MPI oil filter head. Restriction?
 

Morning guys.

With one of my 509s just about done, it's time to work on plumbing of the oiling system. I am trying to keep the MPI brackets and such in place and I'd like to mount the oil filter the way it was installed from Merc. Being that the engine room is tight and there's no place to mount the filter elsewhere, the MPI location is convenient in my TRS 311.

I have a Canton inlet/outlet on the block pad. I will plumb that with -10 fittings. My oil cooler will sit (hopefully) on the back on the engine go to the filter up front. Playing around with the filter adapter, I've drilled and tapped the inlet of the housing for 1/2-inch NPT and can now install an NPT to -10 mail fitting. The problem I'm running into is on the outlet side of the filter. The fitting appears to be JIC and should work but it's a -8. I could add an adapter fitting to go back to -10 but am I creating a significant flow restriction? I believe the outlet is 7/16 but that's no where close to the 5/8 of the incoming side. But again, it's the filter and there's restriction there anyway.

I have no problems trying to get something different to work on the bracket. I was just having fun with tools and thought that it would be cool to get this to work. What do you guys think?

I'm also interested in answers to this. I'm in the same boat with my oiling system. Factory -8 fitting on the remote oil filter base. Right now I have it adapted up to a -10 but I wonder if that is OK.

I did a calculation on the flow rate through that orifice and came up with a little more than 9 gallons a minute. If I'm remembering correctly, the Mobil 1 filters I use flow 7 gallons, but would need more test data to compare.

As is the usual case for me, I'm probably getting too deep into the details.

The OEM head has quite a bit of material that can be hogged out. I went with the Hardin head for different reasons but ported out the oem unit and was pleasantly surprised with how much it can be opened up. I think the oem fittings are the bottleneck.

See if what you are looking fir in arcticfriends 502mpi oiling ‘bible’ thread:
https://www.offshoreonly.com/forums/...-hardware.html

I've been all over that thread. Any time I have a question on oil system plumbing, I refer to what he put together. As always, he did a lot of work point out the short comings and how to overcome them.

The real issue he talked about seemed to be with the fittings. The 1/2 inch lines weren't perfect, but probably "ok" on a 400 HP engine. The fittings were the really bad parts with orifice openings that were restricted to 3/8. Those created real bottle necks.

In the case of the MPI filter head, the flow is going from the filter through the -8 fitting into -10. Technically, that shouldn't be a real restriction to flow because it's going "little to big" instead of the other way around. I have opened my inlet up quite a lot so I doubt it will be any kind of restriction. And this is without hitting it with the die grinder to clean it up more. I'll get a picture of it later today or this evening. It's sitting in my parts washer.

On a side note... I was going to do something similar with with my fuel/water separator head, but there's jut not enough material there to increase the fitting size to 3/8 NPT. I'll order new ones for those.

Tom it sounds like you are like me an tend to overthink things but that's part of the fun I think in building stuff. We've got great resources and experience such as that oil thread and other forum members experience that says don't go with anything less than -10 for oil stuff. Then on the other hand we have for instance a Mercury 496HO that is the only big block to not fail during the 300 hour WOT endurance testing, and has been proven to run for 1,200+ hours no problem with -8 fittings.

Perhaps the real answer is there's no one size fits all. Maybe it's oil pressure and temperature that really matter on a given engine.

^^^^ This!!!

I’m glad you started the thread. It made me think about the filter heads I was planning on using for new builds. Not knowing every restrictive point I like the idea of bigger is better when it comes to oil gpm. One or two choke points are one thing but when you look over the complete oil system there’s a lot going on. Something that can easily be overlooked especially when using near stock oil components and throwing another 25-50% more power at it.