Set-Up Training Ferrari 488GTE--Chapter One--Aero, Rake and Wing/ Drive Train

The first goal of this chapter is to determine how adjustments to the rear wing, chassis ride height and drive train affects the speed and handling of the car. So, we take the Ferrari to Talladega for speed testing.

http://www.formula1-dictionary.net/downforce.html

Click to article

The above link will take you to an excellent "primer" on downforce and drag.

The illustration shows a modern formula car, but the Ferrari 488GTE uses most of the same tricks. Notice that downforce is generated by more than just the front and rear wings. The body, floor, underside, and rear diffuser has a lot of effect. And, all of these are affected by the "angle of attitude" or Rake of the car--relative height of the rear being higher than the front. 

To determine the downforce produced, we first need to establish the relationship between downforce and changes in ride height. To do this, we make a simple test--check ride height empty of fuel and then full of fuel. The change in ride height can be used to estimate the rate of deflection from added weight, front and rear. This is not a perfect figure, as we do not know exactly the center of gravity of the fuel load, but it will do for our purposes:

For the relatively stiff springs we chose for the test, we determine that the deflection rate is:

Front:  870#/inch. (15.6 kg/mm)
Rear:   750#/inch  (13.4 kg/mm)

For the tests at Talladega, we used three different 6th gear ratios:

1.174    192 mph (309 kph)
1.190    189 mph (305 kph)
1.217    185 mph (298 kph)

The car is probably capable of doing well above 190 mph (309 kph) in a draft or when going downhill. I did not test it at Bathurst or Phillips Island, but 182 mph in the first long straight at Lemans was possible without a draft. At Talladega--there is no downhill so it is sheer power vs aerodynamic and mechanical drag. 

With a full fuel load, we tested a top speed of 179 mph or 289 kph (using 1.174 top gear).
This was using ZERO rear wing and minimum toe (front and rear) with static ride height of 2.243" Front and 2.760" Rear = 0.517" (13 mm) Rake

Estimated Downforce:

Front:  376 #  (171 kg)
Rear:   675 #  (307 kg)

Dynamic Rake:  ZERO  (Front and Rear Ride Height essentially the same.)

We ran the test again with minimum 1.6 gallons of fuel and changed the 6th gear ratio to 1.190. Top speed still 179 mph with engine revs a little higher. (Perhaps marginally faster than with full fuel.  Remember that Tallagega is high banked so corner and top speed is not affected much by weight.)

Next test was to see what effect a change in Rake would do to speed and downforce.  We dropped the front 2 mm (0.80") to 2.226" and RAISED the rear 2 mm (0.80") to 2.943" resulting in Rake of 0.717" (18.2 mm).  This is a 40% increase in static Rake.

Top Speed increased slightly to 180 mph (290 kph).

Estimated Downforce:

Front:  675 # (307 kg)
Rear:   947 # (430 kg)

Dynamic Rake:  0.230" ( 6 mm)

Note: Keep in mind these figures above are for ZERO rear wing! A high portion of the downforce is coming from the underside of the car and all the sophisticated body features. And, lowering the front while increasing rake made a significant difference. There is no doubt the car would have more downforce if we lowered the front more, but there is a limit of how low you can go, as the front dips significantly under braking and the car is pushed down significantly in high speed turns.  Any front ride height below 2.226" (56.5 mm) requires a test for ground clearance under braking and in high speed turns. Be especially careful when using the 1029# front springs--watch how the front wing is driven to the ground braking for the hairpin with 1029# front springs and a front ride height of 2.250".

Note: The pics above is a form of "poor man's" telemetry--I change the Z axis in the replay camera to be able to see under the car to see ride heights. 

More comment: One might wonder why not use stiffer springs and adjust the front ride height lower. Well---iRacing does not allow you to go below 2.175" on the front. So, stiffer springs (>1257#) are actuall slower since downforce will not push the front low enough. The best speed in our Talladega test was with the weakest front springs (1029#) allowed!!! (The 1029# springs were too weak for Sebring's braking zones--see above) Here is a video of our fastest run.

