by Freon » Mon Aug 27, 2007 12:15 pm
You can probably get 17-18, but only under 4500rpm, maybe only under 3800rpm. That poor little TD04 has a hard time filling the big 2.5L motor.
Your change in manifold absolute pressure in percent should not be too much more than your change in airflow. If your change in manifold absolute pressure is +5% but your airflow only increases by 2% I would stop there, or maybe even back off.
I.e. at 4000rpm if you change boost from 17 psi to 19psi (about 33psiA to 35psiA), that is a ~6% increase in MAP. If your airflow at 4000rpm only goes up from 190 to 195g/s (~2.5%), that probably means your turbo is already being pushed too far. If you instead go from 190 to 200g/s (5%) that's means you're probably not overruning the capacity of your turbo and/or intercooler.