Hoppy

Sure spoliers make a difference, even if most are mainly cosmetic. Why are rally cars covered in them? Prodrive use a wind tunnel to make theirs and a P1, complete with Prodrive rear spoiler and front splitter, has reduced rear lift and needs 4bhp less to cruise at 100mph IIRC. There was a great thread by Damien Harty from Prodrive last year - can anyone find it and post a link? Very interesting read.

Spoilers reduce lift by "spoiling" the airflow over the boot. They do not give positive downforce like wings, through at what point a spolier becomes a wing is less easy to define - presumably when reduced lift acutally becomes positive downforce. This will hit fuel consumption quite hard and as they only work at high speed a modest spoiler is better than a massive wing for a road car. To work best, both spoliers and wings need to be as high as possible above the boot.

Richard.

Cider boy

Agree with this, if you watch the racers in World Superbike at a track like Hockenheim (lots of very long straits ) the whole race is based on them draughting each other, and when interviewed they say that as a bike comes up behind them and sits in thier slipstream they can "feel" it pulling them backwards, and the RPM of thier bike will drop noticeably.

Scoobypl

some figures of the downforce created by the spoiler on a STI 04
have the pictures to go with it, but no scanning equipment ... so can't post it here

http://bbs.scoobynet.co.uk/showthread.php?t=326998

have no figures for a despoilered one...

StickyMicky

intresting thread regards the water on the back window, mine spirals anti or clockwise at speed

it seams to spin around the back window

this is with the group N/sti 3/4 mid level spoiler
edited to add, mine has a rear window wiper and i wonder if the air is hitting this and causeing a spiral type turbulence pattern??

sideforce

At road speeds there is no real downforce generated by the rear wings of any type on these cars. Your right - you will need to be doing well over 100 mph to feel any benefit. For a road car, we would need wings with a huge cord, or size to generate downforce. It would need to be bigger than a F1 wing, to have the cord to work at our speeds. It would also be causing to much drag - and there would be uproar as it was making our cars slower !

The spoilers at the front do a good job of limiting underbody air flow - which causes a lot of lift and drag. Especially at higher speeds. having a deeper front spoiler limits the air going underneath and significantly reduces lift..

Usually the rear "wing" of a road car is much better thought of as a "deflector", encouraging the air to go where the designer wants it to go...rather than causing lift by flowing over the rear end of the car.

"do you think they would go to all that trouble of making carbon sills plastic front ends aliminium bonnets to make a car faster then go and throw a big high spoiler on the back end just for looks"

YES !!! I think that is exactly what they are there for...because if you look at the science what we have just dont and would not work...if the manufactorers where serioulsy looking for downforce they would be looking under the car and we would be sprouting splitters and diffusers rather than huge rear wings...but you would not be able to see them...

chucknorris

I must agree with sideforce on the "it's there for the looks rather than to do a job". The Rally cars will have them to help with some aspects of handling, because they wouldn't add the weight if it was an unneccessary piece of cosmetics, but the Rally cars corner hard at very high speed on loose surfaces, and that's when i imagine they would want as much down force as possible which goes back to the point about wings don't create down force unless you are going fast.
As for the cars coming out of the factory with the big wings/spoilers on....they are selling them as either homologation type cars or cars that closely resemble the factory team cars, so of course they are going to have a big wing on them because that's the look of the Rally cars....so Cosmetics on the road car and for a purpose on the rally cars.
The fact that they do some work on the road cars is probably more of a bonus.

Another thing, even though a 22b rear wing is going to cost you a fortune ( i don't know how much, but probably £800+) But i bet the actual rally wing that it looks like will come out of a different mold and cost a $hit load more. (in other words it aint the same wing)

I aint no preacher, son!!! So if any of ye critters out there don't agree with me, ye can jist ignore what i've jist said cause i don't know Jack! an i'm jist guessin'.
"Bettsie,.............Pass me the sippin whisky!"

Ye Ha!!!!!!!!

Chuck!!!

Andy McCord

yes agree with the above, youve no chance of creating any significant downforce with the std wing angle IMO

StickyMicky

why did audi fit a small rear spoiler to the back of the TT`s as part of a package which sorted out the "dodgy" handleing early in its life?

the mid level spoiler was used on the early rally cars wasnt it?

i do seriosly belive thge later v5/v6 spoilers were only getting that big because the evo spoilers were getting bigger as well

but as a intresting side note, yesterday i stuck my old copy of grand turismo 2 in to have a oldskool blast about, and it went into sum detail regarding the v6 spoiler and front lip, over the v5`s rear spoiler, acording to the blurb it was part of areo package which was desinged to stop the car lifting at speed (or sumthing simmiler) ill have another look @ it 2morow and copy it word for word

RON

Guy's,
I've been having a lot of trouble with my 22b style spoiler leaking into the boot, and generally annoying me, so, have made steps towards changing it for something more discreet, bearing in mind that mt car is dark blue, and obviously the picture is of a red bootlid with a primered spoiler taped onto it, what d'you think, very unconventional, but I quite like it.

Let me know, honestly!!!

