GTI told you so

GTI

I had never driven any GTI before, so I was eager to try out Tiernans MKIV. I drove it for 4 laps at the end of the day. The first and last laps were not timed so I ended up with a 2:20.088 and 2:22.482. I had to work around a little traffic each time, which in the Hooked on Driving B group means passing only in a few designated zones. I don’t begrudge the traffic because passing Corvettes and Caymans is always good sport.

The 2:20.088 was very similar to the 2:19.60 predicted from Optimum Lap. Also, the 0.95G tire grip was spot on as the T2 min speed was 68 mph, and the theoretical speed around a 325′ radius circle is 67.88 mph. While I didn’t make a prediction that 104 mph would be the top speed on the main straight, I probably would have guessed 105.

The handling was pretty good. It’s a little understeery on brakes or throttle, but does rotate off throttle. After the laps I took it to the figure 8 briefly and it wasn’t any fun because it had so much rear grip. Speaking of grip, I liked the tires a lot. Federal Evoluzion ST-1s are inexpensive, grippy, and have great audible feedback. I actually bought a set for the 318ti for that rosy future where I actually get to drive it (it’s still in the shop).

STI

My student had an STI, and I had also never driven one of those before. I didn’t get to drive it aggressively, but from my 3 laps behind the wheel, I thought it was a solid and fast car. We beat up on a lot of sports cars in the A group. I think we were the fastest car in the group. It is a seriously capable vehicle and the student was a quick learner.

GT

The GT was both amazing and a huge disappointment. The morning started out wet and I got to drive it in the figure 8 drill. I put the Federal 595RS-Pros on the front and left the all season Kuhmos on the rear. I’ll make a post about that experience soon. It was so ridiculously fun I couldn’t help giggling while I was driving.

Later I got to drive the track and the lap time was shite: 2:27.99. That was due to a combination of factors. One of those is that the fenders need to be rolled. I kept backing off because the tires were rubbing. But the main problem was the transmission. It stayed in high gear quite a lot, which meant no acceleration. Perhaps shifting into L2 and L3 would have improved the situation. Something to try for next time.

Back

I had an MRI last week and it showed that my back is both better and worse. The herniated disc is no longer a problem but I have spinal stenosis. The nerves going down my leg are getting pinched in my lower back. That’s why I haven’t been able to feel parts of my right foot for 1.5 years. I’m also starting to experience some of the same sensations on my left side. Changing tires, coaching, and driving turned out to be a pretty taxing day. I’m signed up to drive Thunderhill West backwards next week, but after that I’m not sure how much driving I’m going to do in 2020. I’m certainly not signing up for any races until my back is better. With the progressive slide its been on, I may have to get surgery at some point. That is both exciting and terrifying.

Cliff Notes

Ever since I started track driving, some 6 years ago, I’ve watched videos of people driving Thunderhill. It’s the closest track to me, and also my favorite (the West side is actually my favorite, but the East side is near the top of the list). In the beginning, I was just trying to learn the track. Later, I wanted to see how my lap times stacked up against other drivers. Today, I mainly watch to analyze driving technique.

When watching videos at Thunderhill, I like to focus on Turns 1-3. Each turn exposes specific driving errors and the entire sequence from the tower to the apex of T4 is under 40 seconds.

The video I have for you today features Cliff, a coach with Audi Club. His YouTube channel features a video from 6 years ago with HoD A and S stickers, so it looks like he got started track driving around the same time as me, or possibly earlier. Cliff is driving a 2015 Golf R with a shitload of upgrades. The Golf R has 292 hp stock, and the Stage 1 tune upgrades this to over 350 hp. The car also features Ohlins suspension, StopTech brakes, and 200TW rubber. The car is properly built for track duty. The description of the video says it’s his fastest lap of the weekend. The video doesn’t feature a lap timer on screen, but from the video timestamps I estimate 2:13.9. Seems like he should be able to go faster. So let’s dive in and see if we can figure out why.

Watch the video and then follow along below.

Some of the things I like about this video are the picture quality and overlays. It’s too bad the camera isn’t mounted inside the car, because it would be great to get an idea of what the driver is doing. Given that most overlays don’t show steering data, it’s useful to watch the driver’s hands to see if he’s fighting understeer or oversteer. I also like watching shifting technique. Oh well, not today.

