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European GP – The latest tech, blown diffusers explained
European GP – The latest tech, blown diffusers explained
Posted By: James Allen  |  28 Jun 2010   |  9:55 am GMT  |  65 comments

This weekend’s European Grand Prix at Valencia is a significant event in the story of the season from a technical point of view as it was the race where many teams unveiled a device which copies the Red Bull’s “blown diffuser”.

Last year three teams started the season with a double diffuser and, after establishing the legality of it, the rest of the field was forced to follow suit, including Red Bull. This year’s “must haves” so far have been the McLaren F Duct wing and now the blown diffuser. Red Bull is the pioneer and Mercedes, Ferrari and Renault have followed them this weekend. McLaren and Force India are due to follow at Silverstone.

On the grid this season the Red Bull mechanics have been carefully masking the diffuser from view. Although they do have something interesting to hide, in F1 this is often a bluff, indicating that the most interesting part of the car is somewhere else, but they want you to focus on the diffuser!

A blown diffuser is basically a way of using the exhaust gases to interact with the diffuser, which sits at the back of the car at the end of the floor. There are two main purposes for this;

* to try to move the wake from the rear wheels outwards where it will cause less disturbance

* to re-energise the low pressure air at the very back of the diffuser to create more rear downforce.

Rear downforce is important for driver confidence, if the driver feels good rear end stability he will push harder, so the gain on the stopwatch from this kind of development is often not what a simulator tells you it will be, but what the driver actually delivers from it.

The irony is that blown diffuser is not a new concept, unlike F Duct wings or double diffusers. Renault had one in the early 1980s, Frank Dernie put one on the Williams of Nigel Mansell in the mid 1980s and they were common from 1985 onwards. Adrian Newey’s team at Red Bull didn’t invent it, they revived it. The early ones were crude in that the rear of the car often became less stable when the driver lifted off the throttle. Everyone knows a but more about the science now.

They went out of the sport in the mid 1990s due to a change of wording in the rules, but Newey felt that the current rules would make it worth trying again.

The blown element operates independently of the “double” element of the diffuser and whereas double diffusers are banned from next season, the blown diffuser is here to stay.

The Ferrari’s exhaust exits have been moved from the high exit in the top bodywork, which they pioneered in the early 2000s, to the low exit near the floor to feed the diffuser. They stop slightly shorter than the Red Bull ones.

Low exhausts heat everything up in the area behind them and there is a risk here. Less widely reported, there was a new Ferrari gearbox this weekend, only on Felipe Massa’s car, designed to raise the pick-up points of the lower wishbone, in order to keep it away from the hot gases from the low exhausts.

Keeping temperatures under control is important and it was intersting to see a series of red stripes on the rear side section of the Ferrari diffuser. These stripes are of a special paint, which changes its colour in relation to the different temperature of the surface where its applied. In this way the Ferrari engineers could see which part of the diffuser reaches too high a temperature due to the hot gases directly blowing on them.

Ferrari’s update also includes new cooling ideas in the radiators and bodywork for the series of warm weather races coming up in the summer, as they have had problems with the engines in hot countries earlier this season.

This is an important update for Ferrari, who started the season as the pace setters but then lost ground as they got bogged down with developing the F Duct rear wing at the cost of other avenues. Meanwhile McLaren, Mercedes and Renault all stole a march on them.

Renault also had significant upgrades, including the blown diffuser. In this illustration by our technical artist Paolo Filisetti, you can see the old style high exhausts at the top and the new low style ones at the bottom.

Renault continue to push hard, they brought the 22nd iteration of their front wing to Valencia, the ninth race of the season.

And finally Lotus had a good qualifying session in Valencia, with Jarno Trulli the fastest of the new teams, increasing the margin over the other new teams to 1.4 seconds. That said the gap to the slowest of the established teams, ironically Kobayashi’s Sauber, had also grown to over a second.

One key update for Lotus this weekend was a new front wing solution, which owes a lot to design ideas on last year’s Toyota. Many of the engineers at Lotus came from Toyota so this is not altogether surprising.

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“Ferrari’s update also includes new cooling ideas in the radiators and bodywork for the series of warm weather races coming up in the summer, as they have had problems with the engines in hot countries earlier this season.”- I’d ask, how big influence Pat Fry’s appearance in red team has, with all those ideas?


