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Discussion Starter · #1 · (Edited)
I'm making this thread as a guideline to what I feel is the proper way to dyno your Focus ST. I may have to come in and add more later, but I'll at least get it started now...

1. You should dyno the Focus ST in 4th gear. You want to dyno in a gear that is closest to 1:1 and in the Focus ST that would be 4th gear, which comes out to 1.029 referencing the info Ford has released. If you dyno in 3rd gear your output numbers will be lower. If you dyno in 5th gear, potentially, the numbers could be higher, but with the lack of real world cooling on the dyno and higher speeds mean more heatsoak so it's not a great idea.

2. Hold down the ESC button until the status bar indicates that the system is disabled. This will allow the car to perform at its fullest potential. With the ESC fully active there's a chance that you could have interference from the ECU and you don't want that on the dyno.

3. You need adequate cooling/fans. Many dyno shops have only a large fan that is good enough for a naturally aspirated car, but not enough for a turbocharged car running in 4th gear at 125 mph up top. On the Focus ST we run one dyno fan for the radiator and a separate fan for the intercooler. Two fans are a great idea since one fan is really not enough to emulate highway speeds in 4th gear.

4. At what RPM should you start your dyno runs? Let's look at the big picture. What I mean by this is don't start your dyno runs late and don't end them too early. The Focus ST has a small turbo and it makes its peak torque early because of that fact. OEMs love to do this because it makes a small engine feel like a big engine. Turbo lag is pretty much taboo for OEMs these days. To capture all of the torque at the wheels that you already feel while driving on the street you need to start your 4th gear dyno pull no later than 1900 RPMs. You want to start this early because there's going to be a delay of a few hundred RPMs before the dyno starts recording the run. Since I try to smoothly apply the accelerator pedal I start at about 1800 RPMs. If you start your dyno runs later than that you may see less torque at the wheels. I sometimes hear people and companies try to say that the Focus ST has an artificial torque spike at the early RPMs. I don't agree. If it's there, it's there. If you see it on the chart, it's not imaginary. You will also feel in on the street. Now, not everyone drives at low RPMs in higher gears. If you don't you won't feel as much of the low end grunt that you will see on the chart. If you do, then you will absolutely feel it. I happen to drive on city streets the majority of the time, keeping the RPMs low to conserve fuel since city driving really kills MPGs. I'd rather stab the throttle than downshift and the small turbo is perfect for that. DO NOT dyno the car in 5th or 6th gear. The speed and heat generated are too high for the dyno fan(s) and it's really not good for the engine. If for some crazy reason someone insisted on running the car in 5th or 6th gear you definitely DO NOT want to bog the car down in the low RPMs. I would start WOT no earlier than 2500 RPMs in 5th gear. And for 6th gear I'm not even going to make a recommendation. It's just not a good idea. And I would say to not drive the car like that on the street, either. High gear, low RPMs, and a lot of boost are a combo that can be very hard on your engine and could end up costing you big time.

5. Keep everything consistent! If you are going to post your results or comparison, take the time to record data logs along with said dyno run(s). Often times there are questions about the results. Data logging really helps to answer those questions if they do pop up. Since you will be data logging it will be easy to make sure you start your dyno runs at the same coolant temps if you are doing any kind of comparison. I typically start runs at 175 degrees Fahrenheit unless otherwise stated. This is not too cold and not too hot. This is the ideal temp considering very few dyno fans are really enough for the speeds we hit. If you want to do hot runs, that is fine. Just make note and compare hot runs to hot runs unless you are doing a hot and normal temp comparison. You can and will heatsoak the car after just 2 dyno runs during the warm months. And if you are in some hot weather as we are here in SoCal, Arizona, and Texas at literally 100 degrees Fahrenheit you will absolutely be battling with the heat.

