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