Calculating Injector Flow rate

[joecar]

Marcin's spreadsheet is attached to this post (scroll down to bottom of post #1).

The math behind this is as follows (for those who want to know)...

Definitions

R0 = injector's rated flowrate measured at pressure P0
P0 = pressure at which the injector's rated flowrate R0 was measured (see Note below)
FP = regulator "base" gauge pressure

MAP = manifold absolute pressure
BARO = barometric absolute pressure = 101.3 kPa at sea level = 100 kPa approx. a little above sea level
MANVAC = manifold vacuum = BARO - MAP

gauge pressure = absolute pressure - BARO = value shown by pressure gauge
absolute pressure = gauge pressure + BARO

Pressure difference across an injector: this is the difference in the absolute pressures above and below the injector.

An unreferenced regulator has its pressure set constant; this pressure is FP (gauge) or FP + BARO (absolute).

A MAP-referenced regulator has a reference hose connected to the intake manifold,
so its pressure has MAP added to it; this pressure is FP + MAP (gauge) or FP + BARO + MAP (absolute);
with reference hose removed, this pressure becomes FP + BARO (guage) or FP + BARO + BARO (absolute).

The flowrate of an injector is directly proportional to the squareroot of the pressure difference across the injector (this is the Bernoulli pressure relationship).

Note on Injector Flowrate Measurement:
when R0 is measured on an injector flow bench, P0 is actually the pressure difference across the injector:
absolute pressure above injector = P0 + BARO; absolute pressure below injector = BARO; so then difference = P0.

Note regarding 1997-1998 Y-car:
The FPR is not MAP-referenced (follow the reference hose to verify it sees atmosphere/BARO).

Unreferenced Regulator (e.g. 1998-2002 F-car, 1997+ Y-car)

Pressure difference (of absolute pressures) across injector = (FP + BARO) - (MAP) = FP + BARO - MAP = FP + MANVAC

IFR = R0 * sqrt((FP + MANVAC) / P0) = varies/slopes with MANVAC

At the rail, absolute pressure is FP + BARO, so gauge pressure is FP.
--> Directly measure FP at rail with engine running (FP should be constant).

The spreadsheet calculates this equation (Example 1, post #3).

MAP-Referenced Regulator (e.g. trucks)

Pressure difference (of absolute pressures) across injector = (FP + BARO + MAP) - (MAP) = FP + BARO

IFR = R0 * sqrt((FP + BARO) / P0) = constant/flat regardless of MANVAC

At the rail, absolute pressure is FP + BARO + MAP, so gauge pressure is FP + MAP.

Remove reference hose, regulator is now exposed to barometric pressure (so MAP = BARO),
and rail absolute pressure is FP + BARO + BARO, so gauge pressure is FP + BARO.
--> With reference hose removed, directly measure FP + BARO at rail with engine running.

The spreadsheet calculates this equation at MANVAC=0 if measured FP + BARO is entered (Example 2, post #3).

Units

Rail pressure is measured in psi, and MAP or MANVAC is measured in kPa.
You need to convert one to the units of the other before calculating IFR.

Convert psi to kPa by multiplying by (100/14.5).

14.5 psi = 100 kPa

If injectors are rated in lb/hr:
convert lb/hr to g/s by multiplying by 0.125998 (can round to 0.1260).

1 lb/hr = 0.1260 g/s

If injectors are rated in cc/min:
convert cc/min to g/min by first multiplying by density of gasoline (typically 0.73 g/cc), and then dividing by 60.

1 cc/min = 0.0122 g/s (depending on density of gasoline)

[redhardsupra]

might wanna explain what P0 is, you have no idea how often do i get an email with 'so what do i put in where?' emails...

[joecar]

P0 is the pressure at which the injector's rated flowrate R0 is measured.

Note:
when R0 is measured, P0 is actually the pressure difference across the injector;
absolute pressure above injector = P0 + BARO;
absolute pressure below injector = BARO;
difference (above - below) = P0.

Examples:

An SVO 42 lb/hr injector is rated to flow 42 lb/hr at fuel pressure 43.5 psi across the injector;
so, by definitions (see post #1):
R0=42 lb/hr
P0=43.5 psi

Example 1 (unreferenced regulator):

Suppose measured rail pressure is 58 psi (gauge pressure), this is FP,
so, from post #1:
IFR
= R0 * sqrt((FP + MANVAC) / P0)
= 42 * sqrt((58 + MANVAC) / 43.5) <-- in psi
= 42 * sqrt((400 + MANVAC) / 300) <-- in kPa

As MANVAC varies from 0 kPa (0 psi) to 80 kPa (11.5 psi), IFR slopes upward.

