zimm17

I see lots of EFI setups for sale off everything from 454 mag to 502EFIs. Is this a worthwhile upgrade to a '96 454 mag with carter carb (It's a GEN VI)? What's involved in the swap? Will I pick up any HP? Save any fuel? What models will fit?

East Coast B

I've been researching this same topic for my twins, if you search, you'll find some recent posts..... when you see the mpi's for sale, you have to watch for all the parts that you would need, total intake on up, ecu, wire harness, sensors, electric fuel pump and if the ecu isn't from the same motor, it will have to be reprogrammed. Seems most responses I've gotten is that it's not the way to go, money could be spent with other mods, a lot of guys take the mpi's off to go back to carb for ease of adding other hp parts.... again, just my recent findings, I've sort of backed off the idea myself as it'll cost some bucks for so little gain... Think I'm just going to wait for motors to need work and either add some hp or drop some 502's in....

Good luck!

MACDAD260

I would just replace the Carter? (Weber?, same as Edelbrock) carb with a Marine Holley or Demon. A 750cfm should be perfect on a 454 MAG. It will start better and go faster than before. I replaced a 750 Weber on my 454 to 502 swap with an 800 Holley and picked up almost 2 mph plus the other benefits. You will need to change the fuel ine and find another place for the overflow hose from the fuel pump. You will also need to buy a new linkage plate and maybe fabricate a liitle to make it work. Not a very hard swap and the benefits will be worth it. I think the EFI would be nice but once you see the benefits of a better carb you wil be very happy with the results.

MACDAD260

Here's a pic of my Holley

East Coast B

Has anyone seen any gains from going to a new exhaust system on a stock 454 mag carb? Or is it just a waste of money if you don't do any mods to the engine itself? I'm running 4800rpm with cupped 23" mirage 3 blade and 4500 with 24" bravo 1 4 blades, would like to get the hp up a little to gain a few hundred rpm. Love the 4 blades for getting on plane and midrange is great, but lost top end speed, just not enough horses. Running a 31ss.

open87

a set of stainless marine exhausts will greatly improve and wake those engines up .

East Coast B

I was thinking of putting a set of the revolution marine exhausts... http://revolutionmarine.com/shopsite...bcexhaust.html

Anyone have first hand experience/results of what the exhaust gain would be?? I'll see if I can contact the manufacturer and see what their response is....

Back4More

The only advantage the EFI has is that it cold starts at the turn of the key...other than that I feel the Holley/Demon thing is a better way to go.

QUIKDECISION

I purchased a set of Revoluion marine exhaust for my boat.
Twin 454 mags. Overall I was very happy with these for the $$$.
The performance gain was noticeable, midrange to top end.
My only complaint is that the bracket that is provided, for relocating the power steering and alternator, does not allow enough travel for the alternator ( for belt tensioning ) as would be desired. It requires making an extension bracket to hang your alternator lower. This situation is a little unique for
me, I have a Formula F-311. For different boats it likely would be no problem. Other than that, i am very satisfied with this system. Their customer help is excellent. I had encountered some previous problems and they responded with immediate results. Bottom line... I'd do it again...

jerosejr

With todays gas prices, has anyone seen better fuel efficiency with MPI ove carbs?