Originally posted by raroZ28
it still doesn't make total sense to me how more pumps will really help.
You are looking for more volume, not more pressure right?
Say you're blowing through a straw, and you're measuring how much air comes out the other end. You're blowing as hard as you can, but because the of the size of the straw you can only blow so much. Take a bigger straw, and blow as hard as you can, and you're going to get more air out. Correct? I am not second guessing, I wouldn't second guess Fred when it comes to this, trust me, I'm just trying to understand how more pressure is going to create more fuel volume... I'm not saying bigger is better, because too big would cause a pressure drop, but when talking about fuel line... I would think going up from 3/8" to 1/2" would be more sufficient and not create a drop in pressure, but increase volume.
Where am I getting confused?
You are looking for more volume, not more pressure right?
Say you're blowing through a straw, and you're measuring how much air comes out the other end. You're blowing as hard as you can, but because the of the size of the straw you can only blow so much. Take a bigger straw, and blow as hard as you can, and you're going to get more air out. Correct? I am not second guessing, I wouldn't second guess Fred when it comes to this, trust me, I'm just trying to understand how more pressure is going to create more fuel volume... I'm not saying bigger is better, because too big would cause a pressure drop, but when talking about fuel line... I would think going up from 3/8" to 1/2" would be more sufficient and not create a drop in pressure, but increase volume.
Where am I getting confused?
Keep the small straw. Blow harder. More air will flow. Flow will increase roughly in proportion to the square root of the pressure ratio. Double the pressure (blow harder) and the flow will increase by 41.4% (square root of 2 = 1.414. ) When you put two pumps in series, they can develop more pressure. More pressure flows more fluid through the same size tube.
Look at your fuel injectors..... All the fuel flows through a tiny orifice. The stock injectors flow 24.92 #/HR when the difference in pressure between the injector inlet (rail pressure) and the injector outlet (manifold pressure) is 43.5psi. If you increase the fuel differential pressure to 58psi, those same injectors will flow 28.78 #/HR [ (58/43.5)^0.5 X 24.92 = (1.3333)^0.5 X 24.92 = 1.1547 X 24.92 = 28.78 ]. Same with the fuel line... increase the pressure at the pump end, and more fluid will flow through the lines.
Flow and pressure are intimately connected... you can't separate flow and pressure and treat them individually.
The other thing to remember.... the fuel system in the LT1 is a "return" system. The pump supplies fuel flow in excess of what the injectors can use at their maximum demand. Pressure at the fuel rail is controlled by the fuel pressure regulator, which is on the "return" leg of the loop. Pressure is controlled by opening or closing the pressure regulator to control how much is returned to the tank. As long as the pump can flow more fuel at the rail pressure than the injectors will consume at rail pressure, the system will work.
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