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Why not a 550?

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Well-Known Member
Nov 10, 2012
Reaction score
Sanford, NC
Without getting into all the details let's assume you have an IO-550N/G that you could or want to use in something like a Skybolt/Raven/Ultimate/S1-11 type biplane. I'm curious as to the many people on here who are smarter than me would not do so? I assume the natural reason it hasn't been done is simply... why would you. Most people don't have one already and usually buy an appropriate engine when you reach that phase of the build. In my case I have the engine and would like to build something for it. The biggest drawback I can come up with is engineering an engine mount for it. There are no inverted oil systems designed for it but that seems like a fairly easy hurdle to overcome knowing the design of the engine. I often hear people quote the weight as a deterrent but at least according to the TCDS it's on par or less than a 300 hp 540. There are obviously differences in how Continental and Lycoming quote their dry weights that is really hard to decipher but swapping out some accessories for light weight pieces and I think given the packaging of the 550 it would be the same or perhaps even lighter when installed. With the forward facing mags, cold side induction, integrated oil cooler, and gear driven alternator it's actually a really tidy and easy to package engine. It's incredibly efficient for the power it makes and if you desire more, 340-350 hp should be pretty easy to obtain if you want to turn it up to 3000 rpm. There are obviously some unknowns as to how well it would hold up to hard acro use but if that isn't on your priority list then maybe not a concern. So what did I miss? If you had it, would you try to use it?

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