Five F1 tech talking points of 2017: Wider scope for diffuser development
Posted By:   |  04 Jan 2018   |  5:57 pm GMT  |  53 comments

Our final Formula 1 technical round-up of 2017 ends by focusing on the rear of the car, as we delve into the diffuser development across the grid.

The diffuser is an important part of the aerodynamic structure of an F1 car, which contributes a significant amount of downforce. So as part of the new ruleset, the diffuser width and height was expanded by 50mm in the FIA’s efforts to get the cars going four to five seconds per lap faster. The point at which the diffuser throat was introduced was also moved forward – ahead of the rear axle – to increase the worked volume further.

Increasing diffuser volume helps to develop a more pronounced pressure differential between the top surface of the floor and the underside of the car, providing a greater boost to rear-end downforce.

Here is a short insight into some of the ways that the 2017 grid maximised their overall diffuser performance.

Red Bull’s rakish looks

For a number of years, Red Bull Racing has pursued a very aggressive attitude to the rake angle of the car, keeping the front of the car as low to the ground as possible while keeping the rear high to maximise the volume of air under the car.

Using the front of the floor as a point to accelerate the airflow, the underfloor is then able to generate greater areas of low pressure, improving the overall downforce characteristics of the car.

Although such a design, if not implemented correctly, can result in separation of airflow attachment – and hence producing an inefficient floor – Red Bull’s honing of this concept over the past few seasons has allowed the team to run more extreme rake angles.

This is also an example of using other parts of the car to maximise floor performance, and Red Bull has also made a large amount of progress in defining its bargeboard designs to assist with sealing the floor, ensuring that the larger exposed volume under the floor is not unsettled by turbulence.

Thanks to the successes of Red Bull’s extreme rake philosophy, it has become a design feature that Mercedes has suggested will appear on next year’s car.

Ferrari and Mercedes show different philosophies

The two 2017 title protagonists Ferrari and Mercedes offered different solutions to the 2017 diffuser regulations, each seeking to find the maximum performance at the rear end of the car.

Mercedes used a squarer design, with a slot to the rear in order to combat separation in the underfloor flows as the diffuser ends. With separation, a vortical region is created which cuts the effectiveness of the diffuser, producing a drop-off in downforce.

Ferrari, on the other hand, used a more bevelled design to interact with the numerous elements around the rear axle. This offers a greater platform to clean up the rotational flows associated with the wheel movement, which can have an adverse effect on the pressure distribution around the diffuser.

In preparation for 2018, Ferrari trialled a design solution in practice for Abu Dhabi more similar to Red Bull’s diffuser design, which uses a slightly more sculpted exit – with broken up strakes on the diffuser sides – to manage the flow produced by the rear wheels.

This has also increased the volume of the diffuser, offering the potential of more rear-end downforce.

What do you think of the developments in this area? What do you think we will see in 2018? Leave your comments in the section below

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I think the current designs are half-arsed. We should have significantly more downforce from the floor and greatly simplified wings, just like next year’s Indy Cars that’ll get their downforce almost exclusively from the floor and use the wings for balancing the car. They will be able to follow much closer and create better racing.


Appreciate the explanation of nuances of airflow and downforce generation. Also appreciate the comments relating to how the FIA rules have generated serious concerns about the “racing” part of F-1 in this and engine/PU-related rules.

Given the concerns about following and passing, and particularly relating to the negative undercar pressure generated by diffusers: how much of the “dirty air” is the diffuser idea responsible for where it relates to the “racing” part of an F-1 ‘race’ ?


Re the effect of the diffuser, Garrett,— in view of the fact that only a small volume of air actually gets under the car and it’s stationary on the track, then along comes a diffuser which asks that air to expand and therefore create a depression, I doubt that would have much effect on cars following compared with the effect of the wings which deflect air upwards over a car following therefore making that car’s wings less effective.


The only small problem remained solving or say corrected in F1 racing is RACING. It won’t matter if cars produced downforce that allowed cars to run full throttle all the time or lap time are down by half a minute. There has to be competition for winning the race, not fast car following another fast car, lap after lap. I don’t mind if back field cars are off pace by a second a lap to Merc/Ferrari/RBR/Mcl unless these front field cars are racing closely with each other. Similar race in the back field would be also great. I don’t want to see Sauber humiliating Merc/Ferrari, that would be counter-intuitive But I would love them to have scrap in the midfield with TR/ Haas/ Force India. Sadly, this is not going to happen at least till 2021.


