WillRyan

Used from the Stickys at the top of the page.

Also FuelInjectorConnection states that these injectors will flow 103 lb/hr at 58psi through LS Fuel Rails.http://fuelinjectorconnection.com/sh...p?productid=29

This is some of the info I understand.

Blown06

iTrader: (32)

Well here is the problem with the spreadsheet you posted above. A 4301 will not flow enough fuel with base set at 58 psi and then 1:1 enough boost to make 1250 hp. So effectively, you'll need to find an injector that will flow the amount of fuel you'll need at lower pressures.

My opinion (take it however), 1250 hp on gas needs at a minimum 1 4303 (and that may not even be enough) and a 2000 cc injector with base pressures set closer to 40 psi.

Blown06

iTrader: (32)

I just went and looked at a datalog from a run I made about 1 month ago. Combo weighs 4075 lbs and trap'd 147 mph. My fuel system consists of 2 4303's set at a base of 43 psi and id2000 injectors.

Data points on that run are as follows:
833 lb/hr of fuel consumption at 7700 rpm, 16 psi boost (fuel pressure would only rise to around 53 psi). Injector duty cycle was at 50%.

My fuel consumption numbers are closely inline with the calculation you did above, however there is no way that 1 4301 pump could support that flow volume at 70+ psi as your suggesting in your combination. If I was to substitute 1000 cc injectors in for my 2000 cc injectors and everything remained the same.........they would likely be 100% duty cycle.

Blown06

iTrader: (32)

The problem is not with your math. It should work on paper.........problem is we don't run our **** on paper.

WillRyan

Blown06, Thank you!!

Very informative.

I think for now I'll keep what I have, and see what it does for me. Not necessarily horsepower wise but 1/4 mile times. When the day comes and I want more power the fuel system will be the first on the list to revamp!

WillRyan

And by the way, that's a pretty fast ride you have getting 4075 lbs down the track at 147 mph!

Monte4ever

iTrader: (2)

Nice S10 jimmy WillRyan. I love the big tire look on that body style.

WillRyan

Thank you Monte!

Atomic

iTrader: (37)

Alright man, bottom line is a single 4301 will not even get you close. I ran some numbers just for you, but used a bsfc of a more realistic 0.7 and a max duty cycle of 85%. I am assuming you will need about 20psi of boost to make your power goal. All the power numbers I list are wheel horsepower, if you want crank then add your 20%.

95lb@3bar Injectors
-Single 4301, I would not run less than 40psi of fuel pressure because injector atomization starts to suffer, and at that fuel pressure with 20psi of boost the pump flows 10% less than the injectors, which means you need a bigger pump. Max power at the point where they equal each other at 20psi is around 800rwhp.

-Same story but using a 4303 with a base pressure of 50psi and 20psi of boost will give you 2% excess pump (so perfect match) and be right at 1000rwhp.

-With dual 4301s, base pressure of 60psi and 20psi of boost will give you 27% excess pump and be right around 1100rwhp.

-Dual 4303s same story pretty much since you are injector limited.

127lb@4bar Injectors
Now if you go with a larger injector, like 127s the numbers change a little.

-Single pump still isnt going to work since you need more pump. Single 4303 will get you about 1075rwhp at a 45pis base.

-Dual 4301s and 127s will get you a 60psi base, and a 20psi of boost give you 10% excess pump. You still have fuel pump at 30psi of boost by 2.5%, so pretty much maxed. 1250rwhp at this level.

-Dual 4303s and 127s get you the same thing since you are injector limited, not pump.

Walbro 400 Pumps Instead of Maganfuels
If you get away from running the magnafuel pumps, I would recommend dual walbro 400s or 450s. Be a lot cheaper and work better than the 4301.

-95s and dual 400s at a 60psi base pressure with 20psi of boost will get you 16% excess pump and about 1100rwhp. This is what I would do.


PS. I ran these numbers with Blown's data points and it works out perfectly. His setup is good for about 1700rwhp on pump gas up to about 40psi of boost if he wants to throw that much boost at it.

For further reading and to see my spreadsheet I used to do this, go here: http://www.performancetrucks.net/for...p-flow-510434/

Shownomercy

iTrader: (1)

So a 4301 running rail pressure at 58psi with say 15psi of boost on 80# injectors, isn't gonna make more than 800rwhp?

WillRyan

Awesome info Atomic!! Thank you! My dad and I have both been digging more Into this subject and started to see we would run up short. Also this past weekend I talked to my girlfriends uncle, Bret Bradbury, also known as BlownBlueZ06 in the corvette and HP Tuner world. He talked me into swapping the 95lb injectors for the 127 lbs.
I also called Magnafuel to ask about the 4301. The tech grabbed the flow sheet and said with a base 58psi +20lbs boost the 4301 pump would only support 900-1000hp at the crank.

Then when asked, he said the 4303 won't have a problem!

So with both the injectors and fuel pump in the mail to exchange for bigger, I should be safe from what you said!!

I'll have to look into those Walbros more for future builds.

I chose Magnafuel because a lot of guys in the 1000hp range on yellowbullet and here said that's what they run.

In conclusion I will have (1) Mp-4303 pump with FIC 127 lb injectors!

Thank you again for the great info and the time you took!

Atomic

iTrader: (37)

If those 80s are at 4bar then nope, you need more pump. The injectors should be around 85% duty cycle with a big enough pump to support them at that level. The 4301 only flows about 290L/hr at 85psi, which using a conservative bsfc of 0.72 only gets you about 650rwhp.
The 4303 flows 415L/hr at that point which is about 920rwhp worth of fuel.

Will, no problem! Make sure you set your base pressure around 45psi. If you set it to 60psi you will only have about 950rwhp worth of fuel. Clear example of how running more pressure is sometimes a bad thing. Good luck!

WillRyan

Perfect, will do! Thank you again Atomic!