DF115 prop issue beyond me...Update...

[walleyehed]

Re: DF115 prop issue beyond me...Update...

Test results: (all tests were with 3 adults on board)<br />13-3/4X15 alum-5900RPM, 24.9MPH=23% slip<br />13-5/8X15 SS -5850RPM, 26.2MPH=18% slip<br />13-1/2X15 alum-6050RPM, 26.3MPH=20.3% slip<br />13-1/2X13 alum-6250RPM, 22.9MPH=23% slip<br />14X17 alum-5000RPM, 24.2MPH=22% slip<br /><br />I didn't think to take a 13-1/2X17 to test against the 14"., but the numbers show very clearly that, #1. SS is more efficient. #2. Diameter means nothing unless you are raising the engine to get max potential-again, blade design is more important the size, infact, the 14X17 was one of the most inefficient props we tried. If we would have lifted the engine 2 holes, that may prove different.<br />We chose the 13-1/2X15 for the reason it shows a bit more speed although at 6000+ RPM, when he loads the wife, his 4 kids (grown adults) and their spouses, he's got what he needs, and this is generally how he loads the boat.

 

[rodbolt]

Re: DF115 prop issue beyond me...Update...

walleyehed<br /> looks like your in the ball park<br /> notice how dramatic the RPM loss with the 14x17?<br /> whilke your correct on the avalible air to burn the EFI can compensate automatically for the less dense air. while there will still be some power loss it wont be as dramatic as a carbed engine, which relies on air pressure to move fuel.less air also means less air pressure which affects a wide range of fluid properties. until there is more studies and advancements with propellers were stuck tryng to prop 4 strokes with two stroke stuff. a quick dyno or test wheel session would rule out any engine problems. it could be the map sensor or air temp sensor if used is out of spec some. on most EFI engines now they use a map sensor and an air temp sensor to determine air density. the ECU will then alter the fuel curve and timing curve to compensate for changing air densities(altitude). aint computer controls greaat? no more playing with carb jets you may still have to play with gear sets. but I dont know if high altitude sets are avalible for that motor.

 

[walleyehed]

Re: DF115 prop issue beyond me...Update...

Hope nobody saw that.... <br />Thanks for the help, Rodbolt, and all that contributed...<br />Customer is happy and decided to buy the prop insted of me replacing it. He now has a spare..<br />We also had a dealer out of Central Nebraska come down and play with us for the day on friday to determine we didn't have an engine issue.<br />His comment on props was that we have the best we can get now, until they do some blade design changes to better meet the needs of some of these applications.<br />His operation is at 3000ft and has had quite a few problems with the zuki props being border-line, and has used mostly michigan wheel for replacements in lower pitches, but doesn't like the blade designs they currently have in aluminum. He did mention in his experience, about 75-100RPM drop per 1000ft has been the norm for him, and the dealer in KC just mis-judged by installing the 17.<br />Anyway, all is well and everyone is happy...Thanks!