Pointing fingers

This incident happened at the AER race last weekend at Watkins Glen.

The Facebook thread about this is long and entertaining with people taking both sides. Some think that the POV car did nothing wrong: it stayed on line and got punted by the Miata. Others says that the POV car turned in on the slower car. Who is at fault? Let’s take a look at the AER passing rules to see if they shed some light on the situation. Red text is me making editorial comments.

  • 9. Passing
  • 9.1. Every competitor has the right to racing room, which is defined as sufficient space on the paved racing surface that under race conditions a driver can maintain control of his car in close quarters. There was plenty of track on both sides of both cars. Neither car was forced into this situation.
  • 9.2. The car entirely in front has the right to choose any position on track, so long as it is not considered to be blocking. Blocking is defined when a driver makes two or more line changes in an attempt to prevent the trailing car from passing. The slower car was not blocking. One key word here is entirely. The only car that was entirely in front at any point was the slower car.
  • 9.3. A driver who does not use his mirrors or appears to be blocking another car attempting to pass may be black flagged, and may be penalized. The slower driver certainly didn’t appear to be using his mirrors. If he had, he might have signaled a pass or moved over a bit when the POV car went outside.
  • 9.4. Ultimately, the decision to make a pass and do so safely solely rests with the overtaking car. The car being overtaken should be situationally aware of the fact that they are being overtaken, and not make any sudden or unpredictable moves or blocks to impede the ability of the overtaking driver to pass. The slower car didn’t make any sudden or unpredictable moves to impede the other driver. He drove a very predictable line. The responsibility to make a safe pass rests very much on the POV car.
  • 9.5. When possible and when it becomes apparent that a pass is going to occur, it is a courtesy and strongly suggested that the car being passed to indicate to the passing car on which side they would like to be passed on. Sadly, never happened.
  • 9.6. Cars who are not racing in the same class are strongly encouraged to work with each other to effectuate a prompt and safe pass. Drivers should be aware that they may come upon a situation where two other cars are in a heated battle in their respective class and should try to accommodate any passing required without holding up that battle. It should be noted that this applies to classes faster and slower than you. There was no attempt on either cars part to work with the other. 

Rules shmules. You know what matters more? That two cars ended up crashing, creating a waste of time and money for themselves and all their competitors. If you get tangled up with a much slower/faster car because you can’t figure out how to give each other enough racing room, it’s your fucking fault. If you hit a patch of oil, dude that’s on you. If the other guy hits a patch of oil and smashes into you, sorry, but it’s still your fault.

If lightning strikes the car while you’re in the car it’s your fault. — Doc Bundy

In a race with large speed differentials and driver experience, everyone has to be extra careful. AER cars have huge speed differentials. These two cars in question were lapping 20 seconds apart! AER doesn’t require that much experience to race with them. Some drivers may be professionals, others may be relatively new to the sport. The POV driver is a very experienced racer. But apparently he’s not used to dealing with large differences in speed and ability. As he drove up to the inner loop and saw the slowpoke Miata take a very cautious line, he should have been thinking “this dude is way off pace and may do something unexpected. I had better leave him a lot of room.” Instead, he drove inches away, even though there was a huge amount of track on either side.

In life, sometimes you go looking for trouble. Other times trouble comes looking for you. When that happens, you’ve got a split second to choose your role: hero, villain, or innocent bystander. Being a hero isn’t easy. Making other peoples’ safety part of your responsibility is a pain. It would be a lot easier to take out Doctor Octopus without having to protect Aunt May at the same time. But that’s what heroes do. Villains would try to use Aunt May to improve their chance of winning (which makes most racers villains). And innocent bystanders? Oh, screw them. Anyone not part of the solution is part of the problem.

OK, I’ve gone off track. Here’s the tl;dr. Slow, insecure driver appeared to be unaware of fast driver. Fast driver should have seen those signs and driven accordingly. I lay fault at 40/60 slow/fast.

With great power comes great responsibility — Peter Parker


The 10 cent diamond

Overtaking another car is a great feeling. Passing 5 cars in one lap makes you feel like a driving ace. Passing 5 in one corner is a sign that something is out of the ordinary. Is there a yellow flag you haven’t seen? Is there something dangerous afoot? Is your car/driving just that much better than everyone else? If someone sells you a diamond for 10 cents, it’s probably not worth a dime. And if you just passed 5 cars, it’s might not be on your merits.

