Hell, look at what you can buy straight out of the GM powertrain marine,

ILMOR marine has a 6.0 & 6.2 line up for IO's. http://ilmormarine.com/

I think those Ilmors sound great but it doesn't seem like anyone on this board is running them. I asked a year ago and only one guy was running them. I think they sound like a great idea and I'd love to own one. It'd be interesting if anyone would cough up real cost comparisons of Merc, Ilmor and Volvo.

I am not saying it can not be done with Indmar matching to I/O's - what I am saying is the ECM mapping, ignition curves, fuel curves and so on are tuned for low end power not top end speed, again nothing in their stables really is used at WOT nor top speed above 42 to 50 mph, 90 % of their apps are used for pulling power and running constant 18mph to 38 mph speed range.

Indmar is really trying to push the new Ford Raptor engines, they (Indmar) really likes the Raptor better for the wakeboarder as they have tested apples to apples pulling times and 1/4 mile drags testing in Florida against their LS based engines. They are a good company and know many within the company personally. Most of their engine packages use E-Controls ECM / PCM mapped. They like the Raptor for the end user being used in that specific app. (Extreme towsports only) - it was a joint effort, Indmar, Ford & Roush Racing.

Mercruiser, once the old timer standard 350 / 5.7 goes away if not SOONER Mercruiser will have their own version of the small block marine engine just like the new 4.3 V-6 offered currently by them. They claim not one part is bought thru GM. I know a foundry is making some of their engine blocks for them.

I had a 320 hp indmar in my i/o, it ran .5 mph on GPS faster thank my 6.2 merc.

I think merc really needs an LS motor. They could build one that makes 500hp pretty easy. Then they could offer 5 engines from 500 to 600 hp and clearly they have been trying to see how many motors they can build in that range over the past two years.

2009 or 2010 Merc did have listings to their dealers that the LS base engine(s) - I want to say the 6.0 LS was being tested by them and coming soon but later dropped as said it does not meet their standards nor will hold up in the a 100 % marine environment over time. Not my words.

tmmii I bet yours was the standard 350 CID 5.7L - MPI 320 hp sold by Indmar sister company per their apps but still made by Indmar for repower replacements for the I/O's using MEFI 4 or 5 controller mapped accordingly. Also it somewhat recommended to be used for I/O apps that do not have the shift interrupt system. Volvo and Bravo drives and some OMC apps.

I find that laughable compared to the 1955 technology they currently use for their small blocks.