StickyMicky

unsure

how about you swap the 22b one for a mid level one

RON

To be honest, I want something different from the norm, and some rear vission to boot, so the low ones going to go on the car, when I'm sure that I'm happy with it, the 22b style one will be in the classifieds!!!

Gary C

I used to notice a big difference with my EVO spoiler set in max downforce position, I could not see a thing out the back !

BigGuy

StickyMickey said it. A few years back Audi TTs had to be fitted with spoilers and other electronic stability gadgets because under heavy breaking at high speeds the back end would lift and cause drivers to lose control especially when in a turn. Audi resited the change for a while because id would alter the desired shape of the car but people where having accidents and even getting killed. I guess the shape had to go...

BigGuy

BTW the reason diffusers are not used more often are that they cost so much more than spoilers to design. not everyone can afford Ferraris

akshay67

The Escort Cosworth had to have the wing removed on rally stages across hot surfaces as the downforce that beast would produced often ripped the tyre rubber off - and this was at 80mph is speeds.

So a well designed and tested wing can make a difference at higher, but do-able, speeds!

Edited to add that the wing produced a whopping 200kg of downforce at 125mph

Absolute Shower

I remember when the Escort was released with that monster rear spoiler....read article in some mag and it said it was the only spoiler to give 'real' downforce....Well, what load of bull....any that deflect air will give downforce...it's just the Escort gave enough force same as having an elephant on the rear!

Gary C

I think they were refering to overall downforce (and as I recall it was first said about the sierra cosworth), virtually all cars actually have lift, many spoilers reduce lift and aid stability but no road cars (they claimed) at the time of the Sierra launch actually had overall downforce.

As to deflecting air, if it speeds up the air over the underside of the spoiler as against that flowing over the top (ie a wing), it will create downforce without as much penalty in drag as would simply deflecting the air upwards (ie a simple spoiler a la TT)

Big C

http://www.prodrive-usa.com/productI...sheet_WIND.pdf


Interesting...

C

StickyMicky

i love it when im right

Absolute Shower

Ah, makes sense now re that mag...Might of been a good read then...trouble is, cant remember what mag it was...doh

dibble wants a scooby

Just read the thread
V.Interesting points raised so here's my 2p

Spoilers are there to 'spoil' the airflow. Front ones are to stop (a lot of ) air from going under the car and push it around i.e. negative lift i.e. downforce.
The flat under floor and venturi effect don't really apply (well not much) to Scoobs but look at an F50 or Lotus Elise or any top sports car and see the 'tunnel' type extensions at the back coming out from under the floor...its to tumble the air from out under the car.
The rear is as some have said for downforce and I wouldnt expect to work up to 100 but the big spoilers are more there for homogolation purposes for WRC as they will need the downforce!!
The negative effects of a big spoiler? well drag is the biggest as we all know F1 cars do approx 200mph, well that would be more if the huge wings fell off but then they wouldnt go round corners!! They are supposed to create enough downforce to drive upside down at 200mph and if they get too close to the 'dirty' air of a car in front (thats been 'tumbled' from the venturi) then it loses front end grip as the spoiler is not going through clean air.
The smaller scoob ones would affect fuel use less but dont look as good ! But I wouldn't take it off as it will affect air flow as air will actually go over then be 'sucked back' under and around the back of the car (could affect the water on the back window?) as it's not 'spoiled'
Thats one of the reasons hatchbacks have rear wash wipes and saloon don't (normally) as the boot stops all the crap being sucked back on to the rear window.

Anyone remember when the TT came out and was a nice round back end and when some German died on the Autubahn when he lifted off at high speed he lost control and thats why the TT has a small spoiler on now to stop lift off high speed un-stability and thats prob what the first guy was experiencing

Paul

StickyMicky

you didnt read the thread properlly did you??

Chaddy

Ha Ha
This all reminds me of when I was involved with the development of the Ford Puma. When I was first shown an early prototype car, it had a rounded back, and my reaction was ..that won't work, you'll get loads of drag and instability ! I was politely shown the door, accompanied by the German equivalent of go forth and multiply ! It subsequently transpired that the car had a worse Cd than a standard Fiesta, about 0.4 I think...The production car, as we all know, appeared with a built in 'Spoiler'. Imagine what I thought when I saw the Audi TT !

Gary C

Ah Chaddy,

So the TT's spoiler is their to clean up the air flow over the rear of the car to stop it shedding unstable vortices off the bluff body (, I almost sound as if I know what i'm talking about) rather than providing any 'downforce'. Makes sense.

sideforce

Where do you get these figures from you are quoting?

akshay67

Remember the figure (from a colleague who worked for Ford Motorsport)- but if you Google it you'll also find it somewhere...

sideforce

I have not because it cannot possibly be correct.

akshay67

Really? Well the downforce was strong enough to cause ripping of the rubber on the rear wheels (and thats why in subsequent rallies they removed the beast!).

I'll look into it and see if I can find some information...

sideforce

Yeh that would be good, it proberly wasnt the downforce, as looking at the horrid thing is was proberly the lift at high speed giving wheelspin...LOL