How much downforce does the 197 diffuser give?

[franx]

A couple of months back i spend the afternoon in the workshop of a race team (they used to be racing the 172/182's , now the 197)

They started to experiment with diffusers on the back for more stick and yep ; got better laptimes. Mind you , the diffusers they made up and stuck on there looked like poo but proved to be functional

Every little bit helps i guess

 

[ForceIndia]

A diffuser needs fast, smooth air travelling from the front of the car in order to be effective. Slow turbulent air (ie no flat underbody, or as flat as possible) stops a diffuser from working effectively.
A diffuser works with other components. Without the other parts, it's basically cosmetic.

 

[DNP182]

10 4. take your point. am just sh*t stirring lol

 

[ForceIndia]

10 4. take your point. am just sh*t stirring lol

c**txx

 

[theduck]

How flat does it need to be though? Underside of a 197 is quite flat in comparison to other road cars...

 

[ForceIndia]

 

[theduck]

Not far off then

edit: what is that the bottom of?

 

[ForceIndia]

F430 iirc

 

[alanc1000]

just another example of how fantastic the 197 and how its a great evolutionary development from the 172 and 182.

All this talk about it being marketing only, what piss, as if the any other Clio hasn't had its share of marketing gimmicks (along with all other sports cars)

 

[ForceIndia]

just another example of how fantastic the 197 and how its a great evolutionary development from the 172 and 182.

All this talk about it being marketing only, what piss, as if the any other Clio hasn't had its share of marketing gimmicks (along with all other sports cars)

Exactly. It's marketing, and there's nothing wrong with it.

 

[realnumber 1]

just another example of how fantastic the 197 and how its a great evolutionary development from the 172 and 182.

All this talk about it being marketing only, what piss, as if the any other Clio hasn't had its share of marketing gimmicks (along with all other sports cars)

To be a great evolutionary development over the 1*2's I would expect it to be substantially quicker and more efficient. It's not though!

 

[ForceIndia]

To be a great evolutionary development over the 1*2's I would expect it to be substantially quicker and more efficient. It's not though!

They won't be told!

 

[alanc1000]

To be a great evolutionary development over the 1*2's I would expect it to be substantially quicker and more efficient. It's not though!

Not at all.

A car that evolves does not automatically have to be faster, look back over 10 years or so and most sports models today across manufacturers are by and large the same sort of speed. In terms of efficiency, yes that would be lovely and my BMW is nice and efficient and fast, more efficient than the BMW of 10 years ago - but you dont buy sports cars for efficient and the manufacturers know it! Any efficiency gain is a bonus, not a given!

Warren - in your own words tell me why a 197 would have a diffuser that was like a bit of decoration and that doesn't add any functional use if Renault have a development team available who would probably spend no more of their budget on designing and making one that is functional?

 

[ForceIndia]

Warren - in your own words tell me why a 197 would have a diffuser that was like a bit of decoration and that doesn't add any functional use if Renault have a development team available who would probably spend no more of their budget on designing and making one that is functional?

Erm, the marketing dept perchance? The same marketing dept that fed us the horseshit about special tyres for the 182 cup pack?
A diffuser needs a smooth, quick airflow to have a noticeable effect, if this weren't true why would Ferrari go to the expense of a flat underbody (a clearly non-cosmetic part)? Designing a diffuser for marketing purposes is far easier and cheaper than designing a flat underbody and the associated issues that come with it.

 

[Marv-C]

Didn't realise I was going to start a fire here

Everything I have read about the 197 has said that the diffuser is functional. If you look at the diffuser on the Corsa VXR you can tell that is a gimmick!!!!

BTW, I am well aware that the diffuser does not produce downforce, it does the opposite of 'sucking' (if you have a better word then change it, don't flame me) the car to the ground by reducing drag undeneath the car.

 

[ForceIndia]

May also have been a vain effort to improve the 197's woeful mpg

 

[Marv-C]

A diffuser needs a smooth, quick airflow to have a noticeable effect, if this weren't true why would Ferrari go to the expense of a flat underbody (a clearly non-cosmetic part)?

This has something to do with the price they can charge for the car. You can't have a flat underbody and a cheap car. The Ferrari will produce more downforce than the Clio. That doesn't mean that the Clio does not produce any.

