aerodynamics (LOL)

[ambivert]

so... is there anything that can be done to help a T25 slip through the air a bit better - any sort of body kit, a certain shape of roof, etc...? If so are there any hard facts about how much MPG is improved.

I would guess that adding any sort of spoilers or panels to the outside would surely only increase the drag - even if made the shape more aerodynamic, the size of the actual cross-sectional area presented to the wind would be bigger and the van would also be heavier... And if it was all sleek and teardrop shaped it just wouldn't look like a proper brick anymore either, eh? And that would be a bad thing, right?

[ajp]

Regarding the roof I find that driving with the poptop down really helps...

[Pepperami]

Hi top is best. Try a search. Kev the rev posted a good thing about it with cd factors.

[jamesc76]

Why bother just reaise that these vans are bricks and should be driven so!

[trikepete]

i found that if i removed the windscreen and left the rear tailgate open it helped

[timthetrader]

i found that if i removed the windscreen and left the rear tailgate open it helped

While in france in a old cortina mark 3 my windscreen got smashed but abroad it was a consol not a cortina so I could'nt get a replacement windscreen, so for 3 months i drove around with no winscreen but while driving i would get the old cheeks flapping above 40 mph but it was fine if openned the rear windows! Got some funny looks driving around Monico with my british plates lol.

[Mocki]

hitop, thats what you need.......
and a spoiler........

[Pepperami]

A high top is a spoiler

[ambivert]

Hmmm... interesting that some say a hitop is better, some say its worse (or is that only for side winds) ?
Of course there are also various other factors, as discussed in another thread, to consider when choosing a roof, but as far as aerodynamics go, this is a contentious issue? and Mocki, what sort of spoiler do you advise, ie. where to put it? And I couldn't find the article by kev the rev about cd factors, if anyone else can point me to it, that would be lovely...

[peasant]

See here:
normal van: cw 0.44 X surface 3.06 sqm = cw x A 1.35 sqm
low popup: cw 0.45 X surface 3.11 sqm = cw x A 1.4 sqm
popup with luggage tray: cw 0.51 x surface 3.17 sqm = cw X A 1.62
Dehler high roof: cw 0.40 x surface 3.61 sqm = cw X A 1.44
Karmann Cheetah: cw 0.46 x surface 5.17 sqm = cw x A 2.38 sqm

http://www.t3-infos.de/images/Luftwiderstand_T3.jpg" onclick="window.open(this.href);return false;

So if you have a popup with luggage tray (Westy standard) replace the tray with a spoiler

[Mocki]

the under the bumper spoiler greatly improoves handling , and therefore should improove mpg

[ginge]

handling mpg am i on the right forum

[ambivert]

wow, so that roof really is useful... found some very cool original pics of it in action here, on http://www.ig-dehler.de" onclick="window.open(this.href);return false;

http://www.ig-dehler.de/Ur-Profi/ur-profi.html" onclick="window.open(this.href);return false;
http://www.ig-dehler.de/Ur-Profi/ca_1985/ca_1985.html" onclick="window.open(this.href);return false;
http://www.ig-dehler.de/Ur-Profi/ca_198 ... sines.html" onclick="window.open(this.href);return false;
http://www.ig-dehler.de/Ur-Profi/Syncro/syncro.html" onclick="window.open(this.href);return false;
http://www.ig-dehler.de/Ur-Profi/ca_198 ... klein.html" onclick="window.open(this.href);return false;

is this roof really the westie standard then, should be quite easy to find one?

[peasant]

No, Dehler has nothing to do with Westfalia (they were originally a yacht builder as far as I know)

Dehler roofs a pretty rare and also not easy to put on, there is some major surgery required to make them fit. (Just hearsay, I have no actual experience of fitting a Dehler roof).

Unless you absolutely need and want a high roof for other reasons, I wouldn't put one on just for fuel savings. They'd be negligible to marginal at best.

[Ian Hulley]

Having had The Bus both with and without a hitop and with and without a front lower spoiler I can scientifically say it makes kall difference to the mpg.

BUT the chin spoiler really does help in the vicious front corner cross winds I get on't way to't mill and reduces auto lane change syndrome. Nowt helps with a full side-on cos they have the aerodynamic properties of an outside convenience ... which is after all what it is

Ian.