Rpm

General Chat with an emphasis on BMC Minis & Other iconic cars of the 1960's. Includes information on MK1 Action days.
Post Reply
BLACKJACKф
Posts: 69
Joined: Thu May 27, 2021 9:10 pm

Rpm

Post by BLACKJACKф »

This might be kind of weird question or topic my car does not have a tachometer. My car is a complete stock 1275 Cooper S. I am wondering what is a good cruising speed on Highway. Measured in mph or kph and what RPMs would I be at? I've looked through books watched videos and can't seem to find anything for a safe cruising speed on Highway. Any information would be helpful please and thank you
User avatar
timmy201
Posts: 1833
Joined: Mon Jun 10, 2013 9:57 am
Location: Australia

Re: Rpm

Post by timmy201 »

Tachometers weren’t standard fitment on mk1 minis. On a Cooper S the maximum shift points are marked on the speedo with some Roman numerals - I, II, III

It should be happy to sit on 60-70mph all day which is around 4000rpm
User avatar
mk1
Site Admin
Posts: 19790
Joined: Thu Jun 24, 2010 11:30 am
Location: York-ish
Contact:

Re: Rpm

Post by mk1 »

Agreed, a decent one should pull that sort of speed all day every day.
User avatar
MiNiKiN
Posts: 851
Joined: Tue Oct 10, 2017 3:15 pm
Location: Graz/Austria // NN1 4ST previously

Re: Rpm

Post by MiNiKiN »

BLACKJACKф wrote: Wed Sep 13, 2023 6:45 pm This might be kind of weird question or topic my car does not have a tachometer. My car is a complete stock 1275 Cooper S. I am wondering what is a good cruising speed on Highway. Measured in mph or kph and what RPMs would I be at? I've looked through books watched videos and can't seem to find anything for a safe cruising speed on Highway. Any information would be helpful please and thank you
Here you find graphs for a Cooper S close ratio with 3.44 and 3.76 final drive. Speed on the Y-axis is in kph

Cooper S_CR_3.44-vs-3.76.jpg
You do not have the required permissions to view the files attached to this post.
Yes I am a nerd: I am researching the Austrian Mini-racing scene of the 60s and 70s :ugeek:
User avatar
Exminiman
Posts: 2625
Joined: Tue Jan 17, 2017 8:59 am
Location: Berkshire UK

Re: Rpm

Post by Exminiman »

here you go - you can try out different ratios, tyres etc...here

http://www.guess-works.com/Tech/ratio.htm

If you want to find out what ratio diff you have this is as good a description as I have seen of what to do https://www.theminiforum.co.uk/forums/t ... ?p=2107153
User avatar
BAD942B
Posts: 308
Joined: Wed Apr 05, 2023 6:34 pm
Location: Stratford upon Avon

Re: Rpm

Post by BAD942B »

Chris A
BLACKJACKф
Posts: 69
Joined: Thu May 27, 2021 9:10 pm

Re: Rpm

Post by BLACKJACKф »

Okay thank you so much that information. Is the engine very reliable at 4000 RPM? It is 55 years old . Lol I do know about the three orange colored lines on the speedometer I have never come close to an RPM that high . So maybe I should change my final drive to a 3.1
Last edited by BLACKJACKф on Sat Sep 23, 2023 7:03 pm, edited 2 times in total.
User avatar
mk1
Site Admin
Posts: 19790
Joined: Thu Jun 24, 2010 11:30 am
Location: York-ish
Contact:

Re: Rpm

Post by mk1 »

A 3.1 will decrease cruising RPM, but will have a proportional impact on acceleration.
BLACKJACKф
Posts: 69
Joined: Thu May 27, 2021 9:10 pm

Re: Rpm

Post by BLACKJACKф »

Yes I understand that about swapping to a 3.1. Thanks for the information again. Jack.
Post Reply