As long as there is a massive performance disparity in F1, there will be no real meaningful racing. You can manipulate things all you want and have all the overtaking you want, but there will be no actual racing.

Unless, of course you get a kick out of a much faster car blowing past another car that has a 50 bhp deficit. Personally, that to me is neither exciting, nor would I define it as racing.


Seems crazy wanting to make the cars go 4-5 secs faster! Imo that would reduce potential passing opportunities. Slow them down, I say, reduce the effects of the upper body and front and rear wings, and allow a little more development of under car aero. That way there would be less drag, so faster up the straights, slower cornering, so longer breaking areas, less wake, so closer following through corners, so better chances to slipstream and pass toward the end of the straights or under breaking, also better side-by-side duals through the twisty bits. Plus the cars would be able to slip and slide a bit more without loosing aero grip, (Cos the wings would be less effective), thereby improving the specticle for us fans!
While they’re about it, give em more fuel per race and a greater fuel flow rate, and 5 engines and gearboxes per season, and allow them to rebuild em as required, and use em again. As far as I’m concerned they can keep they can keep the turbos with the motor/generator attached, and the kinetic motor/generators, cos these allow research that might benefit us in other ways in the future/now. And no penalties if they’ve gota replace em during a meeting. Obviously if they break down ,the team is already penalised! I’m getting carried away here but how about going back to crossply tyres so they can hang em out on the corners without totally loosing grip? Phew !!!!


Let us not forget that in the good old US of A top speed is king.


F1 cars had to made faster because they are supposed to be the fastest circuit race cars and F2/GP2 cars were almost as fast. LMP1 cars were faster in some situations than F1. It’s not F1 if it’s not the fastest. The alternative, if they chose to slow down F2/GP2 then they’d have to slow down F3, then F4 and LMP1 and the nLMP2 etc. Slowing down the other categories isn’t the solution as that involves thousands of cars. Making F1 faster involves 20 cars, simple decision.

The suggestion of “less wake” and “better chances to slipstream” are oxymoronic, it’s wake (the hole in the air) that facilitates slipstreaming.

Similarly “the cars would be able to slip and slide a bit more without loosing aero grip”, it is correct that non forward motion reduces the downforce. But, keeping in mind that downforce reduces with the square of the car’s speed, if it starts off with less then it losses even more. Hence there is an even greater need for the driver to keep it straight ie; less slip and slide.

I’m no tyre technician but a number of Historic Formual cars we run in the race team have to use cross ply tyres and based on that experience I doubt that reasonable weight and compliance cross ply tyres would be able to handle the g forces in F1. Catastrophic tyre failures are not something I believe we need to see in F1.

Some of the other things you suggest are worth exploring, allowing more underbody downforce generation and reducing wing sizes could be an answer. But it would need to be tested, not just in the wind tunnel but on the track with 2 or more cars, grouped and following. That’s a lot to ask of F1 teams, expenditure wise, build multiple experimental F1 cars and go track testing, on multiple different tracks. The main reason why ground effects was banned was because of the huge accidents that followed the total loss of downforce as a result of the chassis attitude changes effect. To allow ground effects would also mean allowing active suspension to control the track to underbody interaction. Do we really want active suspension?

The increase in the fuel (flow rate and total amount) whilst a good idea, would be a huge change as it would facilitate increased engine rpm. The current generation F1 engines are designed to run at around 10,000 rpm to maximise the power and fuel efficiency. A change (increase) in that rpm would require massive changes in the engine designs. It would of course have the benefit of increasing and improving the sound, which currently is flat, dull and boring. But its so worthwhile for those multiple reasons that I believe it should be a must have for the next round of changes in 2021.


Thanks for your interesting reply, Gary, you obviously know a thing or two.
Incidently, a 6 cylinder engine will always lack the attractive musical sound that is characteristic of some other engines.
As you know recommended max rpm is increased in the rules from 15 grand to 18 I think, in the interest of improved sound, but the teams have only been using between 11 and 12,000 up till now in the interest of fuel efficiency, so they aren’t going to suddenly up the rpm unless they’re given more fuel.


