Borer + 160hp RPM

[highroad]

Just purchased a used Borer 82x44 that the paperwork says was re-pitched to 42" to put on my Pacer. Wondering what static/climb rpm others are getting with their borers and 160hp? I am getting 2400 static and 2500 on climb out @ 65mph. What rpm should I shoot for for max takeoff/climb performance? I had a 74x56 pitch before and it seems I gained about 100rpm static/climb with the borer and lost 3-5 mph in cruise (thought I would loose more). The borer makes more thrust for sure, as at low idle I have to be on the brakes to keep the airplane from rolling where before this was not the case. It also accelerates and climbs out better and I have noticed less vibration. The propeller is going in for overhaul soon and I am thinking of having them flatten it out some if the prop will take it. I realize that if one gets the prop to flat, it may be easy to overspeed in level flight although I always pull the power out some before going to level flight after climbing and have never seen much over 2500 in my pacer. It will go to 2650 or so at WOT level flight.

What do you think?

Thanks

[Steve Pierce]

No experience with the Borer on a Short Wing unfortunately. On a Super Cub with a 160 hp a 43-44" is optimal. You can figure about 50 rpm per inch. There is a point that the lower pitch looses it's efficiency and doesn't seem to climb that much better vs. the loss in cruise.

[highroad]

Thanks for the response Steve. I am happy with the performance, but wonder what it would climb like if it was turning 2600-2650. I understand the idea that at some point when reducing pitch, you loose thrust, like being in two low of a gear in a car at redline. I would love to put a constant speed MT on the airplane to get the take off climb performance with the engine making full rpm/power and still retain some cruise but the $$$ keep getting in the way. lol!

[Steve Pierce]

I think with those kind of rpms on take-off it would redline pretty easy in cruise. be neat to find a Super Cub pilot with a lower pitch that would let you experiment. Got a Super Cub in the shop right now that has the MT prop. Pretty impressive. What was real impressive is when it had the reversing pitch MT on it. Pretty neat landings and parking.

[Stephen]

Steve....seems to me that the SC-MT needs to be test flow....by you for a report!!

Nice to have a propeller that has the same value as an engine. Is it electric or hydraulic?...can they both reverse?

Hey, if you reverse on final...do you land really short or fly backwords??? Ha!!

[Steve Pierce]

The reversing prop is no longer installed on this particular Super Cub but it was impressive. It is hydraulic. Had to be below 1200 or 1400 to engage the reversing feature. You could land really short with it for sure. Another advantage to the MT is it is light weight so not as much mass spinning it slows down faster and acts like a speed break. Backing up into the parking spot is way cool. I'll see if I can find the videos.