Mercury/Mariner 2.5L 150/175/200 question

[marinesupply]

Hey guys...got a technical question about powerhead fitment wondering if anyone can help...
We understand that all of the 150hp 2.5L carb and efi powerheads from approx 1992-1999 are the same and 2000-2008 are the same.
We understand that all of the 175hp 2.5L carb and efi powerheads from approx 1992-1999 are the same and 2000-2008 are the same.
We understand that all of the 200hp 2.5L carb and efi powerheads from approx 1992-1999 are the same and 2000-2008 are the same.
Here's the question: Can you replace a 150hp 2.5L long block with a 175 2.5L long block in the same year ranges....Or can you replace a 175hp 2.5L long block with a 200hp 2.5L long block in the same year ranges?
From what we understand from pro marines catalog and other research the 2.5L casted powerhead is the same in the same year ranges, they just press different sleeves in the different horsepowers to make the intake and exhaust ports larger for the larger horsepower engines.
Our thoughts are we could use a 175 or 200 for a 150 because the ports are larger and would be okay. We are thinking basically we could use a larger HP for a smaller...but maybe it would be a bad idea to use a smaller for a larger...eg: like using a 150 for a 200.
Any knowledge about using a 150/175/200 2.5L from 1992-1999 -OR- using a 150/175/200 2.5L from 2000-2008 would be appreciated. Thank y'all

 

[Dukedog]

when ya say "long block" do you mean just rotating assy. only (block, crank, rods, pistons, divider plate, and heads) or "drop on power head?

these are tha differences in tha years ya mentioned..... not sure if this is an answer of what your actually askin' but.............

1992 ta 1999 use a "normal" head, block usin' "normal" head gaskets and regular electrics. ie: switch box ign...

2000 up went to an o-ring type block, head makin' tha block have a taller deck..this doesn't really mater IF you know how to change, modify things ta make different head configurations work... also went ta electronic ign (cdm type) so some of tha mounting bosses and/or holes. ign. parts themselves, for such changed.. thats 'bout all ya gotta watch for if you think about swapping ign. parts.....

jan... all 135 and carb 150's or going ta be a 2.0 motor (even if they all look like 2.5's on tha outside) with tha exception of XR6, MagIII and 150 efi's