how much will injector flow change after installing FD fuel pump ?
(useing the original injectors 550 on a turbo2 and no rewire done)

anyone know ? do we have a % number that we can use for tuening after this change ?

/bo

 

Well I would think that unless you've changed the fuel pressure regulator, the amount of fuel coming out of the injectors would stay the same... The system will just bypass the extra flow back to the tank, unless the fuel pump flows SO MUCH that it pegs the regulator open and still manages to elevate the pressure in the rail. But then tuning will be difficult since the pressure will not be constant.
But that's just off the top of my head. I don't have any 1st hand experience with this particular mod.
Good luck

 

I have not changed the regulator, but I did notice that I have increased flow due to that it is harder to start and drinks loads more fuel !

my car is a S5 if that matters ..

/bo, i will test a 3% down tune.

 

MY S5 TII-No changes noticed with the installation of the FD pump. Startup/idle the same. Have had the pump in there for a year.

 

The walbro should be a better upgrade, it will flow more fuel and is brand new as opposed to whatever used pumps yu guys are running. In any event, the FD pump may over-run the stock regulator at idle and will definitely richen things up as the revs rise and fuel pressure comes up.

 

I'm starting to wonder about my waldbro... it makes a hell of a whining sound......

 

Walbro's on Ebay=$90

 

Totally normal, the internal gears are made of metal, not plastic. This makes them much louder...