drothgeb

Tomorrow it's track time, and it's my first time with slicks. (Hoosier 255/50/16 DR2s)
I can find lots of info for launching on streets through the search but not for slicks, if any of the vets could give me some tips it would be much appreciated

Burn out on the DR2: My guess would be a couple seconds long? I have the burn out down on streets, is it different on the DRs? I feather the break a little, turn TC off and giver some gas.

Launch: On streets the consensus is raised suspension, sport mode, TC on. Any different with the slicks, maybe TC off?

Any other drag racing tips much appreciated. Never raced with slicks before, thanks guys!

JoeJErnst

What are your mods? How quick do you expect to go? For reference, I have been running 11.40's with 1.68-ish 60' times on those tires.

Just last weekend I ran the tires at 27psi on a prepped track and picked up over .5MPH over running them at 19psi, with no negative effects on my 60' time.

Traction Control should be OFF. I would suggest starting with the pressure up around 30psi and lower it by 2-3psi each run until it dead-hooks. I do a pretty short burnout. Leave the tranny in S mode, stall up to about 1200-1500 rpm at the light, and smash the pedal at the last amber.

If you still have the airmatic suspension, I would leave it sport I or II. I never saw any difference between the modes when I had it, so I doubt it makes much difference either way.

Good luck and keep us posted! (let's see some pics too!)

drothgeb

Thanks for the info! At the last 5$ track night I ran 5 times for 4x 13.3s and 1x 13.4 with three of them being back to back. Only mods then were cooling. Consistent 2.2 60fts. I obviously could use launch work but there is zero track prep on the open track nights. Oh and 7000 DA

New changes for this trip are 77mm pulley, tune, and slicks. (Also the slicks must be 50 lbs lighter each than my wheels, they are the heaviest wheels I have ever felt in my life)

Tonight will be about 6000 DA, I am HOPING for high 11s, but I will be okay with low 12s haha.

JoeJErnst

Holy Crap! Do you live on top of Machu Picchu or something?

One more pro-tip: The Hoosier DR's are in a little bit of a grey area in the "slicks" vs "street tires" debate because they clearly say "not for street use", but they also have a DOT number stamped on them. Technically, if you run slicks you need a driveshaft loop. If you think your tech guys might be sticklers, you may want to go through tech on street tires and then put on the Hoosiers. If they give you any grief, be prepared to point out the DOT stamp on the tire. (I had to go through this a few weeks ago when there was a new tech guy at my local track)

drothgeb

Haha, just in Nevada with some serious summer temps. Thanks for the tip on the DRs.

When you are launching sounds like it's pretty similar to how I was launching with streets, but are you rolling on the throttle or are putting it through the floor when its go time?

JoeJErnst

The drive-by-wire on our cars has a lag that will kill your reaction times if you go from idle. I get best R/Ts (and 60') by stalling to about 1200-1500 rpm at the light. That seems to be enough to take that "lag" out of the system. Then I stomp that sucker to the floor on the last amber.

drothgeb

Perfect I will give it a shot thanks

EDIT: Just checked drag times, it's supposed to stay at 70* today, DA will be 4900, way better than last time, I'm excited now.

drothgeb

Welppppp it was a fun night but a bit bummed overall. 12.5 at 112 was my best run of the night. I had a couple of issues.

1. I could not get my 60' below 1.8. I got 1.8 a several times, one of them was rolling onto the throttle and dead hooking, and one was mashing the throttle and spinning. But I could not dead hook and launch hard all night. I also could not get a proper burn out with ESP off. I couldn't get them to spin for more then a half second. I put the car in DYNO mode and could roast them just fine. I started at 20psi and dropped to 15 and cooked them good at 15 but still couldn't dead hook :-[
2. IATs were hitting 160. The SC doesn't like the extra pressure very much haha. I'm going to add a second CWA50 and two heater core water to air heat exchangers in parallel to try to nip this in the butt.

trabots

Whatever the tyre, how does one get around the inevitable heat soak warming up your IC water during a burn out? Seems to me one might be quicker launching on cold tyres but with fully cold IC water. I run a KC and can get the IC water below freezing but one good full throttle burst will send it back over ambient.

JoeJErnst

Do you have a limited slip diff? I forgot to mention that I have a Wavetrac, and I guess it helps a lot because I can't even imagine traction being a problem in my car. I go to two local tracks, one is known for a good prepped surface, and the other is known for a crappy unprepped surface and my car dead-hooks on both of them.

Something else to keep in mind is your rear camber. If you car is lowered, or if it just suffers from the MB excessive negative camber that they all have from the factory you may not get the best traction. I got mine sorted and I'm running pretty much zero camber in the rear.

Here's a pic of my timeslips from last night. You can see that the tire PSI (started at 30 and worked my way down to 20) had little effect on the 60'. I think my new normal will be to run between 20-25 PSI, depending on track condidtions





That's exactly what I would see before I added the Killer Chiller. Even with the KC I still see a 60-degree rise, but now my IATs are starting at 57 instead of 90. It shaved about .15s of my ET and has made the car much more consistent.

JoeJErnst

You shouldnt' have that problem if you have a tank with your KC. I just looked at my logs from last night and my IAT was at 57 deg F prior to my burnout. During the burnout it went up to 63, but then dropped back to 57 before the start of the race. Ambient was 65 deg F. I have a 1.75-gallon front-mount tank in place of my heat exchanger.

drothgeb

I do not have an LSD, and toe and camber are all factory. Not going to spend the money on an LSD any time soon but I'll definitely do some research on the camber.

trabots

I have 2.5 gallons capacity in my tank/lines/KC/intercooler volume. I have not yet gone to the strip,, just speculating. Obviously I will have to try it both ways. Cheers.