550cc injectors?

[stil bil]

what hp #'s are the 550cc injectors good for??

what would the walbro 255 fuel pump stand up to??

would the 2 plus an apexi S-AFC combine to provide enough fuel withstand at least 300bwhp??

or would i be better off with this:

Aeromotive Universal EFI Fuel Pressure Regulator

[ih8urdsm]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (stil bil @ Oct. 16 2002,9:38)</td></tr><tr><td id="QUOTE">what hp #'s are the 550cc injectors good for??

what would the walbro 255 fuel pump stand up to??

would the 2 plus an apexi S-AFC combine to provide enough fuel withstand at least 300bwhp??

or would i be better off with this:

Aeromotive Universal EFI Fuel Pressure Regulator</td></tr></table><span id='postcolor'>
1. &nbsp;close to 400 at the wheels.

2. &nbsp;around the 400hp level also.

3. &nbsp;Yes, more than enough

(add a Z32 mafs to the list)

4. &nbsp;no need

[boosteds14]

550CC injectors are good for 17-18psi of boost.

[Jeff240sx]

To get the ammount of power you can make off the injectors, here is the formula.
550cc / 10.5 (this give you pounds per hour.) = 52.38 lbs/hr
Multiply by the number of injectors.
52.38 x 4 = &nbsp;209.52 total lbs/hr
divide by a constant (.6 for a rich, safe estimate.)
209.52 / .6 = 349.2 hp.

Mustang people have said that a high-pressure 255 L/hr pump will handle 500hp on their cars. &nbsp;I'd assume 400-500hp for our cars.

I don't think that you would be able to safely run 550cc injectors off a S-AFC. &nbsp;With only a +/- 50% adjustment, i think you'd run rich at the low rpms. &nbsp;Go with a JWT ecu. &nbsp;They will also program in the Z32 maf, or cobra maf.

You have a lot of research ahead of you before you turbo. &nbsp;Like, get Maximum Boost and learn. &nbsp;Most people's choice for fuel is not 550cc injectors and a big-ass pump, or just a FPR. &nbsp;
-Jeff

[stil bil]

thanks guys,

jeff: thanks for the formula...and yes i have done a good bit of searching and learning..i do h ave the book and have read it and am doing it again...

the only reason i asked about the injectors was because a friend of mine in orange can get me 4 550 injectors and a walbro 255 pump for around $400 &nbsp;but from what you have tld me the 550's are way to much for what i need...i only want 250-300 hp, so i will go with the 370's(maybe the next step up 430 i think out of the sr) and either a s-afc(my current choice) or a jwt ecu, but i read that they cannot make (moddify) one for a 96!!

that is my plan for fuel unless i want to get really crazy!!

[DSC]

to tech talk we go... <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/cool.gif" border="0" valign="absmiddle" alt=':cool:'>

[uiuc240]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Jeff240sx @ Oct. 17 2002,12:47)</td></tr><tr><td id="QUOTE">To get the ammount of power you can make off the injectors, here is the formula.
550cc / 10.5 (this give you pounds per hour.) = 52.38 lbs/hr
Multiply by the number of injectors.
52.38 x 4 = 209.52 total lbs/hr
divide by a constant (.6 for a rich, safe estimate.)
209.52 / .6 = 349.2 hp.

Mustang people have said that a high-pressure 255 L/hr pump will handle 500hp on their cars. I'd assume 400-500hp for our cars.

I don't think that you would be able to safely run 550cc injectors off a S-AFC. With only a +/- 50% adjustment, i think you'd run rich at the low rpms. Go with a JWT ecu. They will also program in the Z32 maf, or cobra maf.

You have a lot of research ahead of you before you turbo. Like, get Maximum Boost and learn. Most people's choice for fuel is not 550cc injectors and a big-ass pump, or just a FPR.
-Jeff</td></tr></table><span id='postcolor'>
Jeff, that formula is missing a big chunk of it (which I can't remember right now).

That's saying that if you richen it up to say .7, you make less power. And that if you went way lean, say .2, you'd make HUGE power....there's more to it than that.

