That special projects page is what i'm following to make my front splitter. Having talked to a few ustcc teams and fabricators that splitter design is almost a standard.

I've considered a rear diffuser and using naca ducts to pull air from the engine bay but I'm not sure how well it would flow.

Niiiice:)

Wally, i would put the side piece even higher and blend it with the contour where the wing meets the extension.
You will also need to close the /extension - side piece - bumper - splitter/ area and also extend the widened wing downwards to the splitter

pretty much you will end up with something looking like the Jsports front bumper...

or you can get the side piece merged with the contour of the extension/wing line, trim the bumper edge towards the centre of the car and project the wing extension until it meets the splitter...

I hope it makes sense

otherwise give me a side view and front view pics of your beetle centered on the area for me to draw it for you...

Chris

Thanks Chris!
I am thinking about/working on the missing side parts to cover the now still exposed 'lower front tire face'. Think I know what you mean therefore, will post up when I have come up with something. I know what I want it to look like, but actually making it with simple materials and attaching it to the existing parts is tricky to figure out.

if you want post a pic before u go and materialize...just in order to give you food for thought..
I will be going away for 4 days to my summer house...partly renovating, getting papers done in order to make a separate garage for my self:)))))))))

Wally, PM sent

I wanted to do the same as you are making at the moment. But I did not like the look of all the loose pieces put together. The plate on top of bumper, bumper itself, the Kamei spoiler and the splitter plate. Thats why I bought a Remmele front bumper and I am adding polyester extensions to fill the gaps on the sides and on top between bumper and bonnet/front fenders. The end result will look completly different than yours. I bought the bumper in Hannover on the firtst of May but I am not finnished jet. (still talking about it instead of finishing the thing.;)

This,

http://i129.photobucket.com/albums/p...eelding057.jpg

has to look like this when it's finnished.

http://i129.photobucket.com/albums/p...7.jpg~original

Seeing youre work motivates me again to do something myself.

I agree, it would be much nicer if everything was 'one piece', but not everything fits as we want to (you know this just as well as I do I think unfortunately) or is available in the first place.
So we make something ourselves ;)

No I see the doctors car again, I see some resemblance, but the form really came as I was duplicating Rummenholls bumper plate and the extensions just seem the most logical thing to do as an opportunity to add some downforce.
If for nothing else, that good in itself :)

Hi

I just saw a photos of a VW fun cup car, they have an interesting front air dam and they may have had access to wind tunnels for the design or at the very least some designers with aerodynamic experience.

Steve

http://img824.imageshack.us/img824/3444/cimg2746q.jpg

what you need to remember with the fun cup cars is that theres a rad in the front of the car, heance the big vents in the valance and bonnet.
not sure how well they would work as the as the splitter/side planes look like they would be a very turbulant area.
http://hooniverse.com/blog/wp-conten.../QuattroS1.jpg
the quattro above is the way i was thinking for my 03 race car but with a slightly more rounded wing to suit the shape of the bug. will have a splitter on rather than the lip that the rally cars had. been playing with drawings on a bug and its just working out how to do the back end to match in with the differnat front end.

Dump the beetle and just buy one of those! Amazing :D I jest but it has got to be tempting.

:goodjob:

Got a few speedholes punched in the fenders. I drove it this morning and it does seem to help already, the car felt more planted to the road on the highway. Gonna try to get the fender flares mounted before tomorrow's autocross race.

http://i52.photobucket.com/albums/g3...11102-1942.jpg
http://i52.photobucket.com/albums/g3...11102-2015.jpg
http://i52.photobucket.com/albums/g3...11102-1942.jpg

Porsche did introduce their 2012 model 911 GT3 RSR today. With the 48mm increased width compared to last year, they relocated the engine intake and did some 'drastic' modifications to the shape of the rear fender.

2012
http://www.skiddmark.com/wp-content/...-911RSR_G4.jpg

http://www.skiddmark.com/wp-content/...-911RSR_G1.jpg

2011
http://chrisescars.com/wp-content/ga...gt3-rsr-15.jpg

Thanks AJ!

I like the ducktail of the 2011 model better BTW :-)

Where did you get those!?!?!?!

