Which IFR calibration to use - Corvette LS6 or Bosch 28.8 ' 58 PSI

Hi,

I've already been using the Calc VET method for a few logs but wanted to check the IFR (B4001) before continuing. I'm using a Holden/GTO 04 LS1 in an RX7.

The injectors I'm using
Bosch: 00 280 155 931
28.55 lbs/hr @ 43.5 PSI

They appear to be the same as the Z06 LS6 injectors so I copied over the IFR table from a standard Z06 tune (02 LS6). However when I did some more reading and found the Bosch injector ratings they are rated 28.55 lbs/hr at 43.5 PSI and not the 58 PSI FPR pressure I'm using (un-reference Corvette FPR). So when I used the injector spread sheet on this site the figures for B4001 came out larger obviously (+13%).

So I'm now unsure if I should use the Corvette IFR values or the corrected figures assuming the injectors are rated @ 43.5 PSI. I've attached the log of my car driving home after 3 corrections using Calc VET. Not the best but it was hard to any sort of open run.

You use the corrected IFR for whatever fuel pressure you run with the FPR disconnected from a vacuum source.
So you should be running with an IFR of 28.55 43.5psi or 3BAR @ becomes 32.94 lb/hr.@ 58psi or 4BAR of fuel pressure.


Calculators old IFR to new IFR based on original and new fuel pressure, will give you an answer in cc/min(2nd calculator from bottom)

http://www.rceng.com/technical.aspx

Then use this to calc from cc/min to lb/hr and vice versa.(bottom calculator)

http://injector.com/injectorselection.php

Always use the KOEO(Key On Engine Off) fuel pressure for calcs, or at least the pressure at KOEO with teh pump running, just in case you have some pressure leaks after the pump stops running. If you use your KOER(Key On Engine Running) with avacuum refernced fuel pressure regulator, you will be using the wrong pressure. A vacuum reference FPR is there to take the pressure differential between the manifold vacuum and fuel pressure inside the injector, out of the equation. The vacuum referenced rail pressure is variable, un referenced rail pressure is NOT variable, it is constant, all else equal.

peace
Hog

Thanks for the reply and very useful links.

I've now seen conflicting data on the injector flow rates, both sources claiming to be from Bosch data sheets! So can anyone confirm if these injectors are 26 lb or 28 lb injectors at 43.5 PSI. I'm getting confused.

I was also using the "LS1-M6 Base tune.tun" as a reference and they appear to have the same IFR data as the Z06 LS6 stock tune which makes those figures look more believeable?

I may just test the damn things myself as I have friend with an injector cleaning rig and he believes he should get an approximation on it.

I've checked them again and they have the GM part number of 12561462 which do appear to be the 28 lb injectors but at 43.5 or 58 PSI?

If it's 28 lbs @ 43.5 PSI that implies to me that the Corvette Z06 IFR values are wrong and my IFR values are currently 13% too low.

Thanks for any help

If it's a GM part, they're probably rated at 58psi.

Where did you buy them from? If it was from a tuner's website, they've probably used them and know the correct IFR.

Quote:

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Originally Posted by ScarabEpic22

If it's a GM part, they're probably rated at 58psi.

Where did you buy them from? If it was from a tuner's website, they've probably used them and know the correct IFR.

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They came with the engine but I used an unlocked PCM with a Camaro tune to get it running. I've only recently gone back to the original Holden PCM (when I bought EFI Live) and used the "LS1-M6 Base Tune.tun" as a base for my mapping.

Here's the IFR from the Holden PCM tune which is neither flat or a straight slope. I was told previously on here it didn't look right and may be referenced to vacuum? So I didn't use it. hence why I'm a bit stuck for which values to trust.

I've read on here you can get an idea of injector characteristics from a log hence the previous attachment. So I've attached my last CAC-VET log as well.

Attachment 14936

Attachment 14937

More info (mathematically technical read): Calculating-Injector-Flow-rate

OK I'll take them all out on Thursday, clean them and see if I can get an accurate flow reading on the rig (it's quite an old bit of kit).

I took all the injectors out today and went to my friends garage. I don't think he's ever been asked to measure the flow of an injector before on his rig he usually just cleans them. Anyway first we ran all the injectors through a standard test and they came within less than a cc apart so essentially the same. Next we ran the pattern test a few times on one of the injectors which simply opens the injector fully. We worked out the flow came to 300cc per minute @ 3 bar which matches the Bosch figures I quoted in my first post.

