I was reading an article about a 3-rotor FD and it said the engine had pins (dowels) added to it for reinforcement. My question is, when is it appropriate to add extra dowels to the engine? That is to say, how much stress can the the Wankel rotary engine, preferably the Renesis, take before you need to add extra dowels? IMO, I don't think power is the only problem. I am also concerned about engine vibration, as well as the extra heat transfer associated with increasing power. Also, is the Wankel rotary engine less thermally efficient than a reciprocating piston engine? I would think so, assuming Q[rejected] is lower than that of a piston engine. Also, I think its relative size and rev ability hurt its efficiency, but I am not sure. I hope someone can answer my question. Sorry it's so long.

 

that's not a long post! wait until rotarygod posts an answer- that will be long! :p one answer i can give you is - yes the rotary is less thermally eficient than a reciprocating engine.

 

Dowel pins are needed when you generate high torque. The normally aspirated two rotor renesis doesn't generate high torque, so it wouldn't need dowel pins. It does have some of them stock - they are hollow tubes that the assembly bolts go through - they allign the sections of the engine and hold them radially aligned when the torque reaction of the rotors tries to turn them.

An example of a rotary engine that needed extra help with dowel pins can be seen at the Seven Stock 7 meet in September. The four rotor Lemans winning 787 engine needed even more help than dowel pins could give - so they fabbed a honeycomb structural plate and bolted it to the bottom of the engine (where the oil pan goes). That engine uses a dry sump oil system so that area was available for other uses. It had rather extreme torque with 700+ HP output.

BTW, they are going to start it up so we can hear it run! It will be awesome!

 

Think they'd notice if I snagged it and put it in my '8? :D

 

Oops I had a brain fart the other day at work. I meant that the rotary engine had a lower heat rejection rate (Q[rej]) than that of a piston engine. My thermodynamics teacher would have kicked me in the teeth if he saw that...Sorry if my qusestion is vague, but I'm concerned about the internal strength of the 13B MSP. Since I cannot afford FEA tools, I'll just use this forum; I'm sure someone knows how strong these engines are

 

Man I am asleep today. Apparently I did write that thing about lower Q[rej]. Also, I am aware of doweling, and that the RE has them stock (I should know since I spent my senior year in high school using AutoCAD to draw a rotary gear pump). I figure I start getting nerdy cause I haven't posted anything in a while.

 

I have no idea what you are saying! :D