Make sure MANVAC, FP, P0 have same units, and then calculate the IFR:
At MANVAC = 0.0 kPa (0.0 psi): IFR = 48.497 lb/hr = 6.111 g/s
At MANVAC = 80.0 kPa (11.6 psi): IFR = 53.088 lb/hr = 6.689 g/s

At MANVAC = 80kPa, you can see how vacuum "assists" the injector's flow rate by almost 10%.

Example 2 (MAP-referenced regulator):

Suppose, with reference hose removed, measured rail pressure is 58 psi (gauge pressure), this is FP + BARO,
so, from post #1:
IFR
= R0 * sqrt((FP + BARO) / P0)
= 42 * sqrt((58) / 43.5) <-- in psi
= 42 * sqrt((400) / 300) <-- in kPa
= 48.497 lb/hr
= 6.111 g/s

IFR is flat horizontal constant ("static") regardless of MANVAC.

Notice that this is the MANVAC=0 value calculated in example 1.

[Redline Motorsports]

Nice job guys! Great information!:cheers:

Howard

[JezzaB]

Sounds like a great spreadsheet but the link is dead for me :bawl:

Jez

[redhardsupra]

yea, that's why i hate direct links, and not pointing to the site that takes care of it :/
here's new linkage
http://www.marcintology.com/tuning/injectors.xls

[redhardsupra]

here's a new twist to injector fueling that i thought up yesterday:
AFR=Airmass/Fuelmass
Fuelmass=IPW * IFR

you got the formulas for IFR on top of this thread, i wanted to concentrate on the other contibuting member--IPW.

BIG QUESTION FOR PAUL/ROSS:
the IPW we can scan, is that the final IPW (after all modifiers, adders, offsets, etc), or is it IPW calculated to be needed to get desired AFR (pre-modifiers)?

if IPW is the 'premod' one, then we need to change
Fuelmass= (IPW+INJOFF) * IFR
in which case we could combine the two formulas with Fuelmass:
AFR=Airmass/(IPW+INJOFF)*IFR
and since we can scan for everything except the INJOFF, we could calculate it:
INJOFF=Airmass/(AFR*IFR) - IPW
once you have that, all you need to do is create a table just like the injector offset table (battery voltage vs manvac) use INJOFF as the data, and v'oile, you get an offset table.

does this make sense or am i completely off my rocker here?

[pkincy]

I wonder if as a group we could approach the mfgs through a retailer or wholesaler to get us offset tables.

It might be tedious but I can't imagine that Lucas, Bosch, etc. want this information secret if they are trying to sell fuel injectors.

Perry

[redhardsupra]

i've bugged every source on the planet i have an 'in' with to get this data, and no go. but then again maybe you got better contacts, so more power to you if you wanna to pry the data out of their cold dead hands ;)

[WiseGuyZ06]

Im confused...

[joecar]

Im confused...Ok... what vehicle do you have, and what fuel-related mods do you have (injectors, pump, regulator...?)...?

[joecar]

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...?

[WiseGuyZ06]

Ok... what vehicle do you have, and what fuel-related mods do you have (injectors, pump, regulator...?)...?

2001 corvette z06, racetronix pump w/ hot wire harness, 30# red top's... everything else stock as far as fuel...

[joecar]

What is rail pressure measured using a pressure gauge...?
Does it vary with RPM or load...?

Are the 30# red tops rated at 30 lb/hr @ 43.5 psi, is this correct...?

[WiseGuyZ06]

What is rail pressure measured using a pressure gauge...?
Does it vary with RPM or load...?

Are the 30# red tops rated at 30 lb/hr @ 43.5 psi, is this correct...?


Not too sure... if it varies....

yes as far as I know thats what they are rated for..

[joecar]

2001 corvette z06, racetronix pump w/ hot wire harness, 30# red top's... everything else stock as far as fuel...Anyone who knows what pressure this runs at, please chime in...

[vetteboy2k]

should be approx 58-60psi

[eboggs_jkvl]

Set it at 58 PSI.

[Bruce Melton]

I ran a stock C5 fuel pump fuel pump with mechanical gauge off the end of the fuel rail. Taped the gauge to the windshield and Seemed to be rock steady @58# thru 89% IJC> SVO 42s. The same with my fancy intank after market pump.

[joecar]

So consensus for Racetronix is 58 psi, same as stock...

And steady across the range of IDC.