Watch below as the unfortunate driver learns a hard lesson about stomping on the throttle on a cold, damp track. Around here, we call such power-oversteer crashes Karma Supra. Video #2 is the rear view.

This YouTuber’s channel features some more entertaining moments (below). From watching their normal race videos, the team appears to have decent drivers and a well-sorted car (which sounds amazing). Sadly, shit happens all the time. Well, if it looks like shit and smells like shit, really, you don’t have to taste it before deciding whether or not to step in it. So be on the lookout for 10 cent diamonds and dog shit. They’re everywhere.

Revisited: … divided we fall

I love quotes. They free you from original thinking. They also make whatever you say seem more important. That’s paraphrasing a couple famous quotes. The following post is one of my all time favorites. Not just because it starts and ends with two great quotes and but also because it crystalizes my philosophy of endurance racing: race with others, not against them.

Heraclitus: “Out of every one hundred men, ten shouldn’t even be there, eighty are just targets, nine are the real fighters, and we are lucky to have them, for they make the battle. Ah, but the one, one is a warrior, and he will bring the others back.”

I think you could make the same observation about a typical amateur race. Some of the cars on track shouldn’t even be there. Most of the cars are just getting in and out of each others way. A precious few cars are actually racing. Like a battle, racing is dangerous and people/cars could get hurt or even killed. The difference, and it’s a huge difference, is that everyone in the race paid money to have fun.

In the aftermath of the accident above, you will find many opinions. Some would say that the Spitfire that got rammed had no business being on track. Some would say the fault lies with the faster car because they can choose to pass elsewhere. Some just shout “noobs check your mirrors” because they learned somewhere that rudeness is an effective form of teaching and communication (it isn’t). Some would blame the entire racing series that allows such a wide range of cars and drivers on track.

Instead of laying blame, let’s try to solve the problem proactively with the simple realization that we’re all in this together. Driving racecars is a privilege. It’s a wasteful and irresponsible activity that brings huge smiles to our faces when everything goes right. Next time you’re on track and you see something dangerous brewing (which happens every time cars are near each other), imagine the person in the other car is your spouse, child, relative, or friend. Would you pass them more safely? Would you allow them to pass you more safely? Would you make sure they are also having a good time?

There is no big prize waiting at the finish line. There is no contract with NASCAR or Formula 1 in your future. There is no point in driving angry. Instead, drive under the platinum rule. No, not the Golden Rule, for that rule is self-centered. “Do unto others as you would want done to you” assumes the other person has the same value system as you. They may have entered the race for completely different reasons than you. If they’re driving a non-competitive car, you can be sure that the reason wasn’t trying to win. The Platinum Rule is “do unto others as they would want have done to them”. This is difficult because it takes effort for you to imagine how they want to be treated. Instead of driving as if the other cars are opponents in battle, drive as if they are kin and you are training together.

In the words of Ian Maclaren (or maybe Plato): “Be kind, for everyone you meet is fighting a hard battle”. And if you are one of Heraclitus’ warriors, thank you for bringing the others back.

Revisited: The four temperaments

Going back in time again to revisit some of my favorite posts. This one is near the top of the list. Why? Partly it’s because I love personality tests. I’ve got one in development especially designed for racers that I’ll drop here one day. And partly it’s the subject matter. Lots of drivers misunderstand the brake pedal. To me, it’s the most important part of the car. For such a simple device, there are a lot of subtleties in its application. But in the end there are really only two sides to braking: early and late. The same is true of leaving a sinking ship. You can leave too early or too late.

Most crashes in amateur racing are the result of late braking. If the car is going straight, it tends to plow into the vehicle ahead. If it’s in a turn, you get an oversteer spin that collects vehicles behind. The best way to avoid these situations is to brake earlier. Unfortunately, many drivers have the misconception that the easiest way to go faster is to brake later and harder. Late braking is actually the easiest way to get in an accident.

In my day job, I’m a professor, so one of the important parts of my job is teaching. Students have different ways of learning. Some are comfortable with abstractions while some aren’t even comfortable with the word abstractions. Some are auditory learners while others like to experience things through touch. The best teachers figure out what kind of student they have and instruct in the learning style of the student (this is made difficult in a lecture class of 180 students but that’s a topic for another day and another blog).

