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I've been waiting for this time to come for months! Fortunately the weather decided to cooperate with my work schedule, and I got to spend a great Test-N-Tune day at Great Lakes Dragaway on Saturday. The weather was pretty good (high 40s - low 50s, humidity under 50%, barometric pressure 29.2, and density altitudes of under 500 feet), but the track was still pretty cold without much rubber build-up, so traction wasn't the greatest.
I haven't had the Sunbird at the track since last July, and I was anxious to see how it would run with it's new exhaust system. I just had a custom-built 2.5" system (minus cat) welded up with mandrel-bends, and a Dynomax Turbo muffler. It's quite a bit louder, but I wanted to make sure that I didn't lose bottom end power with the bigger system. I designed this system to work for the race engine I will drop in this summer, but I feared that it would be too much for my current tired old motor. I also wanted to test a suggestion from my engine builder to reduce my shift points to improve ET. For years I used the same shift points for consistency, 1-2 at 5600, 2-3 at 5600, and 3-4 at 5000. He strongly felt that this was higher than it needed to be.
I started the day off using the old shift points to get a baseline. I noticed an immediate improvement in my mph due to the new exhaust system. In past years, I was usually in the 83 to 85 mph range, with a best ever of 87.25 nearly 10 years ago with only 40,000 miles on the car (I now have nearly 152,000). My first run was 85.77, and then I set a new record of 88.33, followed by 85.79 and 87.25. ETs were better, but not great due to traction limitations, I was only able to launch at 2500 on my Drag Radials (I usually launch at 3000). My best ET with this system was a decent 15.742. That compares very favorably with last year.
I bumped my shift points down to 5400/5400/5000 next, and saw immediate improvement. I launched better (2.109 60 ft) and ran a 15.657 @ 86.39, followed by a 15.679 @ 88.60 (2.159 60 ft, and another mph record). This rivals my best runs of the last 3 years, so I was thrilled.
Next I bumped down to 5200 across the board. My first run I had a horrible launch (2.307 60 ft), but I still ran 15.889 @ 85.70. Then I launched a little better (2.198 60 ft), and ran 15.759 @ 87.62. The ETs fell off from before, but I felt that shifting even lower would help.
Next I bumped the shifts down to 5000. It felt strange because the 1-2 & 2-3 shifts came up so quickly, but the car felt like it was flying! I picked up my timeslip and was thrilled with the results:
R/T - .038
60 ft - 2.044
330 ft - 6.266
1/8 - 9.786 @ 69.53
1000 ft - 12.851
1/4 - 15.471 @ 86.52
That isn't far off the all-time record for the car of 15.416 @ 86.54 when the car only had 40,000 miles on it. The numbers surprised the heck out of me! Now I wish that I had been shifting at 5000 rpm for all these years instead of winding it out. I can only imagine what it might run once the track is a little be stickier so I can launch at 3000 rpm or more! Maybe I'll set a new PB with the old motor before it gets replaced!
Hope everyone else is getting back to the track and enjoying racing again as well!
I haven't had the Sunbird at the track since last July, and I was anxious to see how it would run with it's new exhaust system. I just had a custom-built 2.5" system (minus cat) welded up with mandrel-bends, and a Dynomax Turbo muffler. It's quite a bit louder, but I wanted to make sure that I didn't lose bottom end power with the bigger system. I designed this system to work for the race engine I will drop in this summer, but I feared that it would be too much for my current tired old motor. I also wanted to test a suggestion from my engine builder to reduce my shift points to improve ET. For years I used the same shift points for consistency, 1-2 at 5600, 2-3 at 5600, and 3-4 at 5000. He strongly felt that this was higher than it needed to be.
I started the day off using the old shift points to get a baseline. I noticed an immediate improvement in my mph due to the new exhaust system. In past years, I was usually in the 83 to 85 mph range, with a best ever of 87.25 nearly 10 years ago with only 40,000 miles on the car (I now have nearly 152,000). My first run was 85.77, and then I set a new record of 88.33, followed by 85.79 and 87.25. ETs were better, but not great due to traction limitations, I was only able to launch at 2500 on my Drag Radials (I usually launch at 3000). My best ET with this system was a decent 15.742. That compares very favorably with last year.
I bumped my shift points down to 5400/5400/5000 next, and saw immediate improvement. I launched better (2.109 60 ft) and ran a 15.657 @ 86.39, followed by a 15.679 @ 88.60 (2.159 60 ft, and another mph record). This rivals my best runs of the last 3 years, so I was thrilled.
Next I bumped down to 5200 across the board. My first run I had a horrible launch (2.307 60 ft), but I still ran 15.889 @ 85.70. Then I launched a little better (2.198 60 ft), and ran 15.759 @ 87.62. The ETs fell off from before, but I felt that shifting even lower would help.
Next I bumped the shifts down to 5000. It felt strange because the 1-2 & 2-3 shifts came up so quickly, but the car felt like it was flying! I picked up my timeslip and was thrilled with the results:
R/T - .038
60 ft - 2.044
330 ft - 6.266
1/8 - 9.786 @ 69.53
1000 ft - 12.851
1/4 - 15.471 @ 86.52
That isn't far off the all-time record for the car of 15.416 @ 86.54 when the car only had 40,000 miles on it. The numbers surprised the heck out of me! Now I wish that I had been shifting at 5000 rpm for all these years instead of winding it out. I can only imagine what it might run once the track is a little be stickier so I can launch at 3000 rpm or more! Maybe I'll set a new PB with the old motor before it gets replaced!
Hope everyone else is getting back to the track and enjoying racing again as well!