So that also implies my IFR table is currently 13% too low for my injectors. So I guess I'll be changing my IFR to match and redo my CALC.VET runs :(

I thought the LS6 engines came with the higher flow injectors but clearly from the IFR table I copied over (Corvette LS6) the IFR table was derived from 26 lb @ 43.5 PSI injectors or less.

I thought the injectors used on the Z06/LS6 were rated to flow 28.8 lb/hr at 58 psi...?


28.8 lb/hr * 0.126 = 3.63 g/s

Quote:

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Originally Posted by joecar

I thought the injectors used on the Z06/LS6 were rated to flow 28.8 lb/hr at 58 psi...?


28.8 lb/hr * 0.126 = 3.63 g/s

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Exactly the impression I was under but my measurements today verify the Bosch figures exactly as quoted on quite a few websites! I can only come to the conclusion that the injectors were revised at some point but retained the same GM/Bosch part number. Very hard to argue with real data. Not sure what to expect when I go for another logging run now :)

Bosch: 00 280 155 931
28.55 lbs/hr @ 43.5 PSI (or 300cc / min)


One thing I have noticed in last my log was that the LTFT's were mostly minus when logging (VE disabled, MAF enabled) but after applying the correction to the VE table they then became mostly positive (VE enabled, MAF enabled). So something was going on and I'm still learning what to look for.

Hmmm, interesting.

Post log file, and screenshots of your maps.

I won't be able to post my VE pic for a bit but the two relevant logs are already posted earlier in the thead.

#6 - Log_2407.efi (taken after two previous CALC.VET captures)

#1 - Drive_Home_2704.efi (metric PID, log taken after applying the CALC.VET above)



<EDIT - I've attached my current B0101>

This map is from 3 log runs. Unlike my first efforts I don't use the smooth tool on the whole map just some small areas. I tend to just manually reduce spikes n dips now.

Attachment 14960

Hi

Just to add the more I look at the info for the GM 12561462 injectors the more convinced I am that the LS6 engines did indeed have a 28.8 lbs/hr @ 58 PSI injectors from say '01 - '03. Then maybe from '04 onwards when Holden were carrying on the LS1 in the Monaro's they used an uprated injector from Bosch but with the same GM part number on them (mine have that number on them). Here's some flow data from an LS6 injector (931) with an LS1 (890) injector for comparison. Dated from '05 but the injectors were from a second hand pullout motor in the US.

Also to back this up if you look at the Holden IFR in post #6 ignoring the somewhat odd shape of the slope, the injector values go up to 4.6 g/s which is 14% above the LS6 injectors.

Attachment 14959

I've made two log runs today. First was to get enough data to correct the MAF table. Unsurprisingly after increasing my IFR table to match my actual injector flow rate the MAF table corrected by +12-13% across the cells I was able to hit. I then uploaded that calibration back to the PCM and did another fairly comprehensive run.

I used the VET corrections from both runs to change my old VE (B0101) table and realised it was changing quite drastically so had to fudge about 30% of the table. Mostly the high load cells so they won't be hit very often (until I get on a dyno in the next couple of weeks). I then made another short log with everything re-enabled just doing some driving and straight away the LTFT corrections are very low, actually mostly below 3% already despite my rough table. Much better than before with the LS6 IFR injector data which used to consistently idle with a +14% correction despite doing the RAFIG etc.

Maybe worth a sticky thread just to warn or clarify this observation?

Quote:

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Originally Posted by bimbleuk

I've made two log runs today. First was to get enough data to correct the MAF table. Unsurprisingly after increasing my IFR table to match my actual injector flow rate the MAF table corrected by +12-13% across the cells I was able to hit. I then uploaded that calibration back to the PCM and did another fairly comprehensive run.

I used the VET corrections from both runs to change my old VE (B0101) table and realised it was changing quite drastically so had to fudge about 30% of the table. Mostly the high load cells so they won't be hit very often (until I get on a dyno in the next couple of weeks). I then made another short log with everything re-enabled just doing some driving and straight away the LTFT corrections are very low, actually mostly below 3% already despite my rough table. Much better than before with the LS6 IFR injector data which used to consistently idle with a +14% correction despite doing the RAFIG etc.

Maybe worth a sticky thread just to warn or clarify this observation?

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Good deal... it clearly shows that a correct IFR table allows MAF/VE and LTFT's to fall into place.

