so, a bosch 044 can flow 300 lph in free flow.

free flow means from gravity feed.

bosch say use a 12mm hose, wich will flow 300 lph.

hears a few pics of the std feul line from the tank, the bung itself, and the hose have a 12mm size.

this is a restriction that fitting loads of pumps to will still not achive large flow rates.

fitting a larger fuel hose to the tank will not afford more flow, the size of the orifis from the bung in the tank will restrict the flow.

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__________________
ce 320 amg
widebody
tiwn turbo
Mutty 'der nail'
soon to be a six speed nail


"some mods improve your car and make it into something it never was, other mods, however, although essentially the same, are not, and make that car a ricer"

if your car isnt shiny, you dont know what you are talking about, remember; paint shine = knowledge. In order to be taken seriously, you should spend all your money on paint, (and get a dyno reading).
Dont forget to polish it often

hears the other two pics, no chance of flowing more than afew liters more than three hundred, even if ten pumps were attached...

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__________________
ce 320 amg
widebody
tiwn turbo
Mutty 'der nail'
soon to be a six speed nail


"some mods improve your car and make it into something it never was, other mods, however, although essentially the same, are not, and make that car a ricer"

if your car isnt shiny, you dont know what you are talking about, remember; paint shine = knowledge. In order to be taken seriously, you should spend all your money on paint, (and get a dyno reading).
Dont forget to polish it often

I am running a walbro 255 which I recently put on, you can get them for around $100.00. Just one and it is keeping up with my car on e85 at 85psi. I run around 10-11 psi of boost. I the biggest restriction I found on the factory fuel pumps is the fitting with the check valve on the pump. Where the banjo fitting is. There is one small 3-4mm hole that all the fuel has to go through. I never noticed this before and was running into fuel pressure problems like a brick wall at 6000 rpm. It was like the pumps turned off.

so you run a base pressure of 85 - 11 = 74 psi?????????

this is probbably where your timing issues are, you have posted before about how others are running more timing than you, i dont think you are getting enough fuel.

whilst i was experiancing weird tuning issues, random pinking, days when the car would fly, then days when it wouldnt, i did everything but change my feul pump, guess what? when i eventually got to the '044' (via 345lph pumps by driven automotive wich failed twice), i now have soild feul pressure, and soild tune that doesnt change,

i fitted my pressure gauge inside the car so i could watch the pressure rise as boost builds.

the '044' was designed for porshe turbos, and is as reliable as a oem pump.

the relitave flow rates in 'free flow' are; 044 is 300 lph, walbro 255 is... 255lph, these figures are free flow, ie without any lines and injectors.

the '044' according to the many web pages i have visited, consistantly out performs the walbro and the more pressure you run, the more the '044' come into its own.

i took the check valve off the driven automative pump, but when you think about it, they all come with a check valve, and surely the designers saw the small holes? they must have allowed for it.

the hole i have identified above is on the non pressured side, that is to say the only thing pushin the feul thro it is gravity, that is why it is the restriction in the system, but with your pump walbro, you dont need to worry...

__________________
ce 320 amg
widebody
tiwn turbo
Mutty 'der nail'
soon to be a six speed nail


"some mods improve your car and make it into something it never was, other mods, however, although essentially the same, are not, and make that car a ricer"

if your car isnt shiny, you dont know what you are talking about, remember; paint shine = knowledge. In order to be taken seriously, you should spend all your money on paint, (and get a dyno reading).
Dont forget to polish it often

I do not have a fuel problem. I have good pressure all the way through the rpm range. I do not have knock either. I get knock on pump gas at around 14 degrees of timing when it is warm outside. I do know that when my engine was n/a that anymore than 24 degrees of timing did not seem to gain much and at 28 degrees it knocked badly.
I have read many a car running in excess of 850whp on two walbro 255.
And the check valves from the factory are not made with the intention of running as much fuel as is required for our cars. It simply not possible to run as much fuel through a 3mm hole as the 6an fuel lines. I would think that the stock pumps will perform at a much higher flow rate without that restriction. I may put them back on to see.

the check valve has four 3.5mm holes in it... two walbros are about on par with one 044, and were they in series or parallel? it makes a huge difference. also a non boosted car will make more power from the equivilent pump setup, because the pressure it works against is never raised above atmosphere.