One of the most useful tools for analyzing drivers is a speed trace. Ideally, your data acquisition system updates at 10 Hz or better. Phone-based apps like Harry’s Lap Timer or Track Addict typically record at only 1 Hz unless they are provided with an external antenna. Since I don’t have data for the lap in the video, I made my own by recording the speed of the car in 1 second intervals using the video timestamps. This provides a low-resolution speed trace (blue) very similar to what you would see from a phone app. I’ve also drawn a theoretical speed trace based on my own imagination, which I’ll discuss below.

Turn 1

In the first few seconds, you can see a major problem. The speed trace has a very rounded top. The car is coasting into the brake zone. I don’t actually subscribe to the phrase “you should always be on throttle or brakes” because people who hear that think it means 100% throttle or 100% brakes. And there are also instances when coasting is actually appropriate. But 2 whole seconds of coasting on the main straight is not one of those times. The amount of time lost is only a couple tenths, so it’s not that big a deal in terms of lap times. But it is a big deal in terms of technique. One should drive the car all the way to the brake zone.

The next thing to note is the deceleration. It’s not very steep. A car with 200 TW tires can decelerate at 1.0g. From observing the G-meter, the car never gets close. It spends most of the time at less than 0.5g. Technique-wise, I also brake more gently in high speed corners. My mindset is that I’m trying to set the corner speed at a specific value rather mash the pedal. But the braking here is just too timid. Looking ahead at other corners, he appears to always brake gently. The car and tires are capable of much more.

The final thing I want to point out is the location of the apex. This is the black arrow. The slowest part of a corner should be before the apex, not after. He’s coasting through the corner trying to hold speed. In the overused phrase “in slow, out fast”, the in slow happens before the apex and the out fast starts occurring a little before the apex. Here, the slow is still after the apex.

Turn 2

Like T1, there isn’t enough commitment to the brake pedal in timing or pressure. But the overall shape is pretty good. I see a lot of drivers mash their brake pedal and over-slow the car. Not so here. He’s using the brakes to set his speed, and then he drives through at the speed he set. Good.

Unfortunately, the mid-corner speed of T2 on 200TW tires is not 61-63 mph. Looking back at some of my data, I drive a couple mph faster in the pouring rain or when joking around on 185/60/14 Douglas Xtra-Trac II tires ($38 Walmart tires with a 420 treadwear rating). On a dry track with 200 TW tires, I’m around 72 mph. Why is he driving so far under the limit? Probably because he doesn’t like the feel or sound of sliding tires. Tires are supposed to slide a little on track. That’s where the optimum grip is. Driving a sliding car can be uncomfortable if you’re not used to it. The way to get used to it is to do it.

While T2 is a carousel with a constant radius, it is almost never the case that one should drive a constant radius. On a long corner like T2, you should use the first half for braking and the second half for accelerating. You may be slightly slower on the way out of the corner, but you gain a lot more by using the first half as part of your brake zone. Since there’s such a short straight from T2 to T3, it’s better to take this as a double apex rather than single.

Turn 3 and Turn 4

T3 is tricky because it’s off camber. There are lots lines through the corner, especially when racing wheel to wheel. Although Cliff’s overall grip level isn’t where it should be, the shape of the speed graph is just fine.

T4 is a typical 90, so the minimum speed should be before the apex. Here, like in T1, the minimum speed is actually after the apex. If you’ve got a car with 350 hp, you should use a driving line that optimizes the power of the vehicle. That means getting the braking and turning done early so you can throttle on a straight line. This is doubly true for FWD cars.

Rant on

It’s not really Cliff’s fault that he under-drives his tires. The E in the HPDE system is totally broken. If you haven’t read “Optimum Drive”, by Paul Gerrard, I highly recommend you do. He talks about how backwards the HPDE system is. I won’t repeat that here. Go get his book. Paul also says that if we want to solve a problem, we need to get to its root. The problem isn’t that Cliff coasts into brake zones or drives at 0.8g. The problem is that he’s not comfortable driving a sliding car. Fix that problem, and all the symptoms go away.

What’s the first lesson we usually teach new students? The racing line. As if that fucking matters. The line is a result of optimizing grip. Teach drivers to feel grip and the racing line will follow. The reverse isn’t true. Fuck the fucking racing line. I’d much rather have students drive in the middle of the track. There’s less chance they go off track and roll or hit something.

When drivers get comfortable just under the limit they reach a performance plateau that’s hard to break through. And the better they get, the harder it will be to unlearn later. Stability control, sticky tires, and 500 hp monsters all conspire against acquiring actual skill. But the students show up in Hellcats and Vipers, and I’m not getting in the right seat of one of those things without nannies.

