This is part 2 in a series of posts where I cogitate on what car to buy next. The rules: sporty, practical, reliable, rallyable, and not too expensive.

Civic Si

There are a lot of different generations of Civic Si to consider. Some are too old, and some are too new. Let’s examine the ones in the middle. All have Honda reliability, acceptable power, acceptable weight, and some trade-offs in practicality.

• 7th-gen. (FB6/FG4) 2012-2017. 201 hp. 2877 lbs.
• 6th-gen. (FG2) 2006-2011. 197 hp. 2877 lbs
• 5th-gen. (EP3) 2002-2005. 160 hp. 2744 lbs.
• 4th-gen. (EM1) 1999-2000. 160 hp. 2612 lbs.

Perspective: 2012 Si vs 2018 Type R

The Civic Type R is a monster that has a pile of accolades. It’s a supercar-killer. The various Si models are sporty, but not in the same class. Here’s a nice video of a driver who owns both a 2012 Si and a 2018 Type R. He drives them on the same day at the same track (Thunderhill). The Type R is about 8 seconds faster, but was driven a little poorly in comparison. It could easily be 10 seconds faster over the 3 mile course. However, I am not in the market for a Type R.

Which Si?

The 7th gen is possibly too new. I don’t think I could find one of those cheap, and that would make me less likely to put students in it or drive it in the dirt. My brother thinks this is the one for me, and went as far as researching how to wire in a switch to turn off stability control.

The 6th gen comes in both sedan and coupe body styles. The sedan makes more sense for practicality, but the coupe looks great. Apparently this generation came with stability control (maybe not all models?), so I’d have to figure out how to defeat that. On the plus side, these came with an LSD.

The EP3 has received a lot of hate. From a performance perspective, it’s probably the slowest of the lot. But still fast enough for me. I like the practicality of the hatchback, and it has an endearing rally-esque shifter. Thankfully, no stability control.

The EM1 is becoming collectible. That makes it slightly less attractive, but overall I like it very much.

So, can I imagine owning a Civic Si? Sure. I love Hondas. I currently own a 2010 Honda Insight, and it’s been completely reliable and economical. Any generation of Si is good for me. Looking over Craigslist and Facebook Marketplace, it’s hard finding one with low miles and low abuse. People tend to know what they are worth, so finding a cheap one that has been taken care of isn’t easy.

This is a new series of posts where I cogitate on what car to buy next…

Preamble

I love my Z3, but it’s not a good winter car. In Northern California, where I live, winter means rain, not snow. An old Z3 just isn’t very waterproof. Honestly, it’s not a very good daily driver. Compared to the other cars on the street, it’s very low and hard to see. It doesn’t have much luggage space, and can’t carry more than 2 people. While it is a 1.9L and therefore pretty good on gas, my daily commute is very short and I don’t burn a lot of fuel no matter what I do.

I’ve been thinking about getting another car. I have a lot of desires in my head.

• It should be very reliable if I’m going to use it as a daily driver
• I would like to do some rallycross with it, so it should be lightweight
• I would like to use it as a demo/student car for my High Performance Driving class

When thinking about specifics, I end up with a lot of competing thoughts.

• It should be FWD because I already have a RWD car
• It should be RWD because it would be better for my students to hoon
• It should be AWD because I’ve never owned one
• It should be a BMW so I can share wheels with the Z3
• It should be 4×100 so I can share wheels with the Yaris
• It should be manual because I prefer driving manual and I could teach that to students
• It should be automatic because most students can’t drive a manual
• It should have 4 doors for practicality
• It should have 2 doors because coupes look better
• It should have a lift back and fold-down seats for practicality
• It should be older, so it’s less expensive, but not too old
• I like sporty cars
• I like slightly obscure cars
• I hate stability control, even the kind you can supposedly turn off

My Next Car: Toyota Corolla XRS?

Let’s talk about the merits of a Toyota Corolla XRS.

