dmaxvaz

iTrader: (1)

Holley rates this pump at 80 psi max, and was wondering if anyone has gone beyond 80 psi with it? I am wanting a little more out of my 1000cc injectors. Right now at 58 psi base psi, and 17 psi boost (boost referenced regulated), I am at 90% duty cycle with the injectors.

Wicked69

I would think if you have to get to 80psi it would be time to step up injectors. FWIW-I remember reading something that Skinnies posted saying that it wasn't a big deal to be over a 100 percent duty cycle. I could be wrong but he had hit 135 percent at certain spots.

I only run 50 psi but plan to step up to 60-65psi. Hopefully someone will chime in but I just hadn't seen anyone say that had so I thought I would just give you some info.

rotary1307cc

iTrader: (5)

150 DC is the same as 100

Blown06

iTrader: (32)

Probably wouldn't be worth it as fuel flow from the pump would drop off at that much pressure. I don't know..........never seen a graph on them.

71 chevy

iTrader: (18)

Get a belt drive fuel pump.good to 150+
Psi,

dmaxvaz

iTrader: (1)

sorry, i forgot to mention that i already have the holley installed, so no belt drive yet.

stevieturbo

You might find you can actually get more flow by dropping the base pressure.

All of those Walbro type/based pumps take a dump once past 70-75psi.

Solutions ? Add a boostapump type product, or use a pair of 044's

Although first off, you need to measure exactly how much pressure you have at the rails.

Forcefed86

iTrader: (4)

From what I've read...

You don't want to go over 100psi total on a typical electronic fuel injector.

at 100% DC the injector is wide open (static) and no longer pulses. This may also happen at 85-100%DC range depending on many other factors. That is why injector manufactures suggest keeping the DC around 80%. (I've maxed out DC on about every setup i've ever had without an "issue". )

As far as the pump goes you would just have to try it and watch your duty cycle. impossible to tell without knowing what the holley pumps are and there flow data at higher pressures. If your at 800rwhp on E85 and they flow like two 255 walbros, I'd say they were pretty well maxed out. Buy a boost-a-pump, or add another pump would be my suggestion.

I'd bet they are just a standard 255 walbro type pump. But who knows. Holley doesn't publish tests at higher pressures or release any information like that on any of their pumps. Jayracing tests all there pumps and the leading competitors pumps, then publishes the information for us.

If it's a standard walbro unit you can use this chart.

http://www.jayracing.com/fuel-pumps-...re-p-3570.html

stevieturbo

Pretty sure I seen some tests somewhere ?

From what I gather, the Holley is just a pair of Walbro type pumps in a neat package.

And injector never really sees total pressure, just the pressure across the injector. So 100psi in that respect would either be a very high base, or lots of boost.

Ive run injectors at 95-100psi of fuel pressure before on 4 cyl engines and had no problems., ie 60psi base + almost 40psi boost.

Although some injectors may be happier like this than others. If you dont need to use such high pressures, then dont. Although the Bosch is still quite happy even at 100psi

soundengineer

iTrader: (16)

a while back I did some research on this subject on another site just trying to find out what I could do with it in my car...

the reply I got in a PM after being told who to ask...

you never want to go over 80% IDC if you can... basically anything over 80 is pretty much Static open...

it is physically impossible to actually go over 100% duty cycle...but it is not impossible for the ECU to calculate that you should be over 100%...

best example is to take a garden hose...run water thru it....open the valve up 100%.......now tell me how you open it 120%....you cant..

when you see more than 100% IDC...it just means the injector is open 100% of the time


fuel flow on the Holley 12-1800 should be (by the math)...
will be 120 GPH @ 80 psi

I used the Simple "TREND" function in excel to figure out the flow at 80 psi.

rotary1307cc

iTrader: (5)

some of the high impedance stuff is linear and stable to 95%

best pump out there to hold their capacity at high pressure is the 044s like stevie pointed out

if somone made a pump like holley but used 044s inside i would have it

the 255s look like a bad joke compared to the 044s as pressure goes up

dmaxvaz

iTrader: (1)

what do you guys think about a magnafuel 4303 for daily driving?

Forcefed86

iTrader: (4)

The new 400 series walbros blow the 044 pumps away until you hit 100psi. Even at 95psi they flow more according to this chart. (looks like they are testing it at less voltage too?) The 450lph walbros made for E85 may flow even more at 100 psi I can't find a chart for them.

They are also quieter, cost less, and are made for E85. IMO 2 450walbros would be the way to go.




The flow is not linear and drops rapidly with pressure... At random spots too it seems...

dmaxvaz

iTrader: (1)

do they make the 450s in an external pump style?

Forcefed86

iTrader: (4)

They do not....

schmendog

iTrader: (10)

Lots of discussion over on Yellow Bullet about this. The consensus is that the 4303 is a great pump for DD but is still a little loud. Most say the Holley 1800 is much more quiet, and more affordable than the 4303... but flows less than the 4303. I don't see how it flows less, looking at charts it seems the 1800 flows 140 GPH at 40 PSI where the 4303 flows 137 GPH at 40 PSI. So doesn't that make the Holley 1800 the better choice for 800-1000 WHP E85 guys?

Forcefed86

iTrader: (4)

40psi isn't the plot on the chart you need to be looking at. You need to add the amount of boost your running to the base fuel pressure. For the injectors to see 40psi at 30lbs of boost the pump has to output 70psi. So you'd need to look at what the pump is capable of at 70psi, not 40.

schmendog

iTrader: (10)

That makes sense.

rotary1307cc

iTrader: (5)

LOL... read what I said

The 044 blows them anything away HOLDING its capacity as pressure rises....


From 40psi to 100psi the 044 loses 18.5%

That baller 450 loses 52%

the OEM equipped 044 has untouchable service record compared to all the crap out there /story

soundengineer

iTrader: (16)

FWIW.. I just found a guy running 58 PSI base, with 28 psi of boost.... on e85...
zero issues with the Holley 12-1800

so its doing fine at 86 psi of fuel pressure without issues for atleast one full race season..

a couple of people have replaced (2) A-1000 Pumps with a single Holley 12-1800



and it is NOT a standard walboro pump in the Holley 12-1800...
it is a custom pump designed for holley with Patent's pending
though, it does appear to be similar in design


found these nice images as well












no pumps are truely linear.....most of them are close enough to be able to plot a line for a graph

even if it was a walboro... they are linear till 80 psi...with a slight drop off above that...
it doesnt drop off all that much...in relation to the function of pressure vs volume
it basically becomes linear again...the ratio does change some....but the drop off is still linear....to an extent

what it tells me is that the walboro 255 hits its flow limit/pressure limit of its own passageways at 80psi roughly, and then it builds pressure with a greater reduction in flow based on the orifice size




its not a percentage...
its a physical relationship determined by a simple calculation in physics

Pressure and flow volume are always an inverse of one another based on orifice size.....

if you keep the pipe size the same...and increase pressure...the fuel flow will decrease...and vice versa..
and assuming the pump itself is up to snuff...it will be linear until you start reaching limits of the pump or the pump inlet/outlet


all that the 44 shows is that it is able to flow more at a higher pressure to begin with...
again...this only makes a difference if your fuel line is bigger than the flow orifice of the pump...
and that is a big key to a pump performing well
make sure you have a bigger line than the fuel pump inlet and outlet

and I'm not debating that the 44 is a good pump....
it does flow well...
I do wish it had some data on higher pressures though and some lower pressures as well...