If you really want to get better at driving, you have to have the right environment. Thunderhill in a 500 hp monster is not the right environment. The consequences of crashing at 130 mph are just too great. There’s a reason that the Kenny Roberts school is on dirt and why the Skip Barber school uses all season tires. Learning car control is safest when tires are slippery and speeds are low. Simulators are cheaper and safer still.

Rant off

On the other hand, not everyone needs to be a driving ace. Lots of people enjoy listening to music. Fewer people play music. Even fewer compose. If someone is having a great time driving around a track at 6 tenths, do they really need to turn it up to 8 or 10? As a coach, my #1 priority is safety. The #2 priority is to make sure the student is having a great time. For novices that probably means teaching them the racing line and “advanced techniques” like heel-toe shifting. As students graduate to intermediate and advanced, they need level-appropriate instruction. And just like with music or anything else, the lessons become less entertaining and more work. Drivers who didn’t start with a foundation of car control will take longer to reach whatever level they are trying to attain because they will have to unlearn a bunch of bad habits along the way. Who cares? It’s just time, and last I checked, time on track is a lot of fun.

Conflicted

Personally, I’m really conflicted about driving education. I firmly believe that car control is the only thing that matters, and if I ran a driving school, it would be mostly drills on a skid pad or simulator. However, I also believe that as long as drivers are safe, they should do whatever optimizes their fun. If I ran an HPDE organization, we’d do burnouts, drifts, jumps, and of course, the racing line.

Post-race analysis: drivers

Let’s take a look at some of the telemetry traces of the Triple Apex Racing drivers from the last race.

Danny vs. Danny

The first thing I want to discuss is Danny. I’m usually a couple seconds faster than Danny. I was on Saturday. Then we switched tires on Sunday and everyone went faster. But was it really the tires? In the speed trace below, Saturday is black and Sunday is red. I’ve displayed the top 3 laps each day. Saturday he was doing 3:39-3:40 while Sunday it was 3:36s. What I see here is that he’s driving differently. On Sunday (red) he started backing up the corners. He gets his braking done earlier and gets on gas earlier. Most of the time, his minimum corner speed is higher despite the change. The fresh tires may have contributed a little to his higher speed, but I think it’s mostly because he’s getting better at driving a low powered FWD car with an open diff. His usual car is 911 GT3, so yeah, it’s a little different!

 

Danny vs. Ian

Due to yellow flags, I didn’t get many fast laps. I did a 3:38 and 3:37 back to back. You can see these starting at the 10:00 mark in my video from the last post. In my 3:38 lap, I lose 1 second passing an E36 in T2 when it changes line mid-corner. Then I pass the yellow Miata in T5, messing up my T6 entry, causing another loss of a second on the run up to 9C. The 3:38 could easily have been a 3:36. On the 3:37 lap, I lose a little time making a pass in T2 and then 1 whole second in T3W while I wait for a fast E36 to get around me. So that too could have been a 3:36. Had I gotten a bunch of clean laps, I’m pretty sure I would have been doing a bunch of 3:36s. Could I have broken into the 3:35s? I don’t know. For the most part, Danny and I drive pretty similarly. Below, the red lines are Danny’s fast laps (as above). The black is my 3:37 and the blue is 3:38. This is a speed trace from 7W to the SF line. We have a slightly different way of doing 1W, but the rest is similar enough that you might think it was the same driver.

Randy vs. Danny

So I’m sure everyone wants to know how fast Randy was (green lines below). Faster than Danny (red lines). Where is he faster? You might expect it’s the fast corners, but it’s the slow ones. He gains nearly 1.5 seconds in T9C alone! And he was only 1.8 seconds faster than Danny. T9C is on the far left of the graph. But he’s also faster in T7W and T11. How? Mostly by running over curbs. As the car owner/builder, I don’t really approve of that.

Post-race analysis: aero

At the last Lemons race I did a lot of lightening, which is good, but I also turned the car into a parachute and destroyed our top speed. This race we made two aero improvements.

1. A-pillar deflectors

This is simply a piece of plastic that bulges out a bit. The intent is to have the air go around the window instead of into it. Randy Pobst signed it.

Let’s take a look at the top speed on the main straight before and after the new “aero package”. The top speed went up from 92.0 to 95.4. It’s even more dramatic when you look at the speed trace.

2. Rear wing

Normally, all you have to say is “wing” but I need to emphasize “rear” here because we made an aero joke at the last Lemons race.

