F1 technology in 2011 part 2: Diffusers and more

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In the second part of his look at technical developments in 2011, John Beamer examines the hot topic of exhaust-blown diffusers.

Also, a look at the ongoing dispute over the new engine rules for 2013.

Exhaust Blown Diffusers

Renault R31 exhaust, Valencia, 2011

After much commotion at the start of the season with Renault’s sidepod-exiting exhausts and McLaren’s infamous aborted ‘octopus’ the majority of the front-runners have now imitated Red Bull’s design.

The regulations allow slots in the outermost 50mm of the floor. Red Bull tunnel the exhaust under the floor and exits them in this ‘free’ zone, feeding the hot exhaust gasses into the diffuser.

There are two alternative designs. One is to use the starter motor hole for the same effect but the slot is small and the performance gains minimal.

The second is to simply blow the exhaust over the top of the floor, which doesn’t feed the diffuser directly but does create a region of low pressure aft of the diffuser structure reducing the pressure gradient under the floor. Mercedes has stuck with this solution.

This configuration has caused Mercedes much trouble with overheating rear tyres. In Spain the floor of the Mercedes sprouted a turning vane beside the rear tyre to channel air away from the rubber.

Hot-blown diffusers

One trend to go hand in hand with exhaust blown diffusers has been the application of special engine maps to ensure a consistent flow of exhaust gasses even when the driver is off throttle. This has been dubbed ‘hot-blowing’, but it is set to be heavily restricted after the next race in Valencia.

By retarding the ignition and igniting fuel in the exhaust when the throttle is closed, hot gasses continue to feed the diffuser, generating more downforce.

This technique has a dramatic effect on fuel consumption. Renault estimated that its engines are consuming around 10% more fuel in a race then they were last year because of the retarded ignition approach.

Teams runs two maps: one for qualifying where more fuel is burned to drive faster, more consistent flow; and one for race day which burns less fuel.

A week before the Spanish Grand Prix the FIA made the surprise announcement that off-throttle diffuser feeding was to be restricted.

The precise wording of the revised regulation is still pending but it is likely to mandate engine throttles closing to 10% of their maximum when the driver is off the gas. That is a significant change and will vastly reduce the efficacy of engine mapping.

All the front teams are effected – especially Red Bull and Renault – and a protest delayed the introduction of the ban until Silverstone. Renault in particular could suffer as the front exhaust exists are likely to suffer a larger performance drop-off under the proposed regulation changes.

Flexible bodywork

Mark Webber, Red Bull, Montreal, 2011

Another controversy from 2010 that has refused to die down is the application of flexible body work, particularly for the front wing.

Recall that Red Bull’s car seemed to magically lower its nose at high speed creating extra downforce. Despite the FIA’s attempts to tighten the regulations the RB7 sports the same advantages.

After the Malaysian Grand Prix, when it was clear that Red Bull still had an advantage, utterances from Aldo Costa (Ferrari’s technical director at the time) and Ross Brawn suggested that they believed the more stringent regulations would put an end to flexible bodywork.

They didn’t. Rather, it appears that under the static load test the RB7’s front wing flexes less than its rivals.

However the test is still flawed. In full flight the RB7’s wing flexes a little down but also appears to move backwards a little. This degree of fine tuning will take a lot of skill (not to mention expense in terms of computer software and resources).

It’s fairly straightforward to achieve this kind of bending. By altering the composition of the carbon fibre lay-up process the final, cured product will exhibit different tensile characteristics. There are many parameters at play include lay-up orientation, autoclave temperature/curing time, fibre thickness, resin constitution, and so on.

But the difficult part is controlling these variable to make a wing that behaves exactly as desired under load.

This requires deep understanding of structural mechanics as well as flow analysis – a combination of Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD) techniques.

Despite the immense computing power F1 teams throw at CFD their simulations can only provide an estimate of actual flow – throw in the need to solve FEA equations and the problem compounds. It is thought that through a venture with MSC Software that Red Bull has managed to get around some of these problems and has a very good read on the FEA-CFD interlinks.

2013 regulations

The 2013 regulations, in particular the rules, have received a lot of attention.


At the last World Motor Sport Council meeting the FIA said the controversial new engines rules could be postponed pending a vote to be taken by the end of the month.

The FIA announced in December a switch to 1.6 litre, 4 cylinder engines would take place in 2013. These would include a more powerful Kintic Energy Recovery System and turbo-charging to produce roughly the same power output as the current V8 engines do.

The hopes this might entice more car manufacturers to enter the sport appear to have been in vain so far. Volkswagen, one car manufacturer which was being targeted, instead announced it would compete in the World Rally Championship.

The only engine builder not currently active in F1 to announce plans so far is PURE, a new manufacturer led by former BAR team principal Craig Pollock.

