Roof bars do they add to fuel consumption ?

Post by **sternal** » 06 Jul 2015, 07:42

Some will say yes and other no !

The summer holidays are almost upon us and we had a mock pack this weekend for our 2.5 week trip to Holland we have decided to ditch the roof box as its to high to get up to safely and we can also get our table/chairs packed in the van safely strapped down not going to need leveling blocks along with a whole host of other junk so the roof box is back in the garage !

Ive not taken the roof bars off as part of me says well they might be useful to keep on ??!?!

Do they add to consumption/wind noise ?

Post by **broutta** » 06 Jul 2015, 08:03

depends on the size of them on as to how much so but essentially yes

Post by **ninja.turtle007** » 06 Jul 2015, 08:30

I doubt there will be any discernible difference in fuel comsumption, considering the shape and low MPG of a T3.

Post by **itchyfeet** » 06 Jul 2015, 08:59

Wind noise yes, fuel consumption no as it drinks like a fish anyway
take them off and be done with it, 5 min job.

Post by **HarryMann** » 06 Jul 2015, 12:38

Of course they do... the amount is the issue. Probably not significantly nor measurable until driving fast or in fair to high cross or sidewinds.
If you drive in the 60+ range consistently then maybe remove them.

A large builders rack or expedition rack will make a measurable difference much over 50

Post by **lloydy** » 06 Jul 2015, 13:48

Mine are on all the time, I have found the roof box makes a noticeable difference when removed.

Post by **kevtherev** » 06 Jul 2015, 20:33

At 48p a litre who cares about mpg.

Post by **silverbullet** » 06 Jul 2015, 21:03

Roofbars can really sing/howl/drone at even modest speeds.
One 40mm x 1500mm roof bar adds 600cm2 to the frontal area of a van, equal to two more door mirrors!

Post by **scottbott** » 06 Jul 2015, 21:38

48p a litre!,where do you get it from at that price?,62.9 here,hope to get cheap LPG when I go to the T3 meet in Solihull

Post by **HarryMann** » 06 Jul 2015, 23:31

Ian OK !
Thats about 0.7 sq.ft
About 6 lbf (2.8 kg) drag at 60 mph (ignoring interference drag)

Quick dirty calc says that's 1 BHP at the wheels ... open to correction on that when its not past the witching hour

Post by **kevtherev** » 07 Jul 2015, 06:04

scottbott wrote:48p a litre!,where do you get it from at that price?,62.9 here,hope to get cheap LPG when I go to the T3 meet in Solihull

Yes..and cheaper!

Post by **sternal** » 07 Jul 2015, 06:07

Re: Roof bars do they add to fuel consumption ?

Post by silverbullet » Yesterday, 21:03
Roofbars can really sing/howl/drone at even modest speeds.
One 40mm x 1500mm roof bar adds 600cm2 to the frontal area of a van, equal to two more door mirrors!

Re: Roof bars do they add to fuel consumption ?

Post by HarryMann » Yesterday, 23:31
Ian OK !
Thats about 0.7 sq.ft
About 6 lbf (2.8 kg) drag at 60 mph (ignoring interference drag)

Quick dirty calc says that's 1 BHP at the wheels ... open to correction on that when its not past the witching hour

...and this is just for one roof bar and are you taking into account the fixings

after these calculations they are coming off !

Post by **HarryMann** » 07 Jul 2015, 09:08

kevtherev wrote:
scottbott wrote:48p a litre!,where do you get it from at that price?,62.9 here,hope to get cheap LPG when I go to the T3 meet in Solihull
Yes..and cheaper!

sternal wrote:
Re: Roof bars do they add to fuel consumption ?

Post by silverbullet » Yesterday, 21:03
Roofbars can really sing/howl/drone at even modest speeds.
One 40mm x 1500mm roof bar adds 600cm2 to the frontal area of a van, equal to two more door mirrors!

Re: Roof bars do they add to fuel consumption ?

Post by HarryMann » Yesterday, 23:31
Ian OK !
Thats about 0.7 sq.ft
About 6 lbf (2.8 kg) drag at 60 mph (ignoring interference drag)

Quick dirty calc says that's 1 BHP at the wheels ... open to correction on that when its not past the witching hour

...and this is just for one roof bar and are you taking into account the fixings

after these calculations they are coming off !

Everything counts I suppose but don't throw the baby out with the bathwater... at least keep your wing mirrors