It appears that the TSIO-550C is rated at 310hp at 2,600 RPM, but the engine used on Lancair IVs is the TSIO-550-E rated at 350hp at 2,700 RPM.  Both engines are identical except for where the prop governor is set.  They have the same recommended cruise setting of 262hp at 2,500 RPM.

 

So bottom line, don't trust the information on the Columbia web site.

 

Mike Easley