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As I still await my ONEX kit delivery i have been researching powerplant options. I know the ONEX is designed to use the AeroVee powerplant however the Revmaster has that fourth main crankshaft bearing while the AeroVee has only three. I understand that the fourth bearing beefs up forward crankshaft support which in turn reduces the chance of a crankshaft failure and subsequent prop loss. Has anyone used the Revmaster in their Onex and what difficulties and or changes were made to the engine mount, cowling, baffles etc.
Sherm

Hi Sherm.
To the best of my knowledge there has definitely been one Onex with a Revmaster installed and I do believe at least one more.(last I heard it was for sale)I know that the upper cross bar has to be moved back and other than that the mount is good to go.There was never anything mentioned about having to change the cowling and as to the baffling, I plan to order the Aerovee baffle kit and make it work for my Hummel engine as I know others have done on their sonexes .I consider the Revmaster the top VW engine on the market today but the cost was a bit to high for me and I'm not sure if I like all the proprietary parts that go with it.I would worry about future availability where as the Aerovee Hummel and Great Plains engines will always be available.Still ,a nice robust engine .
Cheers,
Mike

I think you are worrying about a problem that isn't there. There have been two crank failures on sonex aircraft. One was on an aerovee due to the builder improperly pressing off the hub after forgetting to install some parts during assembly. The other was a Great Plains motor where the crank bolt came loose. GP issued a service bulletin that pretty much described the problem and just said to be careful with no permanent fix. As much as the competitors would like you to believe it, the aerovee just hasn't had a crank failure problem

I will say that there isn't anything wrong with a revmaster and it does have a few differences over an aerovee. It would be a good choice if you don't want to assemble the motor yourself. My point is that you shouldn't switch just because of the crank if that is your only reason.

Keith
#554

With the added bearing you could transfer more forces to a part of the crankcase that was not designed to take these kind of forces. Not necessarily a bad thing, but something to think about. An adequately dimensioned crank running on the original bearings sounds to me like a better choice engineering vise.

It is a fact that AeroVee is the only one selling their engines with the shrink fit system, the other 3: GreatPlains, Hummel and RevMaster all have the F1 type prop hub with extra-large bearing in the front.
GreatPlains does sell the shrink fit system on its own but all of their larger displacement engines they sell with the F1 prop hub as standard.

That said, what Keith said is also a fact, at least on Sonex aircraft there has been no proof that the cranks and/or prop hub on the AeroVee fail/separate.

Also, the Great Plains one Keith mentioned was a type 4 I believe which has a different crank that requires a spacer to install the prop hub, see here: http://www.greatplainsas.com/service2.html, I don’t think a solution exists yet and they recommend only to use the Type 4 in a flywheel drive configuration which is not supported on the Sonex.

In the end, you might like one or the other and I’m sure this topic will be discussed for many years to come,
I personally have come to believe though that both designs have well proven their reliability, I would not be afraid of a crank failure and/or prop hub separation on a properly assembled AeroVee, neither am I afraid of any (additional) forces being put on the crank case by the F1 bearing.