Easiest way - converting 502 to EFI
 

Standard 502 Merc. Do they make a top end conversion kit with the computer, harness, injectors, etc from the newer 502 MPIs to essentially convert the 502 to a 502 MPI?

If not, piece together yourself and control with a Big Stuff or the like?

What would you say is the easiest/most cost effective method of converting? Thanks!

I have 2 complete MPI units off a 2001 fountain for sale $2000 pair (716) 510-4411 dan

What all is included with for that?

I have a complete 502 mpi setup off of 2000 mag mpi engine...everything needed is included...upper and lower intake, fuel rail injectors, throttle body distributor, coil, harness, mefi 3 computer even the merc cool fuel setup with pump and regulator. $800
http://i19.photobucket.com/albums/b1...pshqwvvl5s.jpg

I believe cams are different. Besides with all the problems others are having with EFI I would go with a good single plane intake, holley carb and HEI distributor. Think about having the MPI programed and running perfect after the Swap.
Just my 2¢.

Yeah he will need a cam ground for EFI...I dont have the 502mpi cam I sold it with the shortblock.

I have a 502 MPI cam. Just converted the 502 into a 540 , dumped it all except block, oil pan and accessories. Holley HP EFI, 2000 cfm TB with Holley intake. It will be posted on the EFI for everyone thread, once off dyno.

I have 2 100% complete Cutler systems from a 1993 Baja. One has a bad ECM. Bob Lloyd at Full throttle Performance has an ECM. Had I known he had this before I converted back to carbs, my Dad would have kept the system. $1200 for all. These are 100% complete, including wire harness, fuel pumps, and manuals.

If I don't figure my 502efi issue out Ill give this **** to ya! Stick with a carb !!!

Anybody use any of the new Easy type EFI units that bolt on a carb mount?? They look pretty cool and tunable for use up to 600HP.....

I like what FAST is offering for marine apps plus their tech support.

I've got a complete system including the cam, but it's off of a 454 Mag.

http://www.offshoreonly.com/forums/s...ice-parts.html

Aftermarket EFI, screw that Merc crap :poopoo:

I agree especially MEFI 1 & 2 almost worthless at this point & timeframe. - MEFI 3 is ok if you have gen II cool fuel system. The EFI set ups with the VST is so poor and so outdated that some of it is NLA thru the OEM along it seems always to have a problem as far as reliability goes. Also MEFI 1 thru 3 is no longer available you have to buy the conversion kit and install MEFI 4 if you were needing a new replacement controller thru the OEM or any marine OEM's.

Yup, it doesn't get any easier than this for a non technology person. Input timing, cylinders, and target AFR.
http://www.offshoreonly.com/forums/g...mable-efi.html

http://www.offshoreonly.com/forums/g...-everyone.html

Fast looks ok, however I don't think they offer a USCG approved ECU like Holley. The kit that the op is looking at for up to 600hp is the Holley Terminator.

I only am familiar with the FAST and Haltec systems. The FAST system is on 700+ engines and can support 1200. Not bad for a self tuning EFI system.

And the OP never mentioned what hp he has nor looking for, so taking as a stock app (MPI 415 hp), The FAST system for the ease of install - self tuning and money would be well worth the conversion especially for that app..

They do http://www.ebay.com/itm/FAST-Xfi-2-0...779d6e&vxp=mtr

FAST has been as it has been out on the market for while - already installed about 4 of them, thats why I posted what I did about them and it is marine approved.

Being in the marine business we never install non approved marine related parts. A lot of things have to be coast guard approved & or CG rated for installation and parts. Also a lot of things have to meet the ABYC standards. I am generalizing here about the whole picture. Anyways FWIW.

The OP mentioned he had a standard 502 in the first post. Only issue (since he has not been back) as I see it is if he has less then a 415HP engine, that is unless standard means something else then I think it does

The FAST ez efi system is a major upgrade from a carb. I put one on my 496 stroker build and couldn't be any happier. No fuss setup, the default maps are close, and it hones in to perfect very quick. It even tolerates my cam and doesn't load up during those long idles out of those endless no wake areas.

My bad, another member mentioned it.

If you are speaking to my post, notice I said "up to 600hp". The holley Terminator throttle body style would be perfect for a 415 hp 502, or he could do the FAST stystem with throttle body injection.

No, I was responding to BUP post mention about what HP the OP had (Superman09). Being stock it would be either 415 or less as I looked at it.

Reading this thread I'm going to look closer at the FAST or Holley system may be a better then fixing my current running rich VST 502 engine.

Mercruiser stock OEM black 502 MAG MPI is 415 hp and the older carb version was 385 hp. / 1990's apps

454 MAG MPI is 385 hp and the carb version HO MAG was 350 hp / 1990's apps

Gotcha. Yeah the Holley or FAST would obviously be a much better system( I just purchased a Holley HP MPFI kit a few months back). Have several friends who have converted and love it. Just don't expect it's always going to offer more power. The greater gains lye in idle quality, built in safeguards, individual cylinder timing( sequential) tune ability/adaptability to elevation(02 installed) throttle response....... And the list goes on. It's expensive, but then again, so is a new engine. Good luck!

Okay let's relive this. I missed the updates here and have simply been enjoying the boat!

Spec's I should have included:

502ci gone through becoming 505ci.
Dart 310cc ported heads,
Merlin Intake Manifold,
MSD ignition,
Crane #268761 230/352-2s-14-IG cam
Quick Fuel Carb

Made 610hp 613tq on the engine dyno.

Want to convert to EFI for a Forced Induction application. No desire at all to do the blow-thru carb stuff and have a plethora of good tuners around for the EFI.

Looking to add 5-6 psi of boost to it.

Based on that what would you recommend for an EFI set-up? I found this on the forum and also what the guy posted on the first page as well: http://www.offshoreonly.com/forums/s...-up-502-a.html

Look at this..
http://www.racingjunk.com/Intake-Man...IRING-ETC.html

Thanks, however looking for something with a factory style intake and TB!

you are wasting your time or going to need to spend lots of time of money to get that stuff to work at your power level...not going to work with 600+NA HP, ask around..

Why won't it work with the proper sized injectors and pump? Just telling me to ask others and I would be wasting my time doesn't really help me at all....

You can mix and match pieces and it will work but you might want to consider one of the self tune ECM's, they are a lot more user friendly.

I am liking the FAST EZ EFI and thinking of using that with a factory manifold/rail set-up with bigger injectors and pump.

I know nothing about the factory manifold, you may want to see what it's HP limits are. The aftermarket manifolds and rails aren't that expensive.

I like the full EZ EFI 2.0 FAST kit, but I don't like the 4 barrel style TB for boost.

You can use a Fast, Holley, Edelbrock , Accel, whatever manifold with injectors and rails, the Fast 1375 throttle body and the fast XFI 2.0 with self tune.

Just go roots and dual carbs. Easy and reliable or call whipple and get the whole kit.

I am not doing a roots. I am doing a custom turbo set-up and need a throttle body like OEM.

the factory manifold is not going to handle the airflow to make the power you are going after..not even close, a few have spend tons of hours / $$ on making them work ok, think of it like this just put a std performer oval port intake on your engine and then try to make 600+hp...you can ck with artifriends on here he will enlighten you on those intakes..but if you insist go on with your bad self...