520 heat extractor


Anyone have contact info for someone that builds heat extractor for a continental sandcast 520?
Rhodes Marine Services in Plant City is the company that made the shroud by that name.


Their website looks to be dead and I can't advise status. Call Jernigan's, they were a dealer the last time I checked, if Rhodes is no longer in business I imagine they have an alternative.

We run one on a Parallel Valve 540, it knocks about 50 degrees off the cylinder temp measured with CHT. When you install you will likely find that you need to add pitch. Some folks interpret that as more power, but the truth is the shroud interferes with airflow into the prop. It's a tradeoff but you ain't really stuck if the engine is still running 🤓

I will also note that they do fatigue and crack at the flap slits. Just not a lot of meat there. The other option is a sheet metal shroud, but w/o the slits you have to make it taller to get enough suction and that takes more air away from the prop.

Welding cracks has been a maintenance item on the shroud for sure, but the boat won't run dry all day without it installed vs. a bunch of stopping to cool down.
Thank you for the info… I’m looking to get a sheet metal or aluminum one built for my 520 . Talked to a airboat fabricator in Lakeland that’s gonna build one for me.
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