Lowering & the diffuser

[tjthemonkey]

Morning All,

I've done a little aero work on racecars but have no experience with before / after comparisons on road vehicles, or how much of a change is noticeable...

Has anyone noticed if their clio's got a bit more grip from the diffuser working better after it's been lowered - ie when it's closer to the floor?

Cheers

 

[BenW]

I've not noticed any difference and to be honest the diffuser does so little work I wouldn't expect to.

 

[ben_r1]

30kg at 70mph. More of a gimmick I'd imagine.

 

[jostheboss]

Without a smooth floor it does nothing!

 

[sthomasj10]

I think unless you're hammering it around a track you won't notice it.

It's more of a "look" thing than anything else. The only aero feature Renault added what the car actually benefits from is probably the brake cooling vents. Again, only really noticeable/beneficial if you're tracking it.

 

[tjthemonkey]

okidoki, guess that's answered that then lol :-(

thanks guys!

 

[BenW]

I think unless you're hammering it around a track you won't notice it.

It's more of a "look" thing than anything else. The only aero feature Renault added what the car actually benefits from is probably the brake cooling vents. Again, only really noticeable/beneficial if you're tracking it.

There aren't any brake cooling vents? If you mean the vents in the front quarters then these are apparently blocked off behing the arch liner.

Renault do say though that the diffuser is meant to provide 40kg of downforce at 70mph

 

[ben_r1]

The wing vents aren't blanked off they vent out engine bay hot air, there's a fancy illustration on the Renaultsport website.

On a cooler day you can sometimes even feel the warm air going down the side of the door at low speeds

 

[adam1942]

^ really? I put a light + stick in mine and it was blocked up

 

[Raptor6767]

In a groundbreaking first for cars of its class, New Clio Renaultsport boasts a rear air diffuser. Derived from Formula One, this feature has previously only ever been seen on high performance supercars, but now offers Renaultsport fans a taste of ultimate performance.

The diffuser’s purpose is to prevent rear end lift by channelling airflow in such a way that a zone of low pressure is created beneath the car, effectively sucking it to the ground. This eliminates the need for a rear spoiler by producing the equivalent of 40kg of rear downforce at high speed. To maximise the diffuser’s effect, the dual exhausts are housed within the outer channels.

Airflow is also directed by front wing extractor vents, which reduce turbulence and direct air flow along the sides of the car. New Clio Renaultsport comes with a specific bumper and grille, as well as a front aerodynamic splitter to restrict the amount of air passing beneath the car.

 

[Willis]

Stick your hand down by them when the engine is nice and warm and you'll feel the breeze.

Can't say I've noticed any difference to the ''downforce''. Apparently there is some, and the front undertray does go quite far back, it probably makes some minimal difference that you'd pick up in a wind tunnel or what have you but I don't think it's something you'd feel in day to day driving. All I know is she sticks better than any car I've driven before, apart from maybe a Formula Brands, those little things have bags of grip.

 

[BenW]

To maximise the diffuser’s effect, the dual exhausts are housed within the outer channels.

197s had blown diffusers before F1.....another reason the 197 is better than the 200

 

[Fernandez]

The only way to tell if the diffusser works is to try the car without it

 

[ben_r1]

You'd possibly notice it on a speedy track like silverstone, it looks quite cool with the diffuser removed actually, kinda jap with a stainless exhaust hanging side on

 

[930Tech]

IIRC Aerodynamics dont come into effect until around 60 odd 70MPH.

 

[Surrey-Paul]

Plus all forms of spoilers will give negative effects below their operational speed, so most of the time your actually ruining the cars CDa. Also for wings to be effective you need to place them in the clean airflow above the car which is then way above the roof line, although most spoilers like what's on the clio work in not generating downforce but spoil the air as it leaves the rear roofline causing the air to flow past the low pressure zone behind the car which is good as this then means rather than dropping early and havign a pulling effect it then has a pushing effect on the car.

Ground effects work so much better so by lowering a car you remove the amount of low pressure air below a car which increases downforce by the natural high pressure air travelling over it, if you don't lower it then by fitting a deep chin or V-spoiler on front helps again by reducing the amount of air going under the car, along with deep side skirts.

Another trick I read about regarding front spoilers is to create a Vortex tunnel, by having a deep front spoiler to the sides but the middle section no so deep (BMW currently do this) as this then causes the airflow going under to travel much faster which then pushes the low pressure air out the back and if a rear diffuser if fitted increases it's effectiveness and again helps like a roof spoiler by pushing air past the low pressure zone at the backend of the car and having this pushing affect is a positive but without the negative effect at slower speeds that wings/spoilers create.

The RS def. feels more planted at high speed than some cars I've had and this will be due to the diffuser or the fact that the rear bumper is cut away as at speed the air travelling under the car tries to go back up and then with conventional rear bumper this than traps the airflow and acts like a parachute slowing the car down