Along with a feeling that the new rules have not had the desired affect of attracting new manufacturers, there are concerns about the cost of building engines for a new formula.

But in seems inevitable the sport will ultimately need to embrace a more modern solution that follows the car industry trend for smaller, less thirsty engines.


There will also be changes to the aerodynamic rules. Initially a proposal was put forward to simplify the front wing and allow more design freedom underneath the car as this was thought likely to improve overtaking.

However, as we’ve seen this year, altering mechanical grip (via the new Pirelli tyres) is a more effective way to encourage overtaking. Some teams were worried that removing the shackles from floor development would just create a new aero arms race just as costly as the current one.

History supports that hypothesis and as a result those plans have been scaled back. The 2013 aero regulations will be based on the 2011 rules but with tweaks to reduce the design intricacy of the front wing and to further restrict bargeboard and sidepod wing development, which the original 2009 rules did not completely eliminate.

This is a guest article by John Beamer. If you want to write a guest article for F1 Fanatic you can find all the information you need here.

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47 comments on “F1 technology in 2011 part 2: Diffusers and more”

  1. With regards to the hot blowing trick , what is clear is that the team that gets the most benefit from it will be hardest hit .Redbull saying it will not affect them more than others is just a load of bull. No one can figure out why redbull could be 1 sec faster than mclaren in quali(spanish gp) but actually become slower during the race . Silverstone will be the most anticipated gp so far .

    1. ‘perhaps the bigger and much less discussed consequence is that Red Bull’s qualifying dominance is largely down to its ability to use DRS where others can’t.

      At the recent Spanish Grand Prix, coming out of the last corner the RB7 had its wing open entering the last corner where as the McLaren, its closest challenger, waited until the car was past the corner apex’ from the previous article of john Beamer.

      1. Do you make any sense here? . If redbull’s dominance is down to some DRS trick ,how do you explain their 1 sec advantage in 2010 when there was no DRS ? .

        And how much time will redbull have gained from opening the flap before the apex of corners ? 0.5?!. Think for yourself , redbull quali advantage is all internal(engine tricks).

        1. Geordie Porker
          19th June 2011, 11:07

          I think there is a lot of sense in what Eddie has said here – first thing: comparing 2010 quali gaps to 2011 quali gaps is unfair; although the RB7 is an evolution, the MP4-26(?!) is a revolution, so the gaps cannot be compared like-for-like.
          Looking at this year, the DRS advantage for RB7 is huge and I wouldn’t be surprised to see that 0.6-0.7s of their advantage remains with the ban on hot-blowing.
          But I still agree with you that they are making huge gains with the hot-blowing, but since MP4-26 also uses it, just perhaps not as effectively, I doubt that they will lose much of their advantage through that ban.

          1. why is it so hard to educate people? Mclaren went for a DRS that they wanted ,not because they can’t design a similar version to RB’s.

            And I am not disagreeing with the fact that mclaren uses hot-blowing , the extent of its usage is what i am on about!. If you use it the most ,you will suffer the most from its ban.

          2. The reason Red Bull can open their DRS earlier is because of the hot-blown diffuser.

            Take the latter away and the former will be much reduced also.

          3. what Icthyes said

          4. As said by others here, the off throttle diffusor boosting helps them get the DRS activated earlier during Qualifying.

            So it will be a double effect for them, even though they will likely be still a bit in front.

          5. more blown diffuser = more rear downforce = earlier use of DRS

          6. @Icthyes exactly.

            No hot blown diffuser = no opening the DRS early, a double wammy for RBR.
            Of course it there might be other reasons they are so fast but it sounds like most of the qualifying advantage will be gone, although reading a interview with Horner I get the impress they have found a loop-hole.

          7. What Icthyes said is exactly what my uneducated opinion is.

            Lose hot blown, lose the early DRS advantage.

        2. Coefficient
          21st June 2011, 13:37

          There is no single component handing Red Bull the advantage. The car is a “package” with all its elements working in harmony. One reason the RB7 is able to open its DRS so early is because it generates more grip from it’s diffuser than the other cars in qualifying trim. This is partly explained by the superior design of their diffuser but is also couple with the “Quali Specific” engine map used to hot blow the diffuser off throttle.

          In qualifying, RB7 sounds as if the drivers are on the throttle on the way into bends. They aren’t it’s the engine map blowing the diffuser. This technique allows the car to maintain stronger and more consistent downforce from the diffuser at all times relative to its competitors. This means RB7 loses less grip on corner entry which means downforce builds significantly quicker once the drivers do get on the power.

          The net result is that the car produces enough downforce to vastly reduce the traction limited phase of a corner without the need for the rear wing to be fully engaged. This is why RB7 can switch its rear wing off much earlier than others in qualifying. The advantage disappears in the race because the extreme engine map required for this to work would damage the engine over a race distance.

