Havent posted for a few years, but i am running an 11 litre 430 dxi Renault premium 8x4, and the fuel figures could do with improving, getting roughly 7.5 mpg on mixed roads, and motorways.
I know that the engine is the volvo 11 litre, so have any of you fine people got any tips, or possible solutions to get the mpg up?
Thanks in advance
Knock the cruise back 2 or 3 clicks. Let gravity and momentum do the work as much as possible. Come off the throttle at the bottom of an off slip and let the weight take you to the top, and above all ANTICIPATE! Practice coasting up to red lights so that you never come to a complete standstill, you’ll be amazed at the results that alone gives.
Keep tyres properly inflated,
Accelerate gently, Drive smoothly, decelerate gently.
Also what The Moaster said: Anticipate
the maoster:
Knock the cruise back 2 or 3 clicks. Let gravity and momentum do the work as much as possible. Come off the throttle at the bottom of an off slip and let the weight take you to the top, and above all ANTICIPATE! Practice coasting up to red lights so that you never come to a complete standstill, you’ll be amazed at the results that alone gives.
There’s not much momentum with a dd 8 legger m8 ,ease off n it stops 
just saying like 
That’s 'cos you drive this Dan…
Driving style is paramount, the difference between a good driver and a bad one can be as high as 30%. If the 8x4 is a tipper, ensure it’s sheeted all the time and inflate your tyres to the maximum recommended pressure. That’s the free stuff taken care, now onto the speculate to accumulate stuff.
Get the lowest rolling resistance tyres you can for your operation, get it in the workshop and have the laptop gurus flash the ECM with the economy file, while you’re there get them to do a valve adjustment, check the intercooler for leaks, do a four axle alignment and check that the wheel bearings are set up correctly, too loose or too tight will have a detrimental effect on drag.
If you’ve got light bars, Michelin men, mirror guards and a Scandinavian style headboard, take them off and put them on Ebay.
When accelerating do you put boot to floor or halfway??
Some great tips above.
Have a look at your front wheels, covered in brake dust? that’s where a lot of your fuel is going.
Every yard you travel with your foot off the throttle is fuel free (bar a bit for tickover if you’re in some sort of neutral gearbox setting), so try to use the brakes as little as possible, lifting off so momentum takes you all the way to the junction, the only time you should brake ideally is to bring the vehicle to a final stop, all normal deceleration should be done via engine/auxilliary braking and use of the correct gears.
Let terrain power and brake your vehicle whenever possible, no point in staying on the throttle right up to the peak of a hill if the other side will take your motor back up to cruising speed, similarly let the uphill slip road do all the braking for you when leaving the motorway, these points already said by Maoster.
Try to time junctions so you don’t have to stop, if you have an on board fuel instant readout look see the mpg your getting accelerating, especially in the lower gears, your eyes will be sticking out like chapel hat pegs when you see what you are wasting.
Rethink routes where possible, dual carriageways and motorways where you can stay in top gear are much more economical than two way roads where you’re constantly negotiating junctions, traffic lights, traffic hot spots.
Try to avoid routes where every junction means a long climb to get back up to speed, these types of roads gobble fuel at a ridiculous rate.
Even if the motorway/dual carriage is longer it might be more economical than the lesser road direct route, i’ve proved this times by using the OBC to calculate fuel actually used, not counting the decreased wear and tear to brakes and suspension/steering components by keeping to a steady speed cruise, plus the bonus of an easier drive.
The difference in practice when you put these and all the other valid points together can be in the order of 7mpg becoming 10mpg, plus from hard brake wear to hardly noticeable.
We are talking about an 8 wheeler tipper here its possible that the use of the above tips would result in a load a day less being done which was probably the one that made the profit .
Punchy Dan:
We are talking about an 8 wheeler tipper here its possible that the use of the above tips would result in a load a day less being done which was probably the one that made the profit . [emoji38]
A very good point, although driving smoothly and using momentum is usually faster than the throttle and brake style of driving.
Although an mpg figure was mentioned, we know nothing of the operation, it may be that the mpg achieved is about as good as you could get. How does the fuel return compare with other vehicles with the same spec doing the same work? That’s a very important thing to know.
The speed part of the productivety equation is based on an engine under full load.The key in that case being ordering the motor with the best torque output at the least rpm because it’s mostly about getting the most road speed for the least engine speed from that point.Obviously all compared under like with like weight and terrain.Realistically all else being equal the driver’s job in saving fuel ends at knowing the right upshift points and trying to make the brakes last as long as possible.On the basis that it’s more economical to not need to use them to get rid of unnecessary speed on the approach than wasting loads of fuel accelerating to pointless speeds and then having to throw it all away,in the form of heat at the brakes.
Edit to add there is a high torque option for the same engine which from the graph looks like you could knock at least 100 rpm off the upshift points for equivalent acceleration v standard.In all cases taking it up to anything much more than 1,500 rpm under load is going to cost lots of needless fuel regardless.
