Welcome to the home of Miata Tuning. Click the links below to see specific tunes.
Tuning Method: BTree Search Algorithm
The method I've used to come up with these tunes is a variant of the computer programming algorithm called the BTree Search Algorithm. In a nutshell, if you have a list of items in sorted order, you can search that list for a specific value by consecutively dividing the list and comparing the value at that location to the value you are looking for. If the value at that location is greater than your search value, you split the difference backwards. If it's less, you split the difference forward. And so on. In the worst case, you find your search value in N/2 searches.
With tuning a car, we do the same thing. But instead of searching a list, we are searching for tenths of a second on track. We begin with a baseline measurement taking the stock Miata, bolting on all the performance parts but with no tuning. This means taking a car with all the parts installed but in their default values including Comfort Soft tires. I install all the power parts, the suspension parts, the drivetrain parts, LSD, everything. Then I take the car out on a small track and do some laps. Once I have my fastest time, that becomes the baseline.
Now that we have a baseline, it's time to start experimenting. First thing we need to do is lower the center of gravity. Take the ride height and divide it in half. Then take the car out on the track. If it's faster, then it helped. If it's slower, we need to go the opposite direction. In the case that it was faster, we then split the difference between our current setting and the min setting again. Then we test again. And so on. As soon as we begin to be slower, we start moving back up until we once again hit our fastest time.
The problem here is that ride height and spring stiffness are tied to one another. So to solve this problem, we have to begin btree-ing the springs. Stiffen the springs ... then do some laps. If it needs to be stiffer, split the difference. If it needs to be softer, split the difference. At this point, there is some micro-tuning we need to do. Here is where I really learned a lot about tuning the car. As you are doing laps, keep a good eye on the tire temperatures. Ignore heating due to mistakes, but look at the tires on clean turns. If the front tires are heating up more than the rears, add some stiffness to the rear. And vice versa. Once you find the stiffness that gives the fastest lap times, hate to say it, but we're not done. It's kind of like tuning a guitar. Once you tighten one string, the other strings get a little looser. Same is true here. So the last bit is to tweak the ride height one more time. Instead of doing a btree search again, just do a small adjustment one way or the other. If it gets faster, keep it. If it gets slower, go the other direction. All the while, keep an eye on the tire temperatures and adjust as before.
Once we have ride height and springs, everything else is just micro adjustments. You can do the btree method if you like. Or you can just increment in fixed amounts and see what happens. The first thing I tried next was setting the toe back to zero. What I noticed was that the car immediately became much more unstable. It was able to rotate easier. However, every time I tried to accelerate out of a corner, the backend would swing around. I ended up putting it back to .20 and later micro adjusting it down to .16.
Next up was camber. With comfort soft tires, I knew I wouldn't have to go very far to find the optimum. I ended up with 1.5's front and back. However, I knew that I wanted to optimize the tunes for sport soft tires. So I experimented with 2's, 3's, 4's and 5's. After much experimentation, I found that 1.6 was best.
Then it was time to test the sway bars. At this point I was concerned that any extra stiffness was going to send us over the limit. But I was surprised to learn that the car got faster. So again, I tried various stiffnesses and watched the tire temperatures. I ended up going stiffer in the rear despite my desire to not do so. I wanted to leave the rear softer so that it would be more forgiving on corner exit under full power. But the tire temps don't lie.
Once the sways were set, it was time for the dampeners. Again, we're making small adjustments at this point. I added a little more stiffness to the rear again to help with the front tire heat during cornering.
The final piece of the puzzle was the LSD. I lowered the sensitivity and did a few laps. Times got worse. I raised the sensitivity and I got faster. Boom. Then I tried bumping up the acceleration and braking values. Again, I got faster. Voila.
That in a nutshell is how I come up with these tunes. Enjoy.
List of Tunes:
Mazda Miata Roadster RS (NC) '07
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