ORIGINAL: chem16
I have a UCD 46 and UCD 60. The 46 has a saito 72 and the 60 has a saito 100. I'm currently running a APC 13x4W on the 72 at 10700 rpm. Is this prop too small for this engine and what is the ideal rpm range. I was planning on putting a 14x4W on the 100. Is this prop also too small?. What prop is recommended for each engine? I'm sorry if this answer is in this forum somewhere, but I did not want to read all 2000 + post. Any information would be greatly appreciated.
The 14x4w is way too small for the 100. A lot of people are running that prop on their 72's. Try the APC 15x6 on the 100 or the 16x4w if you want a real stump puller. But like the previous poster said, the wide props take a smidge longer to spool up. I know APC makes a 15x4w, but I've never heard any rpm numbers.
Some people don't mind running their 4 strokes over 10K rpm, but I never do. Ideally I'd shoot for a prop that gives you a max rpm around 10K. Then back the RPM down about 200-300rpms. A running RPM of ~9800 is about right in my book.