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Old 03-30-2020, 11:21 PM   #1
cmracing
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Default Re: injector size

Well pbp1, you certainly gave a very detailed explanation!

I find it funny when people think that running a 24lb/hr injector will result in a quicker pass than if he was to run an 80lb/hr injector, both running the same A/F ratio.

I had a friend make a pass with a set of 30's, swapped to a set of 66's, I had already made a fuel map that would be close with the larger injectors, car ran identical. He was very surprised because everyone said it would be slower. He then learned how to time the injector opening event with the larger injectors which he could not do with the smaller injectors.

The only real "disadvantage" to running too large an injector is the idle quality. Running sequential fueling really helps this situation though.
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Old 03-31-2020, 11:38 AM   #2
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Default Re: injector size

I went to smaller injectors, at 60 psi, was due to a suggestion of a long time friend, who is a retired GM Calibration Engineer (“tuner”). Same reason the GM LS series engines went to higher (60psi) fuel pressure than the LT engines the LS series replaced. Higher pressure makes for a finer fuel mist from the injector, which is easier to fire. More consistent. There is some power & emissions improvements from injector timing as well. Large injectors are not required to find power there. My cam position sensor is adjustable. That is where I effect my injector phasing.
I also run mine in Sequential Mode.
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Old 03-31-2020, 12:30 PM   #3
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Default Re: injector size

With a “Firing Order Swap cam”, be sure to program your Sequential Injection for the new firing order.
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Old 03-31-2020, 03:18 PM   #4
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Default Re: injector size

In Seqential Mode, it’s easy to correct individual cylinder A/F ratios on the dyno. I have seen cars at the track with 8 wide band O2s. That would be interesting to log.
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Old 03-31-2020, 05:49 PM   #5
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Default Re: injector size

Quote:
Originally Posted by Ed Wright View Post
In Seqential Mode, it’s easy to correct individual cylinder A/F ratios on the dyno. I have seen cars at the track with 8 wide band O2s. That would be interesting to log.
We can log all 8 O2s (9 actually) on my stocker and on our Sunfire SS going down track with our FAST XFI, but we don't do it all the time. They pull a lot of juice from the batteries.
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