What can I do to My Mercury and not have Computer/injector Problems

[Blown obssesion]

Any one have any expirience altering a Mercury 350 300 EFI motor, I currently have 05 Chevy 350 300 hp EFI motor with a Bravo III, I am looking to replace the motor with a 408 s/b and I would like to keep the Mercury fuel injectiojn but I do not know if it would support 475 H.P.---I fugure it wont.
Next is if I go with a high performance fuel injection what will happen to the smart craft or can It be used without issue,,, Agian I think it will create problems if I switch the EFI.

My Next dillema is the Bravo III, If I get near 500 H.P. I am concerned that it will break. Can the lower unit be replced or do I need to change gimble/trans complet drive or what. Kinda new to the out drive thing.

I guess what I need is the majic formula to make this thing faster and keep the low end manners for the kids wakeboarding. I would fidure that I could go up a prop pitch or two with the 100-150 H.P. increase and not have to many issues with the Bravo III, What I do NOT need is to improve preformnace and lose all the features that the Mercury electronis offers.

Any thoughts on this stuuf thanks all!

[olmo40]

Having been down this path ,if you are looking to go faster than about 60mph you will need a Bravo 1 leg .If you want no hassles 500+ HP bolt up a 525hp Mercruiser .Under 60mph you could probably keep the B3 and bolt up a 496Ho for about 425HP.Raylar make some nice parts for the Mercruiser but IMO you are limited by the internals of a stock engine in the case of the 496.The path you are on will give you brain damage JMO

[Blown obssesion]

Seems like I may already be there. I DO need to know if I change the B-III lower to B-1 with just switching the lower unit?

Please elaborate on your issues that you whent through trying to find some more power.

I was Just figuring I I replce the small block that I can do O.K Its a lake boat, It is touching 53 now,,,bone stock,I have been told that if I just change to a B-1 i would gain 5-7 MOH. I am going for 65 and keep it reliable, without spending 50 K On a 525Merc. Have a few more years on this one till pay off and the kids use it I figure I can do a few mods and not break the bank and after they finish school I get my go fast.

Please advise and thanks for your time.

[olmo40]

The B3 to B1 change on the later models is no problem ,sometimes the B3s are mounted lower in the water ,I think on an older model conversion there is a kit ???? maybe $100 or so .

I did heads, exhaust and Motec injection,all good stuff ,i didnt get to the internals as i just had problem after problem and sold the boat stock and parts on OSO.

The smart craft was supposed to work and it didnt ,i had cooling issues,broke the upper box,rusted sump ,fuel evaporation ,idle problems ,more fuel exaporation,rear oil seal Hey they never fail,im an outboard guy who crossed over and crossed back .

In hindsight i should have had a 6l motor built form scratch or just stepped up in the Merccruiser range .

I hope that makes a bit of sence:confused:

[STV_Keith]

FYI, I have a buddy in Cali that has a 26' Party Cat that runs right at 70 with a B3 and 640hp 540 Chevy.

[Makinwaves]

Not sure about how your 350 Mercruiser is set up, but the injection computations for a SBC 400 are a lot different than for a 350 using the same injectors. I ran the 355's with the Holley Stealth Ram injection system for years before switching to a high compression alum head 406 and used the same 36 lb Holley injectors. The Holley system uses the Commander 950 ECU that you can reprogram with your WIN 95 laptop. The 400 is a totally different animal, way more tq, hp and less rpms doing it, but it may be as simple as switching to larger injectors to retain your present fuel system. Only expermentation and a lot of phone calls will get you close to what it will require. Look up White Performance and Marine in Tennessee. Ask for Fred. They have good prices on small block stuff for Marine or street use. .