There are a variety of ways to describe personality types and learning styles. Two of the most popular are Meyers-Briggs and OCEAN (big 5). These are a bit too complicated to go into in a simple blog post, so I’m going to recommend the Temperament Sorter, which sorts people into only 4 categories: Guardian, Rational, Idealist, Artist: The category depends on 2 scales: concreteness vs. abstractness and utilitarian vs. cooperative.

Here’s a description of the 4 temperaments from the website.

  • As Concrete Cooperators, Guardians speak mostly of their duties and responsibilities, of what they can keep an eye on and take good care of, and they’re careful to obey the laws, follow the rules, and respect the rights of others.
  • As Abstract Cooperators, Idealists speak mostly of what they hope for and imagine might be possible for people, and they want to act in good conscience, always trying to reach their goals without compromising their personal code of ethics.
  • As Concrete Utilitarians, Artisans speak mostly about what they see right in front of them, about what they can get their hands on, and they will do whatever works, whatever gives them a quick, effective payoff, even if they have to bend the rules.
  • As Abstract Utilitarians, Rationals speak mostly of what new problems intrigue them and what new solutions they envision, and always pragmatic, they act as efficiently as possible to achieve their objectives, ignoring arbitrary rules and conventions if need be.

For Harry Potter fans, you might recognize these as Hufflepuff, Gryffindor, Slytherin, and Ravenclaw. More classically, they are Earth, Fire, Water, and Air. Classifying people into one of four categories may bring peace of mind to some and horror to others. Regardless, everyone has each of these characteristics in them to varying degrees.

Back to the topic of late braking, here are four ways of saying “brake earlier”.

Guardian/Hufflepuff/Earth: Late braking is unsafe. Since every racing series has rules against unsafe driving, you are violating the rules by braking late. To prevent late braking, remember these two rules: (1) always brake 1 marker earlier than you think you need to (2) always leave at least 1 car of room in front of you. By following these two simple rules, you will make the track safer for yourself and everyone around you. Your safety record will be something you look back on with pride.

Idealist/Gryffindor/Fire: Racing is really dangerous. It’s our responsibility to make it safer, and to lead by example. Due to varying track conditions, car performance, and driver experience, it’s necessary to give everyone a little extra room for safety’s sake. While it may make your car slower than optimal, it’s a small price to pay for safety (not to mention sanity). Others may take advantage of the extra room you give them, but it will only hurt them in the long run.

Artisan/Slytherin/Water: A friend of mine lost traction because his brakes overheated and he T-boned another driver. Later, in the paddock, that driver tracked down my friend and threatened to beat him up or sue him if he didn’t pay for damages. I would have kicked that dude’s ass, but my friend became a chickenshit and stopped racing. I’m braking a little earlier these days because it’s helps me optimize my corner entry speed and actually go faster.

Rational/Ravenclaw/Air: Getting a black flag in an endurance race can easily cost you 3 laps as you sit in the penalty box. You can’t make up that loss by driving faster. Paradoxically, driving 0.5% off pace is faster on average because you minimize high risk driving. I can show you the calculations if you’re interested.

Dropping 20 seconds in a day

Last week the student I was coaching at Thunderhill dropped 20 seconds off his personal best in one day. I thought it would be fun to investigate how that happened from the perspective of the coach and the student. The statements in blue are from the student.

The student had some previous autocross experience and had been to a Thunderhill track day once before. So he wasn’t a complete novice. The car was more commuter than track weapon. It was quite comfy with heated seats, adjustable bolsters, and nearly silent exhaust. Here’s his description.

2009 E90 328i 6 speed manual with sport package. No modifications except stainless steel brake lines installed by previous owner. Street brake pads and PSS tires (the tires help me to drop 5 seconds). I replaced engine mounts before 2nd track day. (use OEM mounts).

At the start of the day, I asked him what he felt he was good at and what he needed work on. He said his driving line was pretty good but that he should shift to 4th gear sometimes. As it turns out with rookies, perspectives can be misaligned. His driving line wasn’t very good and there was nothing wrong with not using 4th gear. We kept up with the fastest cars in our group using 3rd gear only. But we’re getting ahead of ourselves here…

Once we got in the car and took a few laps, I could see that, in fact, he does not shift. There are two places on the track where one can downshift to 2nd and three or four where one could get to 4th gear. I made no attempt to fix this. Driving is difficult enough without shifting. I wish all my students would drive 3rd gear only. Less power in corners means you have to learn to drive a momentum line. And less speed on the straights is less wear on the car. I’d also much rather top out at 90 mph than 120 mph in a car I’m not driving. Another thing that didn’t need fixing was his hand positions. He anchored them at 9 and 3 and I never saw them come off. Excellent. I did remind him a few times to relax his grip a little. Thankfully, the most important thing, situational awareness, also needed no fixing. He knew where the cars were around him at all times.