@ gary…some good points there. As far as it goes, yes, let’s bring back active suspension. Why not? It is a known quantity and it is effective. Like you i am hoping that we will see some of these ludicrous impediments to performance lifted. . There is one issue that i would like to see explained. The current cars hardly ever exceed 11000RPM and Brawn has talked about an ‘extra 3000RPM’ would be implemented’ so what does this mean? Lifting the fuel flow restrictions to allow 14000RPM or 3000RPM to the current 15000RPM limit making 18000RPM the permissible high? Where would the extra fuel come from?


Gary, my understanding is that the current rpms used by teams is as a result of the characteristics of turbo charging. Whereas the raising of the fuel flow restriction would enable higher rpms, it would be pointless because they can produce all of the torque required at circa 10k rpms with the added benefit of enhanced reliability. Even if they raised the fuel flow limit, I would imagine the ICE builders would keep the rpms roughly the same. This is also an interesting point for those that equate an increase in rpms with the desirable end result of more noise. I am quite fascinated going back to the first turbo era, when NA’s ran side by side with TC cars, no-one ever (in my humble memory) ever gave a sh*t about the noise differential! Sorry, I strayed a bit of topic there..


Floors need to revert to solid flat, unbroken, un-slotted designs.
The Red Bull extreme rake was always under suspicion of unproven “bendy parts” increasing the angle of attack on the front of the flooor/plank/wing assy.
A live ground clearance laser measurement would be interesting, as we know that RB have defeated the bend tests under static load.

I have to agree with those who think a 3 PU limit per car is lunacy. Whilst it was generally felt and often voiced, that the imposition of sometmes tens of grid penalties made F1 a laughing stock and penalised the drivers directly often to ludicrous extremes, to see this now made more likely really brings into question the sanity of the regs writers.


I am all for more “bendy parts”. Flexible wings then throw out the anchors….within whats humanly tolerable considering g’s.


In the photos of the diffusers the contrast is poor and everything looks dark. Could you clean up the photos and repost them?


Mercedes’ decision on this could be the main title deciding factor for the season ahead. If they do go down this route then you’ve got to assume that due to the relative inexperience they have compared to Red Bull and Ferrari they are gonna take one or possibly two positions back. That said, they are a formidable team that could just as likely change design philosophy on the car and build a blisteringly fast car.
I suspect James Allison and team will have been busy all year on this.


I thought this waste of time, resources and money was limited to the front wing. Money better spent elsewhere. Stop the madness.


Mercedes exploring this rake philosophy and perhaps a shorter wheel base sounds rather ominous..


There must be two extremes on that. Either they add the benefits they have previously foregone to their car or the change of philosophy results in them throwing the baby out with the bathwater and they fall behind. The true effect would be somewhere between the two, although we can be confident that what they adopt will have been thoroughly researched.

I tend to assume that Red Bull’s efforts to maximise the downforce coming from underneath the car is part of the reason that they seem to be less troubled by running in dirty air than Mercedes, for example. Does anyone know if that is a reasonable conclusion?


2018 will be the year where James Allison has not started the season taking over the design of someone else. Judging from his history in grand prix car design, this might well be the end of Mercedes’ rule. Luckily for Mercedes, Aldo Costa, Geoff Willis, John Owen and Mike Elliott are still on board.


Hi Matt,

Will be interesting to see how much further Ferrari goes with this philosophy too….wouldn’t surprise me if their pitch (of rake) is even closer to RB than last season!


Bring back the double diffuser Mercedes 😉


And the livery – Simple, but with a brightness factor second only to Ricciardo’s smile 🙂


Isn’t this also what creates more turbulence behind the car, making it harder for the trailing car to get close and/or pass?

I really wish the tech regs would start stripping aero off the cars, instead of enabling even more with regs like this about the diffuser. In my opinion, the racing would be better.


