I spent more time on the phone with Holley today, made some adjustments to the parts list and pulled the trigger. The final BOM as ordered is below. For starters I was looking for larger injectors suitable for E85. The guy at Holley I talked to (Ethan) did a great job steering me in the right direction. First I told him I was looking for E85 to 650 Hp on a 418 LS3 turning to 5,800.
First he asked what intake manifold I would be using and I told him the 2008/2009 Escalade/Truck intake. He said the EV1 injectors in my previous BOM were too tall for this intake and I would be better off with EV6. Next he said to use 0.6 lb/(hr*hp) as the fuel requirement for E85 (48 lb/hr per injector at 650 Hp). But, you don't want them running flat out, so 80% duty cycle puts them at 60 + lb/hr minimum for E85 injector sizing, 70-80 lb/hr range preferred. Make sure to tell them Marine/Airboat application, Holley uses a 5% multiplier for marine duty cycle.
https://documents.holley.com/techlibrary_selecting_a_fuel_injector.pdf
Then I asked about idle control and issues, he said the Holley software allows for fuel pulse phasing based on crank/cam timing. So instead of spraying fuel continuously (with PWM), the fuel pulses can be synchronized with the intake valve to optimize idle. So cool, 76 lb is big enough to support E85 and still controllable at idle on gas.
Then I asked about High vs. Low impedance injectors for this application. The word impedance throws a lot of folks off, but basically means high or low resistance, the low impedance injector requires more power vs. the high impedance unit. High impedance is the standard for typical automotive applications. But, this limits how much power can flow through the solenoid, limiting how much fuel it can control. As the fuel flow rate increases, the solenoid needs more power to control. To support this on race applications they came up with the low impedance injector that can draw more power and support higher fuel flow. But, higher power draw does impact the PWM (pulse width modulated) drivers on the ECU.
As a point of reliability, my initial thinking was it is a tradeoff between lower power injectors that might clog and lower flow vs. the potential for an injector driver failure on the Dominator ECU. Honestly, If I was going to setup for low impedance, high power injectors I would probably use one Holley's injector driver so I didn't burn up my potted ECU due to running too hard in the sun.
The injectors he recommended are 76 lb/hr, High impedance, EV6 - Pico style that can support higher flow due to a difference in design. They are rated at this flow at 60 PSI. This is a key point, fuel pressure. I am designing for reliability, which means a clogged fuel filter. I will be including a fuel pressure sensor to monitor fuel pressure and use that to inform my tunes. If I set my system up for 55-60 PSI fuel pressure, these injectors will support full power on 93 gas and well under 40 PSI. This gives me margin, that's what I want.
Also note the FM at the end of the injector set part number. They offer 2 variations on this set of injectors.
* 522-768X = set of 8 injectors for $387, factory spec 5%.
* 522-768XFM = set of 8 injectors, $525, flow matched to 2%.
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For all the other money I'm spending, yep, $150 for flow matched injectors seems valid. I'm not going to be monitoring each individual cylinder, so whatever each O2 tells me the bank is doing, I want to assume all 4 are similar.
The last problem was the harness, my previous BOM listed a full ECU/Harness kit, but that was for the EV1 injectors. Ethan resolved that with a new ECU and harness part number to match the shorter EV6 injectors. Finally, he asked what MAP sensor I would be using, I told him stock, turns out Holley's harness is set up for a Holley MAP, so had to add another adapter.
Finally (this is where I was surprised), the grand total I came up with was less than what I had lined up previously. Then he gave me the car dealer sales push, he could give me a discount to purchase the whole setup now. Good thing I was ready to buy.
Long story short, call Holley, don't screw around with Summit, JEGs etc. If you want to buy their stuff, call them, figure out what you need, negotiate for a 10% discount for a full setup and buy it.
Here is the final BOM on order (unfortunately the ECU is back ordered until October, good thing I don't need it quick!).