ACC Blog Post - Lamborghini Hurucan GT3.jpg

Kunos physics guru @Aristotelis has published another very interesting Assetto Corsa Competizione blog recently, talking in depth about the lovely Lamborghini Huracán GT3 in ACC...

Assetto Corsa Competizione initially released with just one car and one track as it began the journey into Steam Early Access, and over the following months Kunos have continued to methodically work to develop, improve and enhance the title and add yet more new content from the 2018 Blancpain GT Sprint Series championship.

With the shiny attraction of new cars and tracks, one could easily be forgiven for somewhat forgetting the original Lamborghini Huracan GT3 post build release two, and this is something that the main behind much of the physics work at Kunos is keen to remind us all about, posting up a new and as usual very interesting blog post on what was the very first car to appear in Assetto Corsa Competizione...

From the blog post by Aris:

The 2017 champion car, arrives in the 2018 season in an almost identical form. The Huracan GT3, proved in the 2017 season, to be the car to beat in terms of absolute performance. Nevertheless this top level performance was the result of a very professional team with very talented and fast pro drivers that especially on some tracks were able to destroy the competition. The result of this was a very severe Balance of Performance handicap for all the Huracan cars, that heavily penalised the champion team but most importantly all the other teams using the car, further down in the grid and classification.

Objectively the Huracan GT3 is a very capable car, but at the same time it has some very unique and distinct characteristics that often make it difficult to handle for less experienced teams and drivers.

The car is very compact resulting in a very small frontal area and thus very low drag figures. Top speed is almost everywhere amongst the highest achieving cars, often topping the results. The downforce production is also very high, maybe not on par with Ferrari, Audi and Mercedes, but not that far either. The resulting efficiency is top of the class confirming the qualities of the Lamborghini aerodynamic design aided by the famous Dallara engineering. The compactness of the car dimensions, result on a very small under tray area that is quite pitch sensitive. At high speeds the car will become quite unstable under coasting or even worse, braking. As an example the very fast right bend after the long back straight at Paul Ricard has gave me some of the most violent slap tanks in my whole real and simulate driving life. Brake a bit too hard and a bit too late from 280kmh top speed and try to turn in and I can guarantee you, you’re going to change your mind very fast and thank Paul Ricard circuit designers for implementing those very wide runaway areas with blue and red lines that give even higher grip than normal asphalt (at the exchange of massive chunks of tyre tread flying around…). Small amount of ride height change at the front or rear, will move the aero balance quite a bit back and forth. To counteract this, the suspension setup must be adequate to aid the stability under such conditions, with high front stiffness and good damping work in front bump and rear rebound, more similar to a single seater setup, than a more conservative GT racer. The stiff setup will usually make the car jolt and jump around over kerbs and bumps, but surprisingly enough it will stay quite stable if the driver is precise and remains on power.

The mechanical balance of the car is also particular. The road car has an AWD setup that adds weight to the front axis from the axles and differentials. The GT3 car, by rules, has to be RWD and so the elimination of all the AWD mechanical parts, results in a very rear weight bias. As a matter of fact, the Huracan starts with about 60% of its weight at the rear tyres making it practically a very rear heavy car, similar the Porsche 911 that, let me remind you, is rear engined! A car with such weight bias, would need a staggered tyre setup. This means that the rear tyres should be wider than the front, to handle better the different loads.

Unfortunately the tyres offered by the rules, have very similar dimensions for both front and rear which means the mechanical grip is a bit unbalanced with more tyre at the front, than what the car needs.

To the uninitiated, this might sound like a non issue. The car seems to understeer constantly, so more tyre to the front, can only fix the things right? Why does it make it worse then? To have balanced handling characteristics you need to have a predictable rear grip, so that you can shift the weight with your driving inputs and you get back predictable feedback and reactions. If you have more rear grip than front, then you can use the power on the exit of the turns to rotate the car and it will do so gradually, because even if you lose some lateral grip, you still have plenty to handle. But if you have more grip at the front, the moment you get power understeer (and you’ll get it because of the weight bias to the rear), then trying to power oversteer will subtract important amounts of grip from the rear and it will make it skittish and nervous. On top of that, add a quite sensitive aerodynamic platform that we described above, that moves the aero balance heavily to the front and to the rear every time the pitch of the cars changes by mere millimetres and you get a more clear view of why the car requires skills and respect from its driver.