So what did need fixing?

  • Braking was early, excessive, and abrupt
  • Lack of confidence in grip
  • Driving line was circular

The first thing we worked on was trail-braking. What? Isn’t that an advanced driving skill? What am I doing teaching this first? What about the line? FUCK THE LINE. The most important thing you can learn about track driving is how to apply the brake. Hard on, soft off. No, we didn’t work on rotating the car with the brakes. We simply changed the brake pattern from hard on, snap off, to hard on, soft off. This is how one creates smoothness on corner entry, and it’s the foundation for rotating the car with trail-braking (later).

The next thing we worked on was speed sensing. The reason he was braking so hard was that he had no idea how fast one could go into the corner. Self-preservation instincts aren’t bad you know. They keep you safe. But they can also get in your way. One reason to get coaching is to lean on the coach’s experience to increase your limits. He just needed someone to let him know it was safe. The drill we did may seem unusual. I told him he wasn’t allowed to use the brakes at all. He had to plan the corner far enough in advance so that he arrived there with the right speed. Without the brake pedal getting in the way, he drove the entries much faster. With each corner he gained confidence and was eventually going into T2 (a long carousel) at high speed with just a lift, letting his tires scrub off the excess speed.

Lots of people unknowingly drive a circular arc. How can you tell? If the wheel stays at the same position throughout the corner, it’s circular. Some corners can be done that way, but most benefit from a late apex line where the radius of the first half of the corner is much tighter than the second half. And by the way, the halfway point isn’t the apex. The apex is in the second half of the corner. I call the halfway point the nadir. Ross Bentley calls it the EOB (end of braking). In any case, the point where you start to increase the radius is before the apex.

We spent most of the day working on corner entries. As a result, my student’s entry and mid-corner speeds were so much higher than the others in the group that we kept up or passed many faster cars (M2, M3, M4, 911, Lambo) despite not shifting gears. Nobody went faster in T2 despite having stickier tires and aero. And I guaranty our T8 speed was 10 mph faster than anyone else. After the event I emailed the student to find out how he dropped 20 seconds. Blue text is him. Red text is additional editorial comments.

Q: What was the most challenging thing? Physically became tired after 6 sessions. All that sensory input is exhausting. But you get used to it and driving becomes less taxing.

Q: What was the scariest thing? Saw someone rolled his car on track. This was in the last session of the day. Wisely, my student said he wanted to have a less intense final session.

Q: Was there an ‘aha’ moment or was it very gradual? I think it was very gradual for me. Ian is a good instructor who can explain things clearly. Communication is a 2-way street, and not every student-coach pairing is ideal. We were both mathematically inclined, so we communicated like engineers.

Q: Where do you feel you made the most improvements? On to throttle earlier and understeering out of turns. To get on throttle earlier is not so simple. He had to change his whole approach to cornering to make that happen. his use of understeering isn’t quite right. What he’s doing is adding throttle at the traction limit. This means the radius of the turn increases to compensate. It’s a very mild form of understeer.

Q: What would you tell someone who was going to the track for the first or second time? You may not need to drive a powerful car on to the track at the beginning. A well maintained car can give you as much fun as a Lambo or M3. 

Here are a few things that I learned from Ian:

  1. No braking approach. At second run session, Ian asked me to run a lap without braking.or minimum braking. It helps me a lot but how? I don’t know how to describe it.
  2. My line late apex, early apex, circle arc line. It turned out that some of my lines are just pure circle arc line. My steering input stays same through out my turn.
  3. Gas out approach/understeering. I finally realized that how to use throttle to exit a turn. I will try to use this approach at my next autocross event. I alway thought that understeering is NO good until my 2nd track day.
  4. Learn road/surface condition. It applies to rally racing a lot. At T3, T5, T9, pay attentions to elevation change and bank angle.

Here are a few turn-specific notes he made, some of which are pretty perceptive.

