SKU: 62516865524

HP EFI ECU & Harness Kits - 550-601

Sale price$1237.47 Regular price$1374.97
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Description

HP EFI ECU & Harness Kits - 550-601Overview: 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

Overview:

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:

  • NEW V2 SOFTWARE FEATURES
  • “Quick Start” ignition and fueling strategy for LS x Engines
  • Data Logger. Scalable axes, Smoothing, Multiple graph view ability, Pre-defined notes fields and many more
  • Strip Chart Real-Time Data Viewer
  • Integrated Boost Control - Boost vs Time, Boost vs Gear (Time or RPM), Boost vs RPM, Boost vs Speed, Launch control. Boost launch builder, Over-boost safeties, Boost scramble
  • Traction Control - Power reduction via timing, nitrous percentage or boost (Requires Davis Technologies Holley Module)
  • “Quick Start” fueling for all engines
  • Option for VE based fueling strategy
  • Fuel Map and Learn Function Smoothing
  • Configurable User Password Protection
  • Fully Configurable lap top Gauge Panel
  • 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
  • Plug and Play control of factory GM 24x and 58x LSx engines
  • 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 24x and 58x LSx engines, 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:

Year Make Model Submodel Engine Size
Universal

Specs:

Brand Holley EFI
Emission Code 3
Ignition Type Coil - (No Timing Control)
Ignition Type GM HEI Small Cap
Ignition Type Holley Dual Sync Distributor
Injector Connector Jetronic / Minitimer (Bosch)
Product Type HP EFI Kit
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: 62516865524

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Silvia & Marcus
Massapequa, US
★★★★★ 5
My new favorite shirts!
Fit Type: Regular Fit, Color: Grey, Size: Large
These are my new favorite shirts! I just ordered a 3rd. i wish there were more colors. Yes, the cotton is heavy-weight and I like that. They are just a bit warmer than regular dress shirts. The fit is excellent. I'm 5'9", 200lbs and L fits perfectly. Enough room without being blousy. The sleeves are long enough (finally!). (Most other 16.5/32-33 shirts always have sleeves that are too short). The fit/finish and detail is surprisingly good. They don't really shrink after washing and come out very soft. Not wrinkle-free, but that's ok since it means that the 100% cotton hasn't been dosed with chemicals. I expect they will wear very well over time.
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Reviewed in the United States on May 5, 2025
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Jerry
San Leandro, US
★★★★★ 5
A perfect white work shirt.
Fit Type: Regular Fit, Color: White, Size: Medium
Thick, durable, iron exquisitely and the fit is spot on. Perfect white work shirt. I have a grey shirt too, the quality is the same.
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Reviewed in the United States on March 4, 2026
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Blusher
Grantham, US
★★★★★ 3
Right fit
I love this shirt it was nice and bright when I got it after a few wash it started to fade out a bit was a perfect fit for a medium built person 5’7 I still would recommend this product they are really nice and thick
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Reviewed in the United States on September 14, 2025
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John E. Holiday
Charlottesville, US
★★★★★ 5
Quality shirt. Not too blousy.
I'm 5'11" and hover around 175-180 lbs. so I'm a pretty average guy. I've been thin my whole life but now I'm in my 40's so if I don't watch it, my stomach will get bigger. I bought this shirt in slim-fit first. It was perfect but since these shirts are 100% cotton, I was concerned that after a couple washings, it would be too small (especially in the stomach area). I returned the slim-fit and bought this regular-fit (medium). For this review, I thought it would be helpful to compare the Amazon Essentials shirt to The Gap's regular oxford shirt. I've always liked the fit of Gap oxford shirts. Upon inspection, the weight and feel of the Amazon oxford cloth is exactly the same at the Gap's. I laid one of my old Gap shirts on top of this Amazon Essentials oxford. You can see from the pictures that the torso cut is exactly the same (about 21 inches pit-to-pit seam). I like that. I'm not a fat guy and I don't want a blousy shirt. This is neither too blousy nor too slim. Just right. The sleeves are perhaps 1/2 inch longer than the Gap shirt. Perhaps one negative is the tail. The Amazon Essentials tail is 1.5-2" longer than the Gap shirt. This makes the Amazon Essentials shirt a touch long for wearing untucked in my opinion. However, if you do tuck, a longer shirt stays tucked-in. So it depends how you want to wear it. I have a lady who does alterations. She'll charge $10 to shorten the tail if I wanted that. If I do have the Amazon shirt altered, it would still be a bargain. These are good quality shirts with a nice cut to them. I won't hesitate to buy them again. Highly recommended.
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Reviewed in the United States on January 24, 2020
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Tracy J
Lexington, US
★★★★★ 4
Decent quality. Sizing is normal but a bit generous in the midsection
Fit Type: Regular Fit, Color: White, Size: Large
I was impressed. Shirt is of fairly decent quality- thick cotton. My husband is normally a large. Given the sizing chart we almost ordered a medium, but it was good we bought a large. The sleeves are perfect but afraid it may shrink in the dryer. I think the reason people say loose fit is because it is boxy (square). Fine under a suit and we needed it urgently.
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Reviewed in the United States on January 17, 2026

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