I don't think it is much of a concern, however while we are on the topic. Can I anticipate any damage from leaving my Formula in salt water for a week? (420's open cooling)
This will only occur on my Florida trip.
Thoughts.

Innovation does closed cooling on most of its new motors. All of the Volvo motors are close cooled. That Volvo project ic on hold right now so they have some complete motors that they are blowing out right now with exhaust. 500's and 600's w/ warrenty 16 and 24 thousand.

One thing that is sure "Rust never Sleeps", anything that can be done to eliminate portions of the exposed area (internal or external) from the effects of water contaminates I feel is a good thing. As indicated, maintenance is the key regardless of how the engine is cooled. As for the weight, preventing internal engine component contamination is worth the couple of extra pounds. Nice thread thanks for the feedback.

FIRST of all, understand a few things. What are the problem areas on the engine from salt water? The riser/headers! NOT the block. I have NEVER heard of a block rusting out. Closed cooling still runs "raw" salt water through the risers for coolong...so what is the advantage? It doesn't do what most think it should.

thank u SD :D ....most of our cmi and stelling big tube motor failure have been riser and right at the flange at the head right at the first weld....they need a lot of attention!!

Good point SD. But the block is not the only consideration. Ideally a full system would be the answer to long term freedom from the harmful effects of rust and contamination. I appreciate your response. As indicated, the additional seawater components are the majority of the headaches. It appears the 496 external components have answered some of the issues that were related to the earlier designs. I have noticed the engine temperature is a lot more stable with the 496HO than the traditional approach to cooling used in the open system. Bottom line is Rust Stinks! My initial question was there a kit for the HP500. If anyone knows of any I would appreciate the feedback. Thanks again!!

The risers are stainless steel on the 496HO's...

Hey Reck, Where you been dude!!! Nice seeing you last night. We are getting quite a family majority down here. Your brother seems to be settling in well. Did you get your Mag from the box? When do you want to get together and JAM!!!

donziman2 i have the mercruiser 350 mpi's

Thanks Jim, Nice motors. DMAN2