slant 6 rebuild and upgrade list
using your 1.7 and 290cfm the 14g shows on the right edge of the center "ish" island @74-76% and the 16g (small wheel) is really similar assuming I'm reading it find 1.7 line or place it should be. run it across to the 260-290 line and pick the point they intersect?
They best way I can tell you do this well and right is to look at the first link, and look how the family of engine flow curves (demand lines) are superimposed on the turbo maps. (Those are the multicolored straight lines at an angle.) Then follow that method. They author makes this statement: "Ideally, you want to select a compressor that has a flow map that covers all the engine demand lines up to the boost levels you are prepared to use. If significant portions of the flow map lie outside of the engine demand lines, the turbo may not be appropriate for the engine."
Read all of that several times and absorb it. I set up an Excel spreadsheet to help with these numbers. The demand lines are straight lines that are easy to figure and plot. The bottom of the line at PR=1.0 is simply the engine flow at normal pressure (0 psi boost) with the VE accounted for. In the case of the 225 at VE=1.00 at 1000 RPM, the flow is 65 CFM. At each RPM level, multiply 65 times the number of thousands of RPM's and then multiply by the estimate VE. So, for 2000 RPM and a VE of .90, the 0 psi boost flow is 65 x 2 x .90 = 117 cfm.
Once you make assumptions on the VE at each RPM level (that's the tricky part!) and plot the 0 psi boost points at 1000 RPM intervals, then simply draw lines up the map so that they intersect the PR=2.0 line at 2x the 0 psi boost CFM's. For example at 2000 RPM, that line would be at 117 CFM at the PR=1.0 line, and at 234 CFM where it crosses the PR=2.0 line.
This gives you an idea of how well the engine is going to 'stay in' the turbo across a broad range of RPM's and boosts. If the demand curves crowd off of the left side of the turbo map, then the turbo is big for the engine and will probably not respond well at lower RPM's. If the curves crowd off of the right side of the turbo map, then the turbo is small for the engine, and it will have lowered boost at higher RPM's but should come up on the turbo quickly at low RPM's.