So, let's now test to see how much of this increased downforce was due to Rake vs lowering the front.  Keeping the front at 2.226", we dropped the rear to 2.754" so the Rake was close to our first test with 0.517" (13mm) Rake. (Actually it was 0.528" in this test.) Still running the 1.190 top gear.

Top Speed still 180 mph (290 kph)

Estimated Downforce:

Front: 527 # (240 kg)
Rear:  775 # (352 kg)

Dynamic Rake:  0.040" (1 mm) 

Note: Notice that the downforce decreased but the top speed did not increase.  As is the case in many cars in iRacing, downforce efficiency or drag increase for an increase in downforce improves with a little Rake. 

Next we checked to see what would happen if we raised the whole car 0.30" (7.5 mm) to a higher ride height, keeping the rake the same. The result was very interesting.

Top Speed decreased to 178 mph (287 kph)

Estimated Downforce:

Front: 595 # (270 kg)
Rear:  933 # (424 kg)

Dynamic Rake:  ZERO

Note: Notice that raising the car increased downforce slightly, but the efficiency dropped off dramatically--we lost top speed.

Next, the question you were anxious to ask.  What happens when I adjust the rear wing?  

We set the car with a static ride height of 2.306" Front and 2.862" Rear = 0.556" (14 mm) Rake. 

With a rear wing setting of 2, Top Speed dropped 2 mph (3 kph) to 178 mph.
Estimated Downforce:  

Front:  579 #
Rear:   976#  (about 200# increase from ZERO setting)

With a rear wing setting of 4, Top Speed dropped another 1 mph to 177 mph.
Here we dropped the top gear ratio to 1.217. 

With a rear wing setting of 5, Top Speed dropped another 1 mph to 176 mph.
Estimated Downforce:

Front:   520 #
Rear:    1076#

Dynamic Rake:  Negative 0.270" (7 mm)

Note: One can see that downforce increased the most from ZERO to 2 Rear Wing setting, adding 200# of rear downforce, and at a setting of 5, the downforce increased only another 100#.  One should also note that with the higher rear wing setting, static RAKE needs to increase. 

Well, what does all this mean?

1. Keep the car as low as possible without it hitting the ground under braking, in high speed corners, or when jumping curbs. (A good place to start is 2.226" to 2.306" Front and test from there.) 

2. The car likes a bit of Dynamic Rake. Set rear static ride height higher than the front somewhere in the 0.52" (13 mm) to 0.70" (18 mm) range, depending on spring rates and rear wing setting. Important to note--nothing in life is free--raising the rear to gain Rake and downforce will come at the cost of a higher center of gravity and a bit of tendency for the rear to "roll over" in mid corner. 

3.  Maximum speed is probably best achieved with the 1.190 Top Gear, 189 mph (305 kph) which gives a gain of 9 mph extra speed when in the draft. (1.174 Top Gear, 192 mph (309 kph) did not however cause much lost speed, so it might be best depending on preference and fuel economy.) Best horsepower is about 6500 RPM--4 green lites, the fourth one blinking.(see video)

4) Changing from ZERO to 2 Rear Wing setting will result in a loss of 1 mph if reaching 178 mph +, BUT that change resulted in an increase of 50# more downforce on the front and 200# more on the rear. One should consider the extra corner exit speed gained from this downforce in the corner entering the longest straight and balance that with the slight loss in speed for a very short part of the long straight.  Where maximum speed achieved is less than 170 mph, a setting or 2 should be considered to be minimum. Keep in mind the rear "wing" is not only pushing the car down, it is also "killing" a bit of the lift created by the shape of the body.

5) At speeds below 160 mph top speed (260 kph), a setting of 4 or 5 for the rear wing is probably ideal--choose which based on achieving desired oversteer/understeer balance in critical high speed corners as well as balanced front/rear tire temps/wear/hot pressures.

6) Keep in mind that downforce is proportional to the SQUARE of speed, so downforce increases dramatically at higher speeds---translation: A) You need more wing for tracks having lower top speed; and B) The faster you go thru the corner, the more downforce you have and the faster you CAN go thru the corner. 

7) Keep in mind that while downforce increases proportional to the SQUARE of speed, drag also increases with the SQUARE of speed. And, drag is a force, so since F=Mass times Acceleration...an increase in drag will reduce not only the top speed, but also the rate of acceleration. So you are constantly choosing a balance to achieve the best lap time---and beware that another driver may choose a different balance with a very similar lap time, but with different speeds at different places. 

