Quote:
Originally Posted by michbout
....cut....
In my mind high rpm = fuel
Pls let me know what are your impression on this.
issue.
...cut....
|
When a small motorhome with a 6.8-liter V10 can get around 10 MPG traveling at an assumed speed of no more than 70 MPH, it means that during steady-state cruising it's only burning fuel at 7 gallons per hour or less. At lower speeds the average fuel burn rate is even lower.
If we work backwards (reverse engineering) it means that the V10 needs to be at fairly low RPMs to be at near maximum efficiency. Anything at much over 2,000 RPMs (in this case) will start to decrease engine efficiency and thus decrease fuel economy. Cruising on level roads at 3,000 to 3,500 RPMs would be too high for such a small fuel-efficient motorhome.
For larger motorhomes that require more power at same vehicle speed, operating at higher RPM may be optimum for that RV. Engine RPM itself is not a very good indicator of engine efficiency. It also has to be weighed against load on engine.
For all practical purposes, most gasoline engines can operate over a wide range of RPMs while maintaining good engine efficiency; but only if the load on engine is appropriate for the RPM in question.
Thor Forums
