Considering a 5.9 EFI swap into 68 Val -833 O/D car

goldduster318 said

Honestly, I would personally go stand alone, like a Megasquirt 3 or Megasquirt 3 pro. That way you can do sequential injection, program everything yourself to fix things you don't like, have a self-learning feature, etc, etc. Change/upgrade as you go.

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This is where I start to get very confused. Megasquirt, Holley ECU, SCT. I don't understand what all of these are or what they do.

Does a Megasquirt replace the factory ECU or is it a programmer for an ECU. Do they come with wiring for the engine or do you still use a "Hotwire" type system with them?

Is there a huge learning curve to program your own "tunes?"

Are these systems geared toward those who want to eek out every last 10th of a second on their ET's, or do they make a considerable difference with the same engine as compared to a factory ECU?

Thanks!

CE