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Edelbrock’s Pro-Flo XT EFI

All the way back from the days when raw horsepower dominated the streets, muscle cars have always had their engines topped off with monster four-barrel carbs and aftermarket intake manifolds. Every gearhead with a beefy daily driver migrated to this kind of time-tested carbureted fuel delivery system because it was reliable, simple to adjust and capable of making high horsepower. Those days have forever been changed with a bolt-on, ready-to-use out-of-the-box electronic fuel injection system from one of the automotive world’s leaders in carbureted fuel systems. Ironic and paradoxical as that sounds, Edelbrock has been a player in the fuel injection market since 1979, when they engineered and marketed their first fuel injection system.

The Evolution of Edelbrock’s Pro-Flo Fuel Injection systems
Edelbrock released the original Pro-Flo fuel injection system in the early 90’s in response to the tolling of the bell for the end of the muscle car era, doomed by environmental regulations and federal air pollution standards. The original Pro-Flo system allowed computer management of every aspect of the engine’s operation to the millisecond, and that control increased the power of the sluggish and stifled pollution-controlled engines of that time. The Pro-Flo system revolutionized bolt-on electronic fuel injection systems as a complete package including everything needed to convert older carbureted motors into an EFI engine. Unique to this early system was a handheld controller that allowed the user to adjust the fuel injection parameters without a laptop computer. The first generation Pro-Flo EFI kit is no longer available from Edelbrock and for anyone that owns the Pro-Flo and wants to upgrade to the Pro-Flo 2,
an upgrade kit is available.

The Pro-Flo 2
Edelbrock expanded and modified the Pro-Flo EFI system and released the
Pro-Flo 2 as a direct replacement for the original Pro-Flo system. All the features from the original Pro-Flo system were retained or improved, including a new module that was resistant to EMI electrical noise from high energy ignition systems. The Pro-Flo 2 also allowed laptop tuning using supplied software that allowed calibrations to be saved and loaded. One of the more significant improvements to the Pro-Flo 2 system was the ability of the module to read both wideband and narrowband oxygen sensors. The Pro-Flo 2 can also be configured to use any available manifold pressure sensor, making it perfect for supercharged or turbo charged applications.

The Pro-Flo XT
The
Pro-Flo XT system is a complete and separate EFI system in the Pro-Flo line. Joining forces with EFI Technology, Edelbrock has designed the Pro-Flo XT EFI system for higher-end applications. EFI Technology is instrumental in designing EFI and data control systems for IRL, F1 and NASCAR series racecars. Utilizing their technology and experience, the Pro-Flo XT has the performance characteristics of a cutting-edge performance system with a very user-friendly interface. The Pro-Flo XT is a complete package that includes an assembled intake, fuel rails, throttle body, ECU, wiring harness, fuel pump, fuel hose, fuel filter and all sensors and hardware. Final installation requires the use of a PC for first-time base calibration. The software program is extremely user-friendly and is menu driven. No special computer knowledge is needed to upload or save calibration settings; simply follow the instructions onscreen. While the system may be used by custom tuning facilities, there is no requirement to have special tuning skills or advance tuner experience. The system can be loaded and programmed by virtually anyone with basic mechanical knowledge.

Highlights of the Pro-Flo XT EFI System
The system’s intake manifold design is all new with a “front mount” style throttle body location patterned after late-model GM manifolds. Shooting for a custom-designed look, the manifold is available in cast aluminum or black powder-coat finish.

Included is an LSX-style 90mm throttle body, complete with a four-wire Idle Air Control stepper motor. The full-sequential injection system allows for individual injector firing of the 29 lb/hr-rated injectors. The ECU is flash-programmable, includes several base calibrations, and can be tuned with the handheld controller. In addition to the handheld controller, the ECU can be tuned with a laptop through the included PC software interface and has unlimited calibration storage. Options with the flash controller are MAP-N tuning strategy and Alpha-N tuning strategy.

MAP-N, or “speed-density” tuning uses the engine speed in relationship to the MAP (manifold absolute pressure) to determine the fuel demand and spark requirements throughout the speed range. Speed-density tuning can bring out the maximum performance from an engine, especially a highly modified engine.