6. Stock vs Aftermarket programming? What do people typically do for a comparison? They show up with the stock program or load the stock program and do 3 or more dyno runs. Then they take a few minutes and load up their aftermarket performance program. Takes about 4 or 5 minutes unless you are goofing around. Now, during that time the car has been off and sitting there. Perfect for you to start the car up and do your comparison, right? Not really... Even with the dyno fans on, the car will be really hot after 3 or more dyno runs in 4th gear. The car has just been heatsoaking during that time. It will take a while for it to cool off. How long that takes is really going to depend on how many runs were made and what the ambient temp is at the dyno. A good starting point would be to look at the coolant temp with your ECU flasher. I will usually put my hand on the intake manifold to see how hot it is, too.

7. Impacts of octane. One thing that is fairly well known on the Focus ST with the stock ECU is that if you use 87 octane you will have less power than you would have versus using 91, 93, or 94 octane. And if you use 91 octane you will have less power compared to using 93 or 94 octane. Ford has indicated that there will be gains with higher octanes and we know this to be true. The peak torque is about the same due to the factory programming, but the horsepower does get impacted by the octane choice. This is why some stock ECU Focus ST dynos show 240 horsepower at the wheels; they are running 93 octane. These are not freak cars as some point out, it's by design. If the fuel is high quality 93 or higher octane the horsepower will be pretty nice. In comparison, a car running CA 91 octane ( pretty much the worst 91 octane in the USA ) will show wheel horsepower that is usually in the 220 range on a stock Focus ST ECU. Again, this output is directly due to the octane level and the ECU adjusting for it.

8. Flashing while on the dyno. One thing that I've found, and Cobb has agreed, is that if you flash your ECU while on the dyno and make a pull, the first run isn't going to be as nice as it could be. When I was dyno testing in the colder months I would flash the ECU and instead of just letting the car warm up on it's own at idle I would run the car thru the gears with little or no boost in order to heat up the tires and to hopefully keep the clutch from slipping. In doing so I was inadvertently allowing the new programming to get adjusted. There was a short period of time when I felt this was a waste of time, but I quickly deduced that this was beneficial and now always get new programming settled in by doing the aforementioned after a flash. Now if you don't do this, the programming will definitely settle in, but you've wasted a run and time. And now the car will be heatsoaked a bit. So I recommend doing this whenever possible. And if it IS cold out, you will usually spin the tires so you might as well just do it.

9. Dyno type and brand are something to consider. It's a common thing for someone to post a dyno chart from a Dynocom, Dynapak, or Dyno Dynamics dyno. And the numbers are often times confusing. Even a Mustang Dyno can raise questions. Dynojet dynos are the industry standard. Like it or not, that is pretty much the case. Just about any time you post a chart from a dyno other than a Dynojet, the question pops up: What does it put down on a Dynojet? And because of this a few dyno companies actually have a "Dynojet" setting to help them with these questions. Superflow might have this, but I can't quite recall right now. Many dynos rely heavily on operator input whereas an inertia Dynojet does not. And this is why we use an inertia Dynojet dyno here at Mountune; less opportunity for user error. Occasionally, dynos do not load the car correctly. So you will not see the same type of boost on the dyno as you would on the street. If the dyno operator is not aware of this, this can be a problem and the numbers are going to be off. We don't have this issue with an inertia Dynojet with the Focus ST. If this is a known issue for a shop with a Mustang Dyno, for example, they can try to correct the issue by changing some of the data they input into the system as they set up the dyno for runs. It's just not an ideal situation.

10. Using the dyno to compare hard parts and their gains. This is what most people use the dyno for. The only problem is that in many cases comparisons are made days, weeks, or months apart from the baseline dyno. Any time you deviate from a proper comparison made on the same day, same car, same dyno, same tank of gas, same conditions... the science goes right out the window. Whatever results you come up with are not something that is considered scientific or very accurate. For most consumers doing this correctly is not practical. The costs involved and time usually keep this from happening. So when you see a comparison dyno chart look at the dates and any notes that there taken to hopefully see the full scope of the comparison.
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