  • During my first track day, I wasn’t sure how fast I could enter T1. To be on safe side, I always braked too early during my first track day. I thought my line was fine but during my second track day, I have learned that my line was actually a smooth circle instead of late apex. At the very last session of my second track day, I began to realize that I could accelerate a lot earlier or during my T1 entry point. In this way, with lots of throttle, my 328i could naturally move to right side of the T1 exit. (using natural understeering)
  • T2 is relatively straightforward. I became more comfortable at higher speed to go around T2 at my second track day. In the afternoon session, I started to appreciate the power out approach to exit the turn. Again, using natural understeering of the car. From the entry point to the half of the turn, I gradually added more throttle to almost full throttle. I feel that my newly installed pilot super sport tires have more grip than my old RE050 run flat tires. That is another reason I could run faster at T2 at 65mph(2nd track day) vs 47mph(1st track day).
  • At my second track day, I started to realize that there is a slight up ramp at the entry of T3. So my get off brake point is at the crest of the ramp right before entry of T3. My entry line is too tight to the right. I could have move to the left in one car width to have a diagonal entry point. This line seems to be better. Compared to my first track day, my speed at turn 3 is 56mph vs 50mph(1st track day)
  • At 2nd track day, my car has gained more speed at T5. My initial braking point was at the top of the hill which makes my car slide a bit. At faster speed, Ian got scared and told me to brake early during uphill ramp and turn in earlier. It makes more sense because braking at uphill gives more traction to turn in.
  • At my second track day afternoon session, I felt more comfortable to brake late at T9. I think we could use the uphill ramp to slow down the car and turn in without losing traction. After the crest, it seems that other more powerful cars can accelerate towards T10 a lot faster than my 328i. This is one of the two places at Thunderhill east that powerful cars can make more difference in my opinion. The other one is the straight finish line.
  • At T10, I tried to trail braking. I used to brake late and turn in. After discussion with Ian, it seems that I could initiate the turn earlier and carry more speed. However, there were couple of times that my car became too close to the track edge during T10 exiting.
  • T14-15 seems to be my worst corner. I feel that I could carry more speed at T14. At the end of 2nd track day, I could accelerate earlier before T15. This helps me to reach higher speed at finish line. At my first track day, I slowed down too much. I had to accelerate my car from lower speed at straight line.


Oh yeah, about that car that rolled. It was a brand-new (2018) BMW. The driver had purchased HPDE insurance for the day. Yes, it sucks to wreck a car, but it would suck a lot more if you didn’t have insurance. If you’re taking an expensive car to the track, please get HPDE insurance. It costs about the same as a track day. Driver was fine btw.

An Identical Twin Study of Car Racing

This week we have a guest writer! It happens to be my twin brother Mario. Red text is me making editorial comments.

I think this is as good of an identical twin study as you’re going to get in car racing. I don’t know if such studies exist, but I’ll start with that bold statement. Here’s another bold statement: my identical twin brother is between 2 and 5 seconds faster per lap than me on just about every track.

I feel like I’m a pretty typical amatuer racer. I’m not overly analytical, and I drive more with my heart than with my head. I can’t tell you where all of my braking markers are for every corner, or how many RPMs the engine is spinning everywhere on the track. I have at times even caught myself shuffle steering. But I’m not a total noob. I’ve done 17 endurance races and I’m generally pretty fast and safe, and my abilities are probably a lot like many of you.

My identical twin brother Ian, on the other hand, has taken to car racing like a duck to soup. He coaches, he races simulators, he writes this blog and wrote a book of the same name. Ian is the hyper analytical racing scientist, which is what you’d expect from a genetics professor. Compared to me he’s made a cognitive leap ahead.

Ian and I have a similar amount of racing experience, and when we first started racing I was a bit faster. So how did he leave me several seconds behind? And by the same token, if you’re the everyman racer that I am, and you do everything Ian does, could you be many seconds per lap faster than you are now? Yeah, I’m pretty sure of it.

Ian is lighter

Despite being identical twins, Ian usually weighs about 15-25 pounds less than I do. His diet is a bit better with regular salads, but he has a thing for sugary drinks that I don’t. However, he doesn’t drink alcohol, and I do, and that’s probably most of the difference in our weight. I don’t know what twenty-five pounds of beer does to a lap time, but it sure doesn’t help.

I’ve really reduced sugary drinks in the last couple years. I drink a lot of tea though, and mostly decaffeinated/herbal. I don’t drink beer ever, but I’ll have a glass of red wine a few times per year.

He gets more track time

In the early days, I was the one with more track time, most of it on motorcycles, but track time nonetheless. Since Ian started coaching, and since I moved to NY, he gets more track time than I do.

