I’ve only had my GXP to the track one time, back in September 07. I posted this up on a Bonneville site at the time, but thought I would post it over here as well. The runs were made at Thunder Valley raceway in Noble, OK.
At the time, my car had a partially gutted airbox. Since then, I’ve fully gutted the airbox including a bigger inlet, and cleaned up the throttle body entrance with a die grinder. Traction was not very good that night, as evidenced by my 60-foot times. Not really sure what my car weighs, but I would assume its at least 300lbs lighter than a Caddy.
Temp was a steady 67 degrees the entire evening per my Climate control display. It seemed to be fairly humid. There was no significant wind that I noticed.
I run 93 octane in this car exclusively. I had about ¾ of a tank of gas before I left for the track, and I added about 3/4 of a gallon of tolulene. That might not be beneficial for an N/A car, but I thought it might give me an edge. I did several WOT pulls in town and on the highway thinking that the PCM might respond with more timing to go with the slightly better fuel. By the time I got to the track, I had just over ¼ tank. Now I realize that with a stock PCM, higher octane is not going to help.
Pass#1: For the first pass, I had a bin of tools and misc junk, plus a small cooler in the trunk. I stomped it off the line thinking it would hook because of all the rubber on the starting line, but it spun about ½ way through first gear; here are the results:
1/8 ET 9.832
1/8 mph 74.12
I was disappointed, but knew I could do way better. The car felt like it lacked power for some reason.
Pass#2: I decided I’d go ahead and get everything out of the trunk and hope nobody ripped me off. Rough guess for the stuff I took out 30 lbs or so. I did a better burnout this time. Instead of stomping it I floored it a bit more slowly and was rewarded with much less wheelspin:
1/8 ET 9.633
1/8 mph 75.44
What a relief! I came to run a 14 – mission accomplished, now I could relax and see if I could do better. The increase in mph was a pleasant surprise although taking out 30 lbs does not explain it.
Pass#3: Removed Passenger headlamp:
1/8 ET 9.57
1/8 mph 76.01
Pass#4: Removed jack and spare, hit compressor button to pump up the shocks (and turned it off before the pass):
1/8 ET 9.512
1/8 mph 76.43
Yeah! Solidly into the 14.60s
Pass#5: No more changes. I launched it fairly easy, but still got some wheelspin just off the line.
1/8 ET 9.485
1/8 mph 76.48
Sweet – I picked up on the ET a little more! However something went wrong on the mph for this pass. If you compare it to the previous pass, it’s obvious it fell off at the end somehow. I had less than ¼ tank at this point, so maybe it was that, the fact that I hot-lapped it, or maybe I just didn’t keep my foot in it long enough…who knows.
I expect to run 14.40 next time out, I would like to make it back out sometime this spring.
the bonneville gxp has a curb weight of 3,790 lbs. my 93 sts has a curb weight 3,870 lbs. nice times..i'd like to take my sts out sometime and see what trap times would be. i need good performance tires though.. i have excellent all season passenger tireson it right now..which is good cause its winter! did you power brake it to minimize wheelspin?
I was running the original Goodyear GAs, I have since put on some BFGs that do hook a little better, at least on the street. I was just loading the engine slightly on the brakes (guessing like 1200 rpm but didn't really pay attention), then on green I'd release the brake and give it x amount of throttle. As long as I didn't break the tires loose too bad, the car would take full throttle about 2 car lengths from the starting line. Maybe next time I will try loading it up a bit more and see if that helps.
Not sure if the gutted airbox helped, but the stocker had an internal tube that was 2 5/8" id, so I thought it would help to gut it.
Your decreasing ET and increasing MPH is what I have seen when drag racing at night. As the sun goes down and atmospheric conditions change, I usually see see between 3-5 tenths difference from a 6:00pm pass, compared to a 10:00pm pass. This is without changes in my setup(low 15/high 14 second truck).
I will have to get the STS to the drags. I would guess low 15's.