jewaskiew

i would like to convert my Carb model to an EFI setup. Wondered if anyone has any suggestions. I see complete takeoff efi setups for sale pretty offen. Are the specs pretty much the same for MAG Carb and MAG EFI?

Pat McPherson

Depending on the year, Yes...
Gen VI engines have roller cams.

jewaskiew

Mine is an 1988 365 HP...do the pick up the 20 HP to 385HP with the EFI setup?

jayhawk261

The problem with switching over to an efi set up is going to be getting the computer program right. Doing it on a car is fairly easy because you have a place for an O2 sensor that can send air fuel ratio readings to a monitor giving you the ability to tune the program. With a boat engine, it is a closed efi system without the O2 sensor so no real way to tune the program.

If you add an O2 sensor to the system, then you can tune the program. At that point, I would probably use a carb type manifold system that has port injectors in it and uses the large throttle body for air. You can then use a FAST type computer and have some real adjustment available.

You won't pick up horsepower just by bolting an efi set up on. The reason the efi engines have more power is due to the cam profile being different and also being a roller. Yours will be a flat tappet camshaft. there are better ways to try to get hp from your engine than trying to retrofit later model fuel injection.

FASTTIMES

I've talked to Tyler Crocket and others who say its not a big deal to this. I have 1990 454 mags and complete 454mag MPI systems, wiring harness's, ECU's, intakes, plenums, injectors ect. I plan to do the swap at some point. Look luck and please report back with any info you find.

ENFORCER24

I'm gonna chime in cause i have been toying with the idea myself too , the only hurdles that i can see are with the intake runners , all the MPI's from the Mag motors are rect port , and he's probably doing this to a 330hp early motor with peanut ports , and a steady fuel supply , easy to overcome with an electric fuel pump mounted near the fuel tank
aside from that , you should be able to take the spec's of your engine , size / cam specs / head specs / exhaust / compression ratio /altitude where your running and have the ecu reprogrammed with a good fuel curve for you , hopefully you know someone who has purchased the 800 buck program and cable to do it , cause i'm sure Arizona speed and others charge a mint to do it

jayhawk261

It isn't so easy to just program a fuel curve for the engine. When we went through my 454 MAG MPI, we used Tyler's cam and valve train and had him program my computer with the program for his cam. First run on the dyno, and it wasn't even close. It had to go back and forth to Tyler 3 times to get it right, and even after that my engine guy had to tweak and fine tune the fuel map and timing events after he bought the software to do it.

If you want to put a MAG MPI injection unit on, and make sure that the fuel map is correct, then you need to use the MAG cam, the MAG heads, the MAG injectors and so on. If you're using a different cam and heads, the stock program won't work, and unless you tune on a dyno or with a wide band O2 set up, you are only guessing at the fuel map. Maybe and educated guess, but still it may not be right. It isn't that difficult to lean one of these engines out and kill it with detonation.