ACR Daytona Laps

[Gary Javo]

I took the ACR down to a two day event at Daytona on April 6th and 7th. I had a brand new set of tires and my goal was to run a respectable lap time. After talking to a few experienced friends, the general consensus was that anything under a two minute lap time was ultra fast for a street car.

It was raining the morning of the first day, and the track didn't completely dry out until my third session. There was a lot of traffic and it was challenging to get a clean lap. I still managed to run a 2:01 and a 2:02 in my first session on track. I went back out during the last session of the day and started sorting out my race line. I noticed a vibration above 150mph that had me concerned. I wound up running a 1:58 during that session and came back into the garage.

Upon further inspection, I discovered that my front right tire had a large section of inner sidewall missing. There were three other ACRs there and we wound up having several brand new Kumhos fail this way. Obviously, this was alarming. I thought that I would be done right there since I ran a sub two minute lap at Daytona. Unfortunately, when I checked the camera footage, we had a corrupted video file on the only forward facing camera.

Fortunately, I brought a spare front tire. I quickly took it down to the Pirelli trailer and they mounted and balanced the replacement tire. After quite a bit of discussion in the garage, we all decided to take the tire pressures up 4 psi over the factory recommendations to give the sidewalls a better chance of surviving the downforce that the ACR produces mixed with the g-force stresses of the banked corners at Daytona.

The next morning my goal was simple. I wanted to get a sub two minute lap on video as quickly as possible and put the car back on the trailer. I headed out and did two slow warm up laps. I came into the pit area and had the crew check the tires for any abnormalities. They set the hot tire pressure and I headed back out. I finished that throw away lap at warm up pace right up to the bus stop. Coming out of the bus stop, I was feeling a little unsettled about that front tire. Now, watching the video after the fact, it's pretty obvious that I was a little nervous during this lap. There are some small errors here and there, but overall I was pleased to run a 1:57 at Daytona in a completely stock ACR. I ran exactly one hot lap that day, got my number, and put the car on the trailer.

[BlknBlu]

Nice run, what was that car doing parked on the track....lol

Bruce

[poptarts]

That's awesome. How did you get your g force on the screen? That's cool.

[ViperGeorge]

What tire pressures would you recommend at Daytona?

[Gary Javo]

We decided that 32 rear 35 front hot was where we left it.

[Darius]

Looks like too much fun. It's a shame that the Kumho's fail that often. Get some Hoosiers on the front.

[ViperGeorge]

We decided that 32 rear 35 front hot was where we left it.

So were your cold starting pressures around 25?

[sadil]

That was awesome to watch!

[Gary Javo]

No. We went out high cold, then did two warm up laps. Came into the hot pits and had our crew bleed the hot pressure down before we hammered it.

[Bryan Savage]

That was awesome!! Nice work. Be sure to let us know if there's anything to that tire issue than "that's just what Kumhos do".

[viperBase1]

Wow, that was INTENSE. Congrats on the 1:57.

[Policy Limits]

That's really fast. Impressive video display too. Excellent top speed as well. The highest I ever get is 130mph on the straight at my local track and it's at the start of fourth gear. Thanks for sharing.

The tire issue does concern me. I keep Kumhos at 35 front and 30 rear cold so I'm not sure what reading that will be hot as I'm still in my break in period. What do you recommend for PSI when starting cold? I think I pulled my numbers out of the owners manual.

[ACR]

Gary stock cold is 30 / 34. Doesn't seem you're running the fronts much higher

[ViperGeorge]

At my local track (High Plains Raceway in Colorado) I start the Kumhos at 25 cold. After the session that will all be at 34-35. High Plains has two uphill right turns that push the left front tire pretty hard. Daytona will stress the right side tires pretty hard because of the banking. I would think that at Daytona a couple of easy laps with the pressures at 25 cold would bring them up to about 34-35. I'm told by Erich Heuschele that the Kumhos operate best at those hot pressures. But then again I have not been to Daytona in my ACR-E. I ran it with my 09 ACR a few times.

[SharpMan]

Seems to pull really hard up close to top speed.

[Policy Limits]

Amazing how aero reduced top speed by about 30mph. Can't think of anything that isn't functional on the thing. Just needs some wings and it'll fly. Ha.

[drabe]

Gary, how much neg camber in front?
Abe

[Gary Javo]

-2.5. I started with -2.8 a few track days ago, but I think that was too much and I backed it down.

[drabe]

Thanks. How many days you get out of a set?

[Gary Javo]

I'm really easy on them. I don't spend the whole time on the track. I could probably get 4-5 track days out of the fronts and a bunch more than that out of the rears.

[drabe]

Thank you

[99RT10]

Great job Gary!!! Always driving her hard

[XSnake]

What tire pressures would you recommend at Daytona?

I would recommend anyone that goes to Daytona NOT run Kumhos. We destroyed 5-6 this event and all were new or newer.

[XSnake]

At my local track (High Plains Raceway in Colorado) I start the Kumhos at 25 cold. After the session that will all be at 34-35. High Plains has two uphill right turns that push the left front tire pretty hard. Daytona will stress the right side tires pretty hard because of the banking. I would think that at Daytona a couple of easy laps with the pressures at 25 cold would bring them up to about 34-35. I'm told by Erich Heuschele that the Kumhos operate best at those hot pressures. But then again I have not been to Daytona in my ACR-E. I ran it with my 09 ACR a few times.

Daytona is different from every other track in the country. The loads the rights take is higher that anywhere else, especially with a high downforce car. If you go out at 25 I doubt you'd be able to finish the session. Ron debeaded a tire ar Sebring going out that low. Luckily, no damage done.