Ok, thanks. :cheers:

[joecar]

Im confused...
Ok, there you have it:
a. injectors rated at 30 lb/hr @ 43.5 psi;
b. rail pressure 58 psi;
c. non-referenced regulator;

You enter the values shown in a. and b. into the spreadsheet,
and it computes the IFR vs MANVAC table in lb/hr and/or g/s;
you then copy/paste this into B4001 IFR table.

[WiseGuyZ06]

Ok, there you have it:
a. injectors rated at 30 lb/hr @ 43.5 psi;
b. rail pressure 58 psi;
c. non-referenced regulator;

You enter the values shown in a. and b. into the spreadsheet,
and it computes the IFR vs MANVAC table in lb/hr and/or g/s;
you then copy/paste this into B4001 IFR table.

Thanks joe joe.....u da man....

[99ss]

My racetronix measures 62+ at the rail. 99 Camaro SS

[joecar]

My racetronix measures 62+ at the rail. 99 Camaro SS
Camaro has an unreferenced regulator;

You measured 62 psi at the rail (how much did it vary...? +/-1 is ok);
SVO 30 injectors are rated for 30 lb/hr @ 43.5 psi (is 30 lb/hr correct...?);

Enter those 3 values into the spreadsheet (http://www.marcintology.com/tuning/injectors.xls),
and it computes the IFR vs MANVAC table in lb/hr and/or g/s;
you then copy/paste this into B4001 IFR table;

the IFR table should slope upward to the right as MANVAC increases (remember, MANVAC = BARO - MAP).

If your rail pressure varies more that +/-1 or +/-2, then you have to hook up a pressure sensor and log a map of rail pressure vs MANVAC which you then use to compute your IFR table.

[powertrippin]

BTW FWIW,

I am 95% sure the SVO's are rated @ 40psi not 43
HTH
Ed:wave:

[JezzaB]

BTW FWIW,

I am 95% sure the SVO's are rated @ 40psi not 43
HTH
Ed:wave:

Most injectors have their lb/h rating at 43.5psi as an industry standard, why are these different?
Jez

[pkincy]

the more correct statement is that most GM and aftermarket injectors are rated at 3 bar.

Ford very very seldom rates their injectors at 3 bar. Most are in the 33-39 psi range as a rating.

The prevailing thinking on OBD2 LSX boards is that they are rated at 3 bar.

The OBD1 community has known since the early 90's when they were introduced that they are rated at less. I believe 39 or 39.5 psi although it easily could be 40 psi (except I don't know of Ford ever using 40 psi as a flow rating pressure.)

All my LT1s have the SVO 30s entered at 32 lbs/hr in the injector constant. (OBD1 only has a single constant not a table)

So add 7-10% to the 30 lb/hr and you are good to go.

Perry

[Goldfinger911]

The mystery continues... Read the foot note here:
http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=5772

"NOTE: These injectors are flowed at 40-psi differential pressure..."



BTW FWIW,

I am 95% sure the SVO's are rated @ 40psi not 43
HTH
Ed:wave:

[pkincy]

Finally an answer.

Thank you.

This has been a controversy on OBD2 boards for some time. As this is a Ford site, we can likely count on it.

Perry

[redhardsupra]

eh, who cares what they're rated at, get it flowtested, that will tell you the real story. not all injectors are created equal

[joecar]

Finally an answer.

Thank you.

This has been a controversy on OBD2 boards for some time. As this is a Ford site, we can likely count on it.

PerryThe website is most likely created/maintained by Marketing rather than Engineering... so who would you trust the most...? :D

[gassr]

Hi gang!


The website is most likely created/maintained by Marketing rather than Engineering... so who would you trust the most...? :DI agree with your thinking. :)

It helps to understand the uneven/odd PSI values when one realizes fuel system values are originally spec'd in the metric 'Bar'. To go back and reconvert the PSI values (provided they had not been rounded off) back to Bar makes those values easier to understand and more logical. A problem surfaces when the values are rounded off after converting to PSI. This makes 'close' acceptable. I once had a difference of opinion with a forum guru that was convinced 1 bar and 1 atmoshpere could be interchanged because they were close. Convince a sprinter it is acceptable to call his 100 meter run a 100 yarder.

More to the point of the quote, 40 PSI may have been used to flow test the injectors, but I am confident that PSI value is not the correct flow rating spec of the injector. I believe the Ford injectors are spec'd at 2.7 Bar. It makes it easier to understand when noting the 2.7 is an even value, whereas the 40 PSI is an 'odd' value.

