Fuel consumption.

[Sharpie]

Many thanks

OK I'll give a try as soon as it comes back from service on Friday with its new nissan fuel and air filters, give the ECU a reset fill with BP diesel and go for a 100k spin at 95 kph (according to the gps) down the freeway and see what happens.


Sharpie.

 

[KraftyPg]

At around 97, cruise on a relatively flat road mine sits with the needle smack on 2000 which going by scangauge is around 2050.

 

[Sharpie]

Ya know I've never looked at the revs when I'm cruisin but will pay attention for a while and get back to you after a few test.

Thanks,


Sharpie.

 

[Old.Tony]

I can't agree more with Krafty & Krankin. Speed is the killer, and so is how you get the vehicle up to those speeds. The Navara is a rather blockish shape, and the faster you try to go, the harder the engine has to work to keep it going.

If you plant your foot to get up to speed faster, you will end up using huge amounts of fuel. The acceleration might not take long, and you think "gobs of fuel for a few seconds is better than dribbling it in for a minute" but in reality, hard acceleration is a killer as well.

By accelerating lightly, and sitting on about 95km/h, we can get mid 15LPHK - towing a 1.8T full caravan.

Don't worry about resetting the ECU. When they change the fuel filter, they'll do that for you.

I recommend doing the EGR mod, and then letting the diesel engine work for you - gently apply the accelerator, don't rev it over 2500rpm and just let her wind up. In terms of arrival time, you will find it's hardly different than if you were hammering it all the way there.

A word on the cruising speed: 2,000rpm is about the point where the turbocharger's output ramps up and the maximum torque of the engine comes on. If you can hold your RPM there, you won't have maximum horsepower (acceleration) but you will have the best torque (momentum = cruising) that your engine can provide for the least amount of fuel used.

 

[filobz]

I also agree with Tony & the other guys.
Last Christmas we towed our van (1.6T + about 400kgs of junk) to Bendigo & I pushed the truck to 110kph as often as the conditions allowed. Result was milage between 14.6l/100k & 18.2l/100k.
This year I kept the speed between 90-95kph & the milage was 12.23l/100k & 12.48l/100k AND LESS STRESS!
Cheers,
Phil

 

[KraftyPg]

Dammit I meant to do a little test today while I was out to see just how much RPM and LPH are effected when I travel at 110 but I forgot (I'm just too lazy to drive that fast). I do know however that when cruise tries to kick up the revs to maintain speed the engine can rise 500RPM without sounding like it wants to leap out of the engine bay and the LPH rises about 8 or 9 LPH until the RPM drops back down.

 

[Dave]

Mine is averaging 10.5L/100km's now since I blocked the EGR.

Will see how it goes when I get the newer turbo when ATX pull there finger out.

 

[Sharpie]

Gentle men and anyone else that gave me advise,

Couldn't wait untill Friday to try your recommendations so this morning filled up at the BP at the side of the freeway and cruised at a constant 95kph and the revs sat on the high side of the 2000rpm marker, pulled into the servo. at 100.2 kms traveled and managed to get 10.2 ltrs back into the tank. I actually found it quite difficult to not speed up when I hit the 110zone but can't argue with the facts, I need to think about how I drive this thing. Thanks for pointing out the error of my ways.

Sharpie.

 

[mytonka]

Hi all,
I have a 2008 model and I'm getting 10.5 litres per 100km

 

[KraftyPg]

Gentle men and anyone else that gave me advise,

Couldn't wait untill Friday to try your recommendations so this morning filled up at the BP at the side of the freeway and cruised at a constant 95kph and the revs sat on the high side of the 2000rpm marker, pulled into the servo. at 100.2 kms traveled and managed to get 10.2 ltrs back into the tank. I actually found it quite difficult to not speed up when I hit the 110zone but can't argue with the facts, I need to think about how I drive this thing. Thanks for pointing out the error of my ways.

Sharpie.

I think it's something most of us had to learn after the first few fuel bills if we wanted to keep more money in the pocket rather than giving it to the fuel company's.

I still haven't tested the RPM differences between just under 100 and 110 on the highway but if I remember this arvo I'll have a look just too see how much harder the engine is working to maintain that extra 10kph. Although as you've seen the LPH is effected so while the RPM for a brief time wont make much difference for 100ks it's obviously significant.

 

[Old.Tony]

Krafty it shouldn't be a lot, the torque converter ought to be locked so it'll be the same as the manual as well - a couple of hundred RPM at most.

The big difference is in the effort required to move the air at the increased speed. A more interesting figure to get from your scangauge would be the difference in LPHK at the two different speeds.

 

[KraftyPg]

I wasn't expecting it to be much I was only checking it to see just how many revs it was and yes the LPH was going to be checked as well.

The problem with the LPH is that the run I have to go on isn't entirely flat and whether it's by cruise or by foot there will be fluctuations in the LPH which may not be as noticeable in the RPM. Because SG is taking a reading every 4 seconds and adding it to it's current data there is a tendency to skew the reading a bit on such a short trip because of the dips and rises, but the average trip measurements will be a little closer to accurate.

 

[KraftyPg]

Ok so I did the test and here's the results. Let me start off by saying this is in no way definitive or what all D40's should expect it is just a guide relating to the above information.

At 97KPH (ish) on a relatively flat road and little wind RPM is between 2000 and 2050 and LPH fluctuates between 8 and 12 while the average for the trip is 10.2

At 109KPH same road same conditions RPM sits between 2350 and 2400 and the LPH fluctuates between 8 and 16 while the average for the trip is 12.1

When considering the average though it pays to take into account that for the above test trip I would have spent less than half of it at those speeds as there was 60 and 80 zones I had to travel through to get to the 110 zone and being that I am not a lead foot the low LPH in those slower zones will make quite a difference on the trip averages.

 

[Dave]

Krafty broke the 100km/h mark.

The computer must have thought the mechanic was driving. Lol.

 

[KraftyPg]

Man I was sweating and shaking after it I can tell you, not only that the ute is all dirty and looks like I have been trashing it around dirt tracks, I'm just thankful many wont allow themselves to believe such a story or my reputation will be ruined. It takes a long time to get others opinions as low as they are I don't want to ruin it.

 

[Dave]

I am sure everyone will keep it a secret.

Back on topic though.

 

[Krankin]

Krafty broke the 100km/h mark.

The computer must have thought the mechanic was driving. Lol.

No,
his mum was driving while he was playing with the SG in the pass seat

 

[KraftyPg]

Well I tried to hire a D22 driver but the only ones I could find said the elastic band engines in their tractors would never allow speeds that fast and they wouldn't be confident driving at such speds so mum was the only choice.

 

[Old.Tony]

It's interesting that the average fuel consumption was 2LPHK higher for 12km/h more.

That means over a 100km trip, you'd take 61mins 55 seconds and save about $2.80, compared to the faster speed taking just 55mins 2 seconds.

Almost 7 minutes difference ... not a lot, really. Thanks Krafty, sorta drives the point home somewhat. I wouldn't mind seeing a constant 95km vs constant 100km comparison one day, because then some real calcs on savings could be made.

 

[Krankin]

Well I tried to hire a D22 driver but the only ones I could find said the elastic band engines in their tractors would never allow speeds that fast and they wouldn't be confident driving at such speds so mum was the only choice.

Hey...

youv'e been told today