Langford said, "I'm now flying a "52x54" Sterba prop on the 650 pound KR2. As the engine gets broken in, I expect the RPMs to come up a bit more also, maybe 3500 or so."
You really did something special to Faughn's old engine to be getting those numbers, especially with single ignition. With my Prince 52 x 54 the best I can get is 3150 - which is all I want. I'd still be using that prop if it didn't have those drag-inducing "P-tips" (read Paul Lipps if anyone wants to argue about that) and if it had leading edges that held up in rain (as do Sterba's urethane edges). My current Sterba 52 x 56 gives me 3150 at altitude WOT. That's right around 80% of Mach on the tip speed so anything faster is just creating tip drag and generating more internal friction heat. 3100 is the most efficient RPM for a 52 inch prop and seems to be the "happy place" for my GP2180 as well. Anyway Mark, 3450 on a 2180 with a Sterba 52 x 54 is phenomenol. What did you do to that old engine? Are you sure you've got a 52 x 54 and not a 52 x 52? I had a 52 x 52 Sterba that I have since sent to Ken Cottle for use on his current KR. He needs the RPM for getting in and out of short grass strips. That prop would render 3450-3500 and of course send the oil and cylinder head temps off the chart while doing so. Your figures sound like a 52 x 52. You did some magic ju ju to that engine when you re-built it recently if you indeed have a Sterba 52 x 54 and are getting 3450. Sounds like for the sake of keeping your engine temps down you'll be moving to a 52 x 56 at some point. Mike KSEE ____________________________________________________________ Ally Bank, Member FDIC Consistently competitive rates, 24/7 customer care, Member FDIC http://thirdpartyoffers.juno.com/TGL3141/567afbfab430f7bfa3aaast01vuc
