fuel pump upgrade?

[majorscooby]

I hear and see alot of people who are into tuning cars say that uprating you fuel pump is a good first step tuning point!
But why is this? sorry im not really a tuner head at the mo and need to know these things

As you start to modify you will see that raising boost is one of the many key areas to an increase in power,raising fuel is cruitial too. The standard fuel pumps are known to not be sufficient at pumping enough fuel.
As you raise boost,you require more fuel,bigger imnjectors and so it goes on.
Now thats a very basic explanation.

Scott
If you would care to give a more techy answer i am sure it would help.

[Scott.T]

My opinion has and always will be, if the pump is faulty then fit an uprated one.
Until this time do not bother.

I am still running a standard pump and boosting to 1.4bar. I only recently uprated the pressure regulator, as I have max'd the injectors out on the current map. The car has probably 5 years running more then stock boost.

My car is a MY00, but the MY93-98 and 2001> WRX are a little different as they run smaller injectors. Increasing the fuel flow will help these cars more but only beyond 1.2bar. The standard pump and injectors flow enough fuel at this level of boost, infact they actually run quite rich.

More fuel does not equal more power. I get a few people who have fitted 440cc injectors thinking this will help, whereas actually they will loose power due to an over-rich mixture and it is likley to be running an AFR in the 9's.
If remapped to run an AFR of ~11.0-11.3 you will gain most power without getting to risky/lean.

A stock Subaru ECU runs around 10.5AFR at full chat, so from this you can see that less fuel = more power. It's the greater volume of air/oxygen (hence the turbo charger) that causes the bigger explosion, the fuel is just there to ignite, cool and lubricate. Obviousley you need to increase the amount of fuel to ensure you continue to cool and lubricate.

[dean]

SilverSurfer

Is your previous sentence about fuel pumps still valid? If I do fit an uprated fuel pump is it essential for me to also replace the OE FPR

I have a UK MY00 and have a list of mods to try and get 250bhp out of it(A sort of stage 1) and 1 of the mods was fuel pump.

stage 2 + walbrogh 255
Decat Down Pipe
Cosworth High Performance Panel Filter
port standard headers.
Remap

Its interesting to see so many recommendations for replacing the OE fuel pump.

The fuel pump would appear to be fine on my car.

Thanks

Dean