Grip Engaged: Smashing Lap Times at Auto Club Speedway

"Jake Stumph Racing" (jakestumphracing) 01/09/2016 at 14:00 • Filed to: BMW, Trackday, JakeStumphRacing

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The best improvement you can make to your car in regards to reducing lap times, beyond fixing the loose nut behind the wheel, is tires. Those four slabs of rubber pounding into the pavement constantly will do more to transform a car’s behavior on the racetrack than anything else.

This brings me something fun, my new wheel and tire setup.

Previously:

17x8.5 ET35/ 255/40 Hankook RS3 (Front)

18x8.5 ET52/ 255/35 Hankook RS3 (Rear)

Currently:

17x9 ET35 with 255/40 Hankook RS3 (Front)

18x9.5 ET57 with 255/35 Hankook RS3 (Rear)

Glancing at the figures you might be confused. “The tires haven’t changed compound or size, where is the improvement?” To which I would say, look more closely, the wheels themselves are wider, front and rear. Modern extreme performance “street” tires are giving us a lot more than what the label says, and the Hankook RS3 is no exception. The sidewall may be stamped with “255 section width” but it reality, it’s greater than that, about a 265, really. That means that we need a wider wheel to really take full advantage of the tire, performance stretch, if you will. Running a wider wheel on the same size tire will actually result in wider footprint as the tire is less pinched than it would be with a narrower wheel. Additionally, we get the added perk to increased response the sidewalls of the tire are now tauter, offering a more crisp turn-in and general feedback through the wheel.

With all of that laid out, let’s take a quick look back to our last visit to Auto Club Speedway.

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On my first shot at running the Roval my fastest lap of the day was a very loose 2:00.3. A solid baseline indeed. Worn out Hankooks are still a blast to drive, but not fast, as evidenced when I would try to use second gear at any point, resulting in rolling burnouts for 20-30 feet past the corner exit.

Here are some outtakes and amusing clips from that day:

Enjoy the corny great royalty-free music since YouTube was on my case.

Rolling up to ACS is always exciting, this place oozes motorsport.

Arrival. Unpacking. Inspecting and double checking. With the precision of a broken rifle, I quickly ensured those that I had ensured prior to arriving. Human beings are creatures of habit, repitition of the pre-flight checks can only be a good thing, right?

I’m not the only one shuffling around. A cacophony of speed had begun emanating from pit garages across the paddock. High strung four bangers buzzing away, six cylinders of both V and H configuration sat idly by. Uncorked V6 engines sing a raspier, bluesy note than Louis Armstrong, while Flat-6's hum at idle, quietly waiting for their chance to shine once the needle sweeps past 8-grand. A rouge five cylinder wail heard in the distance. Speed has no prejudice. V8's, many of them, in fact, lope about, their charasmatic big displacement gusto seeping from their panel gaps, as if to say “I make more torque at idle than you do, period.” It’s the sound of freedom, and justice for all.

Pretty bad ass, no mufflers, the loud exhaust badge of pride sewn on our jackets.

Until two race teams rocked up, unloaded two Radical SR3 race cars and an Audi R8 V10 LM. We all play racecar, they are racecar. BRINGGG THE NOIZE.

I know it’s not a contest, but goddamn did they win.

My little twin-turbo, 3 Liter Straight-6, sans mufflers is roarty, but not to that level. Praise be to the Gods of Speed who have bestowed upon us all, no shame for savagely loud and stiffly suspended track toys.

Temporary numbers suck, should have registered earlier. Could have used my nice magnets. Oh well. It’s perfect here, today, I’m here and I can’t complain.

Two minutes flat on shot tires. I want to hit 1:55 today. Yes, five seconds is a lot, but I have faith in the Hankook tires. When fresh, they are pretty much unbeatable for “street” tires on the track (barring the Bridgestone RE71R). Let’s get to it.

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1:58.4 on the first session. Excellent. Most of the first session was just reacquainting myself with the track, turn in points, etc. and learning about the new setup’s limits in terms of tire grip. I was turning in too early initially as I was unsure of what the car’s behavior would be like. Unsurprisingly, with more tire footprint, brake later, and ask more of the front end. Got it.