Thanks for this analysis James. There are some great comments here as well.


Something picked up in the technical scrutiny – the FIA checking that everyone was using their pre-declared gear ratios.

My mates were speculating that this might be that “a team” who knew that they were going to run at a higher top speed through the season might have prompted the scrutiny now other teams have acquired the ability to run with lower than expected downforce due to blown rear wings.

Are any teams compromised with restricted top ratios for their gear boxes? This would limit their top speed when combined with the 18,000 rev limit.


Question regarding Webber’s flight. The TV camera’s actually provided everyone with a glimpse of the underside of the Red Bull, perhaps the first shot of this type this year. Will teams be able to blow it up clearly enough to see how the back end of that car ticks, or have I been watching too much CSI? :-p

Also, were there any photographers who caught the incident or is it only TV?


Hi James,

Lewis was black flagged in Imola GP2 race 2006 for overtaking the safety car; keeping in mind your extensive experience as an objective F1 journo, what is your explanation as to change in the penalty this time around for a same offence and especially given that FIA is “promoting safety”

“Lewis was back in the pits for good courtesy of a black flag penalty for overtaking the safety car on track.”

Thanks for your time



That’s a really great point. I’d forgotten about that incident. I commentated on it too! Thanks


I agree…it’s a funny comment and I don’t even have the slightest idea what he’s talking about.


James, the RedBull exhausts does intermix with the air in the upper diffuser; I think for Valencia it also reacts with the main diffuser via a side slot. Ferrari’s, Ranault’s and Mercedes’exhaust does not interact directly with the air in the diffusers, but goes over the top as you said.


These tech pieces are my favourite. Thanks James, keep up the good work, we really appreciate it.


James did your photo guy (Darren Heath?) manage to get a snap of the underside of the RedBull like he did at Monaco of the Ferrari?


I imagine engineers are drooling over the opportunity to examine the bottom of the Red Bull afforded by Webber’s flip. There is more information there than I’m sure Red Bull would care to share.


Kubica my hero is climbing up thanks to some excellent work being done at Renault. He would have finished 3 if it wasn’t for an odd hick up

with tyres. C’mon Robert! They are now half a sec behind RB and Mac. C’mon, let’s get on with it!


Is it practically possible to hide parts of a car from view…?? has a lot of details about new technical parts


Azlas, have to say that thought crossed my mind too after the accident when I saw the RBR car being craned away. Reminded me of the shot we saw of the Ferrari at Monaco.


Also, you can bet your house on it that many of the other teams thought the same too 🙂


Hi, James. Great article.

I wonder if you could write something about Lewis’ apparent dishonesty yesterday.

His comments about the SC incident are clearly contradictory to the actual events.

Is it acceptable for him to blatantly lie again?


“Lie” is a strong allegation. From my recollection of the post race interview he specifically said he didn’t have a good recollection of exactly what happened but that he _thought_ he had crossed the line before the safety car.

He may have been wrong about that second fact but that doesn’t make it a lie. It’s hardly unusual for someone’s recollection of events to be imperfect.


Thanks for the Youtube link. It shows how marginal it really was!

The reason Lewis slowed was because it looked like the safety car was about to cross his path by coming accross the pit lane exit line, thus giving Bert Mylander a drive through penalty:)

If that had never happened I don’t think Hamilton would have slowed and would have been fully justified to follow Vetel through the lap.

Sorry for the OT rant!!!


no doubt you’ll find alonso’s lie about being “1 metre behind lewis” at the time scandalously unacceptable too? not to mention his libelous claim about the partiality of the fia?


James, it seems since testing was banned Ferrari has struggled the most among the established teams to develop the car during the season. Doesn’t that evidence a weakness in “virtual” development and testing (that is through the use of computing and simulation capabilities)? One would imagine that the testing ban has made simulation and other virtual tools much more relevant in the development race and things like Ferrari’s “test” that wasn’t a test last week seem to support the argument that they rely too much on actual track testing.

On those lines could it be that their constant interest in running a third car would give them an opportunity to use it as a “test bench” in actual races?


I think you’re spot on with your suggestion why Ferrari want to run a third car.