Carryfast:
Edit to add there is a high torque option for the same engine which from the graph looks like you could knock at least 100 rpm off the upshift points for equivalent acceleration v standard.In all cases taking it up to anything much more than 1,500 rpm under load is going to cost lots of needless fuel regardless.
.
Which is only a different ECU map, so you either ask stealer to change the map, or get it done by powerchips or a like. Price dependant, If im correct the difference between the 470+500 is only the way they are mapped.
biggriffin:
Carryfast:
Edit to add there is a high torque option for the same engine which from the graph looks like you could knock at least 100 rpm off the upshift points for equivalent acceleration v standard.In all cases taking it up to anything much more than 1,500 rpm under load is going to cost lots of needless fuel regardless..
Which is only a different ECU map, so you either ask stealer to change the map, or get it done by powerchips or a like. Price dependant, If im correct the difference between the 470+500 is only the way they are mapped.
I was referring to the same peak power but high torque option.Either way assuming it’s just a torque/power increase at equivalent RPM then you’d also expect that to require an increase in turbo boost levels.While it’s clear that running it up to anywhere close to the peak power will ■■■■■■■ the fuel figure regardless.It’s all about how much power it can make without going outside 'the green band.In this case it looks like it is putting up a respectible account of itself without needing to go above around 1,500 if not 1,400 rpm.
You can tell the who has written articles for truck magazines lol
Slackening off the wheel bearings will allow the bloody wheels to fall off ffs,
The 8 wheeler in question will be fitted with cartridge type bearings ( not adjustable ) and one nut which is bloody tight holding the hub on!
Another total waste of time is spending a fortune on low rolling resistance tyres and blowing tyres up to 125psi as you’ll end up taking the middle out of the tread especially on the drive axle, we’re talking about an 8 wheeler tipper here which probably spends little time on motorways and is probably in more danger of tyre damage due to sites.
Yes I’ve driven 8 wheeler tippers and mended them, owned and operated and mended artics and rigid’s, infact still do, though not yet provided any magazine with a load of old ■■■■■■■■!
Moose:
Yes I’ve driven 8 wheeler tippers and mended them, owned and operated and mended artics and rigid’s, infact still do, though not yet provided any magazine with a load of old ■■■■■■■■!
Comparing 8 x 4 on mediocre roads and lots of stop start around town to best case 6 x 2 artic motorway type trunking is apples and oranges.The OP says it’s 7.5 mpg on mixed including motorways.Might as well start with the question of what’s the geared RPM at 90 kmh in top to start with.Assuming that’s well in the green then 8 mpg would be a realistic figure so it’s not far off.Plenty of short shifted upshifts when off the motorways would probably get it there.
Pat Kennett’s “Better Driving” articles in T&D back in the late 80’s were a good source of advice. His tips on improving fuel economy centred around a driving style harking back to the days of low-powered lorries i.e., keep it rolling, use momentum etc., because back then that was only way to achieve half-decent progress!
Since the power outputs improved, faster driving could (and did) result in indifferent fuel economy at the expense of speed - it’s all down to physics
Keeping it sheeted when empty is good advice as the air going over the cab drops down to hit the tailgate which is like a barn door, anticipation is another good tip, every stab of the brakes wastes fuel as you have to get going again, keep the revs down and skip gears especially when starting off down hill you can skip lots of gears and let gravity help you get up to speed, no need to rev the nuts off it in low gears as the next gear up will take you further per engine revolution
Moose:
You can tell the who has written articles for truck magazines lolSlackening off the wheel bearings will allow the bloody wheels to fall off ffs,
The 8 wheeler in question will be fitted with cartridge type bearings ( not adjustable ) and one nut which is bloody tight holding the hub on!Another total waste of time is spending a fortune on low rolling resistance tyres and blowing tyres up to 125psi as you’ll end up taking the middle out of the tread especially on the drive axle, we’re talking about an 8 wheeler tipper here which probably spends little time on motorways and is probably in more danger of tyre damage due to sites.
Yes I’ve driven 8 wheeler tippers and mended them, owned and operated and mended artics and rigid’s, infact still do, though not yet provided any magazine with a load of old ■■■■■■■■!
As I’m the only one here that used to be a writer for a magazine, it’s not a huge leap to assume that you’re referring to me.
I can also read as well as write, it appears that’s a skill we don’t share, so I’ve used big letters to make it easier for you to understand.
Get the lowest rolling resistance tyres you can FOR YOUR OPERATION.
Check that the wheel bearings are set up CORRECTLY, TOO LOOSE OR TOO TIGHT will have a detrimental effect on drag.
I also mentioned in a later post that knowing something about the operation is essential as an 8 wheeler could be up to the axles in snot all day, which would make rolling resistance unimportant, or it could be running aggregates around town, which would make rolling resistance vitally important. That is simple physics and as such it’s a law that can’t be broken.