I have a 2001 Eliminator 300 Eagle with factory 500EFI's with about 390 hours. I am wondering if there are any reasonably priced performance upgrades I can do to the engines this winter to pick up some HP and speed. I always change the plugs every year. I am planning on changing the spark plug wires this winter. I was told the computer(s) can be sent in to Mercury Marine(?)and reprogrammed to increase engine performance. Does anybody know where to send these and if this is safe for the engines. The engines run strong, have great oil pressure and rev to WOT specs. Also, I am going to take the props to the prop shop to have the edges cleaned up. I am running the factory 4-blade 30 pitch props. Thanks for the help.

With 390hrs, they really need to have a complete top end refresh done with valve jobs, springs, head gaskets and lifters. The other option is to look at an upgrade kit with new heads, cam, etc and ecm reprogram. There are plenty of people who reprogram your ecm if you keep it stock. I would send it to Dustin at Whipple.

I agree with griff, your getting to the peak hours to have your valves checked. there are a few different builders that can help you with upgrades. mine are at 625 hp, that was heads, cam, throttle body, injector and computer remap. unless you are going to to the full kit, I really wouldn't change any of it. where are you located and some shop recommendations will come.
call brett at bblades and he caqn get you set up with prop labbing.

Yep.. I agree with Griff. Or we can do it for you if you need a shop.. Jamie / Lakeside

At minimum change your valve springs, your running on borrowed time. I use the Isky plus springs.

thanks for the help. i am in dubuque, iowa. i can do the disassembly and reinstall of the heads, etc. we have a very good machine shop in town that builds alot of stock car engines and should be able to handle the rework of the heads and assembly. i guess i need to track down the parts, valve springs, etc. would you recommend changing the camshafts? if so, can I get a little more aggressive with the cams. does each engine have an ecm, and if so, where are they located. i'm assuming i can go to whipples website for their contact number to send in the ecm's. thanks. the boat run in the high 80's and I would like to push in the low 90's. thanks

I have been looking at this kit, anyone use it?

http://www.offshoreonly.com/classifi...o32451-en.html

that looks like a nice upgrade but I think i will retain the original cylinder heads. however, it does make me wonder if I should replace the head bolts when I do the work? any feedback on this would be appreciated. I would like to upgrade the camshafts to get more midrange torque where are they available

In my research without changing the heads you won't gain anything. The engines in stock form as you have them are producing all they can but with a cam,head and ECU reflash they are capable of producing 625-650hp depending on who does what. I would send the computers to Mark Boos in LA. He's on the site can't recall his username though...He might even recommend a better package than the one that was in the classifieds.

Also might check with Hawkeye Boat Sales if your looking at doing mods I know they've played with alot of hp boats over the years.

Not trying to start an argument. I have talked to two reputable engine builders, on this fourm and a cylinder head guy also on this fourm. All three say the same thing. You are not going to make much more than 550HP tops out of a 500HP EFI. The intake is the limiting factor here. Basically you can have the best heads and cam you want you are suffocating the engine with the intake. This is the reason Tyler Crockett spent so much of his time recreating something that will supply more air.