This is most obvious when we both get to a race. It takes me a bit of time to warm up, and I’m not lapping fast or consistently until 30 minutes into my stint. On Ian’s second lap he’s going about as fast as my best lap of the day. He attributes a lot of his instant speed to sim racing.

Sim racing isn’t the same as real racing, but the feel of the car is close enough that it keeps me sharp.

He races a proper simulator

The only simulated racing I do is Gran Turismo on the Playstation, and with a DualShock controller; no wheel, pedals, etc. I like racing on the couch, and I just don’t want to sit in front of a computer after working on one all day. I suppose I could get a dedicated cockpit setup, and Ian tried to get me started with one, but it didn’t go smoothly due to hardware problems. In the end, I abandoned iRacing rather quickly and went back to Gran Turismo.

But for sure, this is part of Ian’s secret sauce. It’s not just track knowledge and laps, it’s sensing the slip angle, threshold braking, feedback through the pedals and wheel, etc.

I usually recommend iRacing as a first simulator. But that’s because most people suck in traffic and the iRacing rookie ranks have so many horrible drivers that it’s very good training for situational awareness. If you already have your head on a swivel and want to perfect your technique, I recommend Assetto Corsa. It’s cheaper and arguably better.

He has higher minimum cornering speed

When we compare overlays, it’s obvious where Ian’s killing me: minimum corner speed. He simply carries more speed through the corner by slowing down less. He’s good at trail braking, and I’m not. Which is because a) I don’t practice trail braking, because b) I don’t get enough track time, and c) I don’t do sim racing with a wheel and pedal. But it’s also because I have a particular driving style I’m comfortable with, and it’s hard to break old habits.

I’d say it’s 50% trail-braking and 50% figuring out that one corner that really matters.

My driving style is slower

I brake early and get on the gas early. I don’t know why I drive that way (probably came from motorcycles), it’s certainly not productive in a Miata. It feels natural, that’s the best I can explain it. Let’s take a look.

Reading from left to right in the graph below, I’m the red line, Ian is black. We’re braking at about the same rate (the slopes are about the same), but I’ve started braking earlier, so that I can get on the gas earlier.

And it works! You can tell because I have the highest cornering speed through T2 and coming up to T3 (the red line is closest to the top). But… if you look at the time graph at the bottom, oh fuck, I’ve lost a quarter second already.

In the graph below you can see I’m doing the same damn thing in T4, early on the brakes, early on throttle. Again with the highest speed between T4 and T5, but then just throwing that away by braking too early for T5! Looking at this now, I’m like, WTF am I doing out there? By the time we reach T6 I’ve lost .75 seconds. It’s only a bit here and a bit there, but it keeps adding up, and by the end of the lap, he’s got 2 seconds on me.

Where I can improve, you can improve

There are clear areas for improvement. For one, I could lose a bit of weight, and I’m cutting down on beer. I really should get a proper simulator, but they are expensive and difficult to set up. I’d rather just have more track time (wouldn’t we all), but I have to think that sim racing, even with the hardware expense and monthly subscription, is cheaper than a couple DEs.

But I think the hardest part might be breaking bad habits. I’ve taken a bit of pride in being lazy about my driving (“I just show and drive, man!”), and if I want to get faster, that attitude is the first thing that needs to go. I have to become a student of the game, and with that, ditch my rally-like driving style. The data clearly proves that optimizing the corner for early throttle never makes up for what I’ve lost on the brakes.

Identifying the problem is the first part of finding a solution, and I believe I’m well on my way. What about you, where can you improve?

I think there are a lot of ways to improve one’s driving. It’s not just sim racing where I’ve invested a lot of time and effort. I’ve read dozens of books about racing and engineering. I coach for Hooked on Driving and sometimes other organizations. I attend seminars and webinars every chance I get. I’ve paid for coaching, oddly, in the sim world but not the real world. Yes, you read that correctly: I’ve paid someone $100 to critique my ability to play a game. I built my own racecar. I write this blog to cement these things in my mind because I learn by writing. I saw this mountain I had no idea how to climb and became obsessive about climbing it. While I agree with Mario that identifying the problem is the first step, there are many steps along the path and some are painful. Motivation is what gets you past them. When people are interested in joining my research group, I don’t look for previous experience with bioinformatics or genomics, I look for motivation. I can teach you how to become a scientist, but not why you would put up with long hours and a small paycheck. Everyone has to find their own spark. A lot of people say “I want to be a faster driver”. And that want will get you somewhere over time. But not as far or as fast as if you say “I need to be a faster driver”. Why did I need to be faster? That’s irrelevant. Why do you need to be faster?

