Anyone know a correlation between DA and OVERDRIVE?

Some of you know I run a outlaw limited street car with a blown BBC in it. The car is nose heavy and I run a small tire, I have battled to keep the tires under the car and thought we had a good handle on them, but it seems that when I run in mine shaft air I just cant keep the tire under the car. I run the thing so FAT in bad air on the starting line (55 Main) I use 3 stages of fuel control down track, but I need to know how much to back the blower off in REAL good air from where we are as I dont seem to be able to do it any other way. Is there a chart or reference for this???

Say 2000 ft I run 32% over and when I show up somewhere and its 40* and 900 ft, how much should I turn the blower down???
Thanks
Jim

FYI the car 4.93 @ 155.00 mph to the 1/8 at 3410 lbs on a true 10.5 2 weeks ago. But I couldnt get it off the line this weekend in MINE SHAFT AIR

 

fyi

Also I am lookin into building a wastegate(plumbed into intake) to bleed off boost on the line and bring in on a timer... Anyone know of someone who does this now?

 

Yes I am pulling 15 * for 2.5 seconds on launch control and pulling an 2-4 from 3000 to 6500 on the rpm graph, have total timing at 29* Conventional head 509 with BMF heads. 14/71 retro hihelix with k8 rotors. 3 electronic high speeds on timers.

I agree 100% that I need to back it down when the air gets good, but HOW much for every 100 ft??? Thats my problem now, this past saturday night 58* car hooked, 32 over, 2600 ft DA 30% humidity....
By first rd.. Air was 890 ft 90% humidity... and 37*... I turned it down to 24% left timing and fuel alone and smoked the tires AGAIN!!. But it was closer. I have had this problem several times this year when the DA gets below 1200 ft.
Just curious if there is a formula or chart for how much should I back it down or is it gonna be trial and error?

 

Mike I also think a SCREW blower may be easier for me to get down the track with as well, since they dont seem to have as much boost from the hit at the same RPM.. I leave at 32-3600 rpm.

 

I change the main jet. I tune mostly with my 3 high speeds though. I rarely ever burn any cad on the plug untill its in HIGH gear and the last few feet of the track. To give you an idea how fat I have the set up.

 

Where are you lighting the tires up? At the hit, or mid track?

 

I do, call me 214-724-1056

 

Was having trouble getting off line with 522 BBC blown. My problem turned out to be car being nose heavy.Had car scaled by good chassis guy.hAD TO ADD 50# TO REAR OF CAR. Went right down the track.Kept trying to take power away before scaling car.Check shock settings should push down on rear and car should move down slowly to stiff you are scrwed losen them up.Scale out car at least 49-50% on rear then hit with power of course still need some timing retard.Maybe 14 degrees rampeed in over 2 seconds . 29 degrees ain,t nothing for total timing .Will be running my car at Orlando this weekend.

Doug Horween
NHRA 2650