Someone has to make a decision regarding whether you want to achieve the 8 second cycle time or achieve the quality level stated. The two are incompatible on the machine and tooling you describe. You have already used up thousands of seconds experimenting, with little to show for it. Drills are good for removing material and little else. Reamers follow what has gone before them. Your problem has to do with deflection of the cutting tools as they attempt to cut material in an extended mode. Single point boring is the only way you will achieve the concentricity results you are looking for on a consistent basis. You need to achieve the maximum rigity at the cutting tip as possible. Talk to Kennametal about their special boring bar material and make the bars the largest diameter and shortest length that you can.
Make the cored hole as large as possible as long as you are removing material with each pass of the cutting tool.
Secure the bars as close to the spindle bearings as possible. Maybe Hydromat could help with this, it is unlikely that they will be much help regarding the tooling. They may need to upgrade the class of bearings at the station where you are making the final pass.
Instead of zeroing in on the cycle time, look at the total cost, including machine maintenance; tooling cost; downtime cost etc. If you do that properly my guess is that the cycle time will increase, but the number of acceptable parts produced per shift will increase.
Sorry for being so long winded, but I have been in your position in the past and can appreciate what you are going through. Good luck.
