Compacted Graphite Block
 

Compacted Graphite blocks are said to be up to 50% stronger than Iron blocks. CG is said to compete with Aluminum Wt., subject to machining. The bore should easily go 4.60, initial, and have a long life thereafter. There should be a balance between reduced Wt. and rigidity.

The OEM Auto industry is said to be taking a hard look at CG for their engines.

Would a freshened CG engine be more desirable than either iron or aluminum, all other things being equal ?

CGI (Compacted Graphite Iron) requires very specialized (and patented) castings process and the part must be designed for the material.

You're right it is lighter and stronger than grey cast iron that all our BB's use, but its going to take some serious $$$ to commercialize it for the comparatively small volumes left for BBC.

Thanks for your thoughts, do you, including, anyone else, feel there is significant value added, using CGI ? We realize 4.60 bore is commonplace in grey iron. However, CGI should offer a safety factor.

Further, if the OEM's cause the modern method to be CGI, then grey iron could be rationalized as obsolete.

Pure graphite would be the best. No need to cool it even..

First time read, your post was considered humor. However, perhaps you would care to expound, please !!

Well the block would be fine uncooled if it were pure graphite which is tough to burn/melt, but everything else would be a puddle of liquid so it really is unrealistic humor. Maybe all parts could be made of pure graphite? Then there may be structural issues.

It's a great engine block material, hence its adoption for diesel engine blocks and heads which have higher duty cycles and loads than normal gas engines. The problem is $$$ and experience with the material (how will rings seat to it, etc. etc.) that hasn't been developed yet for gasoline engines (diesels use separate liners).

As universal as the BBC is, it's architecture is inadequate for high HP marine applications IMHO. Investing in CGI wouldn't have a good payback.

Dart reports, they are using Compacted Graphite in a race, small block Ford. One customer broke a rod, normally that failure would have poked a hole in the block. However, all that happened was to scratch the pan rail.

Nothing was said regarding rings seating.

Dart also claims core shift doesn't exist with their finished blocks, because the block is sonic tested before machining starts.

Who has an opinion of how much difference there could be in cylinder bore round, CGI vs. grey Iron.

You could just use a sail. They dont need cooling, and they are lighter than CG blocks.:gfight:

Considering the benifits of CGI, would $1,000.00 over grey iron be a good investment ?

I must be missing something, otherwise, it seems there would be some opinion, for or against using Compacted Graphite Blocks. Assuming CGI up-charge is only $1,000.00 over Grey Iron, that is somewhat insignificant. That is, if there are durability and mantainance advantages.

Some show preference for a "used" grey iron block over new. Reason, the aged block has cycled through heating and cooling long enough that it has taken a more permanent set.

After the seasoned block is line bored, deck Ht. squared, bored and locating dowels are relocated it may be better than new.

My hope for the CGI block would be that it includes features of a seasoned block,plus, rounder cylinder holes, less head chatter and lighter wt., if desired. Of course, lighter means extra machining and cost.

Is the initial cost the only extra cost associated with CGI? Extra machining or tooling? If the machining, design and set up is correct with a cast iron BBC block, are there really any issues? I would rather spend the extra $1000-2000 on better valve train design, etc. Also, what are the benefits of a "seasoned" block?...or does "seasoned" really mean, less $ than new, didn't fail on the last cycle and the machining is already complete?
In a marine application, not sure many have ever "worn out" a BBC cast iron block.
Want lighter cast iron? here is an option http://www.lsmeng.com/Block-Lightening.html
We shipped the blocks from Dart to LSM for the 55mm cam boring...too cheap for 30 lbs lightening process :drink:

I have always been curious how much that was, can you share the cost here?

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What about the rates of expansion compared to iron or more importantly, the aluminum heads?

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Just checked, the Dart Big M will lose about 45 lbs...$1800

That's one of the questions I have....Also, thermal shock due to lower operating temp and sustained cold in-rush....We'll know more next week.

Ben, The "seasoned" block and some of the inherent factors that come with it is some baseline. However, new for new is the topic and pros and cons is the comparison.

One concern, iron block machine tooling may not work well when used on CGI blocks. On the other hand, as CGI is more popular, tooling is inevitable.

GM has been using CGI in their 9.8 Pro Stock for awhile and it seems to be working. Granted, that is a different application.

The general statement was heard that CGI will remain straight and square twice as long as cast iron. Assuming that's an accurate statement, heads, lifters, cam and crank should all be happier.

Closed cooling could help that quite a bit.

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How much power are you looking to make ?

I ran a Dart 9.5 deck height sbf compacted graphite block in my 434 inch drag radial motor for my race car

the motor put down over 2000hp with the turbos and there was still a lot left in the tune to make some more power

that being said we never had any issues at all with the motor,
besides performing regular maintenance on it thats associated with all race motors making this kind of power

I really dont think its a necessary option though unless your really looking to put down some serious damn power
but if you got the extra money to put into the motor then go for it

also the block was lighter than the standard iron eagle block they made

and lastly most aftermarket BBC motors will easily handle this power all day long as well

also we went through the same procedures as a regular motor as far as engine break in and seating the rings etc. with the compacted graphite block

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...