Reed Valves and Relative Performance
03-23-2016, 03:26 PM
#2
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I don't think that question can be answered with a simple answer as there are many variables. For a simple answer, I would say a reed valve compared to a piston ported engine is more efficient at low and mid range RPM settings. A reed valve engine seems to produce a stronger low and mid range torque curve where many piston ported engines excel at higher RPM where they really breath well. As a result, over the years I've noted that for otherwise similar engines, the reed valve engine seems happier with a slightly larger diameter, lower pitch prop where the piston ported engine seems to favor a smaller diameter, higher pitch prop. Again, these are just general observations. Not sure I helped much but for general flying, I much prefer the manners of reed valve engines. That's not to knock a piston ported engine in any way ..... they are just different from each other.
03-23-2016, 04:49 PM
#3
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The reed valve engines are usually the newer designs, and as a class, probably represent the latest technology. My favorites for sure. Piston ported vary more. State of tune all over the ballpark. Might be a friendly converted industrial engine, or a refined thoroughbred.
IMHO, the design to avoid would be the front intake rotary valve.
IMHO, the design to avoid would be the front intake rotary valve.
03-24-2016, 11:02 AM
#4
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Join Date: Jan 2002
Location: San Tan Valley,
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The problem with piston port engines is part of the charge goes out the carb when the piston come down. Reed valve engines avoid that but a reed mechanism in the way of the air to enter.
I prefer the front intake rotary valve engine because it has less parts to fail and puts the adjustments in the front where you can get after them.
Its interesting to study the evolution glow engines went thru. They started with piston port(O&R), then tried reed valve(Cox), rear rotary valve (HP) and finally all wound up as front rotary valve engines.
I prefer the front intake rotary valve engine because it has less parts to fail and puts the adjustments in the front where you can get after them.
Its interesting to study the evolution glow engines went thru. They started with piston port(O&R), then tried reed valve(Cox), rear rotary valve (HP) and finally all wound up as front rotary valve engines.
03-24-2016, 12:25 PM
#6
Sorry to disagree with you this time Truckracer. Usually we are pretty much in agreement on engine technical details but I beg to differ with you on this one. Two stroke engines generally have TWO failure modes. One is "BANG!!" and the other is "SCREEEECH!!". Both modes are followed by sudden silence, and an intense pain in the wallet area.
A few years ago, I had one of the "SCREEEECH" failures with a two stroke. This one caused the additional symptom of me sweating, as I was flying IN the machine when the engine failed. That was interesting.... It also proved to me that the prop turning does indeed tend to keep the pilot cool.
AV8TOR
A few years ago, I had one of the "SCREEEECH" failures with a two stroke. This one caused the additional symptom of me sweating, as I was flying IN the machine when the engine failed. That was interesting.... It also proved to me that the prop turning does indeed tend to keep the pilot cool.
AV8TOR
