Angrey
Well-Known Member
- Joined
- Jun 21, 2020
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- 2016 GT350
The OE fuel lines can "handle" as much power as you'd like, it's simply a matter of how hard the pumps have to work to feed fuel at the proper flow at the rails.
A crude rule in hydrodynamics is that if you double the size of a line, you quadruple the flow (at equivalent pressures). Of course this depends on the particular characteristics of the fluid, viscosity, temp, etc.
But the point is, the pressure drop across a 6 AN line is going to be more than across an 8AN line and the losses at fittings are each higher as well.
Combine that with the fact that at some point, there's a transition between gasoline to higher content ethanol (and the flow increase not just from additional combustion and power but from the energy density) and determining a rule of thumb number gets difficult.
I also think you're both probably talking different OE line sizes (I'm guessing the GT500 lines are different).
This is largely the same conversation had around the whipple fuel rails (which feature a 6AN restriction). While it's not TOTALLY fruitless to bring fuel to the front using a larger fuel line, if it all has to squeeze through a 6AN fitting into the rails, the benefits of a larger line are greatly reduced (you're basically just getting a reduction across the fluid friction of the line/fittings to that point).
When you look at the efficiency curves for many typically sized pumps, a pressure drop of say 5 psi from the rear to the front can result in a more than corresponding increase in pump effort to deliver fuel to the rails at the desired pressure/flow.
At least some of the cheaper fuel systems that contemplated multi-pump had cheap "manifold" assemblies at the bucket which squeezed through small diameter feeders to get to a deceptively larger output size.
A crude rule in hydrodynamics is that if you double the size of a line, you quadruple the flow (at equivalent pressures). Of course this depends on the particular characteristics of the fluid, viscosity, temp, etc.
But the point is, the pressure drop across a 6 AN line is going to be more than across an 8AN line and the losses at fittings are each higher as well.
Combine that with the fact that at some point, there's a transition between gasoline to higher content ethanol (and the flow increase not just from additional combustion and power but from the energy density) and determining a rule of thumb number gets difficult.
I also think you're both probably talking different OE line sizes (I'm guessing the GT500 lines are different).
This is largely the same conversation had around the whipple fuel rails (which feature a 6AN restriction). While it's not TOTALLY fruitless to bring fuel to the front using a larger fuel line, if it all has to squeeze through a 6AN fitting into the rails, the benefits of a larger line are greatly reduced (you're basically just getting a reduction across the fluid friction of the line/fittings to that point).
When you look at the efficiency curves for many typically sized pumps, a pressure drop of say 5 psi from the rear to the front can result in a more than corresponding increase in pump effort to deliver fuel to the rails at the desired pressure/flow.
At least some of the cheaper fuel systems that contemplated multi-pump had cheap "manifold" assemblies at the bucket which squeezed through small diameter feeders to get to a deceptively larger output size.
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