Note that we didn’t actually run this on track.  It was just to give Mario and Daniel a laugh when they drove in and saw the wing on the wrong end of the car. Here’s a picture of the same wing installed on the roof. Also, there’s a note I wrote to try to persuade Randy to take a stint in the Yaris.

So what did the rear wing do? The #1 place I felt it did something was in T1. I usually have to brake in T1, but with the wing holding down the rear end, I was able to do a brief lift and then go right back to throttle. You can see how much faster I can do T1 in the graph below (blue is with wing).

The wing also turned T8 into a straight. It’s normally a corner that gives some people a fright, but with the wing on there was no drama at all.

Conclusions

I think the new aero worked. I guess the next question is if we can make it work better.

Randy Pobst is a sweetheart

The Lucky Dog race at Thunderhill was good fun. Ultimately, we didn’t place particularly well, but as we’ve found out over the years, it’s more fun racing for giggles than trying to win. So we were leisurely about pit stops and put some guest drivers in the car. One of those drivers was the Internet celebrity pro driver Randy Pobst. Randy has a reputation as a fast driver but there’s a lot more to the package. He’s very approachable and knowledgeable, and he listens as well as he talks.

FUUUCK. I only had one camera working on Sunday when Randy was driving and it was pointed to the rear.

When Randy got in the car I told him to “bring it back whenever”. Given that he drove it until the end of the race (~60 min), I think I believe him when he said he was having a lot of fun. Apparently the Yaris reminded him of his old 80s Golf. Randy wasn’t the only person who had a great time in the econobox of doom. Lemons veterans “Crazy Mike” and Steve “Chotus” Warwick also drove and loved it. Mike was an “official” Triple Apex Racing driver this race and Steve was a stud driver, piloting some 4 or 5 cars on the weekend. That reminds me of a quote.

I never had a 10, but one night I had five 2s… and that ought to count for something.

— George Carlin

Every time I race the Yaris, it reminds me of why I built it. I love driving and hate wrenching. Despite appearances, the Yaris is a great driving car. It’s also cheap to run and tougher than it looks. It got side swiped twice during the race and just shrugged them off. The one annoying feature of the car is inside wheel spin from the open diff. That’s something I may address in the off season.

Look for some video and telemetry posts in the near future.

Aero Thoughts

I haven’t looked at the data yet, but here’s my seat of the pants impression of what it did.

  • The wind deflectors on the A-pillars did something. There seemed to be less noise in the cockpit. Did they improve top speed? I think so. In the last Lemons race we lost a few mph on the main straight and I think we got that back.
  • The wing probably added useful downforce in T1 and T8. I always take T8 flat out, but this time it was a really boring flat out. In T1, I usually brake lightly, but this time I would just breathe the throttle off for a heartbeat and then go right back on. No brakes needed. That allowed me to make some passes on higher powered cars.
  • The interior of the car still smells a little of catalytic converter, so I think some fumes are getting in from the rear. I want to fix that somehow.

I won’t know if these impressions are correct until I check the data. I’m fully prepared to be wrong!

Thunderhill Ready

Before the last race, I did a lot of lightening. The biggest win was getting an extra set of doors and gutting them to metal skins. While they weigh 50 lbs less each, they leave a larger hole and have no mirrors. That probably negatively affected our drag as top speed was off by 5 mph. Lap times were about the same though, probably due to better acceleration. Since there wasn’t much to do to get the car ready, this weekend we added some features that may improve our aerodynamics.

In the picture below, you can see a white piece of plastic on the A-pillar. This bulges out a little which we hope will deflect some of the air outward, so that the window doesn’t act like a parachute. The plastic is very heavy and shouldn’t move even with high air speed.

I also added a wing to the rear. This is a present Mario gave me that we had at one time installed on the front of the car as a sight gag. Now it’s installed in the correct place with mounts I hacked together. It’s more sturdy than I would have thought. No idea if it works, but even if it doesn’t give much down force, maybe it helps prevent air from the tailpipe going back into the cabin. Or maybe it creates lift and gives us carbon monoxide poisoning. Who the hell knows?

The last piece of our “aero package” is an air dam that I will attach once we get to the track. It will be interesting to compare data from the May Lemons race to see if top speed improves on the main straight and if we get any extra grip in the fast corners.

The only thing I’m concerned about at this point is the rear tires. The 8″ rims aren’t fully covered by the wheel wells. I guess I’ll order some fender flares.