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

1. ## 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.

2. 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

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.

4. 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

5. 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.

6. 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.
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.

Log_2704_1.efi

8. 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).

9. 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.

10. 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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