Jump to content
Click here to contact our helpful office staff ×

mph / engine revs


Nick

Recommended Posts

Can anyone please tell me the road speed per engine revs in top gear of a 1998 1.6K ss with the five speed gearbox, Caterham LSD and running on 13" AO32Rs?

 

My speedo died and the new one seems even more inaccurate, according to my Sigma. I keep forgetting to measure speed over a measured mile, and I haven't got a GPS thingy!

 

Thanks.

Nick

 

Edited by - Nick on 18 Dec 2000 12:33:28

Link to comment
Share on other sites

Thanks Mike. Yup, 185 x 60/13.

 

What are the two diffs? And how do I know which I have?! I specced my 7 with the AP LSD, but can't see any reference in the paperwork to its ratio.

I take it you use 4th gear as it's 1:1?

And... do you know the maths for working it out?

 

Ask a simple question, get a simple answer, stir for 5 minutes... wink.gif

 

Edited by - Nick on 18 Dec 2000 13:37:49

Link to comment
Share on other sites

The AP LSD is independent of the diff ratio, so you could have either. I suspect you'll have a 3.92 since the 3.62 was mostly fitted to Superlights (6-speed 'box with 1:1 top).

 

> I take it you use 4th gear as it's 1:1?

 

Yes. Easy enough to scale it for 5th if you know what the ratio is (0.87 perhaps?).

 

> And... do you know the maths for working it out?

 

I put a spreadsheet together for it. The maths isn't rocket science - you can calculate the tyre diameter given that you know the wheel diameter and the sidewall height (sidewall being 60% of 185, not forgetting that there are 2 sidewalls making up the diameter). From that you can calculate the circumference etc.

 

I'll email you the spreadsheet if you like.

 

Cheers,

 

Mike

Link to comment
Share on other sites

Thanks again Mike. 3.92 gives a more likely result.

5th at 0.87 sounds familiar but I'll check.

I have the actual tyre diameter somewhere as I measured it for my Sigma - I took 10 revolutions and divided by 10 to reduce the error margin.

OK, send me a speadsheet over please - it will give me a break from trying to work out NI contributions! sad.gif mad.gif thumbsdown.gif

 

Nick

Link to comment
Share on other sites

Create an account or sign in to comment

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

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...