What Does Your Rev Counter Read at 70MPH?

[kitesurf_phil]

There has been a debate rumbling down in the Technical section regarding what revs are indicated for a given speed. My 2.4L SSR-X shows 2500RPM @ 70MPH.

This could have a bearing on why there is such a variation in claimed fuel consumption.

[Koi]

There has been a debate rumbling down in the Technical section regarding what revs are indicated for a given speed. My 2.4L SSR-X shows 2500RPM @ 70MPH.

This could have a bearing on why there is such a variation in claimed fuel consumption.

OK is that manual or auto, O/D on off, size tyres, need to put all this if its gonna be any good.

My 2.4 manual with O/D off and 31 x 10.5 x 15 reads about 74ish mph @ 3000 & 85ish mph @ 3500

With standard tyres it was 70mph @ 3000 & 80mph @ 3500.

[slim]

There has been a debate rumbling down in the Technical section regarding what revs are indicated for a given speed. My 2.4L SSR-X shows 2500RPM @ 70MPH.

This could have a bearing on why there is such a variation in claimed fuel consumption.

mines not listed m8 i do about 3450 at 70mph

[da SLUG man]

and having a big tread on the tyre there will be a difference from new tyres to worn tyres... not a lot, but noticeable.


we're having a thing at work as the blokes tacho was calibrated on old tyres and now he's got a new set on the back, his speedo is a few mph out. (i think he's just being picky!)

[RobD]

Wouldn't know,I never drive over 60??!!When the rev counter is at 2000rpm,I'm doing 56mph,if that's any help.

[Gizmo]

Checked it out this morning on the way to work...

Just under 2500rpm @ 70mph
Just under 3000rpm @ 80mph

tyres: 31x10.5/R15
3.0L Automatic
Overdrive not lit on the dash

[kitesurf_phil]

OK is that manual or auto, O/D on off, size tyres, need to put all this if its gonna be any good.

My 2.4 manual with O/D off and 31 x 10.5 x 15 reads about 74ish mph @ 3000 & 85ish mph @ 3500

With standard tyres it was 70mph @ 3000 & 80mph @ 3500.

I was assuming that the majority of Surfs are automatics. I suppose I should have thought of restricting the poll to standard tyres (265/70/R15) and O/D on. I just took it for granted that most people would put the O/D on once cruising at over 60MPH.

Oh well it was a good idea at the time.

[That Ruddy Squirrel]

My 1993 3.0 auto does 2,500 at 70, with Overdrive on - does that help ?


Trev

[kitesurf_phil]

My 1993 3.0 auto does 2,500 at 70, with Overdrive on - does that help ?
Trev

Thanks Trev. I suppose the other data would have made it more relevent. The question arose because one of the members had some work done on his truck and when he got it back it was reading 1000RPM higher at 70. I just guessed that it was because the overdrive was not working.

[andy]

My surf is doing just over 2000rpm at 70mph and 80mph at just under 2500rpm.

[whippet]

OK is that manual or auto, O/D on off, size tyres, need to put all this if its gonna be any good.

My 2.4 manual with O/D off and 31 x 10.5 x 15 reads about 74ish mph @ 3000 & 85ish mph @ 3500

With standard tyres it was 70mph @ 3000 & 80mph @ 3500.

I'm a bit puzzled.......

How does the speedometer or rev counter know what size tyres you've got?

Where is the speedo sender... surely it only counts how fast the final drive from the transmission is turning and converts that to a speed based on the standard diff ratios and tyre sizes?

Alan

[Elvz]

Yeah Whippet is quite right to say that the tyre size is irrelevant....

[kitesurf_phil]

Yeah Whippet is quite right to say that the tyre size is irrelevant....

I have always thought that the diameter of the tyre would make a difference because the larger the circumference, the further distance the tyre would move for one revolution of the tyre. So if the speedo is counting the revolutions of the final drive and converting that into distance/hour the larger tyre would cover a longer distance.

[Elvz]

The title of this thread is "What Does Your Rev Counter Read at 70MPH"

Perhaps it should read What Does Your Rev Counter Read when your speedometer says you're doing 70MPH?

[kitesurf_phil]

The title of this thread is "What Does Your Rev Counter Read at 70MPH"

Perhaps it should read What Does Your Rev Counter Read when your speedometer says you're doing 70MPH?

You are absolutely right Elvz. Too much sunshine has interfered with my brain box