D40 Fuel Economy

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I don't, but it's a bloody good reason to pursue the software issue a little harder. Shame that we haven't seen FB here in a while, he might find the TSB for us. Anyone working in a Nissan dealership want to do it? If you like, you can PM me the information and I'll post it here as "a little bird told me ..." so that there are no repercussions.

I've had one little bird pm me, they wanted my VIN to see if there were any applicable TSBs for it. Sadly my VIN is for a DC STX not a KC, and my economy is just fine, but if any KC owner with poor economy wants to PM me their VIN, I'll pass it on to the little birdy and see what results come up.
 
Tony's recent figures suggest otherwise. Heavier foot, more revs quicker to speed less fuel usage.

I tried a very specific method of accelerating in an automatic for a very specific reason.

At 2,000rpm the torque converter is still in 'slip' mode - so engine RPM are lost to turning the gearbox over. At 3,000rpm the torque converter is almost (or is) in 'stall' mode - where one engine revolution is very close to one gearbox input revolution.

This highlighted an important difference. While the higher RPM attracted a higher fuel flow rate (up to 28 litres per hour at the higher RPM compared to a peak of 14.67 LPH at 2,000 RPM) the car accelerated much more quickly - 13 seconds to 60km/h vs 22 seconds at the lower RPM.

It would NOT work the same in a manual because the whole point of that test was to overcome the torque converter losses (and we proved that they do have an outstanding effect). In a manual, without those losses, you'd be better off short-shifting.
 
The snorkel will make a positive (albeit minor, possibly unnoticeable) difference.

In my car, at 80kmh my MAFS reports the incoming air stream is at the same temperature as the ambient temp sensor. In my wife's car, the incoming air stream is 25-30C above the ambient temperature. I doubt they make snorkels for little town cars but I wouldn't mind!
 
Well my unscientific, non mathematical trial is finished.

Driving at 85-90 km/h (I only do country driving), sitting at about 1700-1800 rpm and changing at around 1800-1900 rpm I reckon I've saved about a quarter of a tank.

This ties in with what I know from my old Hilux, if you drive a diesel fast, it drinks fast, drive it slow and it uses nothing.

Makes me wonder if the D40's getting great economy have different gearing???
 
well as one of those who gets really good numbers

i shift around the 17-2000 mark

cruise around at 90 (speedo is out by 10km/hr, so it reads 100) on highways (rpm about 1900)
some stop start traffic on way to and from uni

i still average around 7-800kms


all this in a fairly stock 6sp with maybe 100kg extra wait in the back
 
I've had one little bird pm me, they wanted my VIN to see if there were any applicable TSBs for it. Sadly my VIN is for a DC STX not a KC, and my economy is just fine, but if any KC owner with poor economy wants to PM me their VIN, I'll pass it on to the little birdy and see what results come up.

PM sent.
 
Well my unscientific, non mathematical trial is finished.

Driving at 85-90 km/h (I only do country driving), sitting at about 1700-1800 rpm and changing at around 1800-1900 rpm I reckon I've saved about a quarter of a tank.

This ties in with what I know from my old Hilux, if you drive a diesel fast, it drinks fast, drive it slow and it uses nothing.

Makes me wonder if the D40's getting great economy have different gearing???

To answer your question , at 100 kph via the GPS and scanguage engine rpm is 2150 using 8.2 Lts per 100 kilometers and 8.4 Lts per hour
 
I've had a couple of VINs pm'd to me, let's see what results we get. Thanks to everyone!

Weight in a vehicle is an issue when accelerating or overcoming gravity (going up hill). At most other times it's meaningless - having 10Kg here or 300Kg there doesn't make a meaningful difference cruising along at 95km/h.

What does make an extraordinary difference is the cruise speed. There are TWO factors at play.

First, aerodynamics. Our brick-shaped utes are ... well, brick-shaped. You'll never see one loading passengers ready to depart from Runway 29. As the vehicle speed increases, aerodynamic drag increases at a faster rate (exponential). This means the required energy input increases at a faster rate than the vehicle's speed.

Second, engine performance. Our YD25 motors (standard, unchipped) develop their peak torque at around 2,000rpm. Below 2,000rpm, the engine is using small amounts of fuel but not gaining a lot in torque, however the amount of torque rises rapidly approaching 2,000rpm. At 2,000rpm the torque curve begins to flatten out - so RPM increases a fair bit more (which is directly proportional to fuel input) but the torque doesn't increase anywhere near as much. It basically means you're pumping in much more fuel for little more gain.

Chips change the equation and could vary it wildly. I think there's a reason why the vehicle's drive train (gearbox, diffs and tyre sizes) were designed at the ratios they were - because at the optimum torque point (2,000rpm) the vehicle is just below cruise speed.

Proof? In my car, at 95km/h over a 1,000km trip, I used just over 10LPHK. At 110km/h on the return trip, I used 12LPHK.
 
At 95km/h (GPS) my RPM is 2040 give or take the variances induced by the ECU to determine that the oxygen sensor is functioning. Importantly, my vehicle is back to standard size tyres (255/70R16).
 
I've had a couple of VINs pm'd to me, let's see what results we get. Thanks to everyone!

Weight in a vehicle is an issue when accelerating or overcoming gravity (going up hill). At most other times it's meaningless - having 10Kg here or 300Kg there doesn't make a meaningful difference cruising along at 95km/h.

What does make an extraordinary difference is the cruise speed. There are TWO factors at play.

First, aerodynamics. Our brick-shaped utes are ... well, brick-shaped. You'll never see one loading passengers ready to depart from Runway 29. As the vehicle speed increases, aerodynamic drag increases at a faster rate (exponential). This means the required energy input increases at a faster rate than the vehicle's speed.

Second, engine performance. Our YD25 motors (standard, unchipped) develop their peak torque at around 2,000rpm. Below 2,000rpm, the engine is using small amounts of fuel but not gaining a lot in torque, however the amount of torque rises rapidly approaching 2,000rpm. At 2,000rpm the torque curve begins to flatten out - so RPM increases a fair bit more (which is directly proportional to fuel input) but the torque doesn't increase anywhere near as much. It basically means you're pumping in much more fuel for little more gain.

Chips change the equation and could vary it wildly. I think there's a reason why the vehicle's drive train (gearbox, diffs and tyre sizes) were designed at the ratios they were - because at the optimum torque point (2,000rpm) the vehicle is just below cruise speed.

Proof? In my car, at 95km/h over a 1,000km trip, I used just over 10LPHK. At 110km/h on the return trip, I used 12LPHK.

So, with that in mind, the most economical driving is done under 2000 rpm.

Ok, here's something else to throw into the equation. The higher the vehicle gets, the greater it's frontal surface area, so therfore the greater it's drag will be.

We need to find a stock D40 low rider and see what they get L/100K.
 
It's the aerodynamic styling of the wagon that slows it down.

ummm...

Aerodynamics 101: the more uniform an object is the greater its efficiency

IE that is why aircraft are shaped like a cigar as this is the most aero dynamic shape

in cars the most fuel efficient cars arent coupes or utes or sedans... its infact small hatch backs and wagons

why, exclude things like weight and power and just take the shape,

similar to a wagon/cigar this allows for the air to go around the car without putting any further down force upon it. creating a negative vortex at the back nuetralising some of the drag created

a coupe and sedan: while most would considered sports cars, they use the shape to redirect the airflow down at the back to gain traction for the rear wheels (this slight increase of drag, greater increases downforce)

Utes are slightly weird in that the air is transformed into a nuetral vortex behind the cab which disturbs all other flow around the car creating further drag
 

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