A lot of turbulence is no problem, if a car is not sensitive to dirty air.
A diffuser causes a lot of turbulence, and the bigger it is, the more tubulence you get. But Mind you that if a car got more downforce from a bigger diffuser and venturi pipes under the floor and had simplified wings, the differemce between clean and dirty air would be less. Because it’s the wings and barge boards that are sensitive to tubulences and they guide the air to seal off the floor and put a lot of high energy air over the top of the diffusor.
So, if you simplified the wings and made the floor more important, the cars would create more dirty air, but also become much more resiliant to it. Teams might need to change to a lower rake setup to keep the sealing if they wouldn’t have big barge boards and complicated wings to play with, just a few small vortex generators from cutouts around the edges of the floor. But the result wouldbe better racing.
Look at the next generation Indy Cars, they have learned their lessons from the aerokit-insanity and go a big step back towards the 90s.


Thats zigactly what I thought. The whole reason that we went to the hideousness of 2009 was that single diffusers were supposed to assist in following closely due to less disruption to the airflow. Theyre going back to square one on this.
Between the stupid halo device, and the even stupider 3 engines per season rule, Im not going to tune in for all GPs next year. Spa, Monza, and Silverstone will not get missed though.


They’ve already done the stripping aero off the cars approach. The drivers are now referring to that era as the “Grandma era of F1” because they had to drive like grandmas.

Driving like grandmas due to lack of grip, while saving fuel and rationing engines is a suicidal direction for F1 to take.

Either they find a way to make passing easier without sacrificing the current levels of downforce, or leave it as is. There really is no other option.


Keep in mind that correlation does not imply causation. The tires were the reason drivers were forced to manage pace during the “Grandma” era. Pirelli made tires that couldn’t last, and would fall off a cliff rather than degrade evenly. This forced the whole “delta” lap baloney.

Also, rule makers have taken a few bits and bobs of aero away, but, you must have a different take on what “stripping away aero” means. In my opinion, it has never been adequate to fundamentally affect the balance of aero and mechanical grip, which is too tilted toward aero.

Fundamentally, they can’t keep current downforce and make passing (following) easier. It’s just not possible. The car in front gets clean air and the car in back gets dirty air. Without making the cars less reliant on clean air (i.e., reducing aero), there is no way get around that problem.


@ John marshall…that is not strictly so. A greater reliance on ground effect would help clean up the wake considerably…not totally of course.


I wouldn’t mind if they took a bit of aero off, if they got the weight of the cars down to about 550 kg. But as things currently are with these bloated, overweight hippo hybrid cars, low downforce combined with fuel and engine rationing does not make for a very exciting formula.

At the end of the day this is supposed to be the pinnacle of Motorsport and having the fastest, most challenging to drive cars is more important than some idealised overtaking quota which states that we must have an X number of overtakes per race and no less.

Also I don’t agree that high downforce automatically means impossible to overtake. There are lots of ideas that haven’t yet been properly tested, including ground effects and wing designs that produce more drag in clean air than when following another car.

The stripping off aero, in contrast, has already been tried and the results were far from earth shattering. All it’s really given us is yet another half-a**ed compromise to add all the other compromises imposed on F1 by forces that have nothing to do with F1.

My view is that fundamentally we need Formula extreme, not Formula compromise. I’m done with formula compromise.


They had to drive like Grandmas because of the comedy tyres which wouldn’t let you push. Tyres can be made to deal with lower downforce as proven by Michelin, Goodyear, etc. Maybe Pirelli can too, but they haven’t had a chance to show it in F1 yet.

Ross Brawn and his group of very clever engineers are looking at this, and now have access to a lot of CFD resource, so I’d prefer to wait for that to be completed. Hopefully a side effect will be less pointless protuberances on the cars to bring back a bit of elegance in the future.


Certainly, the tyres did play a part. But if you have little downforce you’re going to be slow around the corners and no amount of tyre grip will compensate for that. Especially when you’re driving an overweight hybrid.

Combine this cornering deficit with a modern Tilke- designed aircraft runway type track with runoffs big enough to land a commercial airliner on, throw in some fuel and engine rationing into the mix, cap it off with a thong, and you get a product that’s not fit for consumption.


The only tech talking point I want is
Get rid of this stupid 3 engine per season rule.
This is f1 not endurance racing.
The championship will be decided by grid penalties. Brilliant idea Mr todt.


I’m sure this has been suggested before but they should have a engine penalty championship.

