LS1Formulation

iTrader: (13)

Last year before my trans gave out, I did a heads/cam package on my car, along with LTs and true duals. Cam is a TR 224/228 on a 112. Heads are CNC ported 241s Also have a FAST 85MM intake and the typical bolt ons. My ET prior to the heads/cam was 12.70@112. After the install and untuned, I took it out to the track and it ran 12.66@115. Needless to say, I was VERY disappointed. Now I have been looking at cars built similar to mine and they are running four to five tenths quicker in the 1/4 than my car but have nearly identical 60' times and identical MPH. I just pulled my trans out the other day and found a couple of things. First of all, it has a stock replacement clutch made by LUK in it. I can't imagine that was holding the power my engine was making - if it was it would be a miracle. Is it possible the clutch was slipping and I didn't know it? This is my first high performance car with a manual trans, so I'm not quite sure if I could tell if it was slipping or not. It never really revved up in gear under power, which was what I figured a slipping trans would do. My guess is that at higher RPM, the centrifugal weights kept it from slipping, but at lower RPM it slipped a bit, causing my ET to suffer. Secondly, it seems I have a slight rear main leak. That could have effected the clutch obviously, but I have yet to remove it and see if that is indeed the issue. I really don't think the tune could be off so badly that the car didn't pick up any ET, so I'm ruling that out. Any ideas would be appreciated.

*I just found out the clutch was the STOCK clutch with 150K on it. It seemed to hold well though, so I'm not sure it was the issue.*

NSSANE02

iTrader: (14)

I went from a 12.4 to 11.9 with a new clutch, but it was slipping pretty bad. I also added LCA's and SFC's between these runs but my 60' was just about the same so it was mostly the clutch.