bobybeach- thanks for your clear explanations!!!! and the time you've taken to do so!!!! I'm still piecing this whole puzzle together and this thread helped put a couple pieces in place.

 

bobybeach- I'm planning to run 26 lbs on my t-61. What effect does the Q exhaust wheel and large race exhaust port have on torque production, ability to keep it up at top end? How many pounds of boost could you expect this set-up to maintain through 7500 rpm? and how much different would it be if it was a street port with std small exhaust wheel? I'd appreciate seeing your math if you have the time. Thanks!

 

very good question i am interested as well.....
bobybeach, you could just keep explaining and explaining as far as im concerned

 

Thanks IIIGenX,
The Q trim wheel will allow you to make slightly more torque with lees back pressure. It wont effect the point were torque start to drop (the compressor is the only thing that will change that) except that it will be consistantly slightly higher than if you were using a p trim. Note that slightly more torque across the board wil also mean you will have slightly more hp
As for Porting This will allow you to reach the turbos flow limits with less boost, but the power that you make will come from the compressors flow limits and this wont change.
Porting does allow you to drive larger turbos that are capable of more flow.

Wow! now im getting carried away...
Ive made a quike graph that plot torque against rpm.
Asumming same compressor with different turbine trims, and running same assumed boost that will mean compressors have reached flow limits before max engine rpm.

note that on both graph were the torque is level this is were the boost is holding on the turbo to the desired setting.

remember this graph is only a rough sketch, The level or degree of changes in torque here are not to acurate scale.