I have a 1999 Checkmate ZT280 with a Mercruiser 502 MAG MPI that I am transforming into over 800HP. I bored the 502 to 509 cu in. Kept the Stock Mercruiser Crank and installed a Whipple side mount with a Dominator 2000 CFM Throttle Body also milled the intake runners down like the Arizona Speed & Marine Intakes. I added: Dart Pro 1 Heads, Manley Severe Duty Intake and Inconel Exhaust Valves, Isky Valve Springs, ARP 2000 Bolts, JE 700 forged aluminum pistons, Total Seal Gapless Rings, RPM Connecting Rods, Manley Push Rods, Double Roller Timing Set, Hardin Marine Big Block Chevy Circulating Pump Style Serpentine Drive Kit, 14 Quart Offshore Oil Pan, 3" Oil Cooler, Wix Racing Thermostatically Operated Oil Filter, New Mercruiser XR Upper and IMCO 2" Shorty, 280S K-planes, Mayfair full hydraulic dual ram steering, MEFI 4b ECM and Custom harness , Livorsi Monster Gauges.
Tuning is being performed by Eddie Young at Young Performance Marine. I wonder if anyone has gone through this with this style boat before and what I missed?

You can talk with KellyO my good boating friend. He is here on OSO. He had ZT280 with about 875HP+. Your engine sounds like a good combo. Just start saving up your coin. Boat ate drives all the time, and my buddy can drive. Good Luck and Enjoy the boat

Good luck....it's gonna be a handful at top speeds!

I forgot, that too!

It is kind of what I'm shooting for? Otherwise I would have left it stock? Then again it should only get as out of control as I let it? W.O.T. and drag racing will not be the norm since I plan on ***** footing around with it this season.
I think I covered all the safety factors that I could with total hydraulic steering and the 280S K Planes.
I was wondering if anyone knew about the things that I don't know yet like X dimension, trim tab placement, prop selection and if drive spacers are necessary?

http://www.youtube.com/watch?v=XxiAG...ature=youtu.be

That should rock and roll pretty good! A 28ZT is a big hull and should handle great with that kind of power but I am betting the drive will not like all that torque.....

I'm planning on being real nice. It is an XR upper with a 2" shorty Imco.

Hmm.....did you run that shorty much before the engine build? what kind of gains did that get you? how was the handling? Tossing around the idea on my 253.....heard good and bad stories. Actually I would like to install the stainless gimbal ring when I put my new steering on and run a sternjack/shorty combo.

No I didn't. It had a stock Bravo 1. I didn't want to attack this from one dimension. When I decided to go all out with the engine I decided to get a new XR upper and 2" shorty Imco. I replaced the tabs with 280S K Planes and I installed dual ram total hydraulic steering. Since I have to monitor more things...
I ended up replacing all the gauges with new Livorsi Carbon Fiber Gauges
I haven't ran the boat yet. I don't know how it will handle?
I posted most of the pics on my facebook page. http://www.facebook.com/#!/jimmillman