Calculating Injector Flow rate

[odd boy]

You need to do this:

- find out wheather your fuel pressure regulator is vacuum-referenced or not...
if it is, it will be on the fuel rail(s) and have a vacuum hose attached to it;

- find out your fuel pressure:
vacuum-referenced: pull the vac hose and measure it,
non-referenced: measure it;
do you have any [electric/electronic] device that alters pressure...?

- find out injector rated flowrate:
if not stock, what is their rated flowrate and rated pressure...?

Joe,

Isn't equal to the pump pressure? (I mean the rail pressure), so if the pump is a stock one, very easy to know its pressure.

What about depending on efilive scan tool, I found the following (in PIDs):

DESCRIPTION PARAMETER
Fuel Rail Pressure SAE.FRP_C
Fuel Rail Pressure (Gauge) SAE.FRP
Fuel Rail Pressure Relative To Manifold Vacuum SAE.FRP_B

Another question, let's say the stock fuel pump gives 58 psig. Is it possible GM designers will rate engine's injectors at lower than that, so we need to correct it when we start tuning??????

[joecar]

Stock pump/regulator pressure is qouted by the GM service manual as 58 psi.

But don't assume that... measure it, and measure it thru-out the load range (should measure voltage at the same time).

If you're running an LS1/LS6/LS2/LS7 then the PCM is not measuring rail pressure, it doesn't have a sensor.

GM engineers rate the stock injectors at 4 bar (58 psi); they may or may not have put the correct values in the IFR table.

[odd boy]

thx

[mr.prick]

could someone that knows how this spreadsheet works,(math equation)
create a new column to paste fuel pressure data for each area of MANVAC?
so instead of using a constant fuel pressure for each column of MANVAC
you can scale each separately without doing it manually.

[redhardsupra]

you mean like this?
http://redhardsupra.blogspot.com/200...gged-fuel.html

[odd boy]

here is the equation:

new flow in lb/hr = the original fuel injector flow x The square root of ((new fuel pressure+MANVAC) / original fuel pressure)

Example: car with 24lb injectors rated at 40 psig (at the factory) and will be used with 70 psig pump and the MANVAC=0. Take the square root of ((70 psi (new FPR setting) +0 (MANVAC))/ 40 psi (original FP)) = 1.3229 x 24 lb/hr = 31.75 new flow rate in lb/hr

refer to the attached file it includes ur request (MANVAC)

injector calculating for ALL.xls

[mr.prick]

you mean like this?
http://redhardsupra.blogspot.com/200...gged-fuel.html

wow!
your quick.
looks like i need to get out more.

[redhardsupra]

well it's been there since December of 2006... catch up!

[harascho]

Hi folks,
after reading this thread and letting my head cool down I thought about my conversion.
I have a 2007 5.3 "LMG" with OEM in tank fuel pump of the same application. GM went to a single fuel line without return. So how do they control the pressure in the fuel rails? Where could I start for adjustments of the IFR?

Harald

[gassr]

Hi folks,
after reading this thread and letting my head cool down I thought about my conversion.
I have a 2007 5.3 "LMG" with OEM in tank fuel pump of the same application. GM went to a single fuel line without return. So how do they control the pressure in the fuel rails? Where could I start for adjustments of the IFR?

The 'plumbing' has changed with the more recent systems. There is a return of sorts, however it is not external as the more familiar, previous systems. Not sure how helpful this is, as it is a bit vague.