RPM and MPH

[sparkythecat]

My speedometer isn't working (sensor's been ordered) and I need to use my car tomorrow. It's a 98 Chim 400

I know 3800RPM in top is around legal motorway speed.
Can anyone tell me what 30mph and 40mph are in 4th? .

I know it's been posted somewhere befor, but search isn't working

[TimW]

30 prob bout 1500rpm 40 1900rpm? Just a ruff guess thinking about 1st does 35 at 6000rpm...

[sparkythecat]

Ta!

[barreti]

don't know if these are any use because my P&J is a Griff 4.3 pre-cat with a rover box - but here you are anyway.

in 3rd
1900rpm = 30

in 4th
1500rpm = 31

in 5th
1500rpm = 40
1900rpm = 50
2300rpm = 60
2600rpm = 70

Mines playing up and intermittent too !

Happy driving

[GreenV8S]

MPH-per-1000 rpm in each gear is roughly:

7 (1st), 11 (2nd), 17 (3rd), 21 (4th), 27 (5th).

Some useful reference points:

3000 rpm in 5th is 80 mph.
3800 rpm in 4th is 70 mph.
3000 rpm in 3rd is 50 mph.
2400 rpm in 3rd is 40 mph.
2700 rpm in 2nd is 30 mph.

[shpub]

There's an excel spread sheet on www.tvrbooks.co.uk that does all the calcs for you. Works for different tyre sizes, gear ratios etc. It's in the tyre FAQ. The table is also in the bible if you want to manually look it up.

[tahiti450]

sparkythecat said:

I know 3800RPM in top is around legal motorway speed.

Hmmm, in which country would that be! Wish I lived there My '99 450 (T5 box) would be pulling about 100mph at 3800 in 5th.

Peter summarised it above (in mph per 1000 rpm)
quite simple then to multiply by engine speed.

>> Edited by tahiti450 on Sunday 17th July 23:06

[T4NGO]

Hi, maybe mine is different to others???? I got different readings. On mine ('96 Chimaera 400) as my speedo is way out, and according to roadangel, 2000 revs seems to be right for whatever gear. eg 2000 in 3rd is 30, in 4th is 40 and 5th is 50. 70 is about 2800 in 5th. 3000 is about 85(allegedly!). This is what i use when i forget to plug in gps thingy and all ok sofar through the cameras! As far as I know all is standard gearbox/wheels/tyres etc.

Hope helps.
Alan

[tahiti450]

T4NGO said:

.....as my speedo is way out, and according to roadangel, 2000 revs seems to be right for whatever gear. eg 2000 in 3rd is 30, in 4th is 40 and 5th is 50. 70 is about 2800 in 5th. 3000 is about 85(allegedly!). .... As far as I know all is standard gearbox/wheels/tyres etc. Alan

The Road Angel readings are about right (though 3000rpm should be more like 80mph) and suggests that your car is all standard in terms of gearing / tyres.

>> Edited by tahiti450 on Wednesday 20th July 16:42