Is there a direct bolt in replacement for a stock 502 mag oil cooler. Currently running about 650 hp and I would like to increase the coolers capacity for the additional hp.

You could check Harden Marine out. I have have a Harden combo oil and power steering cooler with a built in thermostat that seems to do well on my 696 hp engine. They say it's good to 750 hp. It's about 3 inches OD and is longer than the stock 502 cooler.

What your asking is "does a bigger cooler exist that bolts directly in place of the original without changing factory fittings or oil lines"? As far as the 502 mag efi goes, I don't think so as the factory uses some tiny fittings with small oem ends. I have looked at the stuff off a hp 500 and even older 454 carb motors and everything had bigger hoses and fittings, I may be wrong but I think you will have to re-plumb a few things, Smitty

I went with orca marine due to mounting restrictions , they custom build to your specs. nice units , although expect to spend some cheddar

you need to can all of the oiling system you have now...just did it, larger cooler, eddie marine has a nice one, block adapter eddie marine sells a canton one, new remote filter adapter, I used a moroso, along with that need to run #10 lines, the twist lock set up is great..also need to make sure you have the 30 psi relief valve in the block...

I currently have a remote filter adapter that was installed with the Vortec supercharger package. I guess I will need to check the size of the lines. How can I tell what size relief valve is in there now. The motor is still installed and I wasnt planning on removing it.

the stock merc lines are terrible, very restrictive, need block and filter mounts that use 1/2 NPT and plumb with #10 hose, keep as short as possible..made a huge difference in mine on oil temp...no way to tell the relief with out getting it out of the block and usually destroying it in the process...I just ordered a 30 psi from GM about $6 when got the old one out was a 11psi you can see the difference...

I wanted to say that too BUT everytime I do I get attacked! I wrote a VERY informative thread on just this years ago based on personal experience, I know that YOU know the drill, Smitty
http://www.offshoreonly.com/forums/g...-hardware.html

So I guess with either bypass valve a good share of the oil remains uncooled and not filtered.
When I was building small blocks years ago I would remove the bypass valve and install a pipe plug so all oil goes to the filter.

I have the same setup, oil cooler vertically mounted on front of engine. I also have a ps cooler at rear of engine. I believe the best way for me to add a larger cooler would be to replace the ps cooler with a combination oil and ps cooler because there is room back there for it.

My question is; When I remove the cooler from the front of engine, what do I use for a water hose to hook back up between cool fuel and my t-stat housing? I know where to get the parts for plumbing the oil lines, but how about the water?

There are lots of 454mag/502 mags out there with lots of hp added. Maybe someone should make a kit. Or do they and i have just not seen it.