 

[alanc1000]

May also have been a vain effort to improve the 197's woeful mpg

i've never said the MPG on the 197 was good, it was one of the reasons i got shot of mine, not because i was appalled buy it, but because i get the same MPG now out of a 3.0!

But then again 29mpg from mine wasnt too bad, unlike some of the figures people on here quote they get from theirs!

 

[ForceIndia]

This has something to do with the price they can charge for the car. You can't have a flat underbody and a cheap car. The Ferrari will produce more downforce than the Clio. That doesn't mean that the Clio does not produce any.

But to say the diffuser produces 40kg of downforce is completely incorrect! The Clio was designed as a normal car, where factors like mpg and low drag take priority. I'd be massively surprised given the shape of the car, the ride height and the diffuser if there's 40kg of downforce. If it were such a critical performance part on the 197, why on earth would renault completely compromise the design of the diffuser on the 200????

 

[ForceIndia]

Can someone please explain to me why the Corsa diffuser is a gimmick, and the 197's isn't?

 

[Ex-User (19928)]

Can someone please explain to me why the Corsa diffuser is a gimmick, and the 197's isn't?

I, in particular liked that comment lol.

 

[Marv-C]

But to say the diffuser produces 40kg of downforce is completely incorrect! The Clio was designed as a normal car, where factors like mpg and low drag take priority. I'd be massively surprised given the shape of the car, the ride height and the diffuser if there's 40kg of downforce. If it were such a critical performance part on the 197, why on earth would renault completely compromise the design of the diffuser on the 200????

Agreed. The diffuser looks less effective on the 200 than the 197. I have to admit that 40KG seems alot, but I am still in the honeymoon period of having just bought the car

 

[alanc1000]

But to say the diffuser produces 40kg of downforce is completely incorrect! The Clio was designed as a normal car, where factors like mpg and low drag take priority. I'd be massively surprised given the shape of the car, the ride height and the diffuser if there's 40kg of downforce. If it were such a critical performance part on the 197, why on earth would renault completely compromise the design of the diffuser on the 200????

yet again you are getting all anxious and are looking at the negatives.

The Renault development team know a damn site more about airflow and design than you do, so why wouldnt they be able to acheive this?

Perhaps you should apply for a job and tell them how its really done?

 

[Marv-C]

Can someone please explain to me why the Corsa diffuser is a gimmick, and the 197's isn't?

Hopefully the picture of a Corsa VXR is here. You can tell that this is purely a cosmetic part of the bumper whereas the Clio diffuser goes about 3 feet under the car.

BTW How do you include a full picture in the thread?

 

[ForceIndia]

yet again you are getting all anxious and are looking at the negatives.

The Renault development team know a damn site more about airflow and design than you do, so why wouldnt they be able to acheive this?

Perhaps you should apply for a job and tell them how its really done?

Oh dear, you seem to be getting all hurt and personal. I'm very sorry for 'offending' a car you don't own.
Calm down Priscilla, no need to get anxious.

 

[alanc1000]

Can someone please explain to me why the Corsa diffuser is a gimmick, and the 197's isn't?

yes, because the Corsa has a roof spoiler and the clio doesnt.

Plus your fave mag reckons it does produce downforce on the corsa...

http://www.evo.co.uk/news/evonews/204589/vauxhall_vxr.html

'There’s a prominent roof spoiler, a fat centre-exit exhaust, and a very bold diffuser arrangement. ‘The car has obviously been wind tunnel tested,’ explains Harris, ‘and it generated a surprising amount of downforce. You can really feel its effects on the faster parts of the Nürburgring.’

 

[Marv-C]

yes, because the Corsa has a roof spoiler and the clio doesnt.

Plus your fave mag reckons it does produce downforce on the corsa...

http://www.evo.co.uk/news/evonews/204589/vauxhall_vxr.html

'There’s a prominent roof spoiler, a fat centre-exit exhaust, and a very bold diffuser arrangement. ‘The car has obviously been wind tunnel tested,’ explains Harris, ‘and it generated a surprising amount of downforce. You can really feel its effects on the faster parts of the Nürburgring.’

LOL

 

[ForceIndia]

yes, because the Corsa has a roof spoiler and the clio doesnt.

