Siamese-Bore

[The Cuda Guy]

What does it mean when applied to an engine block?

Cuda Guy

[Moparal]

The cylinders are side by side touching each other.  My 499 mega block is that

[Chryco Psycho]

this makes the block stiffer & helps with power but limits the cooling as wtaer cannot pass between the bores , I have no heard of Mopars overheating due to this but Chevs always used to with Siamese bore blocks

[The Cuda Guy]

Thanks guys!  I just see all these new blocks for sale and they have that style bore. 

Don

[Aussie Challenger]

  Ask any chevy guy what they have to do to try and cool the siamesed blocks. Drill extra holes in the block and head, and I have also seen a couple of blocks with extrenal piping just to try and keep it cool and that was in a street car.
     Bores need to be kept cool especially around the top, if the 2 centre bores are joined together it creates a hot spot which in turn will distort both bores offering poor ring seating.   

[Super Blue 72]

this makes the block stiffer & helps with power but limits the cooling as wtaer cannot pass between the bores , I have no heard of Mopars overheating due to this but Chevs always used to with Siamese bore blocks

Just curious, did the Pontiac 301ci (4.9L) engine have siamese bores also?  Someone a looong time ago mentioned this to me and they said that was one of the reasons that not a lot of hi-perf. stuff wan't available for that engine?  I dunno...   

[Moparal]

The mopar mega blocks with the siameese bore has over a 1/2 thick deck to it. Our big blocks came with long strokes so it has deep walls.  You really wont see a big issue with these blocks.  Or atleast I havent

[The Cuda Guy]

So I take it these blocks are good for cars that are on the street?

Don

[Chryco Psycho]

the Mopar ones seem to be fine possibly the Mopar s just have better cooling design & accomadate the siamese bore better