Like many boat owners, I'd like "more horsepower." I've read through the forum archives on this topic. Looks like there are three choices:

(1) Repower with bigger motor (496/502/540 etc)
(2) Add blower
(3) Build motor with all the right stuff (pistons, cam, crank, intake, exhaust, heads, EFI or carb, etc).

My question is what can be bolted onto to a 454 mag to get 75-100 hp and how much will it cost. I'm thinking intake, carb, cam, heads and exhaust. Can it be done for $3K? Is there 100hp to be gained from these upgrades?

Also, at what point do other systems (such as drive, steering, trim tabs, oil cooling) need to be upgraded to match the new power.

You will get the most bang for the buck by upgrading the heads, cam, exhaust, and some roller rockers. Is your intake and carb spread bore?, If so you might get some minimal hp gains if you switch to square bore. Stock Bravo should handle these upgrades. Hydraulic steering might be something to look into.

A blower kit with 4-6 psi boost will give you the 75-100hp you want.
You can get a 8-71 kit for $3K.
But I would consider better exhaust and better valves and valvetrain if I'd go blown,
and that's another $3-5K.

I would run it another year, save and by a stroker kit and put in it. The mag comes with the big heads, so with the added CID, you can take advantage of the heads. You can get a decent kit for around $2K and have 500 inches

Chris

I would add Lightning headers (1500.00) or Eddie Marine Thunder if you want manifolds (same). A Wiend Accellerator intake (200.00) and Holley 800 (500.00) takes care of the induction. Crane cam and lifter set for the 420 Merc. (200.00) replace the springs while your at it (100.00). Roller rockers are almost required at this point(270.00). A new ignition module and gaskets and little things will eat up the rest and then some.

This will make 450+ hp. Then you do what cstraub69 says and you'll have 500.

If you play your cards right you can get alot of the parts here used and save a ton of $$$$ and get 500 hp easy!!! Intake ,heads,carb,cam,exhaust,rockers....I made 505hp with my 330's buying alot of stuff off the board and spent about 6K on the pair....If your in fresh water get the Lightning headers you wont be sorry...my.02

Thanks for the ideas. How much power can a bravo 1 handle. The boat and motor is 1989 but the drive was replaced in 2002 with a new one, has the low water pickup, not sure if the newer bravos can handle more power than the early bravos.

500-600 is pretty safe if you take it easy on re-entry...gotta run the sticks!!!

Dyno -
Any manufacturer recommendations?
Use existing heads and have them worked or new?
Cam size?

Thanks.

I bought used Merlin oval port heads way better than the stock ones. The cam I'm running is a flat tappet Hydraulic that I get from Federal Mogal I can get the part # for you if you like , Crazyhorse has it memorised. I'd look for exhaust first, a used set of Lightnings or maybe the KE manifolds that DanB has for sale would be great upgrades. I bought the last set of heads for $350 but they were bare dont know what I'll have in them yet till they are done. Patriyaght had a couple sets of rectangular port Merlins ready to run for a good price.
Good luck! The Edelbrock Marine heads arent priced to bad like $1200 with the valves in them......