Transmission Settings:

The Ferrari has 4 possible settings for the Final Drive. Most commonly used is the 2.455 ratio.  The other three being "higher" in number effectively reduce the speed in all gears.

There are three choices for 1st Gear. 2.857 provides 78.9 mph (127 kph) when using the 2.455 Final Drive.  The other choices for 1st gear would reduce speed.  My limited experience with the car indicates that you want and need first gear, and limiting top speed in 1st gear to less than 78.9 mph would be counterproductive--so  run 2.455 Final Drive and 2.857 1st Gear everywhere.

IRacing provides 21 choices for 6th gear. But given that we are going to suggest using only the 2.455 Final Drive, the lowest numerical ratio we would choose is the 1.174 (192 mph). So you only have about 10 to choose from.

My advice is to pick the 6th gear with a top speed that is 105-107% of your desired max speed on the track with no draft and no wind.  Best horsepower is about 6500 RPM--4 green lites, the fourth one blinking.

Choosing 2nd-5th is then a matter of splitting the gears to optimize three issues: A) Gearing for best corner exit speed at specific corner/s on the specific track; and B) The principal of greater speed range in the lower gears than the higher ones; and C) You want to maximize the area under the torque curve for maximum acceleration.

The principal in B) above is simple. In lower gears, you accelerate faster, so you increase speed more mph in less time. So the split between 1st and 2nd should be more mph than from 5th to 6th.  The splits should become progressively "tighter" as you go higher in gear.

You will sense when this is wrong as the car will feel "off" in some gear changes. Or, you may find yourself shifting at an inconvenient place in a corner. Adjust everything for best lap time. 

Example:  (all subject to optimizing for corner exit and drafting capacity)
1st:    78.9 mph
2nd: 103.1 mph (24.2 up)
3rd:  124.0 mph (20.9 up)
4th:  142.8 mph (18.8 up)
5th:  159.7 mph (16.9 up) 
6th:  173.5 mph (13.8 up) 

The principle in C) above is based on the fact that RPM drops when shifting up, so you want to be sure that the engine will pull throughout the range of the next higher gear without bogging down and without acceleration flattening out. 

Baseline Setup for the 2018S1 iRacing FR2.0

Baseline Setups for the iRacing FR2.0

Intro:

The most difficult part of building a setup is often “where to start”.

This article presents a “Baseline” setup, applicable to the iRacing FR2.0 version 2018S1.

The Baseline setup provides a starting point, from which the specific setup for each track and set of conditions is built by the individual driver, through a series of iterations during a testing session or a series of testing sessions.

The basic knowledge required by the driver for this process has been touched on in the previous articles presented.  A regular review of those is suggested.

Keep in mind that the setup will not make a slow driver fast.  Once the car handles reasonably with the right aero downforce, the majority of the difference in lap times achieved by different drivers is the driver inputs. 

And, my personal observation is that 20% of that is choosing the “optimum” racing line, and 70% is how the driver manages the car during the critical “deceleration” stage from the time the throttle is lifted for corner entry, thru the braking zone, to the mid-corner/apex zone where throttle is again applied. Finally, recognize that knowing what to do, and doing it are two very different things. Many drivers know what to do, but do not have the physical capability to execute.

  

So, first, I will present the “Baseline-FR2.0v2018S1”

Baseline Set Up

The file for download from Dropbox. Here is the link:

https://www.dropbox.com/s/vkbkivxkf4uvbil/Baseline0118FR2.0DWSv1.0.sto?dl=0

Discussion of the Process for Each Track (Road America Example)

As an example, we will take the Baseline set to Road America. First test will be running the Baseline at Time Trial conditions: Afternoon, No Wind, 78F, Partly Cloudy, 35% Track State.

My Time: 2:04.983 for reference using the unchanged Baseline Setup above.

It will become obvious that the car is being burdened with too much drag from too much downforce. So, the first step is to reduce the wings. 

