I'm not sure which one would be beneficial for a E85 setup with Grams 1000cc injectors. Around 500whp goal

Normal https://walbrofuelpumps.com/450lph-w...0267.html.html

High pressure https://walbrofuelpumps.com/walbro-4...tive.html.html

What is the benefit of going with the high pressure? I read the differences but I cannot put that information into anything I can understand.

 

How much boost are you planning to run to reach your goal, and what base fuel pressure? The regular one (which I am using, btw) is only rated to 87 psi fuel pressure before the flow starts to drastically drop off - look at the graph on the link you posted. If you're running 4 bar (58 psi) fuel pressure, you can run 29 psi of boost before you start getting into dangerous territory with the regular pump (58+29 = 87).

 

I think max psi from a GT3076R is around 25-29psi from what I've read

 

My guess would be the high pressure version would be for returnless fuel systems that don’t use a map referenced fuel pressure regulator.
or like Dax said high base pressure combined with high boost pressure

 

I ran mine @ 55 psi base with 30 psi+ on top to make 650 with E85

 

Yeah, I'm at 50 psi base + 29 psi boost, and it hasn't shown any signs of leaning out.

 

Might as well get the higher high pressure fuel pump. I think you’d be more safe with it. I used to have a Vortec fuel pressure riser (10:1) FMU using 8psi of boost and didn’t have any problems with fuel on stock injectors and a stock FPR, so I’m guessing I was at 100 something PSI of fuel pressure. The Walbro 255l/hr high pressure fuel pump kept up well. When I went into boost, the fuel pump got louder and had a whine to it.
You might get close to maxing out your 1000cc injectors for 500whp though. If you haven’t purchased them yet, you might want to go bigger, like 1200cc or larger.