I asked the same thing he said datsun 260z

Yep, made for a Datsun Z 240/260/280 car. I just guessed as those cars came with 15" rims and the curve of the fenders looked roughly the same as a bug. I got them off eBay. Various sets are about $110-150 new. These cover 2 3/4" width, actually mounted on the bug I'd say closer to 2" or less extension. Read the shipping time before you bid on a set, I didn't look closely but the auction I won could ship in 11-14 days--meaning I think he waits until gets enough orders then lays the fiberglass.

Anyhoo, I didn't have enough time to mount them before the autocross. I did one this afternoon and it does fit pretty well.

http://i52.photobucket.com/albums/g3...0.jpg~original
http://i52.photobucket.com/albums/g3...1.jpg~original


Just trying to think how I can taper out the transition of the lower edges smoother with the fenders, especially the front. I don't plan to run this car on the track regularly (maybe once, if that), I autocross it mostly and don't plan on putting a front air dam on either as my driveway is pretty steep. I do drive it to work about once or twice a week. I'd like to fab something to at least cover more area where the tire is exposed under the fender here, just send the air down and out to the side of the wheel. Thoughts of something I could use already made to adapt to the car again?

http://i52.photobucket.com/albums/g3...3.jpg~original

Next thing, related to the above about not running a front air dam. I do have a lower carbon fiber shield I made for the underside to close up that gap between where the underside of the front apron and the sway bar exists, or where the stock air-conditioning would be normally.

http://i52.photobucket.com/albums/g3...3.jpg~original

I've done some testing with a generic manometer to see what the readings were (a tube of water mounted at 30 deg. on a board). The slotted vents on the front apron are open. So my results are:

At 65mph:

Underside of the front of the car, tube outlet mounted just behind the front sway bar
--With the CF shield pulled -.25" of water
--Without " " " pulled -.1875" of water

which stands to reason. The shield installed guides more air under the car as it smoothes out the underside. But...

Underside of the front of the car, tube outlet mounted below the spare tire wheel well (or in other words, mounted on the top side of the front sway bar)
--With the CF shield pulled +.1875" of water
--Without " " " pulled -0.125" of water

which I was not expecting at all. That whole area on the underside of the wheel well, but above the sway bar with the shield becomes positively charged. The only way I can justify this would be it helps keep my front brakes cool, but is this creating a significant amount of drag? Would I be better of blocking those vents? I think if I block off the vents though this would send more air under the car and create more lift though, correct? Whew.

when you mounted the fender flares how much of the original fender did you need to cut? could you take a pic with the flare removed or a pic of the underneath wheel well

@Jadewombat: Maybe you results can be explained by a smaller boundary layer under you car (that would be a good thing).
See the picture and text in this link: An overview of vehicle aerodynamics (start reading at the previous page).

Thanks for the link, that helps to visualize it a bit better. Maybe I need to block off the vents and try retesting?? I took another couple of photos, in this photo the area just behind the vents I was getting a positive pressure reading with the shield installed meaning it was a positively charged (high pressure) area.

http://i52.photobucket.com/albums/g3...4.jpg~original

Here where I'm pointing on the underside of the sway bar I was getting more negative draw meaning more air was being directed on the underside with the shield in place.

http://i52.photobucket.com/albums/g3...5.jpg~original

As for the fender, I didn't cut anything. I just lined up the front and rear edges as best as I could while matching the curve of the fender lip. I could still cut it if I get ambitious but this is also a dual-purpose car. I plan to rallycross with it at the next event here. My off-road and snow tires match the fenders just fine so there's not really a need to cut it. What I'm getting at is autocross--flares installed/wide tires, rallycross--pull the flares off and change the rims/tires. In case you can't tell, this ain't a show car. Gonna paint the flares silver to match the underside of the car:

http://i52.photobucket.com/albums/g3...6.jpg~original

With off-road tires:
http://fleurobahn.com/forums/downloa...php?id=549&t=1

The bug is my play car, just trying to have fun with it on a limited budget and power (and time to invest) constraints. My bus is a different story though, just came home from the paint shop today:

http://i52.photobucket.com/albums/g3...9.jpg~original

That link said a lot of drag created from the spinning wheels, what about something like this? Not this exact overpriced piece, just something like it on my front end of the bug:

http://www.racingraven.net/458FLC_Ca..._Splitters.jpg

Hi everyone, im back and about to leave again..:( (I'll just be honest, i like it on the countryside with a new engine in my bug...)