We will start by adjusting the front wing down by 2 “clicks” from 31 to 29. Then, adjusting the rear wing down by 3 “clicks" to 11 so as to maintain close to the same 42.x % Front Downforce in the Aero Calculator provided. (While changing ride heights changes how this calculator works,  I prefer to leave the ride heights in the calculator fixed.)

Since this is clearly a relatively fast and smooth track, let’s try changing the front spring from 800# to 700#. This will drop the front end lower—especially at high speeds with downforce on the front wing. Let’s also try reducing the “rake” by lowering the rear ride height 0.40” (1mm) by adjusting both left and right rear Pushrods shorter by 4 “clicks. (On a bumpy track or a track where you run over curbs, I would leave the 800# springs alone and raise the ride height, front and rear a bit.)

My Time with 29/11 Wings: 2:04.624

Improved 0.359 seconds, but first laps with lower DF, I was actually slower. Had to get used to the lower DF.

Note: For drivers who like a really stiff car, choose the next 100# higher spring rate spring, front and rear.

While running with the lower wing and rake settings, take note of the top speed at the end of the longest straight. We are just hitting the rev limiter, so the car is not “constrained” by aero wing drag. Since it is only briefly, we will choose NOT to change the 7^th gear ratio and will keep the one with more torque/less top speed.

Now, also take notice of any handling issues you would like to “correct”.  And, review your lap in “chase” mode, setting your “Z” camera angle to view the gap between the track and the bottom of the car. Watch for sparks indicating that the car hit the track and is too low. If too low, just increase ride height as required.

I noticed that the car tended to be a bit loose (oversteer) under full throttle in T13 (Bill Mitchell Bend) and was perhaps too understeery in T1.

The understeer in T1 could be corrected by reducing rear wing one click, but that would make the problem in T13 worse. I might also change the rear ARB, but, making the ARB less stiff to correct T13, would probably make the car more understeery in other corners.

I also noticed that the car seemed a bit unstable under heavy braking approaching T5. 

Reducing the Rebound stiffness on the rear dampers 2 clicks to would slow the transfer of weight rear to front during braking and slow the transfer of weight side to side in T13, making the car less loose or oversteery. So I adjust the rear Rebound stiffness from -1.00 to -1.25 on both sides. (This reduction in rear Rebound damping often will allow better handling—but not always—there are some tracks where you do not want to slow the weight transfer and increasing the Rebound setting from -1.00 to -0.75 or -0.50, speeding up the weight transfer can be productive. This is particularly true for drivers who prefer to have the car more oversteery under braking.)  

In the third run, the car feels pretty good.  

My Time: 2:04.480 (Would have been in top ten hot laps in Time Trials 10/2017)

I then change the weather to Mostly Cloudy and make a fourth run. (I find this makes up for my slow reaction time and my time usually is on par with the fast guys running on sunnier track.) I also changed the wings settings down one click to 28/10-the same 42.x % front.

My Time: 2:03.113 (Optimal 2:02.85)  Pretty quick—fastest Time Trial Hot Lap in 10/2017 was Fredy Eugster at 2:03.297 and the David Williams Forum Demo Time was 2:03.856

https://www.youtube.com/watch?v=dGE6hSa1ZKQ&t=197s

Finally, set the Fuel level to 7.9 Gallons (30 l) and make a fifth run—this time also checking the car’s ground clearance with the chase camera.

As a final test, I will reduce the fuel back to minimum 2 Gallons and reduce wing settings to search for better lap times, and make other adjustments as required to address any new handling issues noted that I think I can improve with setup changes. Often, experimenting with damper settings can achieve some improvement.  For advanced drivers, sometimes decreasing front brake bias is productive. And, read the article about differential settings as this may be an area where driver preference comes into play--the Baseline set will have a bit of understeer on corner entry and assume the driver uses trail braking to help rotate the car to the apex.

Montreal Example

Another example. Try out the BaselineDWS Set running Montreal (Gilles Villenueve). First thing to consider is the chicanes here with the large sausage curbs. 

To make the car more "tolerant" of contact with the curbs, whether on purpose or by mistake, I softened the compression settings for the front damper from 10 to 20, and the compression settings for the rear from 10 to 15. I also reduced tire pressure from 21.5 psi to 21.0.

