GPM

I do believe the 250 hp, 260 hp motors have cast cranks, cheap rods and cast pistons, small cam and crappy heads, the 350 mag is forged crank and pistons, a little better cam, better rods and heads, I could be wrong. The 383 with better exhaust, larger injectors, possibly a fuel pump and a reflash might be your best bet.

Blueabyss

I think you would be fine with a set of 383's.. Not 475 hp but more like 400 hp. That way they wont be prone to reversion and prob get you to mid to upper 60's. Personally I have given up on big blocks to go fast. Have had them all 7.4 mpi to 496ho's. I just cant run the crap out of the big blocks and have them last like I can the small blocks. I also think supercharging them is just asking for problems. Plus if you explode a 383 NA, which I have never done, it will be much cheaper to replace. What drives do you have?

Chris

Baja Rooster

iTrader: (1)

In my experience, if you enjoy working on boat motors then start playing with hop ups, but if you actually enjoy boating keep everything as stock as possible.

The 383s will at least let you keep your stock rigging.

BUP

iTrader: (9)

no offense you are completely wasting your time with powering up your small blocks plus a Sea Ray hull is more a pleasure boat and ride not even close to a speed boat or performance ride. If anything you wanted to change engines I would go with something like what Volvo Penta has in the line up of the 6.0 LS version. they have 350 hp - 380 hp and a 420 hp LS 6.0.

Volvo's 6.0 LS 420 hp tested against the 496 HO and beat it everytime in 2 exact Formula boat models comparison across the board in all water testing. The 6.0 is 300 pounds lighter per engine than the big blocks as well. I would look into LS swap outs if you are really looking to completely change your engines out and do a complete drop in.

sunbather1969

Sell this and buy a new boat from my experience

Knot 4 Me

Pretty sure the induction systems are the only differences. I ordered a new boat in '99 and wanted to know the differences between the three versions of that motor at the time. Long blocks were all the same all the way down to the camshaft. Which really surprised me. If nothing else I would have thought the 350 MAG had a little bit better cam.

Budman II

iTrader: (1)

Agree 100%!! Once you step onto that slippery slope of modifying your stock power, you better enjoy turning wrenches because you will probably be doing it on a regular basis. Not to mention that nagging worry in the back or your mind that something - motor, drive, etc. - is going to let go and ruin your weekend every time you go out. There is a lot to be said for having a turn-key boat that you can take out and run around on with the family, and settle into a cove with a cold brew and no worries. If you have the disposable income and the inclination to tinker with it a lot, then go for it.

CIG3

Check out the Ilmor stuff. Plug and play LS power is the way to go in my opinion

http://www.ilmor.com/en/marine/recre...l/MV8-62L.aspx

Budman II

iTrader: (1)

So how much do one of these 570HP bad boys run? (probably more than my first house)

http://www.ilmor.com/en/marine/recre...l/MV8-570.aspx

TooLateVTEC

iTrader: (1)

With the money you're gonna end up spending trying to get this pig to run faster, you could buy a go fast boat that already runs 60+.

Then you would have one boat to make the wife happy and one to piss her off