| AERO TUNING FOR FORZA MOTORSPORT 3 |
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| So, if you’re not new to the world of Forza Motorsport, the ages old question lingers still as we enter the age of FM3: |
| “How much damned downforce is the right amount?" |
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| Unfortunately, this is one of those deals where the only way to find out is to experiment with different settings and observe which settings put your car in that happy place that yields the fastest lap times. |
For those of you that are noobs in the world of downforce, the basics go like this:
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| MORE DOWNFORCE |
| THE GOOD: Better cornering speeds, better grip, and ease of handling. |
THE BAD: More aerodynamic drag, slower straight line speed, and reduced suspension travel in the bump direction. As speed increases, the springs compress, and the suspension gets bogged down.
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| LESS DOWNFORCE |
| THE GOOD: More straight line speed. |
THE BAD: More aerodynamic lift, slower cornering speeds (less cornering grip), car is more difficult to handle.
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| So how much is the right amount? For the most part, an increase in drag and reduction of top end speed is a good trade off for increased cornering grip as it will usually result in faster laps. |
| Here’s a quote on the subject from a great article I read: |
| “Although drag reduces top speed somewhat, the increase in cornering speeds makes for faster lap times, so some drag is acceptable….The key is to produce just enough downforce to maximize the average speed around the track. Produce too much downforce and the increased drag will slow the car excessively, too little downforce will hurt cornering speeds. It usually takes some experimenting with wing settings and other components to find the sweet spot where performance is optimized”. |
| http://www.modified.com/tech/0610sccp_automotive_aerodynamics_part_2/index.html |
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| BALANCING OVERSTEER AND UNDERSTEER WITH AERO BITS |
| Adding the ‘Forza Front Bumper’ will add downforce, which loads the front tires, which adds front wheel grip, which reduces understeer, which makes the car turn in better and keeps it from washing out in mid-corner. |
| Technically, the Forza front aero bit is a splitter. But semantics aside, the important thing to know is that it adds grip at the front. |
| Adding the ‘Forza wing ads downforce at the rear of the car, which loads the rear tires, which adds rear grip and reduces oversteer. |
| If a car is already in good balance without the addition of aero bits, and downforce needs to be added for increased grip. Add the downforce in proportion to the front to rear weight bias as a starting point. |
| For example, on a car with a 50/50 weight distribution, obviously, if you plan to add 100 lbs of downforce to the front, you’ll also add 100 lbs to the rear. |
| In a front engine vehicle with a 60/40 split in weight. 120 lbs of downforce in the front would dictate setting 80 lbs of aero in the rear. |
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| PRODUCING DOWNFORCE WITH RIDE HEIGHT |
| Don’t forget about the ‘rake’ of your cars when tuning. We can create a low pressure area under our vehicles by adjusting our ride height. By setting our ride height lower in the front and higher in the rear we make downforce without the aid of aero bits. |
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| SHOULD I JUST MAX OUT THE DOWNFORCE? |
| I don’t have an answer to this just yet. There’s a new physics engine in place for Forza Motorsport 3, and there’s new emphasis placed on a few things that weren’t in place in FM2: |
| 1 - Hitting the bumps stops is going to be a big problem in FM3. The days of cars running super soft springs and bottoming out all over the Nurburgring are over. Supposedly the car hitting the ground is going to be a very bad thing. At high speeds with max aero, suspension travel will suffer as the car is sucked down to the ground from the aero bits. Since downforce increases with the square root of speed, ridiculously soft setups will surely bottom out the car so conversely max aero will require a stiffer set-up. But a stiffer set up may wreak havoc on our tire compliance, which might dictate that we can’t just max out the downforce for every car on every track. In any event, this time around it seems we may have to adhere to the old race tuner’s axiom of “More wing, more spring.” |
| 2 - Aerodynamic lift will be an issue in Forza 3 at higher speeds.More lift means we need to run more downforce on faster tracks, which seems to present some issues as stated above, as well as being counter intuitive to the old mentality of Forza 2, where we ran less downforce on the ‘speed tracks’ to pick up a few extra MPH on the straights. High speed lift will cause instability and murder our tire compliance in the fast corners and kink turns. The last thing we want in ‘The Kink’ at Road America is for our tires to unload on us at 190 mph. |
| In conclusion, I read another quote from an article that kind of sums up how much downforce is optimal, and unfortunately for us mere mortals that have absolutely no shot at cracking the Leader Boards any time soon, its going to come down to driver’s skill. The more skilled guys will be able to get away with less aero than the rest of us: |
| “An Indy tech told me that the difference between a competitive Indy driver and a great Indy driver was the amount of downforce that was required to get the car to handle. The better driver could live with less downforce and drive their way through the handling demands.” |
| http://jimsgarage.wordpress.com/2007/08/18/aerodynamics-downforce-ground-effects/ |