James Montigny

iTrader: (13)

At what point do I stop letting more air out of my ETDRs and start adjusting
my rear shocks to gain traction?

Obviously, you want to keep the rear from squatting if possible, and you
don't want to run on low tries and introduce drag. But at the same time
pulling 2.5sec 60fts while you spin off the line isn't very productive either.

The car hooked awesome at 18psi with the rears set to 6 (out of 8)
The car would not hook at 17psi with the rears set to 8.

wolfy

iTrader: (1)

bump for interest...

Ranger

Two points to make.

With the MT Street Radials the burnout is crucial to the consistency of the launch. Many folks make too much smoke after the first pass. Instead they should just make "first whisps" of smoke. More than that and the 60' will suffer. So testing at the track requires proper burnout, held constant through the test.

The way to check for max contact patch is to do the standard test.

In a parking lot, at say six different rear psi, without a burnout, spin the tires enough to leave 5=10 feet of rubber. Using chalk mark each patch laid with the psi.

Then study the rubber patches to determine which psi gives the best most even blackness side-to-side. This process will identify ideal psi.

I found on the MT Radials that my 363 rwhp C5Z06 got the best contact patch at 20 psi with stock suspension and standard wheel alignment.

Ranger

James Montigny

iTrader: (13)

Interesting, yet logical
So the goal is to maximize contact patch, then move on to adjust for traction.
I'll mess around with that.

Maybe I should consider 27 or 28" tires.


As for burnouts, I had a horrible time trying to hook with short ones.
Once I started holding the throttle down a bit longer, I was able to hook much better.
From the driver's seat, the burnout felt excessive. But from the 60ft times, it actually helped.

Ranger

^^^ To isolate cause and effect, you need to change one variable at a time. And you need to be very careful with the burnout procedure regarding water. Water on the fronts means your rears will drive through the water track on the way to the line. Don't want that unless they're skinnies. Also if you spin the rears in the water, even a little, you may get water in the wheel wells and it may then drop onto the heated tire after the burnout. Don't want that either.

Anyway, if your launch (Launch rpm, clutch release and throttle squeeze) are completely dialed in and you are changing only burnout duration, then your "longer" burnout conclusion is valid.

I and others have found that MT Radials get greasy when the oils are brought to the surface further with a second long burnout of the day.

Not trying to be argumentative. I've made 500 passes on DRs and kept a log in an effort to empirically determine the techniques that work best in my cars. That's all I'm trying to share. May not hold true in your car with your driving style.

Ranger

gator's 99TA

iTrader: (2)

I totally agree with ranger. 20 psi works great for me and a small burnout. just enough to see smoke. 28" tire works better than a 26" tire.

James Montigny

iTrader: (13)

Thank you for your input Ranger, I do appreciate it.
You certainly have more experience with this than I do.

Ranger

James, Just to be clear on the MT Street Radial burnout procedure.

First pass of the day...full smokey burnout.
Second and all subsequent passes that day...spin the tires to first appearance of smoke. MT Tech calls the "hazing" the tires.

Helps if you adjust your outside mirror (left or right) to give a view of the rear tire. Easier to accurately calibrate the smoke.

Ranger

James Montigny

iTrader: (13)

BOTTLEFEDLS1Z

iTrader: (32)

Great info

REDGAR

Hey Ranger question for you.

Some days I may have a 2 or 3 hour wait between passes. In this situation you the the hazing practice is still best?

gator's 99TA

iTrader: (2)

the overall goal is for your tires to be within 10 degrees of the track temps.

Ranger

Hi REDGAR.

As a bracket racer and auto-tranny guy, you are much more focuse on the goals of predictability and consistency than I am, as an M6/M12 go-fast driver who's not into brackets.

What I found on my 2002 C5Z on MT Radials was when my 60 footers started drifting up, I could solve that by focusing back on the burnout duration, ensuring less smoke rather than more. If the pass-gap was 60-120 minutes, I normally drove the car enough to bring the engine oil to >150. That warmed the tires some. Then just haze for the burnout. My impression is the MT Radials bring oils to the surface if spun too much on 2d-thru-N pass.

Regarding the "ten degree" rule. I did measurements at an Atco November track rental when the surface temp was low 50s. If I kept the DRs to 60-70 degrees, they spun the launch. At 100-110 degrees they hooked well.

Twas a limited experiment, but enough to indicate that the ten-degree guideline didn't work for my car on those tires.

Ranger

gator's 99TA

iTrader: (2)

i live in florida. we dont see 50 degree track temps. ever. lol 110+ is the norm

Ranger

With full sun the black racing surface can hit 100 degrees with a 50 dgree air temp if it's not windy.

In late fall in MD with a full overcast sky the track temp can be lower than the air temp. The traction breakpoint for me has been a surface temp of 43-45 degrees. Lower than that, it's not been possible to produce acceptable launch hook. But at a surface temp of 47 degrees the stock C5Z and C6Z tires will still hook after a proper burnout.

Ranger

REDGAR

Thanks Range.

I am usually of the same length burnout every time theory. With the new 402 in there I have lost some consistency so I find myself revisiting the basics these days.