VTC_CiViC

Simple enough, whats the most hp you guys have seen out a stock GSR fuel pump? This is of couse assuming stock fuel pressure (40-50psi max). I ask because I've already seen 244whp @ 6psi with 440's on my stock pump and I was wondering if considering the size of the injectors and the pressure would it be reasonable of me to assume it'll supply the load for 300whp @ 10psi or no?

RedTegLS

I did not know until 3 days ago that you can buy a Walbro 255 for $99 shipped. My question is for that kind of money why not buy it?

Johnyquest

99? I got mine on groupbuy center, $88 shipped to my door

How can you go wrong!?

VTC_CiViC

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RedTegLS &raquo;</TD></TR><TR><TD CLASS="quote">I did not know until 3 days ago that you can buy a Walbro 255 for $99 shipped. My question is for that kind of money why not buy it?</TD></TR></TABLE>

Yes I know I can get a Walbro for $99 shipped, actually I've seen the intank lo-press. 255lph for $89 shipped...but that wasn't the question, but thanks anways.

htchbak

to answer your question

i was running a turboed h22 (in a civic) about 270 hp on a stock civic fuel pump untill i decided to upgrade it. (upgrading it made no noticable difference)

trbob16a

somewhere in the 3-350whp range with 800-1000cc injectors. The key is just to keep your fuel pressure low.

http://www.hondata.com/techfuelpump.html

and

http://www.hondata.com/images/...l.gif

ELSpool

Good info!

VTC_CiViC

See I know that the pump can flow pleanty of fuel if you keep the pressure down, but in order to supply enough fuel for say 550's or greater and at the same time maintain consistent rail pressure, the pump is going to work harder.. so what I'm trying to see is if the pump will have a problem flowing enough for large injectors even at relative low pressure.

HXMan

Interesting. I have a GSR pump in my civic....but I already bought a Walbro high pressure pump.

Is the GSR pump any higher capacity then the Si pump?

trbob16a

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by VTC_CiViC &raquo;</TD></TR><TR><TD CLASS="quote">See I know that the pump can flow pleanty of fuel if you keep the pressure down, but in order to supply enough fuel for say 550's or greater and at the same time maintain consistent rail pressure, the pump is going to work harder.. so what I'm trying to see is if the pump will have a problem flowing enough for large injectors even at relative low pressure.</TD></TR></TABLE>

Thats one of the reasons you have a fuel rail rather than just a fuel line. Much like the intake manifold, it acts as a chamber to store extra fuel. So even if you are outflowing your pump, you are still OK to a point b/c the fuel rail is going to make up for that. For relatively short time periods it is fine, and even letting off the gas to shift allows the rail to partially refill.

At low pressures this isn't even an issue though b/c the pump can flow plenty. As you increase your fuel consumption on a stock pump, the rail is storing less fuel, which can be dangerous under wot. The point where this occurs diminishes rapidly as you increase the fuel pressure because of the characteristics of the pump.

Assuming a Si pump, you can idle say 1000cc injectors down around 30psi of fuel pressure with engine management. Add in 15lbs of boost bringing your pressure up to 45psi and you'll see that is just above 350hp supported. Which is somewhere in the 310whp range. Of course, these numbers are all theoretical, but you should get the general idea: keep pressure low, go with big injectors, and you're good to a few hundred whp.

VTC_CiViC

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by trbob16a &raquo;</TD></TR><TR><TD CLASS="quote">
At low pressures this isn't even an issue though b/c the pump can flow plenty. As you increase your fuel consumption on a stock pump, the rail is storing less fuel, which can be dangerous under wot. The point where this occurs diminishes rapidly as you increase the fuel pressure because of the characteristics of the pump.
</TD></TR></TABLE>

See that's my point exactly. With such large injectors, they'll be unloading alot of fuel each time they open.. that much MORE fuel the pump is trying to replace after every sequence. So although the pressure at the rail will remain x, the demand on the pump is increased as it tries to supply the rail with enough fuel to keep it filled.

Am I thinking correctly?

HXMan

I think you are thinking correctly but at the 300whp power level it shouldn't be a problem...the pump should be able to supply adaquate fuel.

At higher levels you may run into the fuel rail running low thing.

I think if someone is going for more then 300whp they should definatly invest in an aftermarket pump. Its not like it costs $1000.

