Upgrades for 415HP Merc.
 

Just wondering if anyone had any ideas for performance upgrades. I want to do alittle this spring with the motors in the boat them rebuild this fall.

Typical stuff like flame arrestor, exhaust, and maybe an ECM reprogram will get you a couple MPH. Labbing the prop will help tremendously. I have had real good luck with Darin at Houston Propeller. You also try Matt and Julie at Throttle Up.

At the end of the year perhaps a motor refresh with roller valvetrain and a slight change in cam? Of course you would need to reprogram ECM with this change as well. I'm assuming this is a 502 MPI?

THe boat is a 1999 33 Donzi. Yes 502's.

Would new exhaust or Flame Arrestor require a new ECM?

How hard is putting roller rockers on?

Thanks

I am putting some iron heads with big valves on my 502 EFI this spring. I have Gill with SS risers already. Would like to go to roller cam and rockers. Any suggestions on the cam choice. Was hoping to find something on OSO that would work.

I have spoke with Dennis Moore about an aftermarket camshaft and will quote him here,

"Comp Cams XE268H with 224/230 intake and exhaust duration and .515/.520 intake and exhaust lift with a 110 degree lobe separation angle. This will work without the need to change valve springs or go to adjustable rocker arms. The stock ECM will also work fine. This is NOT the marine cam. "

You may want to view this thread for more information about changing camshafts

502 Camshaft

I would suggest talking to tyler crockett. I talked to him and found out he can get you a reliable 510-575 hp from these engine no problem .