          So, this weekend in Valencia should reveal whether I’m right or not because Charlie has banned the teams from changing engine maps between Quali and Race with immediate effect. Should be interesting.

      2. yes, but the reason they are able to use there DRS during the corner is because they have so much downforce due to the hot blowing

      3. But the last corner in Spain is surely taken on-throttle, so the proposed ban will not affect this (as it is only prohibiting off-throttle hot-blowing).
        But my impression is that RB also have an impressive occasional turn of speed in the race, if they really needed it (Vettel is always long gone after the first lap), and this doesn’t fit with DRS activation.

        1. Exactly. I have a feeling the red bull can turn on its qualifying mapping at will to increase speed as required. It is clear (especially in canada) that at restarts the car was lightning quick and then after a lap or two slowed back down to a similar pace to the other cars. Then when some one was catching, suddenly it was able to put in quick laps again. Obviously there is a limit to how much they can run this mapping as they would run out of fuel but and it does seem as if they need do go slows in some parts of the race in order to save some fuel. If the mappings are restricted then Red bull instantly loose the ability to sprint away to safety and also to qualify so easily along with not being able to use their DRS as effectively for qualifying too. If the FIA get with the modern times in their testing procedures too then Red Bull could be in a lot of trouble as their cheating front wing will also be banned.

          I do sort of dislike all this banning mid season though.

          1. One of those 2483 dials on the steering wheel must do something with engine mapping ;)

    2. RBR and Renault do have a lot to lose, but the other teams do have some benefit to lose as well. I think RBR will lose some of their advantage, but not all of it.

      1. In qualifying RBR will probably still be ahead, but in the race I expext more equal performances by them and McLaren, and possibly Ferrari.

        1. dyslexicbunny
          19th June 2011, 15:27

          I think race pace actually shouldn’t change. I don’t believe anyone is hot blowing during the race just because the fuel demands would be enormous. While you might have more downforce, you’d suffer penalties in time because of higher weight (and you’d have to pit more as we result of wear from more weight).

          Red Bull should drop off a good bit in their quali pace but still probably have a lead on the rest.

          1. They certainly ARE hot blowing during the race; you can hear the engines doing it during off throttle into corners. It’s pretty obvious from the odd pitch exhaust note, sort of like a chain saw.

          2. dyslexicbunny
            19th June 2011, 17:45

            And I thought it was only Saturdays… shows how great my memory is…

          3. Renault say they are consuming 10% more fuel, and that isn’t much to carry for 1 second per lap extra performance.
            It could be that RB are more extreme, say consuming 50% more fuel to get a bigger, 1 second advantage. It would only be worthwhile carrying the extra fuel to use that advantage for a few laps (for example trying to make the undercut).

          4. Most of the cars are using hot blowing all through the race but it seems red bull are even turning theirs up at times.

        2. I think you’re probably about right with that one.

  2. A great article, thanks John and Keith. Gave a me a further insight into all things technical.

    1. Great for me too as I don’t understand F1 technology easily.
      One thing: will Mercedes have to change its exhaust blown diffuser too, as they have a different configuration?

      1. Yes, because they also use more revs during off throttle. I even read that Mercedes and Renault will probably suffer the most of the rule change.

        Which is consistent with my own view ;-) :
        I think Red BUll will not lose so much, because the inherent downforce in their base concept is very good. It has been championship material since 2009, where they got close to the title without starting the season with a double diffuser.

        1. Not sure where you’ve read that, but most places I’ve read have said Merc have the most to gain relative to other teams in that they have the least to lose. That includes Scarbs in his analysis on last week’s episode of The Flying Lap. Renault conversely have the most to loose. Scarabs also hypothesized that Red Bull are not using the hot blowing nearly as aggressively as some other top teams according to sources he has working on dynos. No one knows for sure how this will shake out, not even the teams, and least of all a bunch of fans, so I think we’ll just have to wait and see. After Silverstone we should have a much better idea.

      2. I understand even the likes of Williams and maybe HRT will have to adjust their engine mapping, and possibly rework the diffusor to be best suited for the new situation (even though Cosworth does not work with much off throttle boosting it might be more than 10%).

        That comes from comments at Williams after the initial announcement.

  3. Nicely done as ever!

    I had forgotten about the flexi-wing, I guess the restrictions have mostly done their job and it’s not as big a performance enhancer as it was before.

    I really hope they clamp down on the front wings with a vengeance. Aren’t they ultimately responsible for about 75% of the car’s downforce, as it’s the first thing to hit the air? Maybe then we can even have the old low wings again and F1 cars will be beautiful once more.

    1. Yeah, reading these two updates I realised how much I missed them the past couple of races.

      Thanks you could find the time to get this ready John.

    2. MuzzleFlash
      19th June 2011, 13:48

      Oh how I agree with you.

