SKU: 77262188315

Holley HP EFI ECU and Harness Kits 550-604N

Sale price$1349.97 Regular price$1499.97
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  • USA
  • CAN

Ships within 48 hours · Estimated delivery Jul 18 - Jul 23

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Description

Holley HP EFI ECU and Harness Kits 550-604NHP ECU AND HARNESS, MPFI, NTK Looking for a plug and play alternative for your stock or built late model factory EFI engine? How about a replacement ECU for your older Holley C950? Holley has you covered. HP EFI ECU and harness kits are designed to be used with popular factory EFI engines as an alternative to the factory ECU and harness or as a replacement for your C950 ECU. The HP allows you to accurately control the fuel and ignition of your engine

HP ECU AND HARNESS, MPFI, NTK
 
Looking for a plug and play alternative for your stock or built late model factory EFI engine? How about a replacement ECU for your older Holley C950? Holley has you covered. HP EFI ECU and harness kits are designed to be used with popular factory EFI engines as an alternative to the factory ECU and harness or as a replacement for your C950 ECU. The HP allows you to accurately control the fuel and ignition of your engine along with additional controls for nitrous, boost or water meth.

Features:

  • Optional 5.7” full-color touchscreen LCD allows easy on-the-fly tuning, data-logging or can be used as an easy to see graphical gauge panel
  • Eight sequentially driven 8:2 peak and hold injector drivers, capable of driving up to 16 low or high impedance injectors as a standard feature. Multiple staged injector strategies
  • Eight channel Distributorless Ignition (DIS)outputs capable of directly driving “Smart” ignition coils or Holley DIS coils. Will drive 2 wire coils with the addition of PN 554-112 high current coil driver module
  • Integrated single channel wide band oxygen sensor control. Works with NTK or Bosch sensors
  • Internal data-logging standard with a huge 2GB of memory
  • 4 Stage progressive nitrous control
  • Turbo boost control
  • Integrated water/methanol injection control
  • Self-tuning fuel table strategy greatly simplifies tuning process
  • Individual cylinder fuel and spark control allows you to unlock your engine’s potential
  • Works with 4, 6, 8 cylinder engines
  • Unique lb/hr based fueling strategy greatly simplifies and commonizes tuning
  • Advanced idle, closed loop, and enrichment strategies allow for very stable operation
  • ECU is fully potted and can be mounted in the engine compartment or interior
  • Sealed automotive and marine grade connectors
  • Allows for use of common OEM sensors as well as customer sensor calibration input
  • Ignition Plug and Play with GM HEI, Ford TFI, magnetic and hall effect trigger, and other ignition systems. New Plug and Play applications in process. Custom settings can be configured to allow many other applications
  • 1-5 Bar MAP sensor capability
  • Two channel knock control sensor Inputs for both one or two wire knock sensors
  • Dedicated fuel and oil pressure inputs
  • Controls both stepper and PWM Idle Air Control (IAC) motors
  • Speed density, Alpha-N, or combination fueling strategies
  • 4 Programmable high or low Pulse Width Modulated (PWM) outputs and 4 fully configurable inputs can be configured for use
  • 4 Stage nitrous oxide control
  • Fully featured nitrous control eliminates the need for a separate nitrous controller device
  • Can be configured “Wet” or “Dry” with closed loop feedback
  • Progressive control based on time, RPM, or boost, requires part # 554-111
  • Lean or rich safety cutoff
  • Full timing retard/control configurability per stage based on RPM or time
  • Integrated Water/Methanol injection control
  • Uses Holley Water/Meth solenoids specially designed and calibrated for use with this EFI system to allow the user to enter Water/Meth flow as a percentage of fuel injector flow for Water/Meth tuning precision unmatched in the industry

Application

  • Universal

Specs

Brand Holley EFI
Emission Code 3
Ignition Type Coil - (No Timing Control)
  Ford TFI
  GM HEI Small Cap
  Holley Dual Sync Distributor
Injector Connector Jetronic / Minitimer (Bosch)
Product Type HP EFI Kit
Part Number 550-604N
Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 77262188315

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Denny
Lake Worth, US
★★★★★ 5
Great Protective Case for My Mother’s iPad
Color: 2-Watermelon Red, Color: 2-Watermelon Red
I bought this case along with my mother’s new iPad, and it was the perfect choice. The watermelon red color looks beautiful with the pink iPad and gives it a very clean and stylish look. The case feels sturdy without adding too much weight, which makes it comfortable for her to carry around and use every day. The stand feature works really well for watching videos, reading, and video calls. I also like that the case supports the auto wake and sleep function, which makes the iPad feel even more convenient and easy to use. The cutouts fit perfectly, and Touch ID still works without any issues. The translucent back is a nice touch because it still lets the iPad color show through while keeping it protected from scratches and bumps. Overall, this case exceeded expectations and makes a great addition for anyone wanting both protection and style for their iPad.
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Reviewed in the United States on May 14, 2026
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Leon
Pawtucket, US
★★★★★ 4
Good product. What you see is what you get.
Color: 1-Navy Blue
Material feels sturdy and was a perfect fit compatible for my iPad. There's adequate grip and padding for a comfortable yet slim feel. Magnets hold it close and in one position when propping it up for watching landscape videos. Back is translucent as advertised. Solid product, put it on as i opened my new ipad for immediate protection. Perfectly safe blind buy if you're also getting that 'frequently bought together' suggestion from Amazon.
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Reviewed in the United States on June 1, 2026
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Sue Fowler
Massapequa, US
★★★★★ 5
Nice iPad case. Good price, lots of colors,
Color: Papaya
Nice iPad case. Well made, fits great. Love the color!
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Reviewed in the United States on June 8, 2026
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savvy_shopper101
Carnegie, US
★★★★★ 5
Excellent iPad case!
Color: 1-Navy Blue
Excellent case! Perfect for what I needed, very stable, flexible and the color is great. I've had it for almost a year now and there's no damage or wear. Would buy again! Easy to use, stable mechanism to stand up right and wonderful color options!
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Reviewed in the United States on May 30, 2026
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Summer
Boise, US
★★★★★ 5
Bright & Pretty Hot Pink.
Color: Pitaya Red, Color: Pitaya Red
Very pretty and bright. It’s thick and great quality. Strong grip and doesn’t come off easily. Easy to clean when it gets dirty. It also has a nice backing. I prefer the transparent bright pink backing than the clear version. I love the strong magnetic for when I position it upwards. It can be positioned downwards too.
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Reviewed in the United States on May 28, 2026

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