• Toyota reliability and parts availability
• 4 door practicality
• 2670 lbs is pretty light
• The 170 hp engine is shared with the Celica GT-S and Lotus Elise
• 2005-2006 is not too old and not too new
• It’s a little obscure in a wolf-in-sheep’s-clothing manner

And here are the negatives:

• The engine is high-strung, revving to 8.2k
• The seats don’t fold down
• It’s not very interesting to look at

On paper, the XRS appears to be the kind of car I’m looking for: sporty, practical, and reliable. In an ideal world, it would be a hatchback and have a lower redline. It seems like a good car for rally or track days. But how does it perform on track? Searching YouTube, I came across someone driving a Corolla XRS in time attack. The video description proclaims that the driver “brought a knife to a gun fight and still got the podium”. Excited, I queued up the video.

The driver runs a bunch of cameras and does a nice job incorporating the 360° camera. I haven’t purchased one of these cameras, but it makes me think about them a little more. The spec tire for GTA is the very fast A052. However, he was apparently driving on 500 treadwear Pilot Sport AS3+ tires. So, that’s pretty hilarious. I like.

Since this was a Global Time Attack event, I thought I would go look at the lap times so I could compare it to more common track cars. Here’s what I found. Yes, it’s true that the driver got on the podium: 3rd place. It would also be accurate to say that he was the slowest car in the entire event and placed last in his class. With only 3 people in the Enthusiast class, only a mechanical breakdown before the event would prevent him from getting on the podium. Forget a knife, he could have brought a bowl of oatmeal to this gunfight and he would still be on the podium.

The owner lists a number of common performance mods: suspension, CAI, custom ECU, pipe etc. What most intrigued me were the baffled oil pan and billet oil pump gears. That makes me nervous, like maybe the car wouldn’t be reliable without those. I asked him if he needed those and his reply was probably and that he’s been through 4 sets of cams in 8k miles.

I don’t want to make lots of modifications to a car in order to track it. I certainly don’t want to replace cams on a regular basis. Ultimately, I don’t think an 05-06 Corolla XRS is on my shopping list anymore. Check back later for another episode of “my next car”, and if you have some suggestions, please leave a comment.

OK, so I’m more than just a little late to the party. I just discovered Initial D. This is a Manga that started in 1995 and became an animated series in 1998. As a general rule, I don’t follow any kind of racing. I have never watched an F1 race, and the only NASCAR race I’ve seen was in-person with a free ticket. I’m 100% against street racing and can’t imagine glorifying it in a cartoon. I also don’t like anime-style art or storylines, which tend to be highly sexist if not pedophilic. There is absolutely no reason for me to watch Initial D.

Did I mention I am currently chain-smoking Initial D episodes like a prisoner on death row?

Where do I start? The details. Definitely the details. The sounds are amazing. I don’t know that much about engines, but 4-bangers sound like 4-bangers, rotaries sound like rotaries, and turbos sound like turbos. The tire squeal is also authentic. The animation itself isn’t spectacular, but the cars are almost photographic in detail from the outside to the gauge clusters. I think some scenes are drawn over video.

The driving itself is stylized and often in slow motion. It’s more dramatic than realistic. However, the dialog about driving is amazing. The less experienced drivers say uneducated things and the experts subtly drop gems. It’s fucking fantastic.

There are some interesting characters, but the main character, Takumi Fujiwara, isn’t one of them. Takumi is sort of a vapid, distracted Mary Sue. He walks around in a daze, somehow unaware that he’s one of the best drivers on the planet. He got his training by (under-aged) driving up and down Akina Pass delivering tofu in the early morning hours.

Takumi’s dad, Bunta Fujiwara, plays the role of the quiet martial arts master. He has made his son into a top-notch street racer without him knowing it, and secretly tunes their AE86 before races. Despite the stereotype, I like his character. One of his training tools was putting a cup of water in Takumi’s car. The only way to not spill it is to drive smoothly.

Two important rivals are the Takahashi brothers. Ryosuke is a highly cerebral racer who analyzes everything with computers. His brother, Keisuke, is a hot-head. Both are highly talented bad-asses who drive RX-7s (FC and FD).

Another interesting character is Mako Sato. She drives a Nissan Sileighty with her co-pilot Sayuki. They are the local Aces at Usui Pass. I think they are the only female racers in the series. Their boobs remain clothed, but are on prominent display, of course.