EDIT: &nbsp;All you needed to add was that the "constant" is between .4 and .6...:)

Eric

[uiuc240]

I found this:
*********************************
Fuel Injectors:



Just as the wrong sized jets in a carb can cause decreased performance and driveability problems, so can incorrectly sized injectors. The following calculation can be used for approximating fuel flow per injector based on horsepower (HP) and Brake Specific Fuel Consumption (BSFC).

Note:

1) Engine HP must be a realistic estimate.

2) BSFC is determined from engine dyno measurements. It typically ranges from 0.4-0.6 for gasoline engines. A BSFC of 0.5 is a safe, initial estimate.


BSFC =
Pounds of fuel per hour


--------------------------------------------------------------------------------

Brake Horse Power




3) The 0.8 multiplier for the "Number of Injectors" helps derive a practical "Max Injector Flow Rate" for each injector based on an effective real world injector operating pulse time and fuel flow. It is unrealistic to establish the fuel flow to an engine based on an injector operating pulse time of 100% (wide open all the time). This calculation uses an injector operating cycle of 80%. Some full race engine management systems may operate at 85-95% duty cycle, but extended operation may eventually overheat the injectors and cause irregular flow rates and poor low rpm operation.

Injector Flow Rate (lbs/hr) =
HP * BSFC


--------------------------------------------------------------------------------

number of injectors * 0.8



With a known injector fuel flow rate you can get a rough estimate of the systems capacity by using:

HP =
IFR * number of injectors * 0.8


--------------------------------------------------------------------------------

BSFC


&nbsp;where
&nbsp;IFR = Injector Flow Rate (lbs/hr)


Increasing the fuel pressure can often provide increased fuel flow and better atomization. If you know an injector's static (non-pulsed) fuel flow at one system pressure you can find its static flow at another pressure with this:

F2 =

* F1
&nbsp;where
&nbsp;F2 is the calculated injector static flow (lbs/hr) at the higher pressure

P2 is the fuel system pressure (psi) you want to use

F1 is the injector's static flow (lbs/hr) at it's rated fuel system pressure (psi)

P1 is the fuel system pressure (psi) the injector is rated for

[Jeff240sx]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (uiuc240 @ Oct. 18 2002,12:29)</td></tr><tr><td id="QUOTE"></span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Jeff240sx @ Oct. 17 2002,12:47)</td></tr><tr><td id="QUOTE">To get the ammount of power you can make off the injectors, here is the formula.
550cc / 10.5 (this give you pounds per hour.) = 52.38 lbs/hr
Multiply by the number of injectors.
52.38 x 4 = 209.52 total lbs/hr
divide by a constant (.6 for a rich, safe estimate.)
209.52 / .6 = 349.2 hp.

Mustang people have said that a high-pressure 255 L/hr pump will handle 500hp on their cars. I'd assume 400-500hp for our cars.

I don't think that you would be able to safely run 550cc injectors off a S-AFC. With only a +/- 50% adjustment, i think you'd run rich at the low rpms. Go with a JWT ecu. They will also program in the Z32 maf, or cobra maf.

You have a lot of research ahead of you before you turbo. Like, get Maximum Boost and learn. Most people's choice for fuel is not 550cc injectors and a big-ass pump, or just a FPR.
-Jeff</td></tr></table><span id='postcolor'>
Jeff, that formula is missing a big chunk of it (which I can't remember right now).

That's saying that if you richen it up to say .7, you make less power. And that if you went way lean, say .2, you'd make HUGE power....there's more to it than that.

EDIT: All you needed to add was that the "constant" is between .4 and .6...:)

Eric</td></tr></table><span id='postcolor'>
Yeah. &nbsp;I always try to make extremely safe estimates, becuase I don't want people to run that formula with .4 as their constant, and then use the S-AFC as their only fuel management. &nbsp;People are dumb, and do stupid things, and I don't wanna feel bad cuz people are blowing their motor making 420-ish HP off an AFC and 550cc injectors. &nbsp;
And yes, with PROPER TUNING, you can run leaner. &nbsp;Sorry if I led people wrong. &nbsp;But... like I said. &nbsp;I'll always use conservative estimates.
-Jeff