Here is how I determine what size injectors and fuel pump sizing:
First I determine how much horsepower I want to make on E85, this is not determined by boost, this is the required fuel it takes to make a certain amount of horsepower, a rough estimate to get you going. Next use the calculator to determine the required injectors at the fuel pressure you intend to run, most TD's ran 55 psi base fuel pressure.
http://fuelinjectorclinic.com/flow-calculator
As an example ill use my build, I want to make 500 wheel horsepower at 43.5 psi for a base, so using the calulator I determined that 120 lb/hr (1265cc/ min) injectors will make my 500 goal.
Next you need to figure out fuel pump sizing, I use this link to determine that.
http://www.deatschwerks.com/resource...ump-calculator
So in my example. I input the values of 4 injectors, 1265 for injector flow rate and base pressure of 43.5. You can now here put in whatever boost level you plan to run, just know that as the fuel pressure rises, you will have less capactity by the pump. The fuel pump will no output the same flow at 75 psi and 85, it goes down.
So at this point my example shows 303 L/hr at 73.5 psi, which is 30 lbs of boost.
Most fuel pump manufacturers should have graphs avaialble for their pumps to compare to.
In my application I am looking at either a Walbro 400 e85 or the AEM 320 E85 version.
But to be honest I have read of numerous cars making over 500 whp running on single Walbro 255's (what I currently have) and large injectors on E85, a close friend has been on that set up for years. So in my case with very close watching, I am going to see how far I can push my Relayed 255 on E85 with the 120 lb/hr injectors I already have.
But here is a good starting point for your reasearch.