In addition to the various racing rivals, there are some flavor characters in the form of Takumi’s friends. These are largely annoying. The character storylines can mostly be described as: CRINGE! Skip, skip, skip, skip, skip. You can get through a lot of episodes quickly if you skip over every scene with Itsuki in it (he’s the comic relief who looks more like Chim-Chim than Spritle).

As I write this, I just finished watching Season 1. I AM NOT A BINGE WATCHER. And yet I just consumed 26 episodes in 2 days. The final episode was a great cap to the season, and I look forward to savoring the next season at a more sedate pace.

It’s hard to overemphasize the importance of grip. Braking, cornering, accelerating: everything depends on grip. Understanding how rubber tires create grip is therefore really important for the racing driver. And yet, most drivers don’t know that much about it. Worse, they often have misconceptions that run against the facts.

Let’s first start with some theoretical laws of friction.

• Amonton’s First Law: The force of friction is directly proportional to the applied load.
• Amonton’s Second Law: The force of friction is independent of the area of contact.
• Coulomb’s Law of Friction: Kinetic friction is independent of velocity.
• In addition, static friction is always greater than kinetic friction.

I don’t think many racers actually believe these laws. But should they?

The first law says that a 4000 lb car should stop in the same time as a 2000 lb car. Sure, it weighs twice as much, but it also experiences twice as much friction being twice as heavy. Theoretically, the weight of the car doesn’t matter. So why are there off ramps for trucks on long downhills?

The second law says that it doesn’t matter how wide your tires are. Skinny or fat, they have the same amount of grip. And what about grooves? The laws of friction say nothing about grooves. And yet, given a choice, racers would generally use a wider tire with no grooves. How exactly does width or grooves affect grip?

When considering how speed affects grip, most racers would point to aerodynamic downforce (or lift) rather than the rubber in their tires. Does speed actually affect grip? It turns out that it does, but not in the way you might expect.

If static friction was always greater than dynamic friction, why do race cars slide through corners? Doesn’t sliding produce less friction?

4 Really Important Graphs

In order to understand how tires work, you have to understand 4 graphs. In each of the graphs below, the coefficient of friction, μ, changes. Everything they teach you in introductory physics assumes that μ is constant. Maybe it is for metal blocks sliding against granite table tops at STP, but when it comes to tires, μ IS NOT A CONSTANT.

Graph A shows μ as a function of load (weight). When you double the amount of weight on a tire, it doesn’t give you double the grip. The coefficient of friction, μ, is lower at higher loadings. Is this why trucks need off ramps? Maybe a little, but actually no. It’s because their brakes overheat. However, it is why race cars are low, light, and have stiff suspensions. A low vehicle with stiff suspension doesn’t transfer much weight while cornering. As a result, the overall grip of the vehicle is high because none of the tires are getting too overloaded. Low weight also helps here, as do wider tires.

Graph B shows μ as a function of temperature. Every tire has an optimum temperature. Both cold and hot tires have less grip than one in the optimal range. If your tires are too wide, they may never get up to optimal temperature. For this reason, the optimal tire width isn’t necessarily the widest. TireRack did a great test where they tested a bunch of wheel and tire widths. The fastest tire wasn’t the widest. And when they went to a wet track, the fastest lap was an even narrower tire. One thing that contributes to heat is grooves. Squirming tread blocks are a major source of heat. As a result, grooved tires heat up more quickly than slicks. One reason for using slick tires is to spread the load better, but an even more important one is to prevent the rubber from overheating.

Graph C shows μ as a function of speed. The faster the car goes, the less time rubber has to interact with the road surface. Tires generate grip from molecular adhesion, mechanical keying, and hysteresis. At high speeds, there is less time for rubber to change shape. Under wet conditions, where adhesion no longer applies, grip is highly affected by speed.

Graph D shows μ as a function of slip angle. Every tire has an optimal slip angle. When a tire is twisted, which it always is to some degree, some parts of the contact patch are experiencing static friction while others are kinetic. This mixed state isn’t really addressed by any of the laws of friction.

Visualizing Grip

The main point of this post is to give you a visual model of what is happening at the surface of your tire. With this model in mind, it might help you make sense of the conflicting information in the paddock or Internet.

Panel A represents a tire (squiggly line) pressing into the surface of a road (jagged line).

