Putting different motors in, with a multitude of pumps available, Id like to know what pressures the OEM pump generates on something like a Merc MPI502 etc? Going to try and find number on original pump and see if I can find data on that too

Since no one seems to know... dug around looks like they use Saginaw type pumps, like mid 80s GM trucks. Pretty sure they ran @1200 psi and 2-3 gpm

GPM is what is important. I believe your stock pump is 3.5 GPM. I was running a stock pump for 2 ITS boxes which each have 2 4" rams. The stock pump was not enough. There was not enough output at idle for smooth motion. This year I upgraded to a high output latham steering pump (modified Saginaw). I'm not sure how this will work yet as the boat is not in the water. There are a lot of things to consider. Ram size, number of rams, helm pump size, will all dictate how much volume you will need.

thats what im trying to figure out, where am i starting at, and figure out how to get the same type of flow with the late model type II pumps. The .663" shaft corvette pumps look like closest so far with 3 gpm 1200 psi, Factory bravo steering on a 33 Donzi

Your correct the power steering system produces 1150 - 1250 psi on the high side. The difference between the auto pump and the marine pump is the pressure regulator valve that screws into the back of the Saginaw pump. You can buy the pump alone from the local auto store but make sure to swap out the regulator, otherwise the pressure is lower and it will be difficult to steer.

Have first hand knowledge of this from swapping the pump out and not knowing about the regulator. So later I paid the bog bucks to get a marine one, then later find out the difference.

There are places on the web showing how to increase the pressure on the regulators which were done by racers, which also work for boats.

So as long as I run something that makes 1100psi or higher I should be good to go. Alot of the new heavier cars are around there I think

That would be my guess, but have not herd anyone trying it yet

You are talking me you type steering correct? Not external hydraulic. So you were running the same steering that came with your boat. Why don't you just take the existing pump and attach it to the new brackets?

There are no brackets for this engine type (swapping in small block LS engines) There are lots of pump options out there though that bolt right on from automotive side