I think Ferrari is (was) the team most invested in real-life track testing. Where McLaren spent money on advanced tyre simulation tools (why they were so good in 07, btw) Ferrari had and still has their own private test track. The testing ban probably hurt them more than other teams. They just recently got their own state-of-the-art simulator.


James, I think you’ll find that the Ferrari F300 used in 1998 already has the periscope exhausts. I still remember the ITV commentators ridiculing it as an desperate attempt by Ferrari to get competitive. But low and behold, eventually the rest of the grid copied the design.


It’s a bit off topic but could you please forward this to Martin Brundle. He needs to know that “centigrade” is a deprecated term and that the IS Unit is Celsius. He keeps on using the wrong term.

Thank you


Hi JA,

I wanted to ask you this after Ted Kravitz pointed it during the race, as per your confirmation Renault is now using the 22nd version of its front wing in just 9 races, how did that happen? Does that mean for a given GP on a Friday they had more than one version? or both drivers were using different versions?

As far as Ferrari’s update is concerned, did they use a Fully upgraded car on the Ferrari filming/open day? I know you said this is legal but I find it hard for a team like Ferrari always first to scream for injustice when they’re not so clean themselves?


you’re kidding about ferrari, right?!

although to be fair, it wouldn’t have been a surprise for any of the other teams to have done the same – ’tis the nature of the f1 beast. fair play to them, as it probably won’t happen again now.


How exactly have Renault used 22 different wings?

Even if you say a different one for each race and in both quali and race thats only 18!!

Are they bringing more than 2 types per weekend? or are they counting minor modifications done during the weekend by hand?



Remember the four preseason test sessions they had. They could have used two or three for each test, and then one per race weekend.


They also Free Practice 1,2 and 3. Without testing, teams often use Friday to test and 2 drivers they can test 4 wings on Friday alone.


Yeah, I appreciate they have the TIME to feesably test that many wings, but the fact that they are bringing that many new parts to each weekend is suprising. So much for the budget cuts! From what I gather, teams like Hispania can only manage to bring one spare wing between two!



Blown diffusers left the sport in the 1990s not because of any regulation change but because of demands of the engine makers for shorter exhausts. The Adrian Newey designed MP4-18 from 2003 had them, although in the end that car never raced.

I suggest you read Craig Scarborough’s article on them here:



Interesting point you make about the damage that the heat can do James. Could Hulkenburg’s problem have had anything to do with the design of the Williams’ new blown exhaust?

A great pity for him for it to happen in his best race so far.


Always fascinating, James, thank you for these. Are blown diffusers really worth all this effort? As they as effective as say, an F duct?

Also, are Red Bull going to fit automatic brakes, Volvo style, for Mark Webber in the next race? Or will it be an self righting mechanism of some sort?


A blown diffuser increases downforce on all corners, with the greatest effect on high-speed corners, whereas the F-Duct only helps on long straights.


Could someone explain, or point in the direction of site that does, how the blown diffuser works? It’s been implied above and in other places that it’s isn’t just a simple case of blowing the hot air over the diffuser, but something a little more complex.


It actually pumps the exhaust into the diffuser. It works like a multi-element wing, where gases (i.e. air, exhaust, etc) get sucked through in the middle of the wing, and that high-speed injection of air speeds up the air under the rest of the wing, increasing downforce. In this case, by blowing hot, high-speed exhaust into the diffuser, it helps suck air into the diffuser, thus speeding up the air under the rest of the car. Faster air = thinner air, so more downforce is achieved.

Like I said above, since the exhaust isn’t just completely dumped into the diffuser, it is less throttle sensitive (it is located upstream to minimize this effect, with possibly a small reduction in overall downforce to achieve this).


Yes. Check out Craig Scarborough’s excellent article on the subject:



James, it may be a bit crass considering Webber could have been baldy injured, but his crash gave us a rare insight into what the floor of the redbull looks like (there are some pictures of it on some f1 websites). If possible, could you do a little tech report on that (similar to the ferrari one at monaco)?

If you do could you annontate it since the ferrari underfloor tech report was a little hard to follow. Thanks!


