Caterham CSR 200

[kp nuts]

In order to determine engine working at certain mph, for a Caterham CSR 200, with a 6 speed gearbox and 15 inch wheels, required is engine rpm per unit of speed (say 100 mph) in 6th gear - for (a) a Touring 6th gear and (b) a Competition 6th gear.

[NORMANTHEDOG]

and what is the question

[rdv]

you dont say what the gearbox is or what final drive ratio you are running. assuming 5th is direct and 6th is o/d for touring you could happily run 28mph per 1000rpm in 6th but as NTD says what exactly are you asking

[kp nuts]

To rdv., It is a speculative enquiry prior to a poss. purchase. I cannot find precise spec info., but a performance box on that particular m/c @ 5,000 rpm apparently gives 93 mph., In other words it is a screamer and not suitable for continental motorways. An alternative for a new car is the touring gearbox, hence my requested check on both gearboxes.
The gearbox is Caterham's own, tagged as for the CSR 260. I believe 6th gear is direct (can't substantiate). In fact a 5 speed box is said as seemingly suited for motorways .

[rdv]

it depends what you want to use the car for, clearly gearing of 18.6 mph per 1000rpm in top is only suitable for competition. increasing the rear wheel size would help for motorways but changing the diff isa better option. Caterham should be able to advise but for such a light car a diff ratio of around 3.55 would be better for road use and maybe 4.22 or 4.55 for comp