The car was a bit loose and oversteery in the chicanes and front tire temps were higher than rear , so I changed the wings from 31/14 to 29/15--a lot more rear downforce in proportion to front.  To make the car more "responsive" in the chicanes I increased rebound damping from -1.0 to -0.75 front and rear. 

Car felt good, but i was getting wheel spin in the slower corners so I dropped, ARB from P3 Soft to P2 Soft.

Tire temps were very balanced and the car achieved good lap times at Time Trial conditions. 

Not many changes required. I reached this result in less than 30 minutes. Then I proceeded to try all kinds of additional changes, with no improvement. 

Here is the set for download from Dropbox.

https://www.dropbox.com/s/csbzqfcvob9iita/Montreal01192018DWSv1.1.sto?dl=0

https://www.dropbox.com/s/csbzqfcvob9iita/Montreal01192018DWSv1.1.sto?dl=0

(The VRS set for the same track conditions was MUCH stiiffer, with less wing. But, it was not very tolerant for mistakes. 1 mph faster at end of long straight but the lower wing hurt times in the chicanes. )

My previous experience here is that you will see a few impressive hot laps at Montreal, but mistakes are so prevalent that actual Q and Race times are almost always much slower, so a car that is reasonably tolerant to mistakes (hitting curbs) is usually very competitive. 

On a hot track, I got good results by simply adding wing, changing to 30/17 

Conclusion

These examples are by no means exhaustive. Keep experimenting. Review the articles about the various setup parameters.

In fact, in time, you may choose to create your own “Baseline” for the starting point.

I am sure many drivers will simply respond to this article with the comment, “I already knew this stuff” or “I can do better”. Fair enough. There is no perfect setup and often there are several that achieve similar results—just differently. These articles were designed for newcomers and those with iRating below 2500. The advanced guys do already know most of this “stuff” and I am not in the top tier of drivers.  But, I will say, that in building the Baseline setup, I was actually surprised at how few changes were needed to adapt it to each track. Usually only two or three changes. 

Building setups this way is quick and fun. Sort of practice for the race. By the time you get the setup the way you want, you are hot-lapping at near your best times. 

Wings and rake can make a big difference.  A couple of tracks required a higher 7^th gear. A couple tracks liked a softer ARB.  Tinkering Front Toe Out and Rear Toe In and tinkering with dampers was often productive.  

Take notes for each track. They will be helpful for future tracks and seasons.

Keep in mind that iRacing changes the physics from time to time. Each Season you will probably need to retest your setups.

I hoped you have enjoyed the series of articles and I hope they will help many guys to be competitive and enjoy this great activity. 

Blessings,

Donald

My Brief NASCAR WINSTON CUP Career

My Favorite Race Car-1986

Competing at SCCA Runnoffs at Road Atlanta against future IndyCar driver Jimmy Vasser.

Swift DB1-This exact car won two SCCA National Championships (with other drivers after I sold it with special dampers and engine) The most wins by a DB1 in history. 

Asymmetrical Setups for the iRacing FR2.0

Asymmetrical Setups for the iRacing FR2.0

Intro:

Generally speaking, since the FR2.0 is run on road courses, the car needs to be equally agile in both right and left turns.  There are however a few courses where lap times can be improved by making the car turn better in right turns than in left turns and vice versa.

When we set up the car to turn better in one direction than the other, the setup is deemed to be called “Asymmetric” or lacking in symmetry.

The art of making a car turn in one direction better, without concern for the other direction is essentially a major part of setting up a car for oval tracks.  Note the diagram of the Lotus that won at Indy.

F1 has a recent history of some subtle use of asymmetry in applying aero. See article in link:

https://www.motorsport.com/f1/news/bite-size-tech-toro-rosso-str11-asymmetric-cooling-687756/

And, nothing will teach you more about asymmetrical setups than racing on a dirt oval with limited traction and grip. Remember that we cannot adjust front Caster on the FR 2.0, so that common adjustment used on ovals is not available. But there are many other settings to use.

On road course setups, any asymmetrical setup settings are necessarily subtle as the car still needs to turn well in the opposite direction.  While most road courses where an asymmetrical setup would be beneficial run in the clockwise direction, for the purpose of this article, I am assuming that we are trying to make the car left better than right—following the oval anti-clockwise left turn convention.  