I reckon that Webber’s crash has a significant bearing on why Schumacher is not as aggressive as he used to be. Nowadays drivers can take risks and crash with relative safety. Whereas even 10 years ago that same crash may well have been fatal. Schumacher came up in the era when most drivers would back off to avoid a possible crash, being a tough guy with a reputation, meant people got out of your way. But not any more, now everyone is equally tough and quite unlikely to be seriously injured.


so, you’re actually saying schumacher *is* as aggressive as he used to be, it’s just that everyone else is now too?

i actually disagree. i think the next generation of drivers are more fair/sporting in their racing. they know when to call it a day and cede the place, no point in trying to run your rivals off the track, it’s just not cool (unless your name is mark webber, of course).


A couple of thoughts here. Did drivers in the 50s 60s and 70s still take the risks that they did, knowing that if there was an accident it would result in death? I suspect if you look at shots of the podium from that era, the first emotion must have been – I survived that, not – I won! Safety of all concerned is the highest priority, but is the strength of the safety cell and crash protection generally creating complacency. This is a thought I have had regarding the safety of road cars – we have so many ABS and airbags and electronic controls, that we are somewhat convinced we are immortal. This is a very good thing, but isn’t the best safety protection in the car the driver?

Secondly, I noticed in Montreal that none of the drivers (esp. Kubica!) seem to have the ‘Michael Schumacher’ 7 times world champ thing in mind. He’s just another racer, and I’m going to overtake him, even if he needs to resort to the grass!


Excellent description of the new exhausts, thanks James. I’m still not quite sure how they fixed the problems they had with the original low exhausts from the 80s – was it just due to changing the direction the exhausts blow air out, or is there something else new between the exhaust and the diffuser?

Also, any idea why the blown diffuser wasn’t banned along with all the other technical advances introduced in the last two years?


The old blown diffusers had the exhaust dumped directly into the diffuser, whereas the current exhausts are upstream of the diffuser inlet. This reduces the effect of the blown diffuser, but also reduces the sensitivity to throttle position (if you lift off the throttle, the exhaust gases stop, and with the old blown diffusers, downforce would plummet).

From what I gather, the blown diffusers are really only possible with the double-diffusers, as the upper diffuser is not regulated (I could be wrong on this – James?). This allows the upper diffuser to be slotted, which allows high-speed air streams to energize the flow and further accelerate the air under the car, thus increasing downforce. Also, since these slots are possible, if you point the exhaust at them, the effect can be further increased.


Yes, blowing directly into the diffuser would make it very throttle sensitive with today’s engines so they sacrifice some efficiency (downforce) for a more predictable effect by blowing past the diffuser (or into it through a slot close to it’s exit). In the 80’s they could blow directly into the diffuser, as well as closer to the front of the diffuser to maximize the effect because everyone was running a turbo, and the time it took for the impeller to speed up and slow down as you got on and off the throttle averaged out the gas flow through the exhaust making the diffuser less sensitive to throttle position but still generating more downforce.


for perspective, it would be fascinating to see a picture of the old 80s diffuser next to a new one.


I seem to recall that the exhaust exited through the floor and into the diffuser – imagine the exhaust being horizontal along the floor, and as the floor sweeps up at the rear the exhaust feeds into it.

I remember hearing that the first time the old March team tried this solution in the late 1980’s, the drivers returned to the pits with eyes the size of saucers as they found that, every times they backed off the throttle for the corners, rear grip would disappear. The reason is that the exhaust ‘charges’ the diffusor, so when the driver backed off the throttle the diffusor worked less effictively and grip disappeared.


How about variable vane active exhaust flow for the future?


“Unless I am misunderstanding what you are saying, that sounds like it would be illegal as a moveable aerodynamic device.”

No, that’s what I meant. all right, movable aero devices are on the front wings now and will be on the rear wings next season, for the future variable everything will be with us in a very few years time.


Unless I am misunderstanding what you are saying, that sounds like it would be illegal as a moveable aerodynamic device.

Are you thinking of something that would direct the flow toward the diffuser while on throttle and cornering or braking, but direct the exhaust flow away from the diffuser on the straights to reduce form drag under the car?


I think these blown diffuses don’t blow directly into the diffuser like in the 80s (otherwise you’d get the same throttle sensitivty). Rather they blow near it to gather (or entrain) the turbulent wake of the tires and generally ‘tidy’ the airflow into the diffuser

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