dragonfly

I have been running BFG 295-18 DR's on my 2000 MN6 car. 306 RWHP, and 4.10 rear.

My last 4 trips to the strip have been at 45-50 degrees, and in the evening with a cold track.

I have been disappointed by the 60' times I have gotten. For the most part they are mid 1.90's. This is comming off the pedal quickly but not sidestepping (at 4000-5500). This past trip I side stepped at 4500RPM with a 62 degree air temp and planted a 1.83. As the evening cooled down to the normal 45-50 that evening I could not get better than a 2.0 even with reducing the launch RPM, it still spun bad.

Pressure is usually 15-17psi.

I do a 10 second burn out each time. Currently I have run a best of 12.58@112.35. Still searching for the 11's (hopefully only headers, exhaust and a good launch away)

I was hoping I could get 1.7x on a regular basis.......have any of you data loggers noted a huge temperature effect?

Vette#2

Been there, done that. Try 12 PSI & if that doesn't work go to 10 psi.

Burnouts don't work when the track surface is COLD.

dragonfly

I sort of figured, just looking at what qualifies as a good temp?

above 65? and below 120?

Also looking for reassurance that 1.70 is achievable for stockish 6spd with stock clutch and BFG's.

Ranger

A critical factor in traction is the track surface temperature. Which can be lower than the air temp, depending on many factors.

Even a very well prepared track surface will give less traction as the surface temperature decreases through the mid-40s.

I ran my 315.35.17 BFG DR at 18 psi (on 12" wide wheels). And I would not recommend dropping yours below 16, because they will cup and reduce the contact patch.

You might want to look at how much water you are getting in the burnout box. You may be a little too aggressive there and be getting water up in the fender wells, causing it to drip back down on the tires once they are heated.

As for the duration of the burnout, suggest spinning them until the engine rpm begins to drop (from the growing stickiness of the tires), rather than counting seconds.

As for "an achievable 60'," look for folks with your set-up including rwhp and clutch.

With 50 more rwhp and a stock clutch, my BFGs got mostly very low 1.7s, with some in the mid-high 1.6s and some in the mid-1.7s.

Ranger

'06 Quicksilver Z06

May have been the dew point. The temperature at which dew or condensation begins to form.

I have witnessed the same thing. I was running the car on a cool night As the temp crept lower, my 60s and ETs got worse.

The dew point plays a role. Park your car outside on a cool fall night and you'll see what I mean.

Had I been astute, I would have realized that the fine condensation forming on the surface of my car's decklid and other cars, as the temp started to creep downward, is the same condensation forming on the track. No wonder I couldn't get traction.

REDGAR

10 second burnout might be too much

Qksilver

Burnouts will help and I really don't see much loss of traction until the 40's. Normally on these lower temp. days the humidity is lower which is a great help for the BFG's and Nittos. With these lower temps your gaining hp, which if you can slip the clutch right should decrease your 60's. My best 60's are with the track temps between 45-50. EB20003 is right on the money... If you reach dewpoint or the humidity is high it's a pain to hook up. Worry about these factors more than the track temp. Also, I really doubt going to 10-12 PSI will help either and I wouldn't recommend under 14 PSI.

LSK

I dont know about BFGs but with Nittos you really have to roast them good and hot with the burnout. A lot of folks dont do this and then they say they dont hook, which is BS. I know plenty of A4 fbodies that have done 1.5x 60s on Nittos.

Do not go down to 10 psi. You are good around 20. Just have to get the tire hot.

Dr.Ron

I had my best 60' on DR's (1.68) w/ 17psi. Burnouts are necessary, but I agree if the track is TOO cold, you can't hook. Mid 40's are good temps to run in. It has to be your launch technique that's hurting your times.
Ron

fergy flyer

Orlando speedworld does not prep the track very well. it seems like they use almost no vht and the track is definately not very smooth.
I have tried Gainesville a couple of times with the Vette and a couple of times with my previous F body. Same results, better 60' at G-ville.

If you remember the one time I cut the 1.67 at Speedworld it was cool but the guy ahead of me drop something on the track. They cleaned it and hit it with a torch, and sprayed a little vht right before I launched. We should be coming outta there with VHT all over the back of the cars after making 6 passes, but we aren't.

Are you going on friday? So far I'm in for either Wed or Friday.

dragonfly

I will be there friday hoping for something better than a 12.58

C5 CU

my best runs were on a day with 46* temp...BFGs DR at 16lbs and 4500rpm clutch dump...when temp dropped a few more degrees then track lost traction for my set-up...also found that a little spin gave quicker 330ft time but a little slower 60ft time...a little spin keeps the front up and no loss of momentum (?).