Panel B is what happens when you add load: the rubber goes deeper into the surface, creating more grip. But there’s only so far you can push the rubber in. This is why doubling the load on a tire doesn’t double its grip. Panel B could also be softer rubber or hotter rubber. In both cases, the rubber more easily conforms to the surface.

Panel C shows what happens at high speed. The rubber sliding across the road doesn’t have as much time to change shape, so it doesn’t deliver as much grip.

Panel D shows what happens when a tire overheats. The rubber comes apart, providing less contact with the surface. If the rubber gets hot enough, it may liquify or sublimate, creating a slippery layer between the surfaces.

This visual model isn’t perfect. For example, it doesn’t give any intuition about slip angle. However, maybe it does explain why Miatas are the best cars for rallycross. Seriously? Yes. If you look at the SCCA rallycross national championships over the last 10 years, Miatas have dominated the stock rear wheel drive class. You can literally bring any rear wheel drive car you want. There are no restrictions on power. And yet, Miatas are the dominant car. Why? Using our visual model, let’s imagine what is happening at the interface of dirt and rubber. Dirt is soft and will deform even more than the rubber. As a result, the two surfaces press into each other easily. The total amount of grip saturates very quickly, meaning heavy cars lose more grip than light cars. On dirt, you can only have so much acceleration before wheels spin, so low-powered cars aren’t really at a disadvantage. What’s the lightest RWD vehicle around? Miata. As you might imagine, light FWD cars also dominate the stock FWD class, but there’s a lot more options when it comes to buying a light FWD car.

The usual HPDE curriculum focuses on driving the racing line. The racing line is in every book on racing since the 1950s. Personally, I don’t teach the racing line to novices, or to anyone for that matter. Here are two problems with it.

1. The racing line has the highest speed. For the sake of safety, do we really want novices driving at the highest possible speed? In an educational event, do we even want to promote speed as a desirable metric?
2. While the racing line “uses the most track”, it’s also as close to the edges of the track as possible. Most self-inflicted incidents occur when drivers go off track. Do we really want novices near the edge of the track?

Instead of teaching the racing line, I think we should teach mid-track exit. Let’s see what this looks like and then discuss its merits.

The cars are going from bottom to top. The red line is the geometric line through the corner. AKA, the one with the largest radius. The blue line is also a circular arc, but it has a smaller radius. Both lines start on the outside of the track and apex around the same point. However, the blue line doesn’t go all the way to the edge of the track. It’s done turning by mid-track. Here’s why this mid-track exit is better for novices.

1. It has a slower speed. If something catastrophic happens, there will be less physical damage.
2. There is more space to recover from problems at the exit because there’s physically more track.
3. As drivers get more confident, they can add power, which naturally increases the radius of the corner after the apex, pushing the vehicle closer to the edge of the track.

Teaching a mid-track exit leads to driving the actual racing line, with the car increasing speed and radius in the 2nd half of the corner. The line develops with the driver’s skill and confidence.

In contrast, the typical HPDE coach tells their driver to “use the whole track”, which usually involves them steering out to the exit. This is a fake form of high performance driving: it looks fast but isn’t. It appears to be giving them good instruction, but tells them to follow rules (the line) rather than feel what the car is doing. It’s back-asswards. The HPDE curriculum isn’t designed to make people better drivers. You don’t have to believe me, but you should probably believe Paul F Gerrard. In Optimum Drive, he explains why the HPDE curriculum is misdirected.

If you really want to learn how to drive a car, you should go to a skid pad, possibly made from dirt, and learn how to slide a car around. An HPDE track event is not the place to experiment with oversteer recovery. However, HPDE events are a good place to have some fun with sporty cars. I think driving students will have more fun learning how to feel the grip of a car than robotically following the racing line. When I coach, I encourage students to “explore the space”. I would rather have them driving 6 tenths in the middle of the track than steering out to the exit at 4 tenths. I also teach trail-braking from day one, but that is another story.

I have some funny (at least to me) videos I made about HPDE and the racing line. They seem appropriate in the context of this post.

