Improving aerodynamics with aftermarket parts

[the bruce]

Sadly I have no specific data. They seem to have these huge wings now. In their first season
the Cup Roccos just had the small Votex Wing. I guess VW Motorsport know what they're doing.

[RedRobin]

9) Rear wing:

If you don't want to fit a huge wing some roof spoilers may be a less efficient but
more elegant alternative:



> www.vary.co.jp

....I can't find that carbon add-on roof spoiler on the 'vary' Jap link. Do you have any other info, please?

It looks less 'in-yer-face' than the OSIR rear roof spoiler.

[the bruce]

http://www.vary.co.jp/

First click on the 'Golf picture' above, then on 'Golf 5 GTI'. After that you will be here: 

http://www.vary.co.jp/reife/golf5_gti.html

[RedRobin]

^^^^
Thanking You!! 

Now where can I get one!? (if not too expensive). I don't really need one but I don't really need some of my other mods either.

[Richn83]

Thanks bruce so no under body fuel tank makes that much easier to fit a panel under there as the standard one the tank dips below where the panel would be

ATL Fuel Cell - keep in mind it's a diesel.

http://www.erft-racing.de/fahrzeug.php

http://www.erft-racing.de/galerie_bilder.php

Unfortunately I couln't fid any additonal pics that show the underside, but I guess the above pic
shows most you need to know.

 

[the bruce]

The tank isn't the problem, Ric, but rear exhaust + lower arms are. 

[fuscobal]

Bruce is right but for an efficient diffuser it depends how much further away from the rear bumper you want to go. As the slope/angle is constant (I've read 10-12deg would be best), if you want to make a rear diffuser that extends to the rear wheels, you need to either start the diffuser very low, either reach a high point on the bumper. The diffuser needs to be trimmed around the rear arms as they need to be able to move up-down while the car is on a ramp !

[Richn83]

Hi bruce it is the problem in front of the rear control arms, where I have fitted the larger stone guards backwards is a very messy area that I want to clean up as well as the area across the rear muffler.

I know you guys are after extra down force but i think this is difficult so I think first and to keep the car looking oem the first task is to try and further smooth off the underside of the car as much as can be.

I have some small panels that I want to try over the exhaust and area by the fuel filter as the fuel tank blocks the are in the centre, what I really want is a larger panel to run from the rear axle mounting points I have them on both sides for the pass at panel with cut outs for the suspension arms over the exhaust and finally mount on the rear bumper to fit flush with the tiny lip I think this will give a smoother air flow and hopefully improve the aero up to higher motor way speeds beyond the existing blue motion panels.  And the shape I think will have some diffuser qualities such as an expansion to slow the air.

Aluminium can also touch the exhaust without fear of melting and can act as a heatsink.

[Tfsi_Mike]

Need to get myself a new bluemotion undertray 

[mkviken]

the bruce this ones for you

never thought id say it but i really want a volvo!

[the bruce]

Thank you Ken, have your pics on the other forum.
Did you have a view at the underbottom?

[mkviken]

no i didn't sorry. it was flat though but no large rear diffuser

[fuscobal]

I will probably go with a Reverie wing but have 4 options at this point :

Chord > 150 ; Span > 1250 ; Downforce @ 160kmh and AOA of 10deg > 380N ; BHP absorbed > 2.9
Chord > 150 ; Span > 1400 ; Downforce @ 160kmh and AOA of 10deg > 427N ; BHP absorbed > 3.2
Chord > 225 ; Span > 1250 ; Downforce @ 160kmh and AOA of 8deg > 574N ; BHP absorbed > 5.1
Chord > 225 ; Span > 1400 ; Downforce @ 160kmh and AOA of 8deg > 617N ; BHP absorbed > 6.3

1) To convert to kg we need to divide by 10, so for ex. 380N = 38kg
2) Those figures are in a freestream of air wich means on our car they will be smaller. Also the extremes of the wing wich hang out of the car's limits are the most efficient so in reality, the difference between 1250 and 1400 might be larger. The car has about 1050 at the upper side of the trunk lid, wich means a 1250mm wing will stick out 100mm on each side, while a 1400mm will stick out 175mm on each side !

The wings will be straight and will have endplates of course ! From what I could approximate on Supercopas and other similar racing hatchacks their wings seem closer to 150mm but they also have diffusers to help them with downfoce. From the Golf 5 GTI aerodynamic data presented earlier, the rear had a lift of 37kg @ 200kmh wich will probably be like 25kg @ 160kmh.

How would you guys judge this problem and what would you choose ?

[the bruce]

I guess your thoughts are right. All these wings work. If you don't care about top
speed go for the 225 chord wings and choose span due to your taste.
You will also play with different angles and even with wing position. If rear DF seems
to be too much you decrease wing angle or probably even wanna add a front splitter
to the VWR spoiler.

[mkviken]

i have the S3 engine shield

im considering bluemotion exhaust and tank and rear axle shields

do these make a real difference or is it just in the head do you think?