The best thing you can do is supercharge!!!!!!!!!!

If you do not want alot of hp then go low with boost. You don't have to go "Full Tilt Bozo"!

The price to upgrade to a 500 efi is insane.

To rebuild and upgrade what you have and add 75-100 hp will cost alot more than a supercharger, and once you get your hands in there(meaning in the motor, replacing parts) who knows what mistakes might be made, part failures and also reliability issues. You could talk to 100 diff. builders and get 100 diff. answers on how to upgrade your motor. It can get very confusing and you will always second guess yourself.

I supercharged my 502s with a procharger @ 5lbs of boost and with over 150 hrs and had no problems, no stalling while docking, no outdrive problems, etc. One issue I had was a blown head gasket. During the repair my engine builder inspected the motor said it looked perfect! I have done no other mods and could not be happier.

Low boost, proper fuel system set up, and you will not have problems and you WILL be very happy.

Mikehtmsr24, That is one HOT looking engine dude!!!

Thanks a lot but it's not .........
 

I will second that KAMMA!!!

Now where is that drool rag...gotta clean up my keyboard now!

Re: It's sad but true...........
 

Sorry I forgot to mension that the 10k was just for the 100 hp increase. I had 125 hrs on the original motor the first season. Wasn't happy with the speed so we pull it and stuffed it:p

Check- One thing I failed to mention, but very important, is that the cam you choose must but cut on a wide lobe seperation angle, 112 DEG minimum, 114 deg would be better with the intake C/L advanced only about 2 deg [i.e.: for a 114 LSA cam,have the intake centerline @ 112 deg]
I reread my earlier post, I guess It does sound a little like I'm pro carburator....I'm not at all, FI has alot of advantages that I wouldnt be willing to trade for. What I was trying to convey in a nutshell is that its very easy to go beyond the intended design paramaters of the the system, and once you do, the carburator now becomes the more efficient method of fuel delivery.
There is alot of misinformation out there on these systems, some of it by people that sell products and services for them. Re-programming your MEFI controller is not a panacea for poorly chosen components. Sorry guys, but if it wont run cleanly on the stock programming, your gains are going to be minimal at best after the "tweaking" of the fuel tables. Raising the rev limit and altering the timing curves can be advantageous, however. Good Luck & have fun

Ken:
First off I am not an "BOZO" or an idiot. As others can tell you on this board, I have helped answer more than a few questions here. I am well aware of being able to control the amount of boost. I am choosing to stick with injection because I think it is something that I can make work. For the power that I am loking for, I don't feel it is necessary. I don't beleive that these engines were designed gfrom the factory to be able to handle a supercharger as a " BOLT ON" modification. The very least that I would do if I went that route is inconel valves.

i also agree a low boost supercharger (procharger)is the best bang for the buck....i've got some runnin around with 450hours no problems!
about $7000.00 all done with prop and gauges 12-14 mph increase.
as for your injection john lingenfelter designed it for mercruiser
so if any body knows what to do it's him
expensive yes!
top quality work absolutely!
and he stands behind what he does.

Checkmate454,

You missintepreted me! I am not calling you a bozo. What I mean by "full tilt bozo" is you don't have to go crazy with alot of power. Jjust because someone has a supercharger doesn't mean you have to run alot of boost, or try to squeeze tons of HP out of the motor.

I know first hand that when done right a supercharger will give great all around performance gains without destroying an engine. A stock 454 mag can live a long time with low boost and a gentle hand on the throttle.

Hope this clears things up

Good luck

Checkmate, it sounds like you have a single engine boat?!!? I went through the same dilema with my OLD Formula...supercharge or repower with a 502/502 crate motor etc.. To make a long story short, the repower with the crate motor was what I thought was the best for me, BUT by the time I added up all the $$, it just didn't seem worth it!:rolleyes: :eek:

So I bought a bigger boat with twins and that solved my problem!!:D

Good luck!