OMFG. Here lie's a fundamental misunderstanding on diffusers. The diffuser slows the airflow exiting the rear of the car, reducing turbulence, reducing lift. It will help the function of a spolier. Cars like the F430 don't require big spoilers etc as it has a flat underbody (which creates low pressure and a suction effect).

 

[p@blo]

'no spoilers' to this thread please

Taxi for DNP! :rasp:

 

[alanc1000]

OMFG. Here lie's a fundamental misunderstanding on diffusers. The diffuser slows the airflow exiting the rear of the car, reducing turbulence, reducing lift. It will help the function of a spolier. Cars like the F430 don't require big spoilers etc as it has a flat underbody (which creates low pressure and a suction effect).

hence the reason the diffuser is about 3 foot long on the 197.

Just throw in the towel, admit the diffuser has SOME effect on the 197. No one is saying it glues it to the floor and makes it as good as the Ferrari.

 

[theduck]

Can someone please explain to me why the Corsa diffuser is a gimmick, and the 197's isn't?

corsa diffuser reaches about |-----------| that far under the car. a 197 diffuser does go at least someway to producing a flat bottomed car by being far reaching under the car.

Warren, out of interest and not a intended to be snide etc, but have you looked under a 197?

 

[DNP182]

yeah warren...just throw in the towel lol

 

[ForceIndia]

corsa diffuser reaches about |-----------| that far under the car. a 197 diffuser does go at least someway to producing a flat bottomed car by being far reaching under the car.

Warren, out of interest and not a intended to be snide etc, but have you looked under a 197?

Had a good nose around a few, and the albi 200 that Renault Brum had in a couple of weeks ago. Glad you can discuss the matter sensibly!
I don't full understand how the length of the diffuser affects things, but from what I understand it's the angle of the diffuser that is most important (7-10 degrees being optimum).

 

[ForceIndia]

hence the reason the diffuser is about 3 foot long on the 197.

Just throw in the towel, admit the diffuser has SOME effect on the 197. No one is saying it glues it to the floor and makes it as good as the Ferrari.

It does. It looks awesome.

 

[theduck]

Had a good nose around a few, and the albi 200 that Renault Brum had in a couple of weeks ago. Glad you can discuss the matter sensibly!
I don't full understand how the length of the diffuser affects things, but from what I understand it's the angle of the diffuser that is most important (7-10 degrees being optimum).

My point is that although its not a completely flat bottomed car, that because the diffuser goes back so far, the under tray at the front and the fact the underside of the car is not a complete mess that, although not perfect, its going to be a lot better than it only going back 3 inches.

Just helps to make it MORE flat than it otherwise would be

 

[realnumber 1]

Not at all.

A car that evolves does not automatically have to be faster, look back over 10 years or so and most sports models today across manufacturers are by and large the same sort of speed. In terms of efficiency, yes that would be lovely and my BMW is nice and efficient and fast, more efficient than the BMW of 10 years ago - but you dont buy sports cars for efficient and the manufacturers know it! Any efficiency gain is a bonus, not a given!

Oh right is that why most manufactures are heading towards smaller engines with turbo's and/or super chargers then?

i've never said the MPG on the 197 was good, it was one of the reasons i got shot of mine, not because i was appalled buy it, but because i get the same MPG now out of a 3.0!

But then again 29mpg from mine wasnt too bad, unlike some of the figures people on here quote they get from theirs!

So you call that great evolution when I can happily see 35-45mpg on my 172 (depending on type of journey).
The only thing I can see the diffuser doing is reducing the drag a little and aiding high speed stability. Not a chance it produces 40kg of down force at 70 mph lol.

 

[rory182]

If you hung 40kgs off the back bumper it would fall off, especially being a Renault. Its only clipped in with, iirc a few of 10mms near the rear beam

Think about it

PMSL!

Its more a case of putting 40kg in the boot, think about it

 

[ForceIndia]

PMSL!

Its more a case of putting 40kg in the boot, think about it

If it produces 40kg of downforce, the force exerted downwards on the diffuser would be 40kg. What he's saying that if you hang 40kg off the diffuser, would it stay on?

 

[rory182]

well a few 10mm bolts would take 40kg quite happily then if that was the case

 

[ChrisPearson]

LOL at people quoting the brochure,yes it might help a little but not 40kg its mostly for looks.

I also dont understand why you would need a rear diffuser in a slow FWD car?