Track results are in - converter slippage?

[Craig 94 TA GT]

So I finally took the car to the track. I wasn't expecting much because I had never launched it in this configuration and need quite a bit of bugs worked out. I seem to have a problem with the converter slipping at the upper end because my MPH is pretty low, and varies 2-4 mph on different runs.

Here is the best run (which isn't superb, but it's a start):
60': 1.789
330': 5.143
660': 7.952 @ 87.042
1000': 10.402
ET: 12.49@106.46

The LT1edit program shows that the converter is supposed to lock up at around 90 mph, but I really don't recall it doing it. Of course, I'm not paying attention to that. So if it is locking, the TCC may not be holding well. The converter maker said it's not a beefy clutch and doesn't recommend locking up at WOT. My best MPH of the day was a crappy 108.5, but once I get the converter figured out, I think I can definitely improve on the ET.

[EDIT] After reviewing the Datamaster logs, I think I already found the problem. It is the TCC clutch. I see the RPMs bogging and dancing around once it hits 95 mph for the clutch. With my 1/8 mile speed, I should be around a 110-111 trap speed, so maybe I can pick up a tenth or two and a few to several MPH just from keeping the TCC from kicking on?

Oh and I was the only LT1 there, and everyone was scratching their heads on a 100% smog legal daily driver sub 12.5 sec LT1 because LT1s don't get respect out here anymore.

[Joe 1320]

You'll lose .2 ET and 2 MPH with a bad lockup clutch. Keeping it unlocked isn't the answer. At that point, all locking the clutch does is increase the load against the driveline. Look at your A/F ratio when the converter locks.

[ConElite]

Hey man dont tell me you ran at AutoClub Saterday?

[Craig 94 TA GT]

Thanks Joe, I'll step through the scans and consult with Jeff Creech. On the runs I hit over 108, you can hear it in the video locking up. I can't hear if it kicks in on the 106 runs because of the next lineup prestaging.

Eddie, I'm in the bay area, so I was in Sacramento Raceway. Did you go to the strip this weekend?

One thing Jeff told me was that I'm not getting on the gas hard enough for the launch. That hurts my 60' a little, so maybe I can cut a tenth in the launch, which is about .12 in the 1/4 mile? That should mean low 12s should be easy after figuring out the converter, a/f issue.

[Craig 94 TA GT]

Now that I examined the logs, and had Jeff Creech's help, we have some observations. First, I'm noticing that my trap at the end of the 1/4 mile on the scan shows 109-110 mph. So I'm not quite sure why 106 is on paper. Either the timing sensors were off, or the scan is showing incorrect. All my low traps were on the left side. The right side was over 108 all times. Also, according to Datamaster, the last 66 feet shows it starting at 107 and ending at 109. The average should be 108, which I'd assume should have been the trap.

Although the RPMs still bog when locking up - you can even hear it on the passes. Here is the video and you can hear the lock up on passes 1 and 2. http://www.youtube.com/watch?v=R1-bFjoyjng
You can't hear the others because of the noise of other cars.

Jeff also noticed a problem of the MAF readings where the motor isn't eating enough air for the mods I have. So either the motor itself is an underperformer, or there's some kind of restriction going on. I can go through my intake tract and maybe someone can point out if one of these is a bottleneck, or maybe all combined?

- Moroso CAI. Filter is over 10 years old and was recently cleaned. Not sure if there are limitations to a CAI?

- Stock MAF with screen. I think this isn't a problem as 96Capricemgr is running a stock MAF and trapping at 113 with the same heads/cam.

- Vortech intake elbow. I know this is smaller than the stock rubber elbow, and gets heat soaked, but enough to actually decrease air flow somewhat to significantly?

- AS&M 58 mm tb and ported TB holes on intake but stock intake. I've seen guys running these with a huge cam, but no issues. So I don't think this is a problem.

- SLP 1 3/4 shorties with Carsound cat. I know the cat does restrict and long tubes are better, but could this cause the whole motor to not breathe as good?

- Borla cat-back with small 1/4" deep, 1" long dent in i-pipe and e-cutout before muffler, but after i-pipe. I know true duals or a 4" exhaust is better, but I dont know if this would cause a major restriction.

Thanks in advance for any tips!

[ConElite]

I noticed what the problem was, Your "In reverse" burnout the first run!!!


No but seriously, you can hear it kinda hang when your down the track.

[Craig 94 TA GT]

Oh man, that was so embarrassing. I had no idea it was in reverse, then when I let off to gradually move forward after the burnout, it went backwards. I was like oh crap! And from inside the car, it seemed like the burnouts were pretty good and long. But from the video, they were wussy tiny burnouts. As I found out through the day, the longer I did the burnout, the more agressive I could get on the launch. The first runs at 12.7 were unagressive launches with ~1.95 sixty foots. The last one was way better at a 1.789, but I still could get it down to high 1.6s with just technique. That should get me down to 12.3s, and maybe the converter issue will get another tenth to 12.2. Then of course, there's the bottleneck issue of something in the intake or exhaust. Ugh.