Basically when i rebuild my HP500 carb motors this winter i'm thinking i want efi. They're stock with 525efi cams but am thinking about raising the compression or even stroking them which isn't the issue. The question is how involved would it be to retrofit my motors with 525 or 500 efi hardware? What all would i need? Or do i go with a carb replacement kit from Holley or fast? I really want the stock appearing blue paint but at a certain point it might not be worth the headaches. Theres several twins sets: intakes, intake manifolds, rails, harnesses and ecu's in the swap shop for around a grand or a little better depending on the misc sensors and parts to make them work. i know i'd have to change my fuel system either way. I know these motors are known for being difficult to diagnose and work on but what about setting them up from scratch?
Thanks,
Riley

I would go with Holley HP EFI, with their touch screen dash, single plane intake, and a 1000 cfm body.

I run Holley on my car and love it.

This is just an idea but could it be possible to run Holleys new Terminator EFI. Setup? It's not out yet to the best of my knowledge and is meant for the automotive world but may work for us as I have thought about trying this.

I did this this past winter with my 1995 Top Gun, it had 525SC's and I wanted FI. I went with a Whipple kit which included the fuel system, computer, harness and all sensors, of course in addition to the blowers.

Basically, and others can chime in on where I'm wrong or what I'm missing, you're going to need the fuel system, the computers, the harness (for the engine) which will plug into the main cannon plug on the boat harness, and then whatever sensors are required. It's certainly doable and fairly easy, as always it just comes down to money. Since you have time you can most likely piece it together over the months and then get out of it pretty reasonably I would think.

For me the FI was the only way to go and I'm very happy I choose this route. Good luck whatever way you decide to go!

I have converted from carb to EFI twice.

The first time I used stock MPI stuff and used the MEFI Burn program to dial it in. It worked fine, but was a lot of work. It was all purchased used, which created headaches diagnosing issues and getting them handled.

Second time around I used the Holley HP. What a difference! Self-tunes, and everything was new, making the hassle factor all but disappear. It also appears close to a stock carbed engine when done. I've always hated the look of the MPI system. Do your self a favor and go with the Holley. If you do I would suggest purchasing it from Alex Haxby. He can solve most any tuning issues over the phone in just a few minutes, and his prices are competitive with any of the big dealers out there.

Many things im thinking about. Holley efi on what i have, dual efi quads on 871s or whipple setups? Not looking for crazy power numbers and really want realtime self tuning software for piece of mind and economy. Anyone ever put the dual quad on a blower?

For what its worth, the real-time tuning isn't all that its cracked up to be - however self compensating is what is nice. It took me about 20 minutes on the water to run mine and get it completely tuned after I got it started and running in my driveway. I short blast up and down the river, and my AFR is rock steady at 12.8:1 at WOT, and around 13.3:1 in cruise.

Depending on how far you want to take them I may have something for you. If i decide to go with superchargers I will have a complete set up for you. mine are 640 hp, i would sell everything complete with computer w precision marine tune, Az speed mono blade throttle body, bigger injectors etc. I have one complete set now for sale with everything you would need but has a stock 500 efi throttle body. the twin set up if i sell over the winter will be a matched set to handle your cam and even bigger heads than you have now. I could also help you with setting up a proper fuel system and eliminating the stock restrictive cool fuel. pm me for details if you are interested..

Exactly what i was looking for, someone who runs (im guessing) a holley setup. What exactly do you have and what'd it set you back? Thanks

Rbesola I'm looking for the same thing. I'm just running NA 572's but I'm tired of my carbs.