.php?t=285084

and calculated these ratios from this data

2.286

1.733

1.375

1.091

0.864

With a primary reduction ratio of

2.960

This yielded the following speeds at 9500 rpms for the S with stock rear tire and stock sprockets -

1 38

2 50

3 63

4 80

5 100

and at 90 mph actual - which I think is about the max top end for the S in stock trim - showed engine speed of 8508 RPM's.

If I have any of the drive or primary ratios wrong someone please let me know.

-

Share this post


Link to post
Share on other sites

It's pretty good. I like that it shows the tire diameter. One thing that bugs me is that changing the sprocket size doesn't affect the other numbers. You have to calculate the sprocket ratio and enter it in the secondary reduction column.

This one is a repost. It's nice too, but doesn't show the tire size, so you can't be sure how accurate it is.

Share this post


Link to post
Share on other sites
It's pretty good. I like that it shows the tire diameter. One thing that bugs me is that changing the sprocket size doesn't affect the other numbers. You have to calculate the sprocket ratio and enter it in the secondary reduction column.

This one is a repost. It's nice too, but doesn't show the tire size, so you can't be sure how accurate it is.

I saved the spreadsheet to my hard drive and when I change the sprocket size it automatically changes the secondary reduction. I am running Office 97. You might want to check that again.

-

Share this post


Link to post
Share on other sites
I saved the spreadsheet to my hard drive and when I change the sprocket size it automatically changes the secondary reduction. I am running Office 97. You might want to check that again.

-

Really? I saved it to my hard drive too, but it didn't do it automatically :banghead:

I ended up modifying the spreadsheet. I entered in the formula to do the calculation in that cell. It works now.

Edit: I think I know what I did wrong. I might have deleted the formula by accident when I was playing around with it. I tried your link again and it works fine.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...