      I’d like them to mandate the width of the front wings to be along the centre of the wheels and restrict them to just have one continuous plane, with much simpler end plates.

      Am I right in still thinking they use vortices generated by the end plates to ‘seal’ the floor and generate some ground effect?

  4. Mclaren stopped making any noise about flexi-wings because they got one! . A good look at the mclaren wing onboard shows it flexing , but not as much as the bulls’ .

  5. I honestly hope the FIA’s apparent quest to stop all forms of technical innovation starts to slow down. The techncal regulations are now so tight that the teams can only make a real difference in a few key areas (diffusers, front wings etc). This is why we ended up with innovations like DDD’s, F-ducts and EBD’s, which were fantastic examples of the genius of F1 engineers.

    If the FIA continue to restrict the areas the teams can develop we are going to end up with a situation were we wouldn’t be able to tell the difference between the cars if they didn’t have any aint on them!

    1. Too right GeeMac, I heard a commentator remark that an indycar damaged in qualifying would need to be re-built as it has been many times since it was built 12 YEARS AGO. Can you imagine anyone being excited about F1 if the teams were all running a 12 year old design, and all teams used the same design? This is where Bernie and Jean Todt want to take us.

      1. Agreed as well. The areas they can innovate are ever decreasing. Definitely heading in the direction of a spec series.

  6. Question: if off throttle blowing is off, what will happen to the fuel loads? Will they take less fuel on board or use more agressive engine mapping?

    I wonder where in general the trade off is between fuel load and performance. And if this is the same for eveybody?

    1. I guess they will rather do the second, as the fuel tanks are there anyhow. But maybe some teams will gamble on the first option to have lower starting weight.

      1. dyslexicbunny
        19th June 2011, 15:32

        I actually don’t think it’ll matter. I’m not convinced they’re using it during the race. Now, I would love to see parc ferme for software too so you have to have a switch somewhere to turn it off on the steering wheel.

        But I’m assuming that they qualify the car and the race day, the engineers update the software. They could just as easily have something onboard do that. I actually don’t know.

  7. Indy will have bigger engines (2.2 V6) if F1 goes to I4.

    I would go for: any cylinder configeration, no refueling, a power cap of 10,000cc, and a race fuel limit to promote efficiency.

    But we won’t get that, it will be a uniform engine spec, so I’ll keep trumpeting for V6 Turbos, an idea backed up by Mclaren team principle Martin Whitmarsh.

  8. Can u tell me who are the ones using off throttle diffusers?

    1. I think it is everyone except Sauber, Williams, Virgin and HRT.

  9. I noticed “The hopes this might entire more car manufacturers” Should be “The hope is this might entice”.

  10. I completely disagree with tires and/or DRS being a more efficient way of encouraging overtaking. The new tires and DRS are nothing but a crutch. It’s better than nothing but it still doesn’t produce the racing that being able to closely follow someone in a corner would produce. They don’t even begin to address the real problem which is obviously the loss of downforce in dirty air.

    F1 will be flawed until this problem is addressed and as far as I know, the only feasible way to address the problem while maintaining similar pace in the cars is to restrict the wings and unrestrict underbody aero.

    It will cost the teams more but it’s needed in the long run.

  11. I don’t think Red Bull will lose its ability to open DRS much earlier than others when exiting the corners. This is because drivers are on throttle when exiting the corner and deploying DRS, and only off-throttle blowing is being banned.

    Without off-throttle blowing I would expect cars to be a bit more unstable during braking and turn-in and to have less downforce on corner entry and on the apex (until the driver opens the throttle to accelerate out of the corner).

    This might result in a bit earlier braking and slower apex speeds, but the exit from corners (where Red Bull is able to open DRS very early) should be much less affected.

    Also high speed corners where Red Bull is dominant and can use DRS where others can’t are on-throttle corners, so the ban should not affect Red Bull’s DRS advantage here either.

    On the other hand, maybe Red Bull will have to make some other compromises or setup changes because of the ban and loses some of its performance advantage, but this is also applicable to the other teams using off-throttle blowing — they might lose as much as Red Bull because of the ban.

    All in all, I don’t expect Red Bull’s dominance to vane just because of the ban.

    I am not very knowledgeable in technical matters, so I might be completely wrong, of course ;-). Also note that I am not a fan of Red Bull (or any team for that matter, just a fan of F1) — this is just an attempt to make an objective assessment of the immediate consequences of this ban ;-).

    1. Good point, but what we have seen is Red Bull getting on the DRS straight away because the flow of gases is uninterrupted. With the clampdown, there will be a delay before it becomes 100% effective.

      1. I agree, there might also be some issues with balance change during the off-throttle to on-throttle transition in the corner (while the rear gains downforce), and I have no clue how destabilizing these might be.

        It will really be fun to see what comes out of this ban in Silverstone.

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