1997 Vmax 175 Hpdi?

My buddy and I recently bought a 21ft center console that came with a frozen 97 VMAX 175(he said it wasn't winterized).The guy seemed a little sketchy but the just the boat was worth the money so we bought it.We are weekend warriors and and after trying to free it up for several weeks with everything from mystery oil to Kroil,we havn't had any luck!Got the motor horizontal and filled the cylinders with the above mentioned fluids and they can't seem to get past the pistons.We even rigged up compressed air to try and force(or at least help)the oil past the piston rings and still no go!We have decided to break down the motor enough to see what condition the crank and bottom of the pistons are in.Aside from the fact that we've never attempted anything like this before,(weekend warriors,remember?).we are not even sure of the exact model we have.Like I said,the guy was a little sketchy and the sticker with that info is missing! Coincidence?Maybe.Anyway, can anyone give us info on which type of motor yami made for that year and where we can get a shop manual specific to that year and make?The manual I bought covers every Yami from 15hp to 300hp and its a little confusing for novices like ourselves!!Any help would be greatly appreciated!

[boats.net]

Not sure what you have, there were no HPDI models in 1997. There was a VMAX 175 in 1997, model P175TLRV but was a carb model.