I need some guidance. Have two props and I like them both. They're both quite different in their performance, and I first want to understand the differences fully and second want to decide on which one to keep and be happy about it.
The plane:
RV6A, o-360, carbureted, 1 slick and 1 SDS Electronic
Started out with a Sensenich FP, which worked perfectly fine, albeit a good bit of vibration and noise which I never really noticed UNTIL... I picked up a Catto 3 blade looking to pick up some extra speed. The Catto is a 66x74 and is every bit as smooth as everyone claims. However, with this pitch, the Catto performs more like a climb prop. Climb it does, and does well. It will go almost as fast as the Sensenich, but the downside is that it does so at a considerably higher fuel burn, and tends toward a higher fuel burn at most rpm's.
Cruise Performance:
Sensenich Performance: 8kDA, 2740RPM, 168KTAS, 10gph; That is throttled back some, because it will turn faster than that. Adjusting for a fuel flow of about 8gph nets around 150-155kts@2560RPM. Yesterday I tested it at full throttle, 10kmsl and saw 2800rpm, 170KTAS, and 10gph.
The Catto: 8kDA, 2720RPM full-in, 167KTAS, 13gph flow. Adjusting for a fuel flow of about 8gph also nets around 150KTAS @2450rpm
Static RPM on the Sensi = 2150rpm, held with brakes
Static on the Catto = 2200? but brakes couldn't hold it.
Climb:
Sensi- 1kfpm at 120kts, throttle reduced to keep CHT's below 415.
Catto- seems to accelerate slower, but climbs 1.5kfpm @ 110 kts full throttle and CHT's never try to go over 400. Slighly higher fuel burn.
Conclusion:
I guess where i'm seeing the most significant difference is more subjective than the numbers might imply. A lot of it is just impression because i'm usually too busy to take photos to bring back and compare.
+ & - for the Sensinich=
Better top speed at a lower fuel burn at almost every altitude. Better acceleration after leveling off. This is the big one, as most of my flying is done in the local area down low. I can hit 1500agl and almost immediately be flying at 140kts indicated, which allows me to throttle way back for a pleasurable sightseeing flight with a minimal fuel burn. Push it in, and immediately the airspeed climbs up. I'm based at sea level, and usually do lower altitude local flights, so climb performance isn't really an issue. Basically this prop does exactly what I want it to do, but with two major consequences: RPM and engine temps on climbout. I don't fully understand the way manifold pressure fits into the equation, but this prop burns less fuel at a higher rpm and lower manifold pressure than the catto. That seems to tell me the engine isn't working as hard. Still, it almost always operates at around 2700rpm which i've been told will reduce the life of the engine.
+ & - for the Catto
Smoothness, lower rpm for engine longevity, great climb ability and lower temps on climb out. Looks great!
The main frustration when flying it has been the time it takes to speed up. When leveling out from a climb at 110kts, i've got to leave the throttle in for considerably longer to get it up to speed, thus burning more fuel per local hop than the Sensenich assuming the same speeds.
Interesting observation in case anyone cares: there is a difference in the way I have to approach final with each prop. The Catto seems to lose energy faster and thus speed drops off quickly before touchdown than the sensenich does. My supposition is that the flywheel effect of the sensi keeps it spinning and generating some forward thrust even with the throttle out. Thus, short field landings are a snap with the catto while the sensi, at the same approach speed, just wants to float forever...
Do these observations make sense to anyone else? Can anyone think of some pro's/cons that might help sway me one way or the other that I haven't thought of yet? Am I crazy?
I'm outta money, so I need to sell one of them, and having either of them modified is really out of the question right now as is changing to a CS.
Which prop to keep? another Catto VS Sensinich thread
, which was one of the reasons for the post! The props were tested in very similar conditions, and altitude adjusted for density so that a comparison would be accurate. My thought about the difference in fuel burn for the same speed was that one prop had to work harder to get there which is evidence by a higher manifold pressure for the same rpm. 
Linear Mode