I don't believe it is greatly abused in this industry, but because marketing is paid first and foremost to sell a product, accuracy/integrity of advertising is usually the exception to the rule. :rant:

EDIT: BTW 'joecar', in post #3 you posted MANVAC = 80 kPa = 11.5 psi: IFR = 53.088 lb/hr = 6.689 g/s
In case this is an error, what conversion equation was used to achieve the 11.5 PSI = 80 kPa? Thanks.

Gary

[joecar]

I was making the point that we have all seen too many variations on rating standards for those injectors... :D

Oh, I went: 80kPa / 101.3kPa * 14.5psi = 11.5psi since 101.3kPa == 14.5psi

80kPa == 11.5psi

Sanity check:
11.5psi of vacuum = 11.5psi * ~2inHg/psi = ~23inHg
and then:
80kpa/101.3kPa ~ 78%
23inHg/29.3inHg ~ 79%

[gassr]

I was making the point that we have all seen too many variations on rating standards for those injectors... :D

Oh, I went: 80kPa / 101.3kPa * 14.5psi = 11.5psi since 101.3kPa == 14.5psi

80kPa == 11.5psiWith the above statement I again agree. Obviously, most variations were incorrect. :) The internet is a great info source, but unlike books, there is no peer review of internet info to increase accuracy.

Regarding the equation above... please bear with me.

101.3kPa = 14.69 PSI (1 atmosphere)
100kPa = 14.5 PSI (1 bar)
so.... any value of kpa will also be the % of 14.50 PSI (Remember, it's the metric logic.)
.8 * 14.5 = the answer. Agree? Take care.

Sorry for what appears to be a mountain out of an ant hill. :frown:

Gary

[joecar]

Oh, I see, in error I used 101.3 instead of 100 (or 14.50 instead of 14.69); I see, gotcha, thanks...;)
(101.3kPa == 14.69psi != 14.50psi)

[Dale]

ok, I think I get this, very good info. Butt.....

I have a system designed at 43.5lbs
Running 22lb injectors
I have idle pressure set to 46.
It is vac regulated pressure system.

Is this chart designed for a fixed pressure, or vac regulated?

So, my base 0kpa needs to be entered as 2.85 correct? I just need to know if the chart adjust for my style system. Or I need to take a pressure reading at each kpa mark and enter it in this calculator.

[joecar]

So you have:
- injectors rated as 22 lb/hr @ 43.5 psi,
- vac referenced pressure regulator;

Do this:
- engine running,
- remove vac hose from regulator,
- measure railpressure (in psi).

(--> remember to reconnect vac hose when done).

Then calculate this: IFR = 22 * sqrt(railpressure / 43.5)

The result is in lb/hr; if want g/s then multiply by 0.125998.

Paste the resulting value into B4001 all across in all cells (i.e. flat table).

[Dale]

ok. Will work on that this weekend as I'm going to fix my oil leak tonight/tommorow.

But lets just "assume" its 46psi

IFR=22*sqrt(46/43.5)
IFR=22*sqrt(1.05747)
IFR=22*1.02833
IFR=22.6233

then
22.6233*.125998
so all would be 2.85.

So spread sheet is correct, I just need to measure with line off, rather then on.

[joecar]

Yes, correct.

[Dale]

I just did a fuel reading. Same with vac on as vac off.

How much is 2.91 to 2.85. Is that alot, or a little?

[joecar]

Using a handheld vacuum pump (e.g. Mity-Vac), apply vacuum to the regulator:
for every 2 inHg of vacuum applied, the regulator should drop pressure by about 1 psi;
if it not changing pressure, then the regulator is frozen or leaking.

Also, put vacuum gauge on vac hose from manifold:
you should see idle vacuum (what, about 20 inHg, or similar);
if not, then this hose may be restricted.

(1 psi = 2.036 inHg)

2.91 to 2.85 is about 2%, is not alot.

[mr.prick]

what is the preferred pressure to set the injectors at?
minimum, maximum, or average?

[joecar]

what is the preferred pressure to set the injectors at?
minimum, maximum, or average?Hi Mr.Prick,

Are you asking: to what base pressure (FP) should the FPR be set in order to get the best injector performance...

<rambling=on, not as good as Led Zeppelin>
I don't know the answer... but it would depend on the injectors' physical characteristics... injectors are inductors (inductance L)... when the PCM grounds the injector (completing the circuit) the current ramps up with a time constant of L/R (the beginning part of the red curve)... when the current is sufficient to magnetically move the pintle, the pintle starts opening (the red dip) 1.2ms after the PCM closed the circuit, and fuel flow begins it's ramp up until it reaches it's maxium flow (at the given rail pressure)... then when the PCM removes the ground the injector's inductance self induces a reverse voltage across the injector in an attempt to keep the current flowing (the blue spike), but the circuit is open so the voltage just ramps down... during this ramp down, the pintle is ramped shut by the spring (during which the fuel flow ramps down), and this induces a small voltage (the blue bump)... so fuel was still flowing for about 0.8ms after the PCM opened the circuit...!!!
<rambling=off>

:Nothing_funny_to_ad

As you can see, it depends on many variables and physical aspects, the question can only be answered by empirical means (doing experiments).

