fuel injection plumbing

[philminotti]

I'm using a Mass-flo system on my motor. The following schematic is from their website. (my apologies for any copyright infringement)




The next schematic is from the Aeromotive website:



Notice that in the Mass-Flo schematic, the rails are fed "in series" while the Aeromotive schematic shows the rails supplied "in parallel". I'm sure it works both ways, but does anyone have any thoughts about the pros and cons of each? The Aeromotive scheme certainly requires more fittings...

phil

[bobcowan]

The second rail gets whatever is left over from the first rail. The second rail could see a drop in pressure or volume if supply is on the ragged edge. In series is fine for anything less than 500-550hp or so, NA. I think most factory cars are set up this way.

The second diagram supplies both fuel rails with the same amount of fuel and pressure, almost treating them as two seperate systems. If HP is much more than 500, or you have forced induction, you should probably use the second diagram.

My engine puts 470hp to the pavement, which means about 530'ish at the crank. I have my EFI system set up like #1. I used -6 lines from the pump to the return. It never goes lean or has a fuel delivery issue because of that. At the moment, I'm changing parts to get over 600, and maybe close to 650. So I upgraded the feed to -8, and split them like in #2. Did it need it? I don't know. But it seemed like a good idea at the time. We'll see how that goes.