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The mkiv Supra Owners Club

Rear Downforce- Tech Opinions


Thor

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Originally posted by John Packham

Alex: looking for a big wing that works? you may find one of the GT2 Viper's wings if you ask about.

 

Now that would be just crazy......

 

I want it!! :D ;)

 

Fortunately I don't have the foggiest of where to ask :D I really can't handle subtle hints.

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Originally posted by Thor

Guys, firstly I don't like the F&F look rear wings, but is there any real advantage on a fast RWD road car? If so which type. I have been watching the JGTC & they all use similar huge wings.

 

If there are any proven wings, are there any links to web sites?

 

I've read through this thread and as usual I've learnt alot.

 

Generally speaking the only significant way of achieving downforce from a wing on a Supra is to have a differently designed and much larger one and that it will only really make a difference at speeds of over 100mph.

 

Now I have a JSpec TT without a wing, and my question is, under high speed road driving what difference in handling and downforce can I expect between my car and a similarly spec'd car with a wing? Is it worth going for a wing other than for cosmetic reasons?

 

Pat

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Originally posted by Patrick_Devlin

A claimed 66lb of downforce at 90mph... hmmm

 

So the rear lip doesnt provide any? Is that going to make a noticeable difference other than on the track?

 

You have to remember manufacturers of road cars talk of a wing giving X pounds downforce, but they fail to mention the body shape (and a MKIV is bad for lift as it's an inverted wing shape itself) can cause an uplift of perhaps 120 pounds at 120 MPH, so the "downforce" just lessens LIFT. The stock wing basically does very little, it's not even a proper profile. Mainly cosmetic, doubt you'd notice 60 pounds reduced lift at 90 MPH on a car so heavy.

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Originally posted by Patrick_Devlin

Thats pretty much what I thought.

 

I have been concerned that if I was to drive "fast" that not having the wing may compromise handling.

 

Chris, what would you say the difference between wing and no-wing at 150mph would be?

 

Pat

 

A reduction in speed at a given engine power output, probably, and an increase in downforce fro the wing but a probably greater relative uplift from the roof shape, so overall there might be less weight on the rear wheels still. As you aren't likely to be also going round a corner at 150 I doubt you'll notice much difference, but as Terry says every bit helps, but drag will suffer.

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Originally posted by Patrick_Devlin

Chris,

 

I know you mentioned lowering and smooth undersides, but how much does lowering really help. Would you have to drop the car so much that it would be impractical to use it on the roads?

 

Pat

 

A smooth underside will reduce drag at any ride height, to use a flat bottom with rake from front to rear (higher at rear) to create a worthwhile negative pressure under the car would need a front ride height of 50mm or less with at least a 10mm rake. Impractical for anything but the track. My F3 ran a 10mm front ride height, 40mm at the rear. Big pebbles were a problem :p

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Originally posted by Terry S

Chris, are you saying that a car like a Ferrari 360's flat bottom & diffuser serves no purpose? They are not 50mm from the ground!

 

A clean underside will reduce drag, aiding economy and speed, but I would think its diffuser will do sod all. Purely styling really It can't create much negative pressure if air is free to replace the partial vacuum, hence the need to have the car ultra low.

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Originally posted by Syed Shah

I thought the 360 makes 400lbs at 100mph or something like that?

 

Dunno, but it would be very surprising to me.

 

 

 

 

BTW, a Supra without the standard spoiler apparently has more drag than one with the stock spoiler due to more air turbulance.

 

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It may help clean up the air flow off the roof, Toyota will have wind tunnel data, for sure, but historically getting blood from stones is easier than getting the data from makers.

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Originally posted by Alex Holdroyd

Hmmm how much stock do we put in Top Secret's designers?

 

http://www.intensepower.com/topsecgtiwin.html

 

It looks very nice....possibly the endplates are too small.

 

Oh and its WAY TOO EXPENSIVE!!! It'd better work at that price!

 

Far easier and cheaper to buy a proper profile in the UK, SPA make wing profiles, so does a firm in Derbyshire, DK I think, they make the little bike engines sports and single seaters, but also have a good range of carbon wings. It will need to be carbon or ali, a fibreglass wing of the size needed for a MKIV will weigh a ton in order to be strong enough. It really needs a dual plane wing to be effective without being absolutely massive.

 

The one in the link looks 99% stylised to me.

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Guest Terry S

I mailed SPA Aerofoils yesterday Chris. I'll let you know if the respond.

 

Also Chris, whilst on the subject, what about lift. What would your opinions on lift in these cars at high speed, say 200+ MPH

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