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.

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.