Its alot cheaper then a blown engine.

trbob16a

Yeah you're on the right line of thought.

But remember, more pressure does not mean more fuel. There is a point of diminishing returns where as you increase the pressure your system is actually supplying less fuel because the pump is not capable of dilvering the flow rate at that pressure.

Have you ever used a pressure sprayer? You get tons of pressure up close but your actual water consumption is fairly low. There is so much pressure that the water is broken up coming out of the nozzle and you get more of a misting effect. Now think of a regular hose without any nozzle at all. Thats like using a larger injector. Less pressure but more flow.

edit: see this flow chart here? This demonstrates what I'm saying, as you increase the pressure the volume of fuel you flow actrually drops.

http://www.hondata.com/images/...n.gif

fastludeh22

iTrader: (1)

well i ran out of fuel on my stock pump. i was spraying an 80 shot, waiting for my last turbo part ot come in the mail. i ran lean, det. bunrt valves, destroyed a piston, screwed my freshly sleeved block...and so on. the next day my intercooler pipes came in the mail.

now a few grand(AGAIN) later, my built engine is half-way fixed...so let me ask you, who gives a **** what a stock pump can handle. anything over 6 psi or 50 shot, upgrade your damn pump!!@!!

1dumbscreenname

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Johnyquest &raquo;</TD></TR><TR><TD CLASS="quote">99? I got mine on groupbuy center, $88 shipped to my door

How can you go wrong!? </TD></TR></TABLE>

just get the fuel pump. 5 minutes install and the kickass whine of the pump itself is enough reason, not to mention you WONT EVER worry about the pump not flowing enough fuel

Tinker219

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 1dumbassscreenname &raquo;</TD></TR><TR><TD CLASS="quote">

just get the fuel pump. 5 minutes install and the kickass whine of the pump itself is enough reason, not to mention you WONT EVER worry about the pump not flowing enough fuel</TD></TR></TABLE>
UNLESS you have a 4th gen...ie, DROPping THE TANK

VTC_CiViC

lol.. people keep on with the "just get a pump"... how many times must I state this is not a "should I..?" post!

Charlie Moua

iTrader: (3)

so bottom line what can a gsr fuel pump support with say 450cc at fuel pressure of 38-44psi?

VTC_CiViC

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Charlie Moua &raquo;</TD></TR><TR><TD CLASS="quote">so bottom line what can a gsr fuel pump support with say 450cc at fuel pressure of 38-44psi? </TD></TR></TABLE>

~300whp +/-

Charlie Moua

iTrader: (3)

and stock d16 eg fuel maxout at like 220 correct even at low pressure.... (besides the use of a FMU or inline fuel pump)

VTC_CiViC

If I remember correctly, D-series and B-series pumps aren't very different in flow.

nsxmatt

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by VTC_CiViC &raquo;</TD></TR><TR><TD CLASS="quote">If I remember correctly, D-series and B-series pumps aren't very different in flow.</TD></TR></TABLE>

GSR and SI (DOHC) are the same, SOHC and LS are smaller.

fsp31

can't... stop... must...

Just get a Walbro dude. I'm sorry!!!

This is insteresting. Looks like there is an unusually wide range of experiences here. I wonder what's going on... My experience with the stock pump is that it ran out of steam at well under 200 whp. Not only did I end up replacing it with a Walbro 255 lph high pressure, but I also had to re-wire the pump (with larger guage wire) to get it consistent. BTW, this is with a stock fuel rail and stock FPR.

Charlie Moua

iTrader: (3)

so tell me this
what is the lph rating on:
b16 (99si, delsol)
gsr
ls
ITR
all d series civic ?

b16ahybrid

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by trbob16a &raquo;</TD></TR><TR><TD CLASS="quote">

Thats one of the reasons you have a fuel rail rather than just a fuel line. Much like the intake manifold, it acts as a chamber to store extra fuel. So even if you are outflowing your pump, you are still OK to a point b/c the fuel rail is going to make up for that. ..</TD></TR></TABLE>

Not completly true, even if your fuel rail is full of fuel, your not going to get that fuel into the engine without any pressure from the pump. You still need pressure from the pump to push the fuel through the injector and into the engine, so if the pump is maxed out it's not going to matter if you have a full fuel rail or not...No pressure = no fuel..