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dap930 dap930 is offline
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Join Date: Dec 2011
Location: Virginia Beach, VA
Posts: 417

I have not dynoed the car yet because I know I need larger injectors. I have done a number of datalogs through the year to dial in the VE table in the upper regions. I would like some ID725's or ID1000's but have not pulled the trigger.
You will definitely need larger injectors for 1.2bar boost and your larger engine size.


I had trouble setting up MS3 boost control also. I spent a lot of time datalogging valve DC for various RPM's and loads in the "set up" mode to populate the initial values table. When I switched to the basic mode, I would get overboost spikes when shifting from second to third, yet I had good control from 2500 to 6500 RPM. I adjusted the slider to no avail. It was as if the PID control could not react fast enough when boost come back up after the shift. I could not change the MAC valve DC in that region (around 4200 to 4400 RPM's) because it would mess up the linear pull from 2500 to 6500 RPM. The data logs showed that the DC from the Initial Values table was being applied after the shift but the boost just spiked. The domes on these wastegates are rather large, I came to the conclusion that venting the pressure from the top of the wastegate was taking too long. So, I changed to a high frequency MAC valve that operates at 39Hz. I also left the muffler off the valve vent port to reduce any restriction and kept the hose runs short. Now when I shift, boost rises to 224 - 226kpa (target boost is 217, boost cut set at 235kpa) and settles back. This is in the basic mode with slider at 200. I could go to the Advanced mode and tune the PID parameters but it works like it is. Of course all this varies depending on the turbo you are running, the exhaust manifold and muffler/zork. My GTX3071R spools up very quickly, yet will flow 50lb/min and is a good match for my 3.0 liter engine street driving.
1977 930 Slant, MS3 EFI, Carrera intake, Twin plug, Powerhaus headers, Magnaflow muffler, Garretson intercooler, GTX3071R
Old 08-30-2017, 04:35 PM
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