Simply put, real Formula 1 finishing order is often determined more by pit strategies then actual lap times. The same applies to our sim races and I have been the lucky recipient many times.

Formula 1 cars are extremely weight sensitive. More so then any other car that I know of. Ounces make a difference. Pounds make or break your race. 1 gallon of fuel in your car is equal to 6 pounds of added weight. That additional 6 pounds equals 0.10 added to your lap time. Carrying an additional 5 gallons of fuel (roughly 18 liters) costs you a half-second per lap. Not even tire wear matches the amount of time lost to carrying a few extra gallons of fuel. This fact has to be measured and compared to the time you would lose by making an additional pit stop.

Some tracks have very short pit lanes (Monza, Montreal) with easy entrances and exits. Minimal time is lost entering/exit the pit lane at these tracks. Total loss of track time is under 20 seconds which can easily be made up at a half-second per lap over a 60 lap race (that is 30 seconds for the math impaired). Other tracks have longer pit lanes or very slow entrances/exits (Barcelona, China). They cost you more time and may not warrant additional stops.

It is not that easy though. You have to factor in what type of track it is too. Tracks that demand a lot of accelerating or low speed cornering may works better with lighter fuel loads. Longer straights will less burst-acceleration zones may prefer heavier fuel loads and allow less pit stops. This is something that you have to determine on your own in testing. There is no rule book to lay it out for you.

The pit strategy basics
1-stopper: Less time in pits but slowest lap times. Since each stop costs between 18-26 seconds you are hoping to make up positions on those that pit more often and make mistakes on the track. Great for a driver that can fend off attacks from behind. If you can keep a 2 or 3 stop driver behind you for even 10 laps, he has lost all his advantage over you. You will beat him to the checkered flag at the end of the race. This strategy is advised for those stuck in the back of the grid order. since you probably wont be able to challenge your competition in all out speed, you may want to resort to beating them with their own mistakes. All it takes is for them to make a small spin and you are in good shape. Another great use for 1 stopping is on a track that is difficult to pass (Monaco or any street course). Use those barriers to hold your competition behind you to regain the upper hand.

2-stopper: The standard F1 pit strategy with a compromise between speed and less time in pit lane. Probably the safest pit strategy in a full distance GP and very widely used in real F1. It also allows a lot of flexibility on WHEN those stops are going to take place which is extremely vital (more on that later).

3-stopper: For the all-out hot lapper that wants to put himself at the front of the grid. Being out front in an F1 car means more then you may think. The car's grip is determined by the air flowing over the wings and body. Having cars in front of you will disturb that air and prevent you from lapping as fast as you are capable of. The down-side is having to spend more time at a stand still in pit lane. However, at some tracks, that penalty is not as severe. As I explained above, you can easily gain a half-second per lap over the 2-stoppers and a full second (or more) per lap over the 1-stoppers. This time gained can make up for the time you lose in pit lane.

More advanced thoughts
WHEN is everything: "When" you stop means more then "how often" you stop. In the simplest form, two equal drivers are competing for the lead of the race. Driver-A is 1-stopping and Driver-B is also 1-stopping and both are running equal times of 1:30's with fuel onboard. As the fuel burns off, the cars will lap faster by 1-tenth of a second per gallon of fuel burned. At half-distance into the race, Driver-A pits for fuel and tires. Driver-B stays out for 2 more laps before pitting. During those two laps of overlap, Driver-A is at is heaviest (full fuel) and will be lapping at 1:30 again. Driver-B is is at his lightest (minimal fuel) and will be lapping at his "hot-lap" pace of roughly 1:27's (30 gallons burned at 0.1 second per gallon). After Driver-B pits and returns to the track he has gained 6 full seconds over Driver-A, solely based on the TIMING of the pit stops.

If you are 2-stopping and your competition is on a 1-stop strategy, consider WHEN you are going to be pitting. You know the 1-stopper will be pitting at roughly half-distance. You objective would be to be to take full advantage of his slow lap times when he is at his heaviest. To do this, you need to be at your lightest fuel load for a few laps. if he pits on lap-30, you want to be pitting by lap 35. 5 complete laps at a 3 seconds gain per lap is close to the time it takes you to make a pit stop! Also consider that during the first half of the race you will probably be lapping faster then the 1-stopper and should have pulled a gap to him before your first stop. A gap of 10 seconds is all you need to win the battle (10 sec gap + 15 sec gain from overlapped pitting = 25 sec... the time for your extra pit stop).

You may think additional laps overlap would be better, but you have to factor in the fuel that it takes to run those additional laps. Trying to go 10-12 laps beyond his half-way point pit means you have to carry that much more fuel in your fuel run, at a loss of a few tenths per lap, completely canceling out any gain you may think you had.