Power, grip, aero…

Everyone wants to improve their car a little (or a lot). How much do power, grip, and aero improve lap times? There’s lots of anecdotal evidence out there, but not much rigorous study. One reason for that is that every day is different. Lap times in the morning can be more than 1 second faster than the afternoon in California. One way to test these parameters on equal footing is through simulation. So I decided to embark on such an activity with Assetto Corsa. Why AC? Because it’s easy to modify. I can simply edit the power.lut file to change horsepower. Aero is similarly easy. Tires are more difficult, but there are already 2 tire choices for most cars, so I did that.

The baseline car I started with is 2400 lbs, 120 hp, 0.40 CoD, 20 sq-ft. frontal area. This doesn’t represent any specific car. It’s not far off from a Spec Miata though. The track I used was Brands Hatch Indy. I almost always test stuff on this track because it has a very small layout, about half the size of most tracks, which lets me get consistent numbers in a short time. I also think the mixture of turns and straights represents the average race track pretty well.


Let’s imagine changing horsepower from 1 to 300. I didn’t do that exactly. I drove the car with 60, 80, 100, 120, 140, and 160 hp. Then I did a curve fit to smooth the data points and extrapolate from 0 to 300. The extremes may be inaccurate, but they are also somewhat unrealistic given the starting vehicle. In the graph below, the X-axis is horsepower and the Y-axis is lap time. You can see the diminishing returns with increased power. If your car has 50 hp, adding 10 more makes a big difference. However, above 200 hp, there’s very little to be gained. If your car is a momentum car, increasing the power will lower your lap times. If you’ve got a muscle car, you need to search elsewhere.


For this next study, I once again drove the car with 60-160 hp but with harder tires. The take-home lesson here is that the higher the power of the car, the more sticky tires are important. Let’s illustrate that with a couple data points. If you’re on the red tires and have 173 hp, your lap time is 57.000 seconds. Switching to the blue tires will lower you to 56.336 seconds. You could also increase horsepower to 217 to get the same lap time. It’s a lot easier switching to stickier rubber than finding another 44 hp. Let’s look at a low horsepower example. At 100 hp on red tires, the lap time is 60.454. On blue tires, it’s 59.940. You can also get to 59.940 on red tires with 106 hp. So, sticky tires could be worth 6-44 hp depending on your starting hp of 100-173.


Aerodynamics are modeled with frontal area and coefficient of drag. It’s kind of hard determining what these values are for your car. You can look these figures up online, but I’ve found really conflicting figures. You can also try to estimate these at http://hpwizard.com, which is a pretty awesome website. I urge you to check it out. Another great website is https://mycurvefit.com if you want to do some curve fitting. Below is the lap time as a function of CoD. This was actually done at 100 hp not 120 hp.

Fantasy Enduro Builds

Let’s imagine 2 builders, Mario and Ian, who decide to build endurance racers from Spec Miatas. Mario decides to perfect the aero while Ian decides to reduce weight.

Mario’s aero mods add weight, but since he’s no longer playing by SM rules, he is able to remove an equivalent weight. So his car stays at 120 hp and 2400 lbs, but his coefficient of drag is now 0.30 CoD. I kept the 20 sq-ft frontal area. The aero mods are worth ~6 hp.

Ian guts and chops his Miata, turning it into a freakish dune-buggy like thing. Same power and frontal area, but weight is just 2150 and CoD has increased to 0.45. The decrease in weight effectively increases hp by 14. But the CoD effectively decreases hp by 8. Overall gain ~6. (Note: I don’t believe simply summing up the hp losses and gains this way is very accurate, but for small values around the defaults, it’s probably okay).

So what’s the difference between these two builds on track? To test that, I loaded up Laguna Seca and input the new vehicle parameters. The two cars were nearly identical in lap times. The aero car had a very slight advantage at the end of the main straight. The lightweight car had a very small advantage in the infield. But after T6, the cars were neck-n-neck the whole way back to the finish line. It was a little surprising to me that the advantage of shedding 250 lbs, which is over 10% of the weight, could be completely mitigated by bad aero. I guess I had better add an air dam to my dune buggy.