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.

GT vs GTI

This weekend, March 7th to be specific, Tiernan and I are signed up to coach at Thunderhill with Hooked on Driving. Between coaching sessions we hope to get a few laps in for fun. So which car do you think will be faster, Ian’s GT or Tiernan’s GTI? Let’s look at the specs.

GT

  • 2003 Hyundai Elantra GT with 130k miles
  • Automatic transmission
  • 2698 lbs curb weight
  • 135 crank hp
  • 19.98 lbs/hp
  • 215/40/17 Federal 595RS-Pro (200TW)

GTI

  • 2002 Volkswagen GTI with 109k miles
  • Manual transmission
  • 2932 lbs curb weight
  • 180 crank hp
  • 16.29 lbs/hp
  • 205/55/16 Federal ST-1 (300TW)

Optimum Lap Simulations

The GT has the grip advantage being on softer and wider tires. It also weighs 234 lbs less. Is that enough to overcome the 45 hp engine advantage of the GTI? Let’s ask Optimum Lap.

I found a dyno for a stock 4 cylinder Tiburon, which has the same engine as the Elantra. It has a peak of 120 hp at 5500 rpm. The engine apparently revs to 6.4k, but the auto shifts at 6k. That’s a pity because the tractive force graph below shows I could really use those revs. Each curve represents how much acceleration there is at each speed in each gear. There’s a huge drop-off after 40 mph and 74.3 mph.

The stock GTI dyno I found shows a peak 149 hp at 6000 rpm. As you can see from the tractive force graph, the transmission ratios fit very well with its engine.

Tires are an absolutely critical component of performance and manufacturers don’t label them with their lateral G limit. That means I have to estimate it. I generally set 200TW tires at 1.0G. With such a round figure, you might suspect 1.0G is more convenient than accurate. Indeed it is. The exact figure isn’t so important, but the relative difference is. Given that Tirenan’s ST-1s are 300TW, I will make a wild guess and estimate that they have 0.95G grip

Optimum Lap says the GTI beats the GT 2:19.60 to 2:21.51. However, the predecessor to the RS-Pro, the RS-RR, was definitely on the sticky end of the 200 spectrum. And my car is both lower and stiffer than Tiernan’s. So if my tire and suspension package is worth 1.05G it turns out my predicted lap is 2:19.28, which would beat the GTI by about 3 tenths. So my best guess is that the GT is near the same second as the GTI.

How accurate is Optimum Lap? I think it’s not bad if you have the right parameters. If I input my Yaris in its pre-B-Spec days with 1.0 grip, Optimum Lap estimates 2:23.40. That’s very similar to my real world fast laps, which were in the 2:22-2:23 range. So the GT should be a little faster than the Yaris when they have equal grip. But there’s only one way to find out. Check back for real world results.

Track Prepping The GT

A couple weeks ago I posted about my carpool car: a 2003 Hyundai Elantra GT, which I call “The GT”. I’m doing some light modifications to make it track-worthy. Why? Well, if you have to ask, you’re not the intended audience. Still here? Sweet, let me give you the goods.

Brakes

The very first modification every track car should have is high temperature brake pads and brake fluid. While I have raced cars with fading brakes, and had a good time doing it, it’s safer and more fun if you have confidence that the car will stop every time you hit the brake pedal. There are lots of high temperature brake fluids, and I’m not picky about them. I never bother with fancy disks. Drilled rotors are unsafe. Slotted rotors remove mass. OEM equivalents are just fine.

My usual brake pad is StopTech 309, but I couldn’t find those for the front. I did get them for the rear, and amazingly, they were just $13 for a pair. For the front, I decided to try Power Stop Evolution Z23 brake pads. I’ve never used them before, but if they really are good up to 1200°F, that would be pretty sweet as a set is just $28. Here are some brake pad temperatures I’ve found online. Most of these numbers are coming directly from the manufacturer. Not sure how reliable that is. Boldface below indicates pads I’ve had on my cars.