Pulling a gap early in a race is worth more then a light fuel load late in a race and trying to chase down your competition. Pulling a gap on your competitor kills his will to fight and he will eventually settle for his position behind you. Even if he does keep his will to fight, he is the one that has to push to keep up with you. One missed brake point is all it will take and the race is yours. Also, the later in the race, the harder it is to maintain focus and concentration... for you both. Trying to hot-lap during that time can easily turn into a race ending mistake for you. Lastly, the later in a race the less cars on track. This makes it much easier to make laps around the track without traffic getting in the way. Sounds like a plus, but that same plus works for him too, making it that much more difficult to chase down your competition.

I have adopted a fairly aggressive pit strategy during S6. For qualifying I fuel my car to a 3-stop fuel load. This allows me to qualify up front and hopefully lead the race by the end of the first lap (it's been working in most cases). Now that I am in the lead, I have 10-14 laps worth of fuel to try to pull a gap. If I can pull 1 second per lap from my main rivals, I exit the pits 10-15 seconds behind them. I also plan this first stop to be made just prior to running up on lapped traffic (which usually gets heavy about lap-12 at most tracks). While my competition is in traffic, I have a 10-second gap of clean track. I may be at my heaviest fuel load, but he can not take advantage of that due to traffic. Once he pits, I easily pass him and usually have a much larger gap then I originally had. Now he is at his heaviest and I am fairly light. Again, all I need is to pull a few more seconds gap and I have the 24 seconds needed to make another stop and STAY ahead of him after exiting the pits. My 2nd stop is where I may end up running close to a 1-stop fuel load. It is late in the race, everyone is growing tired, track is empty, and all the gaps are already set. The race is effectively won by this point and there is nothing he can do to challenge it. The race was won back in qualifying, not during the race itself. Fuel load puts me up front on the grid. Fuel load allows me to pull a gap early on. Fuel load allows me to avoid lapped traffic and maintain best lap times longer then my competition. Of course, this strategy can be countered by using other strategies... but Im not going to get into those :-)

Hope this helps guys, GLA!

This was real helpfull. Thanks Tim

Thanks for the summary Tim! Some interesting stuff in there I hadn't though of :-)

I've reworked my PitStop spreadsheet to use Tim's data for Montreal: http://rockn.shackspace.com/PitStops.xls

I think Tim's estimate is very liberal...I find the loss due to fuel a bit less than a tenth of a second...more like .08 or so, but I'm going ahead and use .1 for consistency. What I did was run some laps...came into the pits a few times...and compared the difference between lap times to see how long it took for a pit stop...I also timed the events in the pit such as how long a tire change takes (5 seconds), how long it takes for the crew to put the car up on jacks and to let it down and allow you to go (4 seconds), then added the time it takes for the fuel.

What you will see is that the total time lost for a 1 stopper is 118.6 seconds, 2 stoppers only lose 110, and 3 stoppers will lose 115.7 seconds. And, I can't stress enough that this is ONLY using the fuel data Tim has given...tire wear will be crucial and could make the 3 stop a viable option if you find your grip dropping off after lap 15 with softs and you are trying to 2 stop...you can easily make up those 5 seconds over 15 laps with a set of fresh tires.

The sheet is just for montreal, but if you change the track data on the first page it will change the calculations on the next page.

Very nice Steve.

Can I have your permission to include an adaptation of this in the Setup developer worksheet?

Certainly! You indicated that you would add tire wear and grip loss data...which would be awesome...perhaps another column for tire grip would work best.

I wanted full compatibility with the sheet, so I didn't do any macros, but a simple macro could be used for each track so that the calculations could be switched to a different track with a button click. For now it's just a matter of copying track info into that one column. Alternatively the calculation worksheet could be copied and the forumlas adjusted to the next column over for new track data, but the button thing would be a better solution...it's just that anyone opening it would have to decide whether it's safe or not.

This entire thread perfectly illustrates why F1 teams pay a guy to sit in the garage and calculate all this stuff during a race (so the driver doesn't have to).

If you're married, your wife becomes the person who plays with the calculator for you while you race.

If you're not married, but have a girlfriend, invite her over and make her the person who plays with the calculator for you while you race.

If you're not married, don't have a girlfriend, but live with your mom/dad/both, call her/him/both into your room and make her/him/both the person/persons who play with the calculator for you while you race.

If you don't meet any of these scenarios, pick up a prostitute and bring her back to your abode, paying her to be the person who plays with the calculator for you while you race.

And no, the "calculator" is not a euphenism for... something else. That would be entirely too distracting. Plus, really really disturbing if you fit the "live with your mom/dad/both" scenario.

Sam's logic: If you have an older brother who is doing A level maths and is also doing the race, get him to do both your stategies!

Is it possible to also change tyre compound during the race ?? IE.. like the 2007 F1 season, they HAD to use 1 set of each softs and hard tyres.

I have a strat i would like to test but if its not allowed to change tyre compound at first stop then I wont practice it.

No, once you set your tire compound (by going out to qual), you are stuck with that tire compound all race long too. You can put new tires on during the race, just not changing the tire compound.