$5 on TossaHonda (cheers kenneth 😉 )


@ Random….feel free. i have foregone any royalties simply to encourage mass appeal…hahahah


You’re a gentleman and a scholar kenneth 🙂


This is what happens when a hippie, leftist, pseudo environmental agenda infiltrates something. Suddenly everything is eight times more expensive than it needs to be, and everything has to be rationed.

I consider it lucky that we have the relatively insignificant microcosm that is F1 to act as a laboratory to show us what can happen on a much lager economic scale if this nonsense gets implemented more thoroughly. Still, a part of me is sad that a sport I once loved is ruined.


You’re the only one practising lager economics mate.


Haha well done Bilbo👍


Yeah, well done indeed because when you accuse someone of practising “lager economics” you’re automatically totally right and you no longer have construct a logical, fact-based rebuttal.


Oh come on, don’t wake him up!


I don’t have to practise anything, lager or otherwise. In the real world, which is where I live, there are four magic words that cut through all nonsense. These words are: What are the results? And the results of this hippie, leftist pseudo-environmentalist agenda is plain to see to anyone who has eyes.

Btw, why did you feel compelled to sign up for jA on F1 just to reply to me. Are you in denial, perhaps?


Just stop already..


Since you claim to live in the real world, you would know that one does not have to “sign up” to reply to a comment.


Yes, I do live in the real world. And I used “sign up” in a colloquial sense and I’m sure everyone understood what I meant.


Only in your dimension perhaps… somewhere to the foolish right perhaps 😉


@eric; it’s not my opinion. Here are the facts. Ever since this hippie, leftist pseudo- environmentslist agenda was adopted by F1 the following things have happened:

1. Everything is eight times more expensive than it was before.
2. Resources are now being rationed due to the increase in cost.
3. The gap between the “haves” and the “have nots” has increased.

This is exactly what the “lager economists” have been predicting. Coincidence? I think not.

And by the way, I’m totally apolitical and I don’t vote. I just look at the results and I evaluate the soundness of any philosophy based on the results that it produces. And this hippie pseudo-environmentalist nonsense has ruined F1.


What we understand is that you are bringing politics into this politics free zone and I dare speak for most, WE DON’T WANT IT HERE. There are plenty of forums dedicated to political and economic discussions where you will find a more receptive audience for your ideas.


@Eddie; my comments did get through moderation, did they not? So if you’re uncomfortable with discussions about politics (something from which F1 is not immune anyway) you’re welcome to either find yourself another F1 related site, or just ignore my comments.


So did mine so my comment stands. Stick to F1 around here.


Eddie, how am I supposed to discuss the detrimental ways in which F1 is being affected by political forces without mentioning politics?

Also, in case you haven’t noticed, my original comment that seems to grate you so much has received 12 pluses, which is considerably more than your objection.

I will therefore take it as an indication that your objection is without foundation and can therefore be discarded.

So stick to censoring people on your own websites, it’s not your place to do it here.


Hoping we don’t abuse Jims patience here. Sure you can talk about conditions that affect F1 but in your comment you didn’t. You used the words “hippie, leftist, pseudo environmental agenda “. What the hell does that mean other than a purely political attack. Talk about foundation for comments, explain your foundation for those five words, in a factual and erudite way mind you. As for your twelve likes there are also nine posts indicating the opposite. Posts carry more weight than likes so time to reassess the popularity of your factless catchphrase for the political forces to claim but not detail.
So enough of this you are not worth the trouble anymore.
P.S. Sorry Jim I never thought it would go this far.


“Hippie, leftist pseudo environmentalist agenda”is not a political attack, it’s merely calling a spade a spade.

If you have a problem with discussing the political forces that affect F1 then I’d suggest you stay away from this site because Jim himself very often posts content that brings the political aspects that affect F1 to the forefront.

If you were genuinely interested in a balanced discourse on all matters F1-related you would not try to censor me. I never tried to censor you, and neither did Jim, so it’s only fair if you returned the favour.


Might you mention the engine exhaust gas saga? A part of the past diffuser row was keeping the revs up during gear shifts and directing that airflow over the rear diffuser during cornering downshifts where downforce is needed most. Exhaust is not dumped out there anymore, but ?

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