Sounds like a difficult car to handle and it is when you try to push it hard on the limit. Setup must be balanced and on the stiff side, especially at the front. Don’t try to overcome the power understeer with a more oversteer setup, because you’ll end up with a nervous turn in that will make the car slower. Embrace a hint of understeer, be more precise in your inputs and driving line and learn to take advantage of the aero platform and mid turn speed. You can brake late, start to turn in, but get off the brakes as soon as possible and let the car coast to the apex or with a very very slight brake input, anything more and it will understeer at turn in too. Learn to do the coasting part properly and you’ll be surprised by how much speed you can carry inside the turn, which will be translated in time gains outside of the turn. This is taking advantage of the aero platform, leaving the car as flat as possible instead of forcing it to turn by braking and pitching. The results might surprise you.

If properly setup and driven, the Huracan GT3 showcases a very fast turn in and high mid turn speeds. Exceptional traction and agility makes it perfect for slow narrow turns and chicanes. There’s always an understeery behaviour on power at the exit of the turns and generally the car doesn’t like to change its line once in the turn. Precise driving and proper racing techniques are required to make the car deliver, but even thought it might not feel “fun” and requires lots of self control, concentration and commitment, it is capable of blazingly fast laptimes that reward all the hard work.
Assetto Corsa Competizione is available on Steam Early Access now. Currently at build release 3 status.

To keep abreast of all the latest news and discussions from the world of Assetto Corsa Competizione then don't forget to check out our very own ACC sub forum here at RaceDepartment.


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RaceDepartment Editor-in-Chief, occasional YouTuber, commentator and broadcaster, with a passion for motorsport on both the real and virtual racetrack.

vittau

25RPM
May 1, 2017
34
18
32
Nice writeup, I didn't get one thing though: if the car has so much front grip, why is it susceptible to brake understeer on corner entry?
In fact, what I noticed in the game is that sometimes it will snap oversteer on corner entry if I brake too hard while turning in, which makes sense to me since it has low grip in the rear and you steal even more by braking (which shifts weight to the front).
 
Apr 12, 2015
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It doesn't have that much front end grip. Even though it's a rear heavy car and has relatively wide front tyres, it needs to be set up for understeer, otherwise you'll lose the back end all the time. And also, every car will snap oversteer if you brake too hard on entry.
 
Apr 12, 2015
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The car is rear heavy and has relatively wide front tyres, which makes it inherently prone to oversteer. Because of that, they need to set the suspension up in a way that it actually understeers, otherwise it would have an unpredictable and unstable behavior. Aris even mentions in the text that you shouldn't try to dial out the understeer, because there's a big chance you'll actually lose laptime in doing so.
 

anton_Chez

2000RPM
Premium
Jun 1, 2016
2,183
886
38
Awesome insight from Aris, really helps a noob like me understand the car from a technical standpoint rather that just pointing and shooting. I look forward to diving into more tech info to further help my understanding of how to improve my driving and racing.
 

BP

1000RPM
Premium
Nov 1, 2016
1,391
1,474
I learned so much from that write-up; that exact scenario he described at Paul Ricard has had me fighting with the car for awhile now (granted I'm not very experienced with making good setups)...the "safe" preset is already too loose on that high speed right turn, so the aggressive preset is suicide if you're trying to be fast...it's nice to finally understand how to balance the car out. I'm faster than the AI in most areas, but that one corner I always lose precious time on. Thanks Aris (and Paul for the article)! Looking forward to more info like this on hopefully all the cars.
 
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Xela1

500RPM
Mar 24, 2015
586
441
Is there a feedback of driving this beast of Lambo in ACC/AC from Bortolotti, Englhart or Mapelli? Like Mr. Seyfarth did it on AMG GT3. Idk why Aris talking in such a know-it-all manner?
 

Ricoow

Assetto Corsa Competizione Club Staff
Staff
Premium
Nov 13, 2010
5,486
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Is there a feedback of driving this beast of Lambo in ACC/AC from Bortolotti, Englhart or Mapelli? Like Mr. Seyfarth did it on AMG GT3. Idk why Aris talking in such a know-it-all manner?
Aris has so much track time under his belt in real life as well ;) He knows what he is doing.
 

E304LIFE

100RPM
Aug 28, 2018
199
144
He's been around Lambo's plenty. Given his locations, access, along with experience,...I think I'll take Aris' opinion for now.
 
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Butzemann

... Quick but without hastiness ...
Oct 21, 2011
122
61
Many thanks for the insights ... the lambo seems to be a beast, look how the driver is fighting ...


Motec displays seems to be inactive ...
 
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