The boat is a 2000 Checkmate 259 Convincor we bought new in 2002. The original power was a 454MAG(MPI) in front of a Bravo Drive w/ a Mirage Plus 23 pitch prop. The boat currently has 265 hours on it. At 215 hours we upgraded the motor with a Stainless Marine exhaust system, roller cam, 2.25 intake valves, 1.89 Inconel exhaust valves, new valve springs, locks and seals, milled the heads .020, roller rocker arms, rocker studs, pushrods, valve job and changed the prop to a 26 Bravo labbed. The engine was dynoed at 461HP (5100RPMs) and 514lbs/tq (3800RPMs). The upgraded motor has 50 hours on it. The engine was upgraded by Tyler Crockett and runs great. The boat also has full hydraulic steering and HP trim tabs. I feel the boat can handle more power. I am thinking about installing a Blowershop 250 blower w/ a single 1050 blower carb 5lbs boost, an oil cooler and a MSD ignition. The combo should make around 600HP. I have always wanted a roots style blower. The valve train only has 50 hours on it. The boat is used for all purpose recreational boating. It needs to idle well, start consistenly and run well in most conditions. I am expecting 200 hours out of this engine and drive with this upgrade. Is this upgrade and expectation reasonable with this setup? Is changing the fuel injection to a carb setup crazy? Anything I am missing. Any thoughts and/or opinions would be appreciated.

Sounds reasonable to me. Have Nickerson set up the carb and it should idle just fine.

My 525sc with a 1050cfm idled like an EFI after it was warmed up. They are a little cold blooded at initial start up.

The drive may or may not handle it for that long. It depends on how good of condition its in now and how you treat it.

Thanks for sharing your experience Griff.

That sounds very close to the exact same power/torque and RPM's my cousin Jason's 454's make! Only he's running some real old GM semi open chamber truck heads (large oval port runners) and upgraded to larger valves (2.19"/1.85"), dual plane intakes, heads were pocket/bowl ported by JimV and cylinder bores had a "bore notch" job done to them, 8.6 comp ratio, stock Merc Thunderbolt ignition, cams are Comp Cams flat tapper hydraulic 218*/226* .515"/.515" on 110* lobes......made 461hp @5100rpm and 510 or 514lbs or torque @3600 or 3800rpm on Tom Earhart's dyno with tubular car/dyno headers. Jason runs GIL dry exhaust in the boat.

I think he made good power mostly from JimV's head port work and the bore notch job JimV did as well.

Would you have any concerns running 5 pounds of boost, no intercooler on with this engine with the current compression? I think the compression should be around 9:1, not sure.

Yeah I think the power is good for the displacement and head work. My problem is I can not keep up with the twin engine boats on our local lake. Everyone is always waiting on the Checkmate at the stops. I think 5 pounds of boost will help me keep up with the herd.

I think you won't need the 1050 carb, a 850 will work fine, a weiand 177 will work very well as well on that size engine, I'm running a 251 with a 489 w/850. you might consider H2O injection to help prevent det. be sure fuel delivery is good, the mallory dist will work better as you can dial in the total amount of advance, restricted on the msd with their bushings. you want about 15-18 degree's of initial and about 28 total, your H/P #'s should be close, but pay attention to your cam, a blower profile will help, mine is a comp on a 114 center...hope this helps, Rob

Tyler Crockett recommended the 250 and 1050 carb. Predetonation is a big concern. I am not familar with H20 injection. Would that be needed with 5 pounds of boost? Should I consider less boost? The blower upgrade kit would include an adjustable fuel regulator, blower, carb, oil cooler, fuel pump, fuel line and throttle bracket, billet flame arrestor and MSD ignition. Anything else needed?

I had a cig. top gun, with 525SC's upgraded with blower shop 250's and 1050 dominators. The setup ran great. I would check cam profile, should have lobe centerline of 112 or 114. good luck

How many hours did you put on the motors with this setup? Thanks for the cam profile info, I will look into it.