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5% less than what was posted in post 11. If it's a t04Z compressor you're about tapped out. 72-73 lbs/min and it's usually done and that's with the bigger compressor covers. But usually that compressor isn't done till it won't make anymore boost which means no wastegate bypass.
Thank you..I was thinking I have plenty of turbo..its just that my iron heads are limiting me.
If you have mid 9 sec power it's possible that a good set of aluminum heads could help. What was the drive pressure at flash stall and at the end of a pass?
Bison, I'm not sure what you mean by drive pressure. I have peak HP of 623 at 5300 rpm on dyno at 28 psi of boost. Increasing boost makes no more HP. I have at 9" PTC non lock convertor with a weber 218 cam. When I ran at the track, I could actually feel the car stop pulling on the top end, it would just level out. I'm using FAST XFI and AFR was 11.5.
I mean the exhaust pressure. I suspect a valve train malfunction if it's laying over and you can actually feel it do it. What was the road hp by mph on the dyno? It's a much better indicator of what it will run in the quarter. I made 620-650whp with a 6668 (chitty t-netic cast 66) multiple times at 5200 rpm but it dropped like a rock at 5400 and couldn't keep up with the engine and boost tailed off. It needed more compressor or taller gearing to get more e.t. The 6265 I sell a lot of didn't generate much more than 580whp but it stays within 10hp of it for the first 8 seconds of a full pass. Less peak but a higher average. Same heads and cam and both examples were stock 3.8 GM short blocks. Did eighth mph increase with more boost?
peak hp was 623 at 92 mph and falls to about 570hp at 134 mph. I went back at looked at my logs from the track and noticed my PTC convertor is only dropping 100 rpm on the 1-2 and 2-3 shifts. I believe my convertor may be slipping. I went back and looked at some time slips and it looks like my 1/8 mph stays around 102-106. not much change with more boost.
It would depend on what rpm you shifted at to determine the drop. If it's dropping to 5200-5300 after a shift it sounds about right for what you have. You mentioned you felt it fall off in the quarter. If it's picking up close to 25% mph in the back half it's not falling off. 102-106 is a huge range for eighth mph. 102 should net 127mph. 106 should be 132.5mph. So a 10.5x vs a low 10.20. If you're running out of turbo gains will taper off as boost increases. If exhaust pressure is increasing at close to 1:1 compared to manifold pressure it's not out of turbo. Id expect exhaust pressure to be in the low 40's at the end of the pass. You're definitely not out of head.
