ok, if a fuel injector flows say 48lbhr at 58psi and you are runing 7psi boost should you subtract the amount of boost from the fuel system flow psi? it seems if the fuel system has to push against pressure then it would lower the amount it can push out. am i wrong on this? its hard to explain what i'm thinking but thats best i can do.

 

I would think not. While I see your thinking I think the pressure difference would have to be much greater to have any effect.
I would also wonder if the opposite might be a little true where the venturi affect would actually help pull some fuel out of the injectors.

 

Yes.

 

I stand corrected!

http://www.racetep.com/begiregins.html

 

Your abacus must need oiling. My calculator sums that equation at 56.832.

 

You know I thought that number looked way high, but I didn't check it out. I just copied it from the page it came from. Looks like they made a mistake.

 

Oh, sorry. it's Top-End Performance's abacus. Anyway, aren't most boost referenced pressure regulators set up to raise fuel pressure at a 1:1 ratio?

 

Yes, the differential between the rail pressure and manifold pressure are what determines the flow rate.

 

The same is true with vacuum, that's why returnless fuel systems have a sloped flow rate table in the PCM and return system have a flat flow rate table.

 

Yes. If you are running a 1:1 boost ref'd reg, then this problem goes away.