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New Mercury Outboard Engine Project — This Time on a Sonerai

By Ted Kiebke, EAA 837375

May 2018 - They say time flies when you’re having fun. I must have been having lots of fun since the summer of 2014 when I wrote about the project to install a Mercury engine in an Acro Sport. Over the winter I did some mods to the cooling system for the engine, and it should run a lot cooler. Testing on the Acro Sport will start imminently, and we’ll update you with a video when it flies. One element of fun we’ve had this winter is that the hangar door froze in the down position. Like I said — lots of fun.

This is an update on a new project, a Mercury engine in a Sonerai. As you will see from the pictures below, the engine is still in many pieces. All have been machined to specs and are ready for assembly. The propeller reduction drive is almost complete and is sitting on a mock engine. The Sonerai engine will be belt driven and, so far, will be very light. For the Sonerai I used a 175-hp carburetted engine. On a little side note — Mercury uses the same block for the 135-, 150-, 175-, and 200-hp engines. Each engine is modified to produce the desired power.

The new Mercury engine is based on the idea of how light in weight I can build one. For the Sonerai, I wanted to keep it very basic so I chose a carburetted-style induction system and a belt drive that weighs 20 pounds.

A few photos of the mock-up engine can be seen in the gallery above.

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