Alpha-N tuning uses the engine speed against the throttle position to determine the fuel and spark requirements. This tuning approach can be very desirable when an engine is upgraded with a big, gnarly cam that can cause low speed or idle problems.

Tuning Strategy Comparison

MAP-N
Advantages

  • Relatively quick and easy to tune
  • Base fuel map is graduated in units of injector pulsewidth
  • Very common tuning method used in many popular aftermarket EFI systems.
  • Works well and easy to tune for boosted applications
  • Easy to modify calibration if larger injectors are installed

Disadvantages

  • Does not work well with large overlap camshafts due to low idle vacuum signal
  • Requires temperature-based trim tables
  • Indirect measurement of load
  • Calibration can be inconsistent if trim tables are not properly tuned

Alpha-N
Advantages

  • Works well for large overlap camshafts – not affected by low idle vacuum signal
  • Relatively quick and easy to tune
  • Base fuel map calibrated in units of injector pulsewidth
  • Easy to modify calibration if larger injectors are installed

Disadvantages

  • Idle mixture affected by closed throttle TPS voltage drift
  • Requires temperature-based trim tables
  • Indirect measurement of load
  • Does not work well with idle air control motors.
  • Calibration can be inconsistent if trim tables are not properly tuned

Like the Pro-Flo2, the Pro-Flo XT accepts either a narrowband or wideband oxygen sensor. The difference between a narrowband and wideband sensor is the range over which the sensor is accurate. A narrowband is basically a switch that only tells the ECU if the air fuel ratio (AFR) is richer or leaner than 14.7:1. A wideband sensor typically has a linear voltage output that is accurate over a range of 10 to 20:1 AFR.

According to the EFI engineers at Edelbrock, to get the most out of any fuel injection system installation, a proper wideband oxygen sensor installation is hard to beat. At typical cruising conditions, it is difficult to tell (by the seat of your pants) the difference between an engine running at an AFR of 13.0:1 and one running at 14.5:1, but the difference in fuel flow and economy between those conditions is huge. A wideband will tell you instantly exactly what the AFR is under all conditions.

Pro-Flo XT Additional Specs:

  • 4×6 fuel table / 3×6 spark table (Handheld Calibration Module)
  • 11 x 16 load and RPM tables if using PC software
  • Closed loop fuel control
  • Adjustable rev-limiter
  • Two-piece EFI harness connects the engine harness and chassis harness at the firewall for quick connection and easy removal


Unlike the earlier generations of fuel injection systems, the current technology in Edelbrock’s electronic fuel injection (EFI) embodies the best of the tried and true carburetion systems; the reliability, ease of use, simplicity, and the stand-alone design. In addition to becoming even more “user-friendly”, these electronic fuel injection systems meet federal environmental air emission standards while improving engine performance and fuel economy. According to Scott Armish, EFI Engineer at Edelbrock, “Installing and maintaining the Pro Flo XT EFI no longer requires specialized training or a degree in engineering. Seriously. The accuracy, reliability and affordability of the Pro Flo XT system is far beyond what previously existed in EFI upgrade systems”. Scott also directed us to asupport forum group, operated and maintained by the Edelbrock Corporation. The support group is relatively new having launched in July of this year.

Availability of the Pro-Flo XT
Currently the Pro-Flo XT is only offered for small-block Chevy applications. Scott Armish explained that “within 4 to 6 weeks” the manifold development would be complete for big-block Chevy engines and should be available to the public within two months. Like the small block Chevy manifold, the intake in the big block package will be a “front mount” style intake. If you have a small block Ford or big block Mopar and want the Pro-Flo XT system, Scott has assured us that these applications would be available early next year.

Pro-Flo XT Plus
Also available is the Pro-Flo XT Plus for those tuners that want to have the ability to live-tune on the fly with a laptop computer. It also has provisions for four stages of nitrous and has three-dimensional fuel and spark maps. More information on the Pro-Flo XT + is available on
Edelbrock’s dedicated support forum.

Lastly, there will be a high end Race version of the Pro-Flo system for the hardcore racer that is capable of handling up to 3,000 horsepower. The engineers at Edlebrock tell us that this kit will feature military-style connectors and nitrous control. Expected release date for this unit is still pending.

Sources

Edelbrock
Phone: (310) 781-2222


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