Hi Lynn,

 

You're right that I would truly be surprised IF this were true.  I don't buy it though.  Got any evidence to support this statement? 

 

Cheers,

Rusty (180+ HP Lyclone on the way)   

There is ample evidence. After a thousand or so hours in the dyno room, you can develop a feel for such things. Look at the ID of the carb or TB on the 180. How many CFM? Enough to support the advertised HP? At what rpm is that HP rating? Can't get a dyno sheet for your new engine? And if you could, what is the date on that sheet? Is it for your engine, or for an engine built years ago?  

 

Typical of the breed is a HP rating at 3,200 to 3,400 RPM (from years ago) and with a prop on them they won't turn up 2,700 on the ground. And only get to the rated power RPM in a dive. Hardly usable power. If you get behind one of the Black Max type rebuilds it feels like a rocket, because it is at or very close to its (Factory) advertised HP. And they do that with porting to match the flow rates of the cast heads. And you cannot put your finger in the ring end gaps.

 

If you can find a list of torque outputs for a list of aircraft engines, compare them to the rotary driving through a 2.85:1 reduction box. Now you see that the rotary does very well against the airplane engine. Look at it backwards and compare the swept volume of the two engines at any prop RPM. Since the rotary does outrun most of the 160 HP powered planes, would you assume that those rotaries have way more than 160 HP? Or, perhaps the 160s had a bit less.  I can get 3+ HP per cubic inch, would that make a great Lycoming or what?

 

Take off in a Cessna 150. Alone, so it won't be over gross. Did that feel like 150HP?

Did it feel more like 79HP? Why yes it did.   

 

Lynn E. Hanover