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Going back out there, ready to crush some lap times.

I was in the groove now. With the first session under my belt, I was ready to hit it hard, and hit it hard we did! Coming through the T9-T10 chicane, carrying over 110mph I cut the inside curb a touch too tight and bounced it. It was a pretty big two-wheel moment with a substantial hop, but no lost momentum. Listen to the audio and you can hear me say “Sorry car!” but goddamn was that fun.

If the “OH SH*T!” at the end of the video didn’t queue you in, we dropped a TON of time running a 1:54.8 hot lap.

Well Internet, my job here was done. I surpassed by 1:55 benchmark. Time to kick back and relax for the rest of the day...

That last quote came from the GoPro, unfortunately, not me. So for the remainder of this story I shall regale my tale the old fashioned way with prose and stationary videos aka pictographs.

Oh wait, my girlfriend got this quick fly-bye video. Here’s the thick end of 130mph from one pissed off Bimmer.

Well. since we still have half the day left, may as well whittle down that 1:54.8. I bet there’s a few tenths left in terms of my level of talent. A wheelman of greater skill could probably take a few seconds off where I stand, but I am not that person, yet.

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I began to focus on carrying more speed through the bowl. From leaving the infield, freightraining through the front straight and making it through T2 is approximately 45 seconds of your lap. Needless to say, finding the nuance of speed here will seriously help your lap time. It’s a tricky corner, with no one set line, seriously, some people take it high, some people hang out in the middle, and some cut it tight and hang out at the bottom. A banked NASCAR oval is no joke, especially for passenger cars not explicitly setup for it. My goal was to carry 130mph through there. So lap by lap, I slowly added speed, learning what the car would do through the oval.

I’ll take a two-tenth jump every day of the week. If I improved by two-tenths every time on track for the rest of forever, I would eventually be running negative time . “Did you hear about that guy, Jake?” “Yeah, I heard he ran the oval so much that his times were faster than 0 seconds.” Goals.

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“C’mon, get in the car!”

“Wut.”

“Wheeeeeeeee!!!!”

Whoever said that showboating didn’t lead to good things?

Dropped four-tenths from my peak lap time, down to a 1:54.2, and consistency shot up across the board. :54's and :55's across the board, barring my cool down lap. Damn you, GoPro, you missed the good stuff! Crested 130 through the bank and held tight lines through the infield.

The new setup on the car works, no doubt about it. Combined with my last showing at !!!error: Indecipherable SUB-paragraph formatting!!! , which resulted in heavily dropped lap times, this outing was an incredible success. The car worked tirelessly all day and was one of the fastest RWD, street tire cars there. Very happy with how this all turned out. Except, now I want to run 1:52 and really give those GTR’s something to fear when I catch them up in the infield.

SnapUndersteer, Italian Spiderman > Jake Stumph Racing 01/09/2016 at 15:34

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Next time, go for real grip in the 200TW category and get RE71R tires.

I bet that’s easily 1 second

Jake Stumph Racing > SnapUndersteer, Italian Spiderman 01/09/2016 at 17:04

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Very easily a second or two, but RS3 are so cheap and available used that I still have another year’s worth of RS3 stored away.

I use the Re71R for my autocross Civic since it is the gripier tire.

PG; the scalpel wielder > Jake Stumph Racing 01/09/2016 at 17:23

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great job again bud! I’m itching to go back to the track again after I install my RB PCV valve and DPs. I just walnut blasted the car with a friend of mine and oh boy it was awesome! MHD flash stage1 at the moment is doing the goods too.

One suggestion to you is perhaps buy an external mike for your go pro, and feed it through the boot and clip it on the underside of the diffuser using an extension cable. Makes a big difference since the car is so insulated.

Jake Stumph Racing > PG; the scalpel wielder 01/09/2016 at 20:04

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I usually do use an external mic, I just forgot to bring it. :) See here: