larrynew

larrynew

Well Known Member
Crankshaft - Hollow or Solid?

I'm ordering my engine very soon and can't decide between a hollow crankshaft or solid. I've already decided 0-360, carb, Sensenich fixed pitch and the vendor. I am NOT planning a constant speed upgrade. Flight profile will include frequent positive g aerobatics up to limit. Hopefully this won't be my last RV so I may sell it in the future. A few questions:
  • Are there any differences in prop RPM restrictions with the different cranks?
  • Are there any problems or restrictions with hollow cranks due to frequent high g maneuvering?
  • Any significant value in resale with a hollow crank?
  • Any other concerns I should have between the two?
Searched the archives and Sensenich website but not sure I even know the questions to ask. Almost all of my time is in front of turbines with very very little behind pistons. Thanks for the help.
 
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Yes.. hollow.. even if you don't need it, your buyer may want it.. why restrict the pool of buyers?
 
I went cheap (by about $300) and got the solid crank. If I had it to do over, there seems little reason not to spend the extra on the hollow crank (there are some potential issues with the plugs, but nothing major that I can tell) JUST IN CASE you change your mind (or, as noted above, it doesn't restrict your buyer pool). In terms of airplane $, 300 is pretty small potatoes.

greg

and, the hollow crank might just save you a pound or two.
 
Greg Arehart said:
I went cheap (by about $300) and got the solid crank. If I had it to do over, there seems little reason not to spend the extra on the hollow crank (there are some potential issues with the plugs, but nothing major that I can tell) JUST IN CASE you change your mind (or, as noted above, it doesn't restrict your buyer pool). In terms of airplane $, 300 is pretty small potatoes.

greg

and, the hollow crank might just save you a pound or two.
Click to expand...

Actually, the solid crank weighs 8 pounds more than the hollow crank, at least that was the info I got from BPE a couple years ago. The standard Lycoming kit came with a hollow crank, there would have been a delay getting the solid crank, so we went with the hollow crank and left the aft plug not installed to run with the Catto prop.

Go hollow. The next owner will appreciate it.
 
It is not as easy as just bolting on a C/S prop

and getting the in crank plugs right - there is an oil relief port in the nose bearing of F/P engines that vent oil out of the nose bearing back to the crankcase. This port must be plugged when going to a C/S prop.

The only way to do it is split the cases.

There are several threads regarding this on the forums and there is an ECI tech bulletin regarding it. Since Lycoming never built engines intended to switch from F/P to C/S, they do not address this and many A&P's aren't aware either.

I would go with the hollow crank anyway - lighter and does give you the option, just not as easy as some believe.
 
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