Converting carb to multi-port EFI, reuse Big Shot plate?

[Glen Koenig]

I have a 496" BBC with a single plane intake, a 1050 Dominator and a Big Shot plate kit. I'm running a single stage up to 350 HP.
New setup is Dominator EFI with EFI Super Vic intake, an elbow and a 102mm (Nick Williams) LSx throttle body.
It makes sense to run a dry shot and leverage the ECU to manage the extra fuel.
I don't know if I can run the Big Shot plate under the elbow, or if I need a different N2O delivery method. What are my options?

TIA, Glen Koenig

[Danny Cabral]

It makes sense to run a dry shot and leverage the ECU to manage the extra fuel.

I agree. I believe dry N2O injection (Closed Loop to New Target A/F Ratio) is best.
(LINK) Just need to know/tune the Added Fuel Enrichment - lb/hr of fuel:
http://documents.holley.com/199r10585rev2.pdf (Chapter 3, Page 12)

I don't know if I can run the Big Shot plate under the elbow, or if I need a different N2O delivery method. What are my options?

The Holley ECU can control up to 4 stages of N2O injection; wet or dry, progressively or not, direct-port or plate type.



The Holley EFI software can operate wet or dry N2O systems (progressive or non-progressive too).
If installing a dry N2O kit, there are no "fuel enrichment" solenoids; only N2O solenoids. I know you're aware of this.
When configured, it creates an N2O Stage Output (which must be Pin Mapped) to activate an N2O relay.
Read section 10 "Nitrous System Wiring" and view the wiring diagram on page 29:
http://documents.holley.com/techlibr...10555rev17.pdf (See N2O Wiring Diagram - Figure 17, Page 29)
or
http://documents.holley.com/199r10585rev2.pdf (See N2O Wiring Diagram - Figures 6 & 7, Pages 11 & 12)

When uploading the Nitrous ICF, the software creates an arming Input - N2O Enable.
After programming the Nitrous Parameters & Stage 1, enter Inputs/Outputs
(still in Nitrous Parameters ICF) and set the Input & Output Types.
Then click on the Pin Map to assign the awaiting Inputs & Outputs.

TIP: I'd use Holley's 554-111 High Current Relay (device/solenoid driver) even for non-progressive use, so the N2O kit is already wired
for either type of usage; allowing software changes without the need to rewire anything. Also, one less wire for easier installation.

If the "Nitrous" menu icon (ICF) isn't already uploaded (added) to the top Toolbar, follow these instructions:
The "Nitrous" function is an "Individual Configuration" of the Holley EFI software.
At top of screen, Click "Toolbox" and "Add Individual Config".
At top of new window, select "Individual Configuration Library".
At bottom of new window, select "Holley EFI Nitrous Config".
Select "Nitrous" and open "Base - Single Stage Dry.nitrous".
The "Nitrous" icon will then be present at top of screen.

[Glen Koenig]

I agree. I believe dry N2O injection (Closed Loop to New Target A/F Ratio) is best.
Just need to know/tune the Added Fuel Enrichment - lb/hr of fuel (Link).

Danny, thank you for the quick and thorough reply!

I'm very curious about how nitrous tuning works with the Dominator ECU. My plate kit was calibrated by Steve Johnson, and so I could just follow his expert advise. I like the thought of having an ECU take out much of the tuning guess work.

I did consult with tech support about the injector size and he recommended the 83 lb/hr injectors for the 750hp NA plus the 350 shot. The likelihood is that the engine is closer to 800hp NA. Should the 83s be enough?

The Holley ECU can control up to 4 stages of N2O injection; wet or dry, progressively or not, direct-port or plate type.

I don't foresee ever needing more than a 350 shot. However, I'm beginning to wonder if I should be looking for a dual stage kit anyway. The car is a '96 Impala with a hefty 4100# race weight. I was planning to use the progressive control to help tame the launch. Do you think that should suffice, or would I be better off using a 2 stage with a small shot (100) off the line and then a bigger shot (250) past the 100'?

TIP: I'd use Holley's 554-111 High Current Relay (device/solenoid driver) even for non-progressive use, so the N2O kit is already wired
for either type of usage; allowing software changes without the need to rewire anything. Also, one less wire for easier installation.

I ordered the 554-111. Can you recommend a relay to use with this?
Likewise, does the ECU require a specific type of relay for the outputs? I normally use a typical SPDT 30/40 amp relay.

[Danny Cabral]

My plate kit was calibrated by Steve Johnson, and so I could just follow his expert advise. I like the thought of having an ECU take out much of the tuning guess work.

