flyrotary@lancaironline.net Mailing List Archive

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Thanks Chuck, We don't have a large aviation user base so every bit of hard data we can get is invaluable.

Virtually all of the feedback on RA seals I get (the car guys came up with this name, not me) is from the racing community. Could not have continued improvement of the design without it. They were (and are) the Beta testers.

FWIW, there has not been a single case of broken RWS apex seals in NA engine use and most of them are used in racing applications. There has been one case of a broken apex seal in a turbo charged engine but both pieces stayed in groove and resulted in no rotor housing damage. This was a drag racing engine run at 40 PSI boost and 9500 rpm. The engine detonated severely due to ECU setup and all corner seals and 7 side seals were shattered. Rotors faces were dented in from over pressure, not debris. Although there was no FOD damage to the rotor housings I would suspect that they were deformed in some way from this event. Everything has failure modes but we think breakage has been virtually eliminated from RWS apex seals.

Tracy (shamelessly plugging RA seals)

----- Original Message -----

From: Chuck Dunlap

Mazda's new 2mm seal design is 2 piece (introduced in 2004 I think), the 3 piece is obsolete.   It is quite possible that Chuck got his prior to the new Mazda design so he could have the aftermarket parts.   RWS does not furnish seals to Mazdatrix so guess they would have to be Hurley or Atkins (same material AFIK).

Hi Tracy,

Hopefully Chuck can clear this up for us, as well as providing many more answers once he gets into the engine. I would probably be more suspicious of the "aftermarket" seals than the stock ones, mostly because we don't know where they came from, or should I say we know where they didn't come from :-)

Does Chuck run the oil injection pump, or pre-mix? Losing oil flow to one rotor would eventually lead to loss of compression, though I don't think it would happen that suddenly.

In trying to think of recent problems,  the only one I can recall that didn't have a very clear cause was Ed's tailwind to Shady Bend issue. I recall there was a theory of ingesting something, but it was never proven. Other than that, Paul's accident wasn't absolutely proven, but I don't think anyone blames the engine itself. Any others?

Again, the lack of unexplainable "engine" failures is good news, but that fact is hidden under a bunch of "engine installation" failures (ahem, like mine).

Rusty (RV-8 QB delivery finally being arranged)

I could not find the paper receipt from Mazdatrix, but I found it in my old saved email from 2003 - Thank goodness for computers! The apex seals I used were Mazdatrix part number 112N326 which is listed as an aftermarket steel seal.

I premix the oil, I use cheap Wal-Mart 2 stroke oil in gallon size. The oil mix was likely on the lean side when the failure occurred, because someone filled up my fuel tanks the night before without asking. I always add oil during fueling to insure proper mixing. In this case, I had to add the oil after it was full, so the oil was probably rich at the outboard side and lean at the inboard side. My return line goes back to the tank right at the inboard side so does not help mix the oil much. I don't really think any of this had anything to do with the failure though.

Chuck (still a rotorhead)