Originally Posted by arghx

Mazda's basic formulas were published 40 years ago in the book Rotary Engine by Kenichi Yamamato, one of the leaders of the early rotary engine program.

It can be found in the section "engine vibration" on PDF page 88 of this document on Google Docs: https://docs.google.com/viewer?a=v&p...hl=en_US&pli=1

Originally Posted by John Huijben

What I think is wierd is that every documentation I was able to find says to take the weight of all the seals into account, including the apex seals. The people that do rotary engine balancing therefore also need to know what kind of apex seals your using, since the weight difference between steel, carbon or ceramic seals is pretty huge. But when you think of it, when the engine is running the apex seals ride against the rotor housing, and are not attached to the rotor, the rotor just moves the apex seals around, so I think that alone causes a big error. In fact, the seal springs kindoff push the rotor away from the rotor housing. What it boils down to is that a large part in engine balancing is probably based on experience, and using what has worked in the past. Which is what I did too with my bob weights, I found out what has worked for others, and then checked if it's accurate by weighing the rotor, the rotor bearing, all the seals, and I actually filled the rotor with oil and weighed how much oil fits in there. The 2 matched up within a few grams, so I'm confident that I'm on the right track.