oklahoma

I am drag racing a 2016 c7 a8 with Nitto 105 drag radials. Most of the time throttle response is instantaneous but sometimes when I fail to do a dry hop after my burnout I experience a delay in my SOTP message that acceleration has started relevant to going WOT. On these occasions my 60' time will be off by .1 to.2 seconds but the rest of the run is normal. Tire spin does not appear to be occurring but could the presence of cars in the other lane with open exhaust keeps me from hearing any tire spin and my pit crew says that they can't see any. I am running 19# of air in the tires and would like to go lower but they have begun to spin on the rim about a 1/4 inch per run now. I run in track mode with TC off and leave at 1800-2000 rpm. At Atlanta with DA 3500 best run 1.79 60' and 11.77@119.5. Any thoughts ???

C2367

Too many unknows, is the car stock or any mods? Base or Z51? Tire/wheel size? Would say at that 3500 DA on a Stock car you are doing a great 60, ET and MPH. Best run I got on a great day around 400 DA is a 1.67 60', 11.51 @ 120.90 on my Base A8 NPP, no mods with 285/35/19 MT DR's @ 26psi.rear and 45 psi front. Best 60' to date 1.636. I leave from a dead Idle and stomp it, that is the only way I can get a good 60".

Dcasole

C2367 , not to go off topic but what rear wheels are u using for your MT's as it looks like I am going with the 285 19 also , are they stock c6 base rims ?
One more question , do you get the drag radial wiggle ?


Oklahoma Commerce is my home track and our DA just sucks …..plus on Friday night test and tune the track prep is worse than the DA
When are you running ? if its Friday night it could be the traction going away , last time I was out I wanted to set a baseline before putting MT's on the car , tune and CAI , 1st run was a astonishing 1.7 on the stock MPSS , the next run the sun was going down and the track started to cool down ,was a 1.8 and then the last was my personal worst 2.0 . I am pretty sure it was not me as I was using Launch control ….

Dave

C2367

I am using Stock 2017 C7 Base OEM 19X10 but a 19 x10.5 or 11 would be best to get more contact patch. TSW makes 19X11 with the correct offset. I race in sport with T/C off, tried L/C and got awful 60's. My car does not hook with the OEM Run flats, tried but was dangerous and spun crazy. Yes, the DR's get the wiggle on most runs around 100+ mph and it feels unsafe. When running the 1/8 mile it is fine, don't notice the wiggle but my best 1/8 mph is only a little over 97mph. The DR's seem to dead hook most runs after a good heat-up.

Dcasole

thank you !!!
that 100 mph wiggle gets your attention fast ......I wish I could find a tire that does not wiggle
I can pop a 1.7 - 1.8 60 with Launch control as long as the track has bite and is hot with the MPSS ....but let nite fall hit and all the grip is gone

Dave

Mike Jesse

oklahoma

I am running 225x45 17's on the front and Nitto 285 35 18 on the back using c5 rims on back and American Racing 17x7.5 on the front. I agree with flooring it from idle gives the best ET but reaction time suffers leaving off of the 3rd yellow. The car tracks like an arrow and I have noticed the "wiggle" at higher speeds with other setups on my c3,c4, c5,and c6. I am bracket racing on Saturdays and usually the DA starts at 2500 to 2800 and gets worse for the duration of the event. Track prep is repeated 2 x per event usually but sometimes more for oil downs etc. I think I am getting silent tire spin from overheating the drag radials. Currently I am holding the car in first and letting the tires spin up to 3000 for a count of 3-5 seconds and then the dry hop before staging. At what rpm will your cars push out of the staging lights? My car is pure base car with only mod being tires and Using factory e 85 sensor from Dave Stick and stock ECM programming for e85 and usually about 77-80% alcohol per the sensor.

C2367

Do you get anything out of the stock ECM programming for e85, heard you do not have a loss of power from heat soak.

oklahoma

For me the main advantage of using e85 with its surplus of octane is that I can zero out intake air temp retard and engine coolant temp retard to 160 degrees and 220 degrees respectively which allows more accurate et prediction based on DA only and not having to worry about variable levels of heat soak while working up the staging lanes during actual racing. I have recorded my runs and see no ignition retard with this setup.

Poppacapp

If you gentlemen are running the full sized oem tires up front with Drag radials in the rear you can eliminate the sway by running a set of skinny front runners up front(I use the MT Sportsman SR 26x6-18 on my 18x5 Forgestars.

You will still lose power due to Coolant temp being too high, or IAT temps being too high. The PCM will pull timing even on E85

You will still get retard with Coolant temps/IATs getting too high.

oklahoma

I failed to mention that I also have max fan at 203 degrees and even with hot lapping never see ECT above 215 degrees.

Poppacapp

It just depends on where the ECT adder table is set at. Running E85 won't affect coolant temps.

383vett

Back to the op's original post. A dry hop after the burnout does nothing but give the drivetrain added stress. Save it for the launch.

Mike Jesse

I had a M/T rep. tell me that doing a dry hop after the burnout will take heat out of the tire. Not good for max traction.

Bubbletop409

When running NHRA Super comp/gas with my 540 powered Z-34 Lumina coupe I was told the same thing by an MT rep. I was also cautioned about doing an excessive burn out, five seconds at the most, roll forward and stage. Air pressure and side wall construction are also very important, as is matching rim width to tires size. What is doing a dry hop suppose to add to the traction co-efficient at the launch?