Fuel pump internal/HPFP,really necessary?

[bykeryder4life]

Could it be that the amount of fuel injected is simply a product of fuel (rail) pressure and the injector pulse width?

this is basically true, theres more factors that go into how much fuel is injected at a specific moment though, but an upgraded pump flows more volume at the same or greater pressure, meaning more fuel gets injected during each pulse. If it didnt work like that then everyone would be fully bolted on stock pumps, but theres a reason people rave over getting an upgraded pump and how much better/richer the car runs with it...

Please feel free to explain how the same pressure being applied to the same diameter fuel rail by a different pump equals higher flow. I may be a little dense here but that does not make any sense.

when you get a set of internals, look at the size of the bore of them compared to the stock ones, they are much larger. Each stroke of the pumps piston through the bore pushes through more fuel volume while maintaining the same or greater pressure. Just because the fuel rail is the same size doesnt mean it cant flow more volume still. Like I said before, if a different set of pump internals didnt equal higher flow on the stock fuel rail then all these high hp cars would be on stock pumps still happy as s*** on 1700psi, but its not the case.

The bigger pump can't push more volume without greater pressure. X psi on Y diameter pipe produces the same volume. Greater volume down the pipe would increase the pressure. Presumably the lines can stand it. Probably not a large increase.

if probably not a large increase then why does literally every person who does multiple bolt ons have to upgrade the pump? Its a huge difference, even on a stock car. Theres a spill valve that will open and relieve pressure once its past a certain point, but at that point theres still plenty of volume flowing.

 

[bykeryder4life]

all of you guys who are sitting here talking out your asses on the subject of fuel pumps/pressure/volume.....Have you installed a set of them? what were your mods at the time? did you datalog pressure and afr's before and after the install? what were your impressions of how the car drove/felt? If you did install and datalog a set, you wouldnt be questioning all this talk about a set of internals being able to flow more volume on the stock fuel rail.

 

[matsuda]

all of you guys who are sitting here talking out your asses on the subject of fuel pumps/pressure/volume.....Have you installed a set of them? what were your mods at the time? did you datalog pressure and afr's before and after the install? what were your impressions of how the car drove/felt? If you did install and datalog a set, you wouldnt be questioning all this talk about a set of internals being able to flow more volume on the stock fuel rail.

No one is questioning that a good aftermarket pump has the capability to flow more volume. What people are saying is this:

Inadequate fuel volume = lower fuel pressure

When the stock pump cannot supply the required volume of fuel, the pressure will drop. If the fuel pressure is the same and the injector pulse width is the same, the fuel volume (amount of fuel consumed by the engine) is the same.

 

[smakdown61]

You guys are missing the point about DI. It's not about how much fuel you can get into the motor. DI motors actually inject LESS fuel per stroke than normal port injection. The high pressure atomizes the fuel so you get a much more EFFICIENT burn with less fuel. You can run 800 psi on this motor and still get your target AFR, but the car will run like s*** because the combustion chamber was designed specifically for 1800psi atomized fuel for optimal combustion.

 

[bykeryder4life]

You guys are missing the point about DI. It's not about how much fuel you can get into the motor. .

if you wanna make any decent power on this car it is about how much you can get in the motor in that small window of time. just to run the motor tho, your right it isnt.

 

[smakdown61]

if you wanna make any decent power on this car it is about how much you can get in the motor in that small window of time. just to run the motor tho, your right it isnt.

Right, for big power obviously you need more fuel which is limited by the injector pulse width. The ecu will purge any pressure over 1835psi according to the mazda training document. My info was more related to the purpose of the high DI pressure.

 

[boostntomuch]

If u get new fuel pump internals or whole new pump. Do you have to get your car tuned or will i be ok? I have intake ,inlet.cat less down pipe and cobb ap stage 2. It still feels like in hitting fuel cut in 3rd at high rpms

 

[8.5MS3]

a new pump does not require a tune. if you do internals you must do a break in period to prevent seizing