cbellamore, Thanks for the comments.

Power ? Not sure, focused more on durability at any given power level.

Did you see any difference in main and cam bearing wear patterns ? Or, did it look life the block had more rigidity than you had seen in grey iron ? Also, did you see any difference in the dyno numbers ?

i haven't seen any 100+ mph sail boats lately? have you

no difference in the wear main bearing wear patterns,
they looked to be about normal for the type of engines we were running,
the block looked pretty much like the same Dart Iron Eagle block that they make as far as extra supports, and thicker main areas, etc. that are offered in all the Dart blocks

As far as dyno numbers were concerned also no we didnt see any major differences
we changed a few things from the last motor to this one and the gains in power were expected because of the changes to the cam, and turbos, and tune we used,
I honestly could not chalk the gains in power up to the block alone
I really would not bother with the compacted graphite block at all to be honest with you
unless your looking to make a 3000hp motor (which is what we were shooting for) or looking for the weight savings, (again we were after that to get the weight off the front of the car)
and even at that power level Ive seen aftermarket grey iron Dart blocks live just fine at those power levels
the motor that we had in the car was a top notch dedicated race motor with the best of everything in it
we made over 2000 hp at the wheels of the car on a chassis dyno, and we were spinning the rollers

what are you planning on putting this in ?
the price difference on the blocks is kind of big also so I really dont think its necessary
if your looking to make a 1500-2300 hp single motor then I would just go with a regular Dart block not the compacted graphite and spend the money on other things for the motor

cbellamore, Again, thank's for sharing your experience. It would be helpful if there was input from someone that has used CGI in marine application as well.

The power level will not exceed 93 octane pump gas, regardless of what forced induction is used. The exception may be a dual fuel system that would include some grade from the "C" family in one set of tanks.

Price is always a factor. However, increased cost is a relatively small percentage of the total.

Price and machining are the only negatives that have been read. Perhaps there are more.

Conversely, after weight, such things as aforementioned, extended align bore life, round cylinder bore longer and theoretically, more power longer, makes CGI interesting. Beyond that, CGI seems modern.

Improvement in less scale at the drain plugs would be nice. (It's a nuisance to use a piece of wire to start water running after the plug is out) It would be nice if harmonics changed frequency to allow for improved knock sensor performance. For that matter, any harmonic ring improvement would nice. (It should be better or worse, because of the CGI density.)

The application is a twin engine boat.

Generally, it is silt/mud/sand that plugs up the drain holes, not rust scale. Once you shut off the engine, the sand/mud will come out of suspension in the water that is in the block and settle to the bottom of the block. Unfortuately, this is where the plug is.
As for the knock sensor, false knock detection is usually do to either excessive valvetrain noise or some other mechanical noise either in the bottom end or in the drivetrain/u-joints, etc.
Eddie

Thanks Eddie,

Your comment regarding dirt and sand is well taken. However, I recall fighting to remove the plug and scale in automobile engines, maybe even more. Of course, the automobile engine is closed cooling.

The CGI block may reverberate frequency identical to grey iron. A Spectrum Analyzer would be one tool to find a specific frequency. The frequency from higher density CGI "should" cause detonation ring to make a significant Mhz change. Higher frequencies are typically easier to manage. Therefore, the pickup would/could operate with a narrower band width. Thus, ignoring some of the otherwise traditional noise.

enter Ice boats...

if your just looking for something to run on 93 out of the pump gas then I would not even consider a CG block
look at a bowtie block or a BBC dart block, or even a world products block then,
they will provide all the strength you would need over a stock casting block,
Friend of mine has a twin turbo 632" BBC motor in his drag car makes over 2500 hp with the turbos and has had zero issues with it, been together for a few years now and races it on steady race schedule, its a Dart block regular iron block he's using
everytime motor is apart everything checks out to be pretty good,
I wouldnt worry at all about running one of these at all in what your looking to do,
hell the motor might even out last most of us with the power level your looking to run,

Who is actually making these in a BBC? I did a search and couldn't find anyone.

Try, Kevin Hayes @ Dart Heads ...Ph. 248-362-1188...