I believe the system will work on your engine but depending on what year your engine is, you may need a V Belt drive pulley for the crankshaft. The 500 EFI were all serpentine belt accessories. I have purchased a 500 EFI set up to run on my 1997 502 MPI but have not yet tried to trial fit everything together (I have been searching for a V Belt drive pulley for a while). As mentioned earlier you should expect to upgrade the cooling and fuel systems and may want to go to inconel exhaust valves. Beyond that you will need to find a way to control the engine with boost. If you have a MEFI 1 that will not work unless you plan to run the "Add On" whipple PCM which is generally not recommended. If you have a MEFI 3 you should be able to find someone with a program to match your engine they could flash for a fee. Once the installation is complete you will need to be nice to your Bravo Drive...

I am running the V Belt 454 MPI Mag. The boat is a 255 Z Mariah with a Bravo 3.

Any suggestions on what cooler to run? Link?

Fuel system upgrade? What is limited to? New pump and regulator? Larger injectors?

I knew I would be on the hook for the whipple $$$$400 crank pulley.

Here is the tag on the engine.

The B3 will limit your speed.

Something like the Hardin 3" x 20" Hi-Performance oil cooler could work for what you are doing. They also make the 3" x 25" that is a double cooler. It has the same oil cooling as the 3" x 20" but with a power steering cooler as well. Could be a way to go if upgrading to full hydraulic steering.

http://www.hardin-marine.com/p-13582...il-cooler.aspx
http://www.hardin-marine.com/p-13617...il-cooler.aspx

The thermostat coolers is an option as well. They cost a bit more, but are great units. Here is a link to all the Hardin coolers.

http://www.hardin-marine.com/c-731-t...l-coolers.aspx

You may also start to experience prop burn depending on how much HP you end up making and what speeds you end up running. I would definitely look to swap out your BIII for a BI (lower only or entire drive). Go with a 1.50:1 ratio. It will be easier and cheaper to then dial in the right prop for the boat.

I understand the limitations of the BIII.

I am really looking to net 500 HP. Not looking for fast than 60MPH. I live at 5200' elevation and regulary boat at 6500'. Air that thin turns a 385HP MPI MAG into a 300HP weezer.

Is 60 to fast for the counter screws?

How can I tell if I have the MEFI 1 or 3?

If the wiring harness to the computer comes out each end its the mefi1 if the wiring harness comes out the sides of the computer its the mefi3. But Its not cheap it all adds up fast.

Got ya. i think you would be fine to stick with the BIII.

You'll need a new belt system (crank pulley, idlers and spacers, drive snout, support stands, SC pulley, belt), possibly injectors (we used 8 50's on 454, same on early 500's, but 8 63's on later 500's), new mapping and if you don't have MEFI 3, you'll need to update to 3 or 4 and repin the harness, or buy new harness which then requires new brackets, etc.