Quote:

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Originally Posted by bimbleuk

Hi

Just to add the more I look at the info for the GM 12561462 injectors the more convinced I am that the LS6 engines did indeed have a 28.8 lbs/hr @ 58 PSI injectors from say '01 - '03. Then maybe from '04 onwards when Holden were carrying on the LS1 in the Monaro's they used an uprated injector from Bosch but with the same GM part number on them (mine have that number on them). Here's some flow data from an LS6 injector (931) with an LS1 (890) injector for comparison. Dated from '05 but the injectors were from a second hand pullout motor in the US.

Also to back this up if you look at the Holden IFR in post #6 ignoring the somewhat odd shape of the slope, the injector values go up to 4.6 g/s which is 14% above the LS6 injectors.

Attachment 14959

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Hmmm, interesting, 2 injectors, with 2 different flowrates, using same GM part number.

Quote:

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Originally Posted by joecar

Hmmm, interesting, 2 injectors, with 2 different flowrates, using same GM part number.

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I realize this is old, but am I missing something? Fact: LS1 and LS6 used the same injector but different FPRs for different IFRs. Would this tidbit have alleviated all the confusion in here? Or was it already pointed out and I missed it?

I thought LS6/Z06 used 58 psi rail pressure with filter style FPR at the rear (outside the tanks)...?

Yes, but the LS1 used less than 58psi with the same injectors. I know the early returnless systems used that filter/regulator deal out back, but around mid 03 GM got rid of the filters and changed the tank design on the Corvettes so I wonder if they went PWM then? On my 04 Z06 there is NO filter to be changed, just wait for the pump to die and the injectors to clog and deal with that.

EDIT: I stand corrected. Looks like there is still an in-tank regulator with the FFS system. And everywhere I look, people claim the LS1 runs 58psi. When I first got my car, I remember finding a page that broke down the differences between the LS1 and LS6 (which I of course can't find) and it claimed LS6 used higher fuel pressure with the same injectors thus producing the increased fuel flow alluded to by John Juriga when the LS6 debuted. Now I feel like a dumbass for spouting off nothing.

I'll have to research it...

Bringing this back up. So if I have a set of the 12561462 injectors and am using them on an Fbody, can I use the data found in Greg Banish CD or take the data from a factory 01-02 Fbody tune?

Anyone???

Thanks for reminding me, I have to finish researching this.

Note to self: Injector GM PN 12561462 -> IFR from 2001-2002 F-car LS1 GM calibration, 2001-2002 Y-car LS6 GM calibration, Calibrated Success DVD.

haha, thanks Joe. Let me know what you come up with. I tend to lean on using the stock 01/02 F car data since that was from GM, but I'd rather avoid the headache if I should use something else.

I have the same injectors and I've been using the 2001/2002 F-car stock IFR.

Quote:

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Originally Posted by joecar

I have the same injectors and I've been using the 2001/2002 F-car stock IFR.

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Cool, good to know. I always get confused when the fuel pressure reg is manifold referenced vs. not if you end up with the sloped line or straight.That, and the offsets seemed different based on voltage and such.

Think of it like this:

referenced FPR has MAP added to it, so injector sees MAP at its top and bottom, so MAP cancels out, so pressure difference is constant, so IFR is flat.

Quote:

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Originally Posted by joecar

Think of it like this:

referenced FPR has MAP added to it, so injector sees MAP at its top and bottom, so MAP cancels out, so pressure difference is constant, so IFR is flat.

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Makes sense, and stock Fbody's have no manifold vacuum reference since the FPR is intank right? Been so long since I've played with a stock Fbody I tend to forget what stock looks like :)

Yes, correct, so F-car IFR is sloped.

Good stuff, I'll have to see if the 01 and 02 fuel tables are the same and then pick one to use as the base before redoing ve and maf tables

This thread has driven me nuts for many moons because I could never find the info I'd previously read to substantiate my post on page 2. Here's some more generic info from a guy who seemed pretty confident in this data on IFR for Corvette injectors.

Injectors @ 3 bar / 4 bar
GM 12554271 24.7/28.5 97-98
GM 12555894 22.3/26.3 99-00
GM 12561462 24.7/28.5 01-04

Not sure if this helps or further muddies the waters.

I thought 1999/2000 IFR were same as 2000/2001, but I'll have to take another look at 1999/2000 stock IFR tables.