It's best to have your N2O system "flowed", so you know exactly how much lb/hr of Added Fuel Enrichment to program in the ECU.
http://www.yellowbullet.com/forum/sh...=Dry%20nitrous (Related Forum Post)

http://convert-to.com/conversion/flo...line-flow.html (convert gal/hr to lb/hr)
http://convert-to.com/conversion/flo...line-flow.html (convert ltr/hr to lb/hr)

I did consult with tech support about the injector size and he recommended the 83 lb/hr injectors for the 750hp NA plus the 350 shot. The likelihood is that the engine is closer to 800hp NA. Should the 83s be enough?

Yes, 83 lb/hr fuel injectors should be enough:
http://documents.holley.com/techlibr...l_injector.pdf (Selecting a Fuel Injector)
https://www.injector.com/injector_selection_guide.html (Marren Fuel Injection Calculator)

I don't foresee ever needing more than a 350 shot. However, I'm beginning to wonder if I should be looking for a dual stage kit anyway. The car is a '96 Impala with a hefty 4100# race weight. I was planning to use the progressive control to help tame the launch. Do you think that should suffice, or would I be better off using a 2 stage with a small shot (100) off the line and then a bigger shot (250) past the 100'?

Yes, that's usually why racers change to progressively controlled N2O activation.

I ordered the 554-111. Can you recommend a relay to use with this?

You misunderstood this. The Holley 554-111 is the relay for progressive N2O use. Nothing else is required.
Read section 10 "Nitrous System Wiring" and view the wiring diagram on page 28:
http://documents.holley.com/techlibr...10555rev17.pdf (Holley EFI Wiring Manual)

Likewise, does the ECU require a specific type of relay for the outputs? I normally use a typical SPDT 30/40 amp relay.

A relay must be used because all the ECU's Outputs are rated at a maximum of 2 amps.
It's nothing special. Although for ECU wiring, a relay with a resistor or diode (across the coil) should be used.
It's a typical five terminal automotive relay (Bosch/Tyco) that can be obtained at your local auto parts store.
The first five relays listed below, are all the same five terminal SPDT configuration, with bracket & resistor:
Tyco V23234-A1001-X043
Bosch 0 332 209 161
Hella 87420
Pico 5591PT (Relay/Wiring Kit)
Echlin/Napa AR143 (Wiring Kit)
Echlin/Napa AR204 (50 amp, diode protected - correct wiring polarity required.)

If you don't want to concern yourself with the correct wiring polarity, just use a resistor type relay (no polarity wiring matters).
For diode relays, the relays have a schematic diagram on their side. Follow the directions below regardless of relay manufacturer:
+12V - Cathode
Ground - Anode

http://www.autoshop101.com/forms/hweb2.pdf (Diode vs. Resistor Relays - Page 12 & 13)

[Glen Koenig]

Thanks for the link, in reference to flowing the dry shot. I had a feeling that Steve and others could flow the dry nozzles too. I'll give him a call to see what he has.

I may not be able to afford the direct-port setup now. Am I correct that I can just use my existing (and flowed) plate kit for now?

Also, static compression ratio is 10.5:1 and I run 93 octane pump gas NA. I assume I'll need to run race gas when spraying it, especially for the 200 and up shot sizes. I'm curious to know if there are any creative options for accomplishing the fuel swap other than draining the tank each time I need to change fuels. Dual fuel tanks, a separate fuel cell for the race gas with a transfer valve?

Thanks again for all the help. Much appreciated!

P.S. I like what you did with the mounting of the Holley 60-2 wheel behind your balancer. I've ordered the kit for my BBC. Do you know if I could do the same with my setup (ATI Super Damper), or do I just put it on the front like normal?

[Danny Cabral]

I may not be able to afford the direct-port setup now. Am I correct that I can just use my existing (and flowed) plate kit for now?

Yes, and you'll discuss this in further detail with your N2O injection professional.

Also, static compression ratio is 10.5:1 and I run 93 octane pump gas NA. I assume I'll need to run race gas when spraying it, especially for the 200 and up shot sizes.

Yes. https://www.holley.com/document/tech...ech_info_2.pdf (N2O Tuning Tech Info, pages 3-6)

P.S. I like what you did with the mounting of the Holley 60-2 wheel behind your balancer. I've ordered the kit for my BBC. Do you know if I could do the same with my setup (ATI Super Damper), or do I just put it on the front like normal?

Thanks, but that's a totally custom made 60-2 crank trigger kit (Link). Due to the type of off-road motorsports I participate in, I didn't feel comfortable with positioning the crank trigger in front of the damper (in danger of debris impact). A drag racing application should be fine with a commercially available crank trigger kit. If fabricating something custom, I don't know if purchasing a complete kit would be advantageous?