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phunk · 02-20-2013, 10:00 PM

Restrictions in fuel system plumbing will cause a pressure drop between the fuel pump and the injectors. Every car will experience this to some degree. The amount of pressure drop between the pump and the injectors will be awfully dynamic and impossible to determine off hand.. you have to do individual testing per application.

At engine idle, or lower power needs such as cruising, there is less fuel flowing through the lines, and the pressure drop will be less. As power climbs, fuel flowing through plumbing in the vehicles starts to increase, and each and every restriction in the fuel system will start to manifest into a sum of pressure drop.

The 370z, in factory configuration, regulates fuel pressure off the side of the fuel filter housing, inside the fuel tank, immediately inline after the fuel pump. What this means, is that the pressure regulating system is regulating pressure at the fuel filter. Before any of the substantial drops in pressure on the way to the engine bay.

If you converted to a return system, you will now be regulating pressure in the engine bay. So instead of seeing pressure drop between the filter housing and the rails, you will see steady pressure at the rails, and pressure increased at the filter housing, to compensate for such the inline drops.

At what quantity of fuel does pressure drop begin in a stock 370z fuel system? There is only one way to find out. Place a fuel pressure gauge off the rails, and place a fuel pressure gauge off the fuel pump. Nobody has done this yet. But only by doing this will someone have completed the R&D to give accurate estimates to how much the 370z fuel system can push, before pressure drop is imminent.

This final number can only be accurately described as a measurement of volume, not HP. However, it would require too much additional R&D to translate this number to a volume of fuel, and then that information would be worthless to the consumer who would be unable to translate that back to a HP figure they can relate to. Injector spray quality, fuel temperature will somewhat effect how much HP you can say the factory plumbing is good for before pressure drop. Tuning and fuel type will *drastically* effect this number. As a couple degrees of timing can go plus or minus 25 HP without changing fuel requirements.

02-20-2013, 10:00 PM	#533 (permalink)
phunk A True Z Fanatic Join Date: Mar 2009 Location: Chicago Posts: 3,668 Drives: 370 Rep Power: 974723	Restrictions in fuel system plumbing will cause a pressure drop between the fuel pump and the injectors. Every car will experience this to some degree. The amount of pressure drop between the pump and the injectors will be awfully dynamic and impossible to determine off hand.. you have to do individual testing per application. At engine idle, or lower power needs such as cruising, there is less fuel flowing through the lines, and the pressure drop will be less. As power climbs, fuel flowing through plumbing in the vehicles starts to increase, and each and every restriction in the fuel system will start to manifest into a sum of pressure drop. The 370z, in factory configuration, regulates fuel pressure off the side of the fuel filter housing, inside the fuel tank, immediately inline after the fuel pump. What this means, is that the pressure regulating system is regulating pressure at the fuel filter. Before any of the substantial drops in pressure on the way to the engine bay. If you converted to a return system, you will now be regulating pressure in the engine bay. So instead of seeing pressure drop between the filter housing and the rails, you will see steady pressure at the rails, and pressure increased at the filter housing, to compensate for such the inline drops. At what quantity of fuel does pressure drop begin in a stock 370z fuel system? There is only one way to find out. Place a fuel pressure gauge off the rails, and place a fuel pressure gauge off the fuel pump. Nobody has done this yet. But only by doing this will someone have completed the R&D to give accurate estimates to how much the 370z fuel system can push, before pressure drop is imminent. This final number can only be accurately described as a measurement of volume, not HP. However, it would require too much additional R&D to translate this number to a volume of fuel, and then that information would be worthless to the consumer who would be unable to translate that back to a HP figure they can relate to. Injector spray quality, fuel temperature will somewhat effect how much HP you can say the factory plumbing is good for before pressure drop. Tuning and fuel type will drastically effect this number. As a couple degrees of timing can go plus or minus 25 HP without changing fuel requirements. __________________ Charles @ CJ Motorsports : Website \| Facebook \| Instagram \| YouTube Home of the 9 second, stock longblock, stock drivetrain 6MT 370z. 9.91 @ 142mph Last edited by phunk; 02-20-2013 at 10:28 PM.