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What is my 1147 cc engine ticking over at with overdrive?

Posted By : Stephen Coates, 02-Aug-2007, 03:34pm

I have a 1200 estate which has a D-Type overdrive gearbox fitted.

The 1200 has its original 39 bhp engine and rear axle.

What would the engine be ticking over at at 60 mph in overdrive please?

I have not got any rev counter to tell me.

Steve

Followups :

What is my 1147 cc engine ticking over at with overdrive?

Posted By : Ian Mulford, 02-Aug-2007, 04:42pm

Give this a go:

http://www.mintylamb.co.uk/gearspeed/
- What is my 1147 cc engine ticking over at with overdrive?
  
  Posted By : Mark Hammond, 02-Aug-2007, 05:27pm
  
  I can tell you that a standard (non overdrive) 1200 Estate with the 39 bhp engine is sitting at approximately 4500 RPM at 70 MPH, therefore an overdrive car will be doing around 3600 at 70 MPH, my guess is about 3500 RPM at 60 MPH.
  
  Mark
  - What is my 1147 cc engine ticking over at with overdrive?
    
    Posted By : Chris Taylor, 02-Aug-2007, 11:30pm
    
    Depending on exactly what tyres are in use, an overdrive car with 4.11:1 diff (Herald, Vitesse 6, Spit 1-3) will be doing about 20mph per 1000rpm engine speed in overdrive top, so 60mph will be around 3000 rpm and 70mph = 3500rpm. In direct top the ratio is about 16mph/1000rpm.
    The exact speeds can be found from Mr Lamb's calculator, and include all intermediate gears (and different gearboxes and back axles) and both D and J type overdrives.