Does it affect mpg?

[(RIP) PLANK]

Originally Posted by Adz

Its not over length & doesn't need CAT 1 / 2 / 3 & is legal FACT

They way they got round it for the UK market was to only put the 4 wheel tractor units on sale in the UK & then Volvo followed suite.

You will see more bull nose recys & where there more commonly used as the Dutch do many & various axle conversions & the bull nose models in general had bigger engine options.

look, this is going way off course, i reffered to one specific scania model circa 1990, not current models, so your point is missing the point! The point is tractor units are not the most aerodynamic vehicles on the road and are designed for overall capacity not fuel efficency - that was my point and it is still very true.

For example, take a given truck and through an aerodynamic cab profile increase the fuel efficency by 10% and in doing so reduce its overall load capcity by 10% you now need 11 loads were there were 10 so 10% more trucks on the road and 10% more fuel used, not gains whatsoever.

in these new fuel efficent times economy will drive design, but only to an extent it will allways be a compromise;

my point in short:

Whatever you bolt to your roof will afect fuel economy - full stop.

and comparing it to a huge pantechnicon will not help!

Now lets get back on topic

[(RIP) PLANK]

[QUOTE=Fez_uk;126406]it will effect it but to say exactly how much is difficult.
QUOTE]

spot on

[Deleted account DD]

Originally Posted by Adz

All flat cabs with i.e. Scania Topline are double bunked

the one I was in yesterday wasnt

[Deleted account DD]

Definitely getting less mpg on mine on a mixed driving cycle with the supposed "aerodynamic" roof bars fitted.

Theres absolutely no dount that anything that disrupts the airflow will affect consumption. May be so neglible you wont know it I suppose.

Thanks for the input, i posted the question before I logged off for the night and I cant believe the number of replies

[extreme-4x4]

what you mean is you planted the seed before logging off, then left it for all the following inevitable disputes.

[Deleted account DD]

Originally Posted by extreme-4x4

what you mean is you planted the seed before logging off, then left it for all the following inevitable disputes.

no wouldnt do that.

I just suspected there may have been someone had worked it out, I know it does affect it bt I just dont know how much by.

I was reading up on those kenlowe heaters and theres one bloke worked out using it saves him 2.7mpg during the winter htf did he work that out so precisely

[Kamsin]

The maximum lenth for a Lorry on uk road is 16.5 meters, that is why the bull nose lorry never caught on here. They did have a few running tippers as they can get the weight up to 44 tons.

A UK road train, classed as a wagon and drag is 18.5 meters.

Any how, this was about drag and fuel, YES the roof bars will increase you fuel consumption. I did say i was going to post tips on this but have not had the time to do it yet, as i want to make sure its right.

But here are a few:-

Dont let your car warm up before driving it, modern cars dont need it, just dont thrash it to death before its warm and its fine.

Reverse into your driveway or garage, because the engine is warm it will use less fuel for this manover now than reversing out in the morning when its cold.

Dont drive with your window open if its warm and you have aircon, Yes Aircon uses more fuel when its running than when its not, but having the windows open cause drag and that uses even more fuel.

When in heavy traffic or at traffic lights turn the engine off, BMW have add this to some of their cars as standard, they just cut out when stood, then dip the clutch and they start back up and drive away.

Just a few to be gettin on with, i will do a more detailed one soon.

[Deleted account DD]

Originally Posted by Kamsin

When in heavy traffic or at traffic lights turn the engine off, BMW have add this to some of their cars as standard, they just cut out when stood, then dip the clutch and they start back up and drive away.

The missus's SEAT Leon does that , its quite spooky at first but it does save a massive amount of fuel

And as she refuses to have roof bars fitted ...........................

[Adz]

Ya wind-up merchant

Unless ya ars sqeeks while ya walk to your vehicle As soon as you move its causing drag
The more you put on or in its obvious its going to increase drag
But i will stick to my words & say it doesnt make a difference, in the respect of it being noticeable to your fuel bill
If you want fuel efficiently used then get a push bike

[(RIP) PLANK]

if i fill my tank and get 300 miles fomr it

then pot 33 inch tyres on and still get 300 miles

is it possible the milometer is now out of calibration due to the wheel size change, if the speedo reads diffreent then so will the milage?

[Adz]

Originally Posted by PLANK

if i fill my tank and get 300 miles fomr it

then pot 33 inch tyres on and still get 300 miles

is it possible the milometer is now out of calibration due to the wheel size change, if the speedo reads diffreent then so will the milage?

Not when I use GPS

[makeitfit]

Originally Posted by PLANK

if i fill my tank and get 300 miles fomr it

then pot 33 inch tyres on and still get 300 miles

is it possible the milometer is now out of calibration due to the wheel size change, if the speedo reads diffreent then so will the milage?

I worked it out on mine with 33s on the speedo UNDER reads by about 6-7% vs the sat nav.
I know with all my mods I'm still around 26 to the gallon
Which I'm quite happy with as I've got lead soled boots and roof lights and 'king heavy winch and it runs on bio at 82p a litre

[(RIP) PLANK]

Originally Posted by makeitfit

I worked it out on mine with 33s on the speedo UNDER reads by about 6-7% vs the sat nav.
I know with all my mods I'm still around 26 to the gallon
Which I'm quite happy with as I've got lead soled boots and roof lights and 'king heavy winch and it runs on bio at 82p a litre

that's abut all i get running standard! so you must be doing somehting right

I think the key phrase in all of this is about, GPS (with a mileometer? ) or not. There is no way to tell unless the difference is pretty large.

[Adz]

Originally Posted by PLANK

that's abut all i get running standard! so you must be doing somehting right

I think the key phrase in all of this is about, GPS (with a mileometer? ) or not. There is no way to tell unless the difference is pretty large.

The bloody speedo don't read right even with the correct wheel size & inflation
GPS is the only way

[illy]

My Mav's got standard wheels and tyres, got roof bars across the top, filled up today it worked out to 32 mpg. Mind you I've driven like my grandma on the last tank.

illy