treynor
Enthusiast
Yep, I grabbed Liz's '03 SRT/10 and headed back to the dragstrip for grudge night yesterday. I had installed Purner's 18" wheel / BFG g-force drag radial setup on the rears, and was ready to go lay down some numbers.
Upon arrival I set the rear tires to 18 PSI and the fronts to 33 PSI. Runs were coming every 20-30 minutes throughout the evening.
My first run was fairly mild, with a short rolling burnout and a launch at 2500 RPM and netting a 11.8 @ 121 with a 1.90 60'.
The next run I did a slightly longer burnout and launched at 2800 RPM, netting a 11.7 @ 121 with a 1.82 60'
At this point I was fairly excited. The rear tires were easily holding everything I threw at them, and visions of 11.5s danced in my head. However...
The next run I did a similar burnout and launch at 3200 RPM. The revs rose immediately on launch, and for a moment I thought I was spinning - except there was no sensation of tire spin. After a second I realized the clutch was slipping badly. I aborted the run, and sure enough the delectable smell of heated clutch wafted into the cabin shortly thereafter. I had found the weak link, and it was no longer the tires.
Figuring that the clutch was simply overheated from the initial series of back-to-back runs, I did the next run with a 1200 RPM launch and no slip. This netted an 11.9 and a much happier clutch. However, on the following run I tried a more aggressive launch again and the clutch once again slipped. The message was clear: good launch traction was too much for the stock clutch to handle.
At this point I considered my options. Since the clutch was not going to tolerate hard launches, and soft launches left the SRT out of its powerband for far too long, the only other obvious option was to let the tires do the work for me. A plan was formed.
The next run I skipped the burnout entirely, and launched with a 2000RPM clutch drop. The tires spun, the clutch held, I floored the gas, and the SRT scooted out of the gate with both DRs spinning, then hooking up at about the 60' mark with a good shove in the back. The timeslip told the tale: a 1.9 60' and a 11.66 @ 122 and 96 MPH in the 1/8th (!) as the SRT made great use of its power down the strip. The clutch was also completely happy with this treatment. I backed the run up with an 11.688 on the following run. The last two runs of the night were 11.8s as I experimented with tire pressure in a vain attempt to find additional ET without changing my launch technique.
Conclusions:
* The stock clutch is not up to real dragstrip duty. The SRT's tall 1st gear demands a clutch slip launch to get good 60's, but the stocker will not tolerate that treatment.
* The SRT needs only DRs, a 3.55 gear and a stronger clutch to be a real dragstrip terror.
* All that said, consistent 11.6s @ 122 is not too shabby
Upon arrival I set the rear tires to 18 PSI and the fronts to 33 PSI. Runs were coming every 20-30 minutes throughout the evening.
My first run was fairly mild, with a short rolling burnout and a launch at 2500 RPM and netting a 11.8 @ 121 with a 1.90 60'.
The next run I did a slightly longer burnout and launched at 2800 RPM, netting a 11.7 @ 121 with a 1.82 60'
At this point I was fairly excited. The rear tires were easily holding everything I threw at them, and visions of 11.5s danced in my head. However...
The next run I did a similar burnout and launch at 3200 RPM. The revs rose immediately on launch, and for a moment I thought I was spinning - except there was no sensation of tire spin. After a second I realized the clutch was slipping badly. I aborted the run, and sure enough the delectable smell of heated clutch wafted into the cabin shortly thereafter. I had found the weak link, and it was no longer the tires.
Figuring that the clutch was simply overheated from the initial series of back-to-back runs, I did the next run with a 1200 RPM launch and no slip. This netted an 11.9 and a much happier clutch. However, on the following run I tried a more aggressive launch again and the clutch once again slipped. The message was clear: good launch traction was too much for the stock clutch to handle.
At this point I considered my options. Since the clutch was not going to tolerate hard launches, and soft launches left the SRT out of its powerband for far too long, the only other obvious option was to let the tires do the work for me. A plan was formed.
The next run I skipped the burnout entirely, and launched with a 2000RPM clutch drop. The tires spun, the clutch held, I floored the gas, and the SRT scooted out of the gate with both DRs spinning, then hooking up at about the 60' mark with a good shove in the back. The timeslip told the tale: a 1.9 60' and a 11.66 @ 122 and 96 MPH in the 1/8th (!) as the SRT made great use of its power down the strip. The clutch was also completely happy with this treatment. I backed the run up with an 11.688 on the following run. The last two runs of the night were 11.8s as I experimented with tire pressure in a vain attempt to find additional ET without changing my launch technique.
Conclusions:
* The stock clutch is not up to real dragstrip duty. The SRT's tall 1st gear demands a clutch slip launch to get good 60's, but the stocker will not tolerate that treatment.
* The SRT needs only DRs, a 3.55 gear and a stronger clutch to be a real dragstrip terror.
* All that said, consistent 11.6s @ 122 is not too shabby
