Just completed the install of a Yank 2800 torque converter in my Edelbrock supercharged 6.0L 2006 convertible. After the install, which I completed on Sunday the 11th, I took it for a test drive of 150 miles plus for break in. Everything worked quite well with no problems, operating as the stock converter with no issues. Took it to the track for test and tune night to see how it would perform under WOT, race conditions. Just after launch while in first gear and just before shifting into second, the transmission would slip and catch a couple of times before shifting into second. Second gear and Third worked quite well with no issues. Even with the slipping, my times in the 60 foot and quarter were two or three tenths better than with the stock converter. Any ideas on what could cause the momentary slipping just after launch?

Low fluid. Most people overfill by at least a half quart and as much as 1.5 quarts. The harder launch tends to drive the fluid to the back of the pan and away from the pickup. If you look at a scan, you'll see the dip around 5K when the pump can't suck up enough fluid. By the time you get into 2nd gear, the fluid has come down to the lower pan again.

Add one quart and test again.

Thanks for the reply HOXXOH. I have added more fluid, adding 1/2 quart to start. When installing the converter, I drained and changed the filter of the transmission. I monitored the amount of fluid extracted when performing this function and tried to replace what I lost or removed. I pumped what I thought was just shy of 2 gallons in the transmission and thought I had more than required but when I went to check the level I found I was a bit shy, nothing drained from the plug when removed at 100*. I added what I thought was about 2 quarts and tested again, this time about a quart came rushing out while I waited for just a drip. Like you I suspected perhaps I needed to add back a bit of fluid so I am starting with 1/2 quart. If there is no change, I will add another 1/2 quart. Appreciate the help, thanks again. I will report back on the results following a return to the track, Friday the 16th (tomorrrow).

Three things come to mind after reading your posts:

1) The "momentary slipping" just sounds like wheelspin which is common after adding a higher stall converter and if you're not running drag radials and/or the track prep isn't great it'll be even worse
2) If your fluid level was actually low you'd most likely experience slipping in all gears. While it does help having an extra 1/2 quart in it for good measure, I doubt your car is launching hard enough to really need it
3) See #1

Without having HP Tuners to scan your runs, there's no definitive way of verifying that it's wheelspin or a different issue. Something that would give you a reasonable idea would be to watch your speedometer when the "slipping" appears to be happening. If your MPH jumps and drops along with your RPM then it's probably wheelspin. If the MPH climbs at a fairly steady rate without any spikes but your tach is bouncing up and down then it may be something else.

Launch problem solved! Adding 1/2 Quart (adding fluid as HOXXOH suggested) fixed the slipping issues at launch. The car ran perfectly through all gears (1st, 2nd 3rd) providing a personal best ET of 11.2 with a DA of 8800, Temp of 81*, at 77% Humidity. Had adding fluid not fixed the problem I would have been data logging with HP Tuners as suggested by Subfloor. I use to data log every run but stopped to concentrate on driving rather than collecting and analyzing data. The Yank 2800 was good for 3 to 4 tenths in the quarter. Launch characteristics of the new converter are much different than the stock converter which has messed with my reaction time. I will have to practice with the new set-up to determine how best to launch for a consistent RT / ET. Thanks for your help and suggestions. I used Subfloors tutorial when installing the new converter. It took me about 5 days of slow meticulous work to change out the converter. I wasn't rushing but taking my time, cleaning, inspecting, and enjoying the process. I have a lift system which allows for 50" of clearance under the vehicle. At 71 I'm not quite as strong or limber as I once was so when confronted with functions requiring muscle, I recruited the help of my son who has an abundance of muscle and was happy to help his old man. Most the work I accomplished by myself but when dropping the rear cradle, and separating the transaxle from the torque tube flex plate, I had the help I needed to accomplish this task.

Glad you figured it out.