Starting back down the turbo path....

     I still have the used turbo from a Saab (9000 I believe) that is basically a T25 that was on a 2.0. I'm only going to use it for mock up, not planing on actually using it because it needs rebuilt. I rather buy one and use the old one for mock up, that way if I destroy it in the process I won't be out anything.
     In my search for the right size turbo I've visited many sites that have calculators to help recommend a turbo. But they ask so many questions that I don't know the answers to that they were almost useless. All I wanted was a simple answer to my problem.
               When will the turbo start to make boost??
     Too big of a turbo and I might have to rev the motor to 3500 or more to get boost, then what's the point? I want boost down lower, like starting around 2000 to 2500 for more fun on the street. The other concern, although highly unlikely to ever happen, would be using too small of a turbo that would spool quickly but run out of flow before my red line.

     So I found a site that gave the mathematical formulas to do your own calculations and links to compressor maps to use your data. And there I was, a D math student calculating stuff light years above what I barely got in high school. I gave up when my eyes started crossing and the numbers started running together before I could figure out which turbo I needed.
     So I tried the same approach that got me through math, find a shortcut to the known answer and generalize the next set of data.  

     So I did the calculations my way-

               2.0 liter engine with a 6500 red line -- 2.0 * 6500 = 13,000  stock Saab setup
               2.5 liter engine with a 5500 red line -- 2.5 * 5500 = 13,750  my setup
     So using my backward method math a T25 will be perfect for the 2.5. Now I could rev the 2.5 higher, some guys on the net brag about spinning theirs to 6500 with no problems, but I'm going to try and impose a 5500 red line to help make the engine run longer.
     During my searches I found places selling twin turbo headers for 350 chevys with T25 flanges   
               5.7 liter engine with a 6500 red line -- 5.7 * 6500 = 37,050  normal red line
               5.7 liter engine with a 4500 red line -- 5.7 * 4500 = 25,650  just under 2x the 2.0 saab
     If they think that two T25s can feed a 350 on the street and my math says it would take 2 T25s to feed a 5.7, I must be in the neighborhood of close to correct if you set it up mildly. Obviously a 350 could handle much much bigger turbos, I've read articles on 1000hp twin turbo setups, but I'm only looking for 200 tops.