Multi stage sea pump questions
 

So my first question which is pretty straight forward....

I pull water for the engine through the outdrive and I'm wondering if the plastic hose barb deal on the transom housing will allow enough flow to feed a dual stage sea water pump? If not...what are the options there?

Next couple questions are specific to my boat and I'll do my best to explain what I'm asking....

For ease of conversation...let's say we are talking a 500 efi as that is the belt system I have converted to....I like the idea of hardin's single stage pump upgrade however I am not sure I can make the pulley system work with it? I will post a link but it appears they only make it for the non sea pump fuel pump models? I am not using a mechanical pump as I am fuel injected but I believe I need that "style" of pump to get the belt spacing right correct? So I guess my question is can I make it work without reinventing the wheel and get my pulley spacing right? I also noticed that it takes the bolt on style mandrel for the pulley and the OEM one I have for the pulley is a press on....what can I do there?
Hardin Marine - 1 Stage Aluminum Sea Pump (hardin-marine.com)
This is the single stage I'm talking about

Next questions....Not sure if I actually need a multistage pump as I have never had an issue with water temps on the boat but would like something more robust than the OEM pump. I am also adding a bigger oil cooler so extra flow won't be a bad thing. My questions here are that the one I see listed as working for a gen 5 which I believe is what will line up with my belt system is like 1300 bucks. Says in the instructions that it can be used on a gen 5 if the mechanical fuel pump is not being used which is where I'm at...my question with that is there is a 2 stage also on their site that is like 400 bucks cheaper and looks to just have a different bracket? Same as above...can I make this cheaper option work with a little bracket spacing or something and save the 400 bucks for something that is essentially the same?

Expensive version....
Hardin Marine - 2 Stage Sea Pump for Gen 4 & 6 Mercury Applications (hardin-marine.com)

Cheaper version....
Hardin Marine - 2 Stage Aluminum Sea Pump (hardin-marine.com)

Now I know being cool isn't cheap but I have a hard time spending an extra 400 bucks if I can simply fab up some bracket spacers or something pretty quick and have the same result?

I know this could have been summed up by simply asking who's done a multi stage pump upgrade on a 500 efi but I wanted to add the specifics to see if anyone has any ideas or options that I haven't seen or thought of yet?

Thanks for staying with me hahaha

Little more info...

Engie is a 540 14-71 roots deal with efi and bravo style outdrive....may be a determining factor for the 1 stage vs 2 stage?

Also to note...I would prefer the single stage route the first one I posted but the bracketry and pulley mounting is my concern.

I have used hardin's stainless OEM replacement housing deal and did not like it. Smoked 2 impellers very quick and switched back to plastic with no issues...not sure that the deal was there so I'd rather stay away from that route.

Thanks

I used a standard plastic pump on a 900hp engine in my cat with a thru-hull pickup to feed the intercooler at speed. I had no issues with cooling whatsoever. No need to reinvent the wheel if not necessary.
Your mileage may vary.

That's how mine is plumbed now...separate pickup for the IC with no pump just force fed at speed.

What I was really trying to accomplish is to get rid of the fuel pump nose on the water pump. The pump is originally off of the 525 SC that came in the boat and I currently just have a block off plate on it and was planning on just pressing the new serpentine pulley boss on the existing pump but I worry about losing the oil in the pump and smoking the bearings which has happened before on this boat. Was trying to simplify it a little bit but it seems like it's getting more complicated hahaha.

Is there a merc replacement pump that is the right length for the pulley but does not have the pump boss on the snout? Seems that may be the best way to go to achieve what I'm wanting to achieve?

Good info snap thanks!!

May have answered my own question...

Stainless Steel Sea Pump Assembly - Hardin Marine (hardin-marine.com)

Would this work for what I'm trying to do?