Did a tiny bit of research thought...
most importantly

the air cooling the brakes is the air flowing under the car.

This is true for every vehicle that has enough ground clearance ( us for example). the opposite is true for purposely built track cars (i.e lmp class, gt2/3, and road going versions such as the radical sr3 etc)
Imagine top view of the car and the front at the top. the air goes under the front valance/splitter, under the front section (along the front wheel wells) and then it gets sucked outwards each side, due to the vortices created by the rotating wheel. Going super low requires another means of providing the brake disks of cooling air ( naca ducts on the bottom of the front splitter/ air intakes on the front surface of the car). In plain words the wheel works as a "fan" and sucks air out through its self (weird wheel covers on 934/5 P cars etc)

Jadewombat: if I understand your testing correctly there is a possibility that the positive value that you get is due to the flow reduction caused by the louvres on the front valance. Sounds weird doesn't it?? The louvres actually by letting air flow through them act like a "see through" fabric...its there supposedly covering up something but actually you can see through...
but what you see is a differentiated image of the original. If you had the normal front valance maybe you could still gain negative values (due to high turbulence) in the same area...

Now as for the rear diffuser discussion, aartjan thank you very much for the pics, on the new cup car we get a very nice idea for a diffuser.
IMO that would be, fabricate a symmetrical 4-1 exhaust system that fits and has EQUAL primary tube lengths.
Chop the rear part of the rear fenders and enclose the exhaust manifold within the diffuser.ie place two vertical pieces (one each side) somewhere between the rear upper shock mount and the inside fender wheel well (where the Z bar attaches on swing axle beetles).

I strongly believe that much is to be achieved by splitting most of the air around the engine (still providing airflow to the sump) and then expanding the air flow in a sideway's manner since the engine sits in the middle


Sooooooooooorrrryyyyyy for the long post.:o:o:o:o
I hope it makes sense

Chris

have a look at this

http://www.youtube.com/watch?v=uMEYe...BDD1ACE&lf=BFp

Chris

Thats what i'm doing in the back of my front fenders.
http://img819.imageshack.us/img819/91/hpim1905.jpg

Uploaded with ImageShack.us

Well, did some more testing. I put my off-road and snow tires on the car as I'm having the five spokes updated with semi-slicks for this weekend. Anyhoo, I decided to test with the louvers completely blocked off and see what happened. Mind you, this was different than with the 215/55 16 sticky street tires I had before and the rallycross tires put the car higher off the ground. Even so:

-Louvers blocked off pulled -1" of vacuum under the car just behind the front sway bar
-Open louvers was not even registering under the car " " " (I'm guessing this was because I'm higher off the ground than before when I tested)

So, what next I thought to improve the front area?? High positive pressure in that are behind the louvers or no pressure and send all the air down and below the car. My first thought is sending that air below the car will cause lift, but it may be smoothing out airflow though reducing drag? I've decided to split the difference and installed some screen material just behind the louvers to let some of the air pass through.

http://i52.photobucket.com/albums/g3...4.jpg~original

In case you're wondering why I don't just install an air dam, my driveway is way too steep. Will retest once I get the front end aligned. I also drilled the inner edge of the fenders, trying to shave as much weight as I can and hopefully vent more of that trapped air out from under the fenders.

http://i52.photobucket.com/albums/g3...2.jpg~original

I tested it once more:

-Screen material behind louvers yields 3/8" of negative vacuum under the car

Took it out to the autocross today, did pretty well. It was my first time on semi-slicks which made the car feel quite different. Just trying to forge ahead and do any more low-cost aero. tricks to go faster then look at modifying the engine and trans.

http://i52.photobucket.com/albums/g3...4.jpg~original
http://i52.photobucket.com/albums/g3...1.jpg~original

One thing I also noticed looking at the front of my Audi RS4 (mine's black, I borrowed this picture below), there's these short deflectors almost like mudflaps on the front to counter the drag of the front tires. Gives me an idea...

http://www.distrocar.com/wp-content/...de-590x442.jpg

Yes, those are called "wheel deflectors" or "wheel spats". I am planning to make a pair too.

