make sure you use a big enough in tank pump i recommend in tank pumps its way cleaner and less headache

 

so many opinions... its probably better to upgrade both. haha

 

I'm not stating an opinion, its theory...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Sunrise City Rider &raquo;</TD></TR><TR><TD CLASS="quote">I'm not stating an opinion, its theory...</TD></TR></TABLE>

Actually I think it's more of a hypothesis

 

No, its not a guess, its simple fluid dynamics with a little bit of electric motor theory and Ohms Law...

 

Have you tested your "theory" yet?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b16ahybrid &raquo;</TD></TR><TR><TD CLASS="quote">Have you tested your "theory" yet?</TD></TR></TABLE>

i know i aint tryin to be the guniea pig...

 

Its not "my Theory"...This is the only way to make the most out of any fuel setup in any car...Go to the track and see if the pros use 2 or more pumps in series in any of their setups...Go to any race shop, domestic or import, and see what their high horsepower, high fuel demanding engines use...

Anything in the way of the getting fuel from the tank to the chamber is a restriction...The banjo bolts on the filter and on the fuel rail is a restriction, the "piggyback" inline pump is a restriction when you are using a pump before it thats much more effeicent than the inline...

I have a Celica Alltrac that I had an inline pump on the stock pump and I wasn't getting the fuel I needed for the turbo I upgraded to and went with a Walbro to solve my problems...The stock fuel pump can flow enough fuel at high pressures to support plenty of additional power...But, you should keep in mind that it will take a toll on it if its not designed to work at that speed...

Its an electric motor, they are built to spin, this spinning pulls the fuel through its body and down to the chambers...Stick something inline thats equal or stronger to help it and it will have less work to do, stick something thats weaker to help it and it will end up with more work to do...

Have you ever moved alot of things by having someone standing in the middle of your path that you hand that item to? If that person is not as fast or faster than you, you will end up having to wait on them to come back for you to make the hand off to them...The time waiting is a restriction and takes away from the effeciency rate of moving those items...

Now, we are human and are able to compensate by slowing down or speeding up, but these pumps are mechanical and operate at a constant speed...So, you will eventually wear out that better initial pump because the secondary pump is a slug...Then, you will have no initial pump to move fuel to the secondary pump...Then you will have no fuel and a possible blown engine...

 

so youre saying.. if the intank is efficient enough to suppy fuel... then its all you need. if you use an inline, it helps if its as efficient at the intank... but a restriction if not up to par as the intank. so in other words, you recommend a strong intank... or an equally efficient inline to go with the intank.

ok... so explain why people who have upgrade intanks are not getting enough fuel to the "chamber" at certain pressures, such in the case of turbos.

 

Well, this is the FI forum, so I assume that what we talk about will be with respect to FI...


If you are not getting enough fuel to the chambers than what you need, look into increasing the injector pulse width until you reach max duty cycle...Now, injector duty cycle is basically the rate of time when the injector is open and closed with respect to its flow rating...Increasing the fuel pressure, will result in more fuel being able to flow at the same duty cycle as when the fuel pressure is not increased...


If you need more fuel, there is only so many things you can do...Change the injectors to a larger model, add secondary injectors, increase fuel pressure, upgrade the fuel pump, swap to higher flowing fittings, increase the diameter of the feed/return lines, using a larger diameter fuel rail, and increasing the injector timing...

 

I have purchased an apexi power fc which is setted up on a 12.1 FMU and an inline pump. As everybody knows this is not a quite good set up. i would like to change my set up by installing a 255lph walbro high pressure pump, and buy an fpr....

Could somebody give me a help in figures pls.

If i ve read the topic quite well the sum, should be:
40psi+10psi 50psi) + 10psi of boost *12.1=120

So that should be equivilant to set my fpr too 120psi. fuel pressure.

So if i would be applying 20 psi of boost then the sum should be 290psi . fuel pressure. on the FPR.

Pls correct me if i am wrong!

 

Get rid of that FMU and increase your pulsewidth on your injectors to meet a 11:1 or so A/F ratio...Tune with a Wideband O2 sensor...If you run into 90% and up Injector Duty Cycle, turn your boost down until you can get a higher flowing injector in your setup...

Your setup is not gonna increase Fuel Pressure to that level...The FMU is designed to be used to increase fuel pressure but the maximum fuel pressure will not reach past a "safe" level as its physically not able to restrict flow to pressure levels beyond that "safe" level...

 

The power fc has got four programs installed, which is setted on 550cc injectors and the FMU.

Prog 1: 8 psi
Prog 2: 10 psi
prog 3: 18psi
Prog 4 : 22psi.

If i would change the FMU with an FPR, do you have any idea how much i should keep the pressure on the FPR? cause i cannot understand how the last 2 programs have been used on a FMU with a 550cc injector size? I cannot imagine how much the duty cycle is on these 2 programs ! As i am still waiting to receive this engine managment.

 

Please make a new post about your particular problem...