If you have been playing with these machines very long, and if you have had (or even just worked on) more than 1 of a particular series/brand, I'm sure you have seen that most tractors have come with many engine options on the same chassis, with the same attachments that will work among the different models in the series. Now I know I can't go down and buy a new CC quietline or an Ariens S series (using those as examples since those are what I have); but Sears, Deere, MTD-- they have all done this... among IH... 109,129,149,169 same machine with different HP engines... and we all have some "Tim Taylor" in us..... ya know, "more power arrghhh"....
but seriously if a CC 1250 will power a 50" deck just fine, and propel the machine forwards and backwards, and do so at the same speeds as a 1650,(gearing and drive system ratios are all the same) other than "bragging rights" what does the "extra power" get you?
now I know that there has to be a line drawn somewhere.... even though it would fit I don't think I'd put the 50" deck on a 109, a smaller deck would be more suitable unless you are mowing every other day like a golf course, where you aren't hardly throwing much for clippings/ and I certainly am not giving any credit for newer machines which are largely junk/ and companies have been sued over the over-rating the power of their machines (who needs 20HP for a 42" deck when a 12HP will carry it just fine) where a HP increase was just a peel and stick deal it seemed (so they don't deserve any credit for their "claimed" HP)
I have a CC 1650 that is a ways away from getting its due garage time as it has to "wait its turn" but as I got it as a roller and am looking for a replacement engine as it awaits its turn, ya know, "get while the gettin's good" for a better deal, I have a 12hp here that may work to get the machine going, and am supposed to be gettin a 14 just like it soon. If either of these are drilled for the Kohler narrow base pan (another story) I could make either "work" (I have another pan as would be needed for the application "if" the block is prepped for it)
and I know someone with a 1250 on which I have plenty of seat time that does what is asked of it "just fine" and IDK that for what it is used for, that the extra 4hp would really be "noticed"
again just using the machines that I have and those that I typically work with here..... but within a given series how much power is "enough" for normal use on a given chassis?