  • Hawk HPS 700°
  • Hawk HP+ 800°
  • Hawk Blue 1000°
  • EBC Green 1000°
  • Hawk DTC-30 1200°
  • Raybestos ST43 1200°
  • PowerStop Z23 1200°
  • G-Loc R8 1250°
  • StopTech 309 1300°
  • EBC Red 1400°
  • G-Loc R10 1475°
  • Hawk DTC-60 1600°
  • EBC Yellow 1650°

In case you’re wondering how I rate these, the worst feel are the ST43. Too much on/off behavior. They last forever though. Hawk HPS and EBC Green feel okay, but melt quickly. They may be fine for autocross, but not for track. EBC Red/Yellow, StopTech, and G-Loc all feel about the same and have similar longevity. But StopTechs are half the price of EBCs and EBCs are half the price of G-Locs. If it turns out that PowerStop is good enough, that’s great because they are even cheaper than StopTech.

Transmission Cooler

I don’t know much about tracking an automatic, but my understanding is that autos fail when they get too hot. I recall being at a track day where they had to shut the track down for 30 minutes to clean up an exploded slushbox. I don’t want to be that guy, so I need to protect and monitor the transmission. Unfortunately, not many cars report their transmission temperature on the dash and getting the temperature out of the ECU can be complicated. To keep things cool I got a Hayden Automotive 677 transmission cooler ($38). I haven’t yet figured out how I’m going to monitor the temperature.

Suspension

I’ve driven lots of cars with stock suspension on track and I really don’t mind a bit of body roll. But The GT suspension was in need of replacement anyway, so I decided to upgrade. The few people who autocross Elantras say that a good handling formula is KYB GR-2 struts, H&R Sport springs, and a Tiburon rear ARB. None of that is very expensive. The struts were about $60 each, and the springs were on sale for $200 from Tire Rack. I picked up the ARB from Pick-n-Pull on a member’s 40% off day for $25. The whole suspension package was under $500.

Wheels and Tires

I have nothing against tracking a car on all season tires. I actually have a lot of fun with that. But I’d like to embarrass some actual sports cars with The GT, and the simplest upgrade is sticky tires. The original wheel and tire sizes are 15×6 and 195/60/15. There are no decent tires in that size so I went looking for 16″ and 17″ rims on Craigslist in 4×114.3 bolt pattern. I got lucky and found a set of Team Dynamics in 17×7 for just $250. They were previously on an autocross e30 with an S52 swap. They are nearly new, and even though I don’t have much preference for wheel aesthetics, I like these well enough that I may have picked them out of a catalog.

The stock tire has a 24.2″ diameter. The closest 17″ sizes are 215/40/17 (23.9″), 205/45/17 (24.3″), and 215/45/17 (24.6″). There are a lot of sporty tires made in those sizes, so it was a matter of choosing the tire that maximizes some function of price and performance. I love Bridgestone RE-71Rs, but they are pretty expensive in 17″. Federal 595RS-RRs have nearly the same performance for a lot less money. The only downside of RS-RRs is the vape-inducing tread pattern. When I went shopping for RS-RRs, I couldn’t find a set of 4. Recently Federal introduced the 595RS-Pro, and maybe the reason there aren’t any RS-RRs around is that the RS-Pro is the replacement. It has the same treadwear rating as the RS-RR but a more typical tread pattern. The only place I found selling RS-Pros was Phil’s Tire Service. I ordered a set in 215/40/17.

After mounting, the total bill was about $550. You can see how little sidewall there is. I might be worried about damaging a rim if I hit a pot hole on the street, but these are going to be used for track only.

Engine? Weight? Aero?

I’m not going to upgrade anything on the power line. OEM from intake to muffler. For me, the whole point of going to the track is to drive around corners fast. I don’t really care what happens on the straights.

Removing weight helps a car accelerate, decelerate, and turn. But this is still my commuter car, and it needs all its comforts. The only weight reduction I’m doing is taking out the spare tire and tools.

While aero can counteract both drag and lift, I’m not doing any. I hate aero on street cars.

Summary

OMG who spends $1200 to track a $2000 car? Every Miata owner ever? OK, so an Elantra GT with an automatic transmission isn’t exactly the answer to many car questions. But in its own way, The GT is going to be awesome. Don’t believe me? Check back for the track report. I’m going to run circles around some motherfuckers.