if what i say doesn't ring true,go read the ricers gtr, escort cosworth and Porsche pages, who all have much more experience running boost than merc guys.

have you got an in car gauge that you can watch the fuel pressure rise on, most injectors are flow rated at 42.5psi, set the pressure with the engine running and the regulator NOT CONNECTED. vacuum hose blocked.

when you connect the hose the pressure drops,due to engine vacuum, and then as you drive it should raise back to 42.5 (or what ever pressure you set it at) as the boost/vac gauge reads to zero (no vacuum) and then every 1psi of boost should raise the fuel pressure by 1psi, so if you run 12psi boost, so if you set 42.5 psi base pressure, the gauge should read 42.5+12 = 54.5.

you say 84 psi, i dont think a single walbro can flow much at that pressure.

__________________
ce 320 amg
widebody
tiwn turbo
Mutty 'der nail'
soon to be a six speed nail


"some mods improve your car and make it into something it never was, other mods, however, although essentially the same, are not, and make that car a ricer"

if your car isnt shiny, you dont know what you are talking about, remember; paint shine = knowledge. In order to be taken seriously, you should spend all your money on paint, (and get a dyno reading).
Dont forget to polish it often

also the fuel pressure is the limiting factor on the flow, a pump that will flow 255 lph in free flow, will not flow that ammount under say 60psi. tihs is the 040 bosch, wich pumps less than the 044, and murders the walbro.

i aint tryin to dump on you, i am just sharing my findings from the issues i had with my pumps.

__________________
ce 320 amg
widebody
tiwn turbo
Mutty 'der nail'
soon to be a six speed nail


"some mods improve your car and make it into something it never was, other mods, however, although essentially the same, are not, and make that car a ricer"

if your car isnt shiny, you dont know what you are talking about, remember; paint shine = knowledge. In order to be taken seriously, you should spend all your money on paint, (and get a dyno reading).
Dont forget to polish it often

in fact, using e85 calls for a 30% increase in sizings and volumes, so, with all due respect, your figures sound even further off. and i still dont wanna fight over it!

at 85 psi you are flowin around 160 lph, an 044 @ 85psi would be flowin the 255 that a walbro flows in free flow.

__________________
ce 320 amg
widebody
tiwn turbo
Mutty 'der nail'
soon to be a six speed nail


"some mods improve your car and make it into something it never was, other mods, however, although essentially the same, are not, and make that car a ricer"

if your car isnt shiny, you dont know what you are talking about, remember; paint shine = knowledge. In order to be taken seriously, you should spend all your money on paint, (and get a dyno reading).
Dont forget to polish it often

I think that maybe I have given the impression I am arguing that the walbro out flows the bosch. I was just stating what I have. I have no flow issues at this time. I have thought about either adding another walbro or simply putting one of the stock pumps back inline as a feed pump. I do need more flow to go any further and I need larger injectors also. Right now though I am ok.
The check valves do have one hole though if you look at the inside. I thought the same thing about the four holes but if you take the fitting out of the pump and look inside the end you will see what I am talking about.

this is a good idea, and i have two 044 in line as we speak, it seems not to be a good idea to mix pumps, according to some of the info i have seen, maybe use two walbros?

also info i have gleaned from other sites seems to indicate that using a feed pump will increase the available pressure of the working pump significantly, but wont increase the flow rate by much.

Bosch do a higher pressure pump than the '044' but it is still rated at the same flow rate, just does the volume at a higher pressure.

increasing the pressure will also make your injectors flow more, thereby making them artificially 'bigger'


yeah i have seen what you mean, but i 'hope' the figures quoted are with the check valve in place, i removed it from the first da31 i used, and it died after about 1000 miles, the guy replaced it, and advised me that pump needs a 15mm inlet pipe and the check valve in place to allow it to run as specified.

the new one only lasted two days! he reckoned it was down to the inlet pipe being too small, as all these type of pumps dont suck well, they push the liquid.

maybe removing your check valve has upped your pumps output, but it will probably strain it more?

__________________
ce 320 amg
widebody
tiwn turbo
Mutty 'der nail'
soon to be a six speed nail


"some mods improve your car and make it into something it never was, other mods, however, although essentially the same, are not, and make that car a ricer"

if your car isnt shiny, you dont know what you are talking about, remember; paint shine = knowledge. In order to be taken seriously, you should spend all your money on paint, (and get a dyno reading).
Dont forget to polish it often