These things can be found more and more on modern cars. Not only at the front wheels, but also at the rear.
I want to make a set for the rear wheels.
It can't be hard to make, it's just a piece of flat plastic/fibreglass that sits just in front of the wheels.
I only wonder how to determine the correct size and position in relation to the wheel..

Gerrelt - surely on the front the Kamei does the job of this?

Yes, you are right. That's why I want to create a set for the rear.. :)

:) Just checking that I wasn't missing something!

Is it worth it going to flat taillights?

http://www.ebay.com/itm/Flat-Tail-Li...ht_1425wt_1185

Possibly if you want it to look hideous... They ain't for me regardless of what they do!

I guess I asked the wrong question, I don't care about the style, etc. but along the lines of:

http://images.thesamba.com/vw/classi...ls/3037298.jpg

Does the taper of the taillights rolling off the back of the fender make an area of dead air? Would smoothing this out to follow the contour of the rear fenders be better for flow/drag or would it not matter? Plus it looks like the flat ones are a little bit lighter than the stock ones.

http://www.gerrelt.nl/roofspoiler/be...unnel_test.jpg

I think it doesn't matter anything. The rear lights are probably allready in a turbulent or low pressure area.

I don't like the look of the new beetle style rear lights.

I've grown quite fond of the elefants feet rear taillights. They have a really nice functional look.
I only wished they were a bit better build.

+1 'Scheisskwalität'...
I have one taillight reflector housing that has two seperate departments and is a cast/mold alu-like material and very nice quality. Never could find another one though...:(

+1 al kaholic...
I don't like the look of the new beetle style rear lights either. :rolleyes:

Ah, thanx for posting that. I never new there was a "metal" version of these lights.

I think they are from the late model VW thing (181).

Do they look like this?: Link to samba add

The Thing got them in metal for sturdiness for going off-road, is my theory..

I want a set! :D

Aerodynamics of a bug
 

Hi very interesting thread here.I would like some peoples views on the best way to dissperse air out under the car once its been through the front grill and through the rads.I do have a box section made up to cover the rads but I am sure that this could be better designed to creat downforce instead of lift and also channel air better under the floorpan.I have also been tinkering with some designs for the rear wings, apron and bumper set up I will post some sketches when I get time thanks.
[IMG]http://i291.photobucket.com/albums/l...1.jpg~original~original[/IMG]

[IMG]http://i291.photobucket.com/albums/l...1.jpg~original~original[/IMG]

Thanks for the link Gerrelt!.Think they are those.
Mystery solved!

Nice car Graham! I like some more ideas for backside front fender vents. I think you could make them so that the escaping 'high pressure' air adds a little in downforce.

Nice car. I think dispersing the air under the car from the front grill may create more lift by making a pocket of more air between the car and the road as you're trying to minimize the amount of air passing under the car. Sending the air up and over the hood through a scoop about 1/3 way up has been proved to create more downforce on the front end as seen on this Acura here:

http://www.germanlook.net/forums/sho...t=2820&page=14

and 911:

http://forums.pelicanparts.com/uploa...1318119333.jpg

...although I don't think you'd want to cut up that beautiful black hood of yours though?? Looks like your car is pretty sleek as it is. You could maybe install ducts from the grill to the backing plates of the front brakes to keep them cool. What kind of front bumper is that?

the aim is to get the air to flow quickly under the car, thus reduceing its presure. so as flat, leval and clean a underside as you can get will help. also deeper running boards to stop the air under the car spilling out at the sides.
the other option is to stop as much air as possable getting under the car but this can cause a lot of turbolance at the rear of the car creating a lot of drag.

Aerodynamics of a bug
 

Nice car Graham! I like some more ideas for backside front fender vents. I think you could make them so that the escaping 'high pressure' air adds a little in downforce.[/QUOTE]

Thanks for that Wally it means a lot coming from someone who owns a car like yours.:notworthy:

I will try and upload some pics of my sketches to show the ideas