MPG - Gear : Specific Vehicle Stats?
Discussion
Is there such a thing. Perhaps Parkers or by the Manufacturers themselves.
Where there is some sort of grid chart from tests done on a flat surface.
Vehicle gear / speed / then effective MilesPerGallon.
i.e in a 2010 BMW E90 320d is it more efficient to travel at 50mph in 6th or 55mph in 7th etc.
To a certain degree it's real-world testable but the difference of a few mph and a few hundred revs is not as easy to ascertain.
Probably look a bit like this sort of style...
Where there is some sort of grid chart from tests done on a flat surface.
Vehicle gear / speed / then effective MilesPerGallon.
i.e in a 2010 BMW E90 320d is it more efficient to travel at 50mph in 6th or 55mph in 7th etc.
To a certain degree it's real-world testable but the difference of a few mph and a few hundred revs is not as easy to ascertain.
Probably look a bit like this sort of style...
Krikkit said:
The problem with this is the immense amount of variability involved.
As a general first-approximation you'd look at a BSFC map for your particular engine, then work to get as close to the highest efficiency zone with gearing, but obtaining it isn't straight-forward.
In theory, would there be a peak MPG RPM.As a general first-approximation you'd look at a BSFC map for your particular engine, then work to get as close to the highest efficiency zone with gearing, but obtaining it isn't straight-forward.
Regardless of gear or conditions.
Is 2000rpm in 3rd the same as 2000rpm in 6th as far as MPG goes?
My mind can't quite wrap around this exercise!
EmailAddress said:
In theory, would there be a peak MPG RPM.
Regardless of gear or conditions.
Is 2000rpm in 3rd the same as 2000rpm in 6th as far as MPG goes?
My mind can't quite wrap around this exercise!
In isolation, yes. See below for a Brake Specific Fuel Consumption map - this is slightly limited because they're typically done at full throttle on a dyno, obviously if you're not at full throttle you can often have other losses which change it (e.g. on most petrol engines you have a throttle plate which will cause more pumping losses)Regardless of gear or conditions.
Is 2000rpm in 3rd the same as 2000rpm in 6th as far as MPG goes?
My mind can't quite wrap around this exercise!
The region on this graph denoting 250g/kWh is the peak efficiency area.
In practice you can plot power levels on these, which are the curved lines running from left to right:
Many years ago, I was involved in tests with an automated 5th gear.
The theory behind this was that the average driver ( who had probably been using a 4 speed box) made the wrong choice of gear between 4th and 5th about 40% of the time.
I designed a box in which the 4th gear had a freewheel and the 5th gear was engaged automatically with a wet clutch pack when conditions were appropriate ( as determined by the engine map). In tests, this measurably improved fuel consumption, but for various reasons was not pursued further.
The theory behind this was that the average driver ( who had probably been using a 4 speed box) made the wrong choice of gear between 4th and 5th about 40% of the time.
I designed a box in which the 4th gear had a freewheel and the 5th gear was engaged automatically with a wet clutch pack when conditions were appropriate ( as determined by the engine map). In tests, this measurably improved fuel consumption, but for various reasons was not pursued further.
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