Last weekend, we entered a Lemons race and got 13th place out of ~90 cars. We were 2nd place in the C class, but not really threatening the leaders. Overall, that sounds like success, but we also had 4 black flags, which sucks. My brother did a really nice write-up, which is linked below. Check out his blog and also his articles on aerodynamics.

Beating up Miatas in a Yaris

Classes start this week and I’ll have a new cohort of students in my High Performance Driving class. In the first week we just hang out and meet each other, but in the second week we start talking about linear and circular performance. That is, how fast do cars go in a straight line (e.g. 1/4 mile or 0-100-0) and how fast do they go around circles. This will be their homework problem.

Given an autocross course with 4 cones, are you better off taking a large, circular path or a smaller square path? For the purposes of calculation, I have given them the following values:

• The straights are 280 ft long
• The small corners have 60 ft radii
• The large circle has a 260 ft radius

They are given a spreadsheet with various linear and circular formulae. It’s all very simple and doesn’t include gearing or aero. The inputs for the vehicle are these:

• Engine acceleration
• Brake deceleration
• Cornering grip

As part of the discussion, I ask the students to ponder how much each of the inputs matter. And even though we haven’t talked about aero, I ask them what they think will happen once it has been taken into account.

If you make a comment, please don’t provide any math or numbers. I want them to figure it out for themselves. You are welcome to predict which one is faster in qualitative terms!

As you may know, I teach a class on high performance driving. What do we talk about? I present to you the final exam from the last time I taught the class. Feel free to suggest new exam questions!

Question 1: Friction Circle

Given: Miata, 1.0g grip, left-hand drive, driver is highly skilled, no passenger, track is clockwise and shaped like the letter “T”.

• Draw a circle and label the axes
• Draw appropriate dots on the friction circle
• Place the letter “A” at the location where power-on understeer might happen
• Place the letter “B” at the location where over-braking understeer might happen
• Place the letter “C” at the location where lift-off oversteer might happen
• Place the letter “D” at the location where power-on oversteer might happen
• Place the letter “E” at the location where trail-braking oversteer might happen

Question 2: 90° Corner

• Draw the geometric line (dashed)
• Draw the typical late apex racing line (solid)
• Label the entry, apex, and exit
• Place an X on the racing line where the driver should apply throttle
• Place a Y on the racing line at the position of minimum speed
• Place a Z on the racing line at the position of the highest speed

Question 3: Suspension

• Why does lowering a car reduce body roll?
• Why does stiffening the suspension reduce body roll?
• How does an anti-roll bar reduce body roll?
• What is the advantage of reducing body roll?
• Why do racers soften suspension in the rain?

Question 4: Grip

• State Amonton’s First Law of Friction and describe a flaw.
• State Amonton’s Second Law of Friction and describe a flaw.
• State Coulomb’s Law of Friction and describe a flaw.
• Slicks vs. grooved tires: what are the advantages and disadvantages?
• Wide vs. skinny tires: what are the advantages and disadvantages?

Question 5: Tire Graphs

Draw the following graphs. Label the axes.

• Coefficient of friction vs. Load
• Coefficient of friction vs. Slip Angle
• Coefficient of friction vs. Temp
• Coefficient of friction vs. Speed

Question 6: Corners

Draw the following corners: esses, chicane, carousel, 120° decreasing radius. Label the corner as Type I, II, or III.

Question 7: Puzzles

• You notice your friend drags his clutch during braking (i.e. uses the engine to help slow the vehicle). You ask him why and he claims it helps him slow down faster.
  • Is he correct?
  • How does this change braking in a FWD vehicle?
  • How about RWD?
• When cars go off track at the exit, they often end up crossing the track and crashing against the inside wall. Why does this happen?
• Cars often lose control when cresting a hill. Why does this happen?
• Label each shape below with an approximate drag coefficient. Assume the object is traveling upwards on the page.

I love comparison tests. Before we get to the newest test, let me look back at other wheels I’ve had the opportunity to test back-to-back.

• Logitech Momo vs. Logitech G25 – If this was a comparison of food, it would be like comparing shit to a shit sandwich. At least the sandwich has some bread in it.
• Logitech G27 vs Logitech DFGT – Shit sandwich vs. shit hogie.
• Logitech G27 vs. Thrustmaster T150 – Shit sandwich vs. shit over rice.
• Logitech G29 vs. Thrustmaster TS-PC Racer – Shit sandwich vs. a decent burger.
• Accuforce vs Thrustmaster TS – gourmet burger tastes the same as decent burger.