(I have seen large injectors work more "precisely" at lower rail pressures.)

Cheers,
Joe
:cheers:

http://img206.imageshack.us/img206/5056/injectorwaveformsfl6.png

I borrowed the diagram from the picotech site.

[mr.prick]

i mean when using the IFR sheet.
which logged fuel pressure would be best. (min/max/avg)
the IFR table for 02 fbody OS is static,
i guess i could change it every time i drive though. http://smiliesftw.com/x/deadhorse_1.gif (http://smiliesftw.com)

[joecar]

i mean when using the IFR sheet.
which logged fuel pressure would be best. (min/max/avg)
the IFR table for 02 fbody OS is static,
i guess i could change it every time i drive though. http://smiliesftw.com/x/deadhorse_1.gif (http://smiliesftw.com)Oh, I would use the average.

I like the emoticon...http://smiliesftw.com/x/deadhorse_1.gif (http://smiliesftw.com/)... :cheers:

[mr.prick]

Oh, I would use the average.

I like the emoticon...http://smiliesftw.com/x/deadhorse_1.gif (http://smiliesftw.com/)... :cheers:
thanks
i thought it would fit.

[427]

Great read fella's

Thanks for the info

Nick--

[SRT10KLLR]

Good read as I will be changing the stock injectors out in the truck for 8.1 Marine injectors that flow 42lbs @43.5.

Also, I have used the Blue Ford Cobra injectors a lot and even though Ford Motorsports rate them as 30lbs at 40PSI they actually flow 42lbs.hr at 43.5PSI. Note converting them from 40 PSI to 43.5 gives you 40.67 but I have had them tested on a couple different machines and they have always been 42+lbs.:nixweiss:

Moreover, injectors from different manufacturers can both be rated at 43.5 PSI and flow the same yet actually flow different on the vehicle. This is because they are rated based on Open/Static flow(which basically grounds the injector) but you vehicle does not do that it pulses(like stated by Joe) the injectors on/off. So the Pulsed/Dynamic flow is really what the vehicle will see unless your injector is defective and gets stuck open.

In one example I had on injector flow more in open flow yet it flowed less in pulsed flow.

BTW, I have noticed a couple people state that their IDC was over 100% based on their EFI log. How is that possible?

[joecar]

When the IDC is over 100%, it means the PCM is commanding more fuel, but the most the injectors can deliver is 100%.

[SRT10KLLR]

I figured that since an injector can't flow more than open flow(100%) but thought it was strange that people said their injectors were at 125% IDC.

[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??????

:thankyou2:

[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/2006/12/ifr-spreadsheet-for-logged-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)

3789

[mr.prick]

you mean like this?
http://redhardsupra.blogspot.com/2006/12/ifr-spreadsheet-for-logged-fuel.html

wow!
your quick.:hihi:
looks like i need to get out more.:doh2:

[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.

[harascho]

Hi,
in the '07 system I transfered to my 1997 Tahoe there is definitively no external return line to the tank, only a single line from the pump to the fuel rail on the intake . I don't see any sort of return ??

Harald

[joecar]

Return systems: FPR is MAP-referenced (located between rails), IFR table is flat across, return line goes from FPR (located at the rail) all the way back to the tank.

Returnless systems: FPR is unreferenced (located in tank), IFR table is sloped (i.e. the PCM looks up IFR based on MAP (or rather MANVAC)), return line is at the FPR in the tank, FPR is BARO referenced.

[rumblebox]

could someone direct me to an IFR spreadsheet? the old link is no longer active.

[Mikz86ta]

PM me I may have what you are searching for

[DrkPhx]

This one?

[joecar]

That is the one, thanks :cheers:

[rumblebox]

Bingo

[joecar]

Please note the following with regards to the 1997-1998 Y-car:

the FPR has a return fuel line and a reference hose, but the reference hose references barometric pressure

(i.e. the FPR is open to the atmosphere, it is not referenced to manifold pressure);

this categorizes this FPR as un-referenced;


this is supported by the fact that the IFR tables are sloped (and calculation shows they agree with the Bernoulli squareroot pressure-flow relationship).



I made suitable corrections to post #1 above.