For right hand turn preference, simply do everything on the other side. (I chose the left preference for this article to be sure that any application by the reader for the more normal right preference in road racing to be only after thorough thoughtful consideration and analysis. This a very advanced technique and should be used only after you have mastered all the other setup parameters.)

Balance

Other than driver feedback, the only analytical indication of a “balanced” race car is tire temps and wear. Below is an example of a reasonably well balanced race car where tire temps front to rear are close to equal on the right side, but the left side tires are being stressed slightly more.

Baseline

Below is a symmetric car. Note the Cross weight: 50%, the Corner weights, and the ARB Preload -0.1 to +0.1.

Spring Change

Let’s assume that we would like to make the car turn a bit better to the left because we have noticed the car is understeering a bit in left turns and the right front tire is running hotter than the right rear.  We could change the right rear spring to 900#. This would make the car rotate faster and oversteer more.

Note the ARB preload has been adjusted to 0.0. The Cross weight is now 48.8%. The total weight of the car has not changed, but the LR and RF together are no longer 50%....they are now less = 271+360 divided by 1294 = 48.8%

Essentially we have made the right rear of the car stiffer (reacts faster to weight transfer) and have increased the weight on the LF and RR by 8 pounds each or a total of 16 pounds.  We have reduced the RF and LR by the same.  

So in a left turn, the right front will have less weight, less heat and tire temp, but more importantly, the left front will have more weight and more grip while the left rear will have less—the result—the car will have less understeer in the left turn.

On Legend cars running on dirt in real life, we would have different spring rates on all four corners depending on the track. Sometimes a bigger spring on the inside rear to give the car more understeer “bite” coming off the turn—sometimes with a bigger spring on the outside rear to make the car rotate faster on throttle in mid-corner.

As shown above, one could accomplish something similar by simply adjusting the ARB preload, without changing the spring, but this is usually not recommended.  Mostly because, at least theoretically, it can cause the inside tire (LR) to lose traction.

Weight Jacking

Rather than changing springs, the most common adjustment is adjusting Pushroad length. In NASCAR, this is called adjusting “wedge”.  Indy Cars actually have an in-cockpit adjuster to perform this change. At Indianapolis, the Weight Jacker is often adjusted differently for each corner!

Adjusting wedge or Pushrod Length changes the Cross Weight. In this example to 48.3%, with 11 pounds each added to the LF and RR by increasing the RR Pushrod length by only 0.027in (0.7 mm). This is probably the most you would ever want on a road course setup. This will have a similar effect as changing the spring, but with less change in the handling immediately after throttle application.

Tire Pressure

One way to make a subtle change is to change the tire pressure, increasing the RR and LF or decreasing the LR and RF. (Increasing tire pressure is like increasing Pushrod length as it makes the tire larger in diameter.) This is essentially what people are doing when they adjust tire pressures on each corner to gain equal 160 kPa pressures, for example.

Rear Steer

Another, less common, but still effective way of making the car turn faster is to introduce “Steering” or a “rear slip acceleration” by pointing the rear tires outward in the corner- the inside tire having toe-in, the outside having toe-out. As shown for a left turn bias:

Camber

Reducing the negative camber on the inside tire will give that “axle” more relative grip. So to make the car turn better left, by decreasing understeer, simply decrease the negative camber of the inside front tire.

Sometimes, we are not seeking a change in the understeer/oversteer balance, but rather to just give the car more overall grip in one direction.  In that case we would reduce BOTH the front and rear camber on the inside of the corner we wish to improve.

Remarks

Keep in mind that on most road course, what is gained in one corner is likely to be lost in another, so generally asymmetrical settings should be limited to improving handling on “more important” corners that lead to long straights.

From personal experience, asymmetrical settings have provided benefits at Lime Rock and Silverstone for example.  Limerock is almost an right hand oval with only one left hand turn. Silverstone’s two longest straights were punctuated at the beginning and end with right hand corners that benefited with slight asymmetry--reducing the weight on the LF helped reduce understeer in these important corners.

Like all setup settings—test, experiment and test some more. (Watch for tire temperatures showing “out of balance” and push the car hard in all corners to test limits.)