The two products I am comparing today are the Thrustmaster TX and TS bases. The TX can be found in the “TX Servo Base” by itself or with wheels such as the “TX RW”. It appears to be the same product as the T300. The TX/T300 base is an older design than the TS, which comes in several flavors: “TX-PC Racer”, “TS-XW Racer”, “TS-PC Racer Ferrari 488 Challenge Edition”, or by itself “TS-PC Racer Servo Base”. The TX has a built in power supply while the TS has a separate one (which looks like a turbo snail). The most important difference is that the TX has about 4 nM torque while the TS has about 6 nM. For comparison, Logitech wheels and the Thrustmaster T150 have about 2 nM. From my experience, the torque is absolutely critical and more is generally better.

Driving the two wheels back-to-back is enlightening. The TX doesn’t have the same feel. I don’t feel as connected to the vehicle dynamics. It’s definitely harder for me to drive. It’s much harder to sense and correct oversteer when the wheel has low torque. If you rely on trail-braking to sense speed and rotate the car, you will be much better served by a high torque wheel. Spinning is frustrating. You will spin a lot less with a high torque wheel. That said, my lap times were about the same with these two wheels. Should you buy the more expensive TS for the higher torque motor? Yes. The higher torque makes driving more authentic and more enjoyable. Should you buy an even more powerful direct drive wheel with an even higher price tag? Maybe. If you are using sim racing for real-world training, and have enough money to buy actual racecar stuff, then I think you have enough money to buy a direct drive wheel. If you’re mainly into sim racing for the sake of sim racing, the TS is a very good wheel base. I love mine. If you’re on the arcade side of things, then Logitech might be fine. The TX is in an odd spot: clearly better than Logitech, but also clearly worse than TS. Personally, I wouldn’t buy one. But for someone mainly interested in sim racing I think it’s fine. What about Fanatec? They make a lot of wheels and I’ve only used one. It was very good.

Over the years, I have owned a variety of sim racing wheels. Since I’m a professor, I’ll give them grades in red ink.

• Logitech Momo – The force-feedback is just vibration and the pedals are crap. Still better than a hand controller. D-
• Logitech G25 – Durable and the pedals are built well. Swapping a load cell on the brake pedal makes them top-notch. C
• Logitech G27 – Very similar to the G25 but with a less good shifter. C-
• Logitech DFGT – Cheaper than the G25/G27 but essentially the same thing. C
• Logitech G29 – Wait, are they still making the same shit? Yes, but it costs more now. C-
• Thrustmaster T150 – Thrustmaster’s attempt to make something just as bad as Logitech. With a 2 nM wheel and shitty pedals, they succeeded. C-
• Thrustmaster TX – Almost good enough to recommend. Sometimes packaged with spring-based (crap) pedals. B-
• Thrustmaster TS – Acceptable. T-LCM load cell pedals are a good match. B+

YSAR reader Gary emailed me and asked me if I would be interested in having my students drive his sim rig. A whole driving sim? Yes, the whole thing: Thrustmaster TX base with Sparco wheel, Fanatec ClubSport V3 inverted pedals, Fanatec H-pattern shifter, gaming computer with RTX 2080 GPU, 32″ curved monitor, Occulus Quest 2, speakers, headphones, and a custom-made cockpit with a Mustang seat complete with electronic controls. Not only did he donate this to the class, he also drove it up from Berkeley and installed it in my office. Who does things like that? Gary, apparently.

Oh yeah, my students are going to love this. Me too. This means I can get twice as many students in at a time. Also, they can race each other. I still have some minor adjustments to make on both rigs and some tidying up, but this is what my office looks like this afternoon.

The only downside to this is that my colleagues will think I’m loony. They already think I’m sus, but this is going to end up as cringe. Sorry, I don’t actually know what those words mean to young people, it’s just me trying to keep up with the times. In addition to the usual time trials and training sessions, I’m going to have to figure out how to get togue races going. Stay tuned.

Again, thanks Gary.