kapedogg

iTrader: (5)

On street tires and easy-off-the-line launches I was consistently putting down 12.7-12.8’s with 2.1-2.2 60’ at 114-115mph.
I put on a pair of Mickey Thompson ET drag radials on 16” rims and made some runs, most of which were 12.8-12.9 with 1.88-1.91 60’ at 109-110 mph, but had one run at 12.39 with a 1.91 60’ at 114 mph.

I compared the runs with the drag radials and found consistency through 330’ including the fastest run. But my 12.39 run was .4 faster (9.02 compared to an average of 9.4) and 5mph higher at the 1/8-mile mark. And gained another .1-.2 in the last 1/8 mile.

I’m launching them around 4k with 19-22 #’s. The fast run, my *** was all over until I hit 2nd gear then took off. It wasn’t spinning, just getting pushed around by torque and traction. The other runs were smoother feeling off the line, but obviously slower over all, shifting was pretty much the same across the board.

How can I have better 60’ times but slower runs with the drags over streets, but then one considerably better run? What forces are playing together and what do I need to do to improve consistency and faster times?

LS1 Sounds

iTrader: (11)

Your air pressure is too high in the slicks. They need to be able to wrinkle the walls in order to expand the contact patch, and 19-22 #'s is working against that. I would try 15 psi as a max starting point, and go lower from there checking how they hook.

kapedogg

iTrader: (5)

That was the plan, but we ran out of time. I know I can cut lower 60' times, but any clue why the runs were so outrageously different and why launching at 4k with those et drags and getting faster 60' times made my run slower overall than with street tires except for the 12.39 run and a 12.65 run?

tektrans

iTrader: (23)

You're running the ET drag Radials, right?
If so your air pressure is fine. I ran my best 60' on the drag radials @20 psi.
So you made 1 really good run and an xtra 4 mph. Your shifting at the same rpm every time? hitting the limiter? maybe your clutch is slipping and it just didn't on the 1 good run?
Now, at 114mph your 60' sure could be better. 16" rims/tires aren't the best for consistency.
I'll bet it's your clutch is slipping, tires spin, driver inconsistency, knock retard.
That 12.3 and 114 mph is very promising. Get that 60' down and you'll be knocking on the 11 sec door.

LS1 Sounds

iTrader: (11)

ET Drag Radials? In that case, never mind what I said... I just saw ET Drags in the subject and thought you were running slicks.

Ranger

Issue is likely to be the burnout. Please describe the procedure you used.

Properly heated, the MT Street Radials give very consistent results.

Ranger

kapedogg

iTrader: (5)

I know it's not the clutch slipping. It's got about 1,000 miles on it, and it holds really tight. Shifting felt pretty much the same, same RPM's thanks to a shift light. it's just that from 330' to 660' 4 tenths is a huge difference, so I thought it may have something to do with how far I actually moved in 1st gear and what speed I was going when I hit 2nd gear, even though 60' times were almost identical on all the runs. I know those can come down. My last run was the best 60' and felt the best in terms of shifting and the car running, but had a dissapointing 12.9 et.

In regards to heating them, I would start a burnout in the water in 2nd gear, and then let that push me forward and spin them for about 3 seconds on the dry surface. From what I've read, you don't want to get these too hot.

kapedogg

iTrader: (5)

I'm just confused as to how tire spin, launches, 60' times, horsepower, 1/4 mile times, and trap speed, are actually all effected by each other.

Ranger

He is driving MT ET Street Radials, not bias-ply. The radials don't flex the sidewalls and as pressure drops, the tread cups. I ran ET Radials at 20-22 psi on a 363 rwhp Z06 with stock rear and M12 tranny. 60' were consistent within .03 on a decent prep with dialed-in driving.

Ranger

Ranger

An easy way to look at it is th break the 1320 into two parts:
(1) 0'-60'
The driver variables are: PSI, coolant temp, burnout, launch rpm, clutch release, and throttle squeeze

(2) 60'-1320'
The driver variables are: shift points, speed of shift, throttle position on the shift, and hook on the shift.

Track prep and weather including surface temperature play roles too.

Keep track of both segments indepently. But your PR will alway be when both segments were driven well.

Ranger

Opinions and techniques vary. Here is mine.

Burnout Procedure Without a Line-lock

1) Put car Traction System-Off

2) Drive around the water.

3) Back into the damp area, not the wet area. Back up enough to get 3/4 or more of the tire tread damp. Don't spin the tires in the water. You just want to get most of the tread with a sheen of water.

4) Roll forward to the leading edge of the damp area. Start the burnout there. Do NOT roll so far as to put the rear wheels onto the heavy sticky rubber/VHT prepped area.

5) The car should start and finish the burnout with no more that a foot or two of forward movement.

6) Put the tranny in 2d gear. This will enable the tires to heat faster, because they’ll spin at a higher indicated mph. Since the tires are damp, they spin quite easily in 2d.

7) Drop the clutch, feed the throttle and immediately lightly apply the brakes with your left foot. The brakes are helpful for keeping the rear-end from walking sideways.

8) Bring the rpm to about 5000 and hold it there until the tires smoke well and start to drag down the rpm. At that point, back out of the throttle and release the brakes. You'll roar forward. The tires are heated.

9) It is helpful if you adjust the driver’s outside mirror to view the left rear wheel/smoke.

10) Warning, if you botch the burn-out, DON'T retry it with dry tires. Doing that will likely glaze the clutch...or…break an axle shaft.

11) Practice will help get synchronization of the foot movements.

You can practice in a level asphalt parking lot with water from a couple gallon jugs.Draw a couple lines with chalk to help establish an alignment guide. Pour out three or four gallons of water generally at the wheel points. Voila. You’ve got a pseudo water-box. An observer/spotter is a plus.

Don’t worry about brake wear. Four seconds on the brakes is like braking 60-10. You do that every time you drive the car.

Here is a link to a video of Ranger's Burnout without a Line-lock Please right click save as......

In the vid I'm on DRs.

Backed into the damp area just past the concrete stripe and then pulled forward to the leading edge of the damp area.

Play it slow-mo. I drop the clutch and hit the brakes. You can see the brake lights. I spun them to strong smoke; and when the rpm began to be drawn down...then backed out of the throttle and released the brakes. You can see the two marks in the surface where the tires spun. The whole process took four seconds.

If you spin the tires in the water, water is thrown into the wheel wells and will drip down onto the heated tires, making the 60' and beyond inconsistent.

A four tenth difference in the 330'-660' incremental is a notable anomoly suggestive of a track-timing issue.

On ET Street Radials, first pass of the day, full smokey burnout. All succeeding passes that day, heat them just to first smoke. MT Tech calls that "hazing" the tires. If you over-smoke them on the 2d+ pass you lose .10-.15 in 60'.

But your water-box burnout is the first issue to correct.

Ranger

kapedogg

iTrader: (5)

Thanks for all the guidance guys. It may sound dorky, but I'm going to keep a spreadsheet tracking as many variables as possible, and review the videos to judge shift speed and apparent throttle positions.

Does that sound about right for heating them properly. I found out a buddy of mine has a heat gauge so I'll start using that.

I know this thing can run in the 11's, the sooner the better!

LS1 Sounds

iTrader: (11)

Yeah, I picked up on that later in the thread... That's what I get for trying to read the board at work, on a Monday.