Just 1 mph faster

I think most people who read this blog would like to go just a little bit quicker around a race track. In fact, that may be your New Year’s resolution in a couple weeks. Rather than trying to make a huge leap, like 5 seconds, focus on something more realistic, like averaging 1 mph faster. How much faster is that in terms of lap times? It depends on the car and track. For example, in the Global MX-5 Cup at Laguna Seca, lap times ran about 1:40 in the ND2 Cup car. That’s a nice round number because it’s 100 seconds. Anyway, it turns out that 1 mph amounts to about 1.3 seconds.

As a complete aside, if you’re wondering how much faster the ND2 MX-5 is compared to the ND1, both models are raced in the Global MX-5 Cup (in different classes of course), and the answer is about 2 sec at Laguna Seca. That’s a pretty significant gap, but there’s a lot more gap to be found among the drivers. The top ND1 driver runs about the same speed as the middle of the pack ND2 driver. The difference between the two cars is 26 hp. It’s kind of amazing that even among very good racers, some drivers are effectively 26 hp better than others. Among HPDE drivers, the gap can be huge.

So back to that 1 mph faster. How are you going to go about averaging 1 mph faster? It turns out there are two ways.

1. Enter the corner with more speed
2. Enter the corner with more yaw

1. More Speed

For most people, more entry speed is the low lying fruit. That’s because most people brake too much and enter the corner several mph too slow. To go 1 mph faster, just enter every corner 1 mph faster and everything should sort itself out, right?

Let’s take a look at some real data from my team at a Willow Springs race a couple years back. The driver on the red trace is braking way too much, on the order of 8-10 mph in T1 and T2. That results in a lower speed all the way to the next corner and a lot of time lost. You might think the red driver is a novice, or this isn’t his fastest lap, but he isn’t a novice and this is his fastest lap.

If you’re over-braking your corner entries, as do most drivers, then there’s certainly room to enter with more speed. But how can you determine if this is the case?

• The best way is to compare your driving to someone in an identical car with identical setup and identical weather. That’s easy to do in the sim world, but hard elsewhere.
• Have a coach or local hotshoe drive your car so you can compare data between drivers.
• Compare your data to someone else driving a similar car. Perhaps you both have an GT86/FRS/BRZ.
• Compare your data to someone else in a different car. If you’re on similar tires, your entry speeds should be similar.
• Compare your data from different laps. You might find some laps you go in faster than others.

Perhaps you’ve noticed a theme here? You’re going to need some data acquisition gear and do some comparative telemetry analysis on the speed trace. Phone apps like Harry’s Lap Timer, RaceChrono, CMS Lap Timer, Track Addict, etc. work well enough. What if you can’t use a smartphone app? I’m not sure what world you’re living in where you’re worried about lap times and can’t use a phone app, but here’s my simplest advice.

• If you can get to 100% throttle immediately, without any kind of maintenance throttle mid-corner, you probably entered too slowly.

One of the reasons people enter corners too slowly is that they’ve heard the phrase “in slow, out fast” too many times. Another reason is that going faster would scare the shit out of them. In any case, one of the problems of entering slowly is that being under the limit gives you an invitation to add a lot of throttle mid-corner. Here’s a pretty common sub-optimal control input sequence that’s very common among intermediate drivers.

1. Mash brake pedal – leads to low entry speed
2. Mash throttle – leads to mid-corner understeer
3. Lift throttle – to prevent running out of room at the exit

One of the misconceptions of the intermediate driver is that they should mash the throttle mid-corner. That will get the car to rotate, right? Somewhere in their past the driver not only heard “in slow, out fast”, they also heard “loose is fast”. So they think mashing the throttle will get the car to loosen up. Spinning the rear tires isn’t the same as transferring weight to the front. Drifting greatly reduces the overall grip of the car. Transferring weight does not.

Too much speed

As you get better at optimizing your entry speed, you will eventually run into another problem: you can’t actually enter any faster. Let’s assume that 66 mph is the limit for a specific vehicle in a specific corner. What happens if you try to go 67 mph? The corner radius has to get bigger. The equation that relates speed, grip, and radius is: speed = sqrt(grip * radius). If you decide to enter a 66 mph corner at 67 mph, the radius of the corner will have to get larger to compensate because grip is a constant. In other words, you’ll fall off the track at the exit. If you don’t want that to happen, you’ll have to lift off throttle to tighten the radius and now you’ve basically done the corner backwards (in fast, out slow).

The intermediate level of driving is a mixture of too little and too much entry speed. In both cases, drivers are fighting understeer at the exit, but for different reasons. In either case, if you have to lift at the exit, you’re killing your lap time. The whole point of the typical late apex racing line is to optimize the power of the car in the second half of the corner. Lifting ruins that.

Even if you’re not lifting at the exit, you might still be in the “too much entry speed” category. Some drivers have enough discipline not to mash the throttle, so they don’t have to lift later. Instead, they spend a lot of time coasting in the mid-corner and are late on throttle. The time to add throttle is actually before the apex, but mid-corner coasters add throttle at or after the apex.

The high intermediate performance plateau

There is a very natural performance plateau associated with optimizing entry speed. Eventually you can’t go any faster and you learn the exact entry speed that maximizes every corner. If you accidentally enter 1 mph slow, you add a little extra throttle mid-corner, but not so much that you run out at the exit. If you accidentally enter 1 mph too fast, you coast a bit mid-corner, and end up a little late to throttle. This style of driving, where you modulate mid-corner speed with the throttle can be pretty fast and consistent. It isn’t actually the fastest or safest way around a track, however. Breaking out of this style of driving can be difficult, especially if you’re good at it. If you’re a racer whose been hard stuck 1-2% behind the front runners, this is probably the reason.

Brace yourselves, another tennis analogy is incoming…

One of the greatest tennis players of all time was Steffi Graf. She had a huge serve, killer forehand, tireless legs, and a consistent slice backhand. But no matter how good your slice backhand is, it is a liability against a serve-n-volley player who loves slow rising balls. In order for Steffi Graf to beat Martina Navratilova, she had to learn how to hit a topspin backhand. It’s a completely different stroke requiring changes as fundamental as how she held the racquet. Eventually she learned the stroke and the rivalry ended shortly thereafter. A similar situation existed with Ivan Lendl and John McEnroe. In case the analogy isn’t crystal clear, slice backhands are like intermediate driving. If you want to get to the advanced levels, you’ll have to learn how to rip a topspin backhand.

2. More yaw

The other way to lap 1 mph faster is to enter a corner with more yaw. There are two main advantages to this technique.

• The front wheels do less steering
• The drive wheels are pointed towards the exit sooner

Steering slows the car. The phrase “in slow, out fast” is not nearly as important as “the driver who steers less wins”. Having the drive wheels straight sooner leads to opening throttle sooner. Entering a corner with more yaw means less loss of speed and more gain of speed. It’s a win-win scenario. So why don’t more people do it?

• Yaw leads to spinning

That’s reason enough. Spinning is dangerous. It wrecks cars, injures people, and gets drivers kicked off track. Lose-lose-lose. So why bother learning how to do it? Safety, paradoxically. A driver who can deal with yaw can deal with other adverse conditions such as rain, dirt, oil, and off track excursions.

How are you supposed to learn to drive with yaw when practice may endanger people or property? Thankfully there is sim racing. Your body can learn how to drive with yaw without breaking stuff. All you need is a sim rig and the motivation to unlearn your bad habits. But wait, what about that blog post a couple weeks ago where I was giving 12 reasons not to buy a sim rig? Those reasons are good reasons. But training your muscle memory to automatically correct for oversteer? That one positive is worth a few dozen negatives.