Small ear chopper vs. Big ear chopper RPM's

[Blown Up]

What would the RPM difference be between 30 pitch small ear choppers and 30 pitch big ear choppers?

[rev.ronnie]

If all things were the same, there should be little difference..Theoretically ...but...the big ear generates more bow lift in my experience. If you have to trim a small ear more to get the same lift, it may have more slippage in the same rig as a large ear, and therefore run a higher rpm. Even at the higher rpm, it may not be as fast as the large ear.
This scenario may be sound with an 18 foot boat, but may work the other way on a 15 footer where it may not need the blade area.

What type of a boat/motor combo?

[1FASTLASER]

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[Blown Up]

I was under the impression that the small ear's were only 14" diameter, while the big ear's were 14.5" diameter. I was thinking this alone would cause the small ear's to spin more rpms? I am running a 28' cat with twin 300's. I turned a set of small ear 6300-6400. I want to get down to 6100 range and was just trying to explore options.

[David]

If it were me, I would not run a small ear with 300 HP. "Everyone" says the small ears will break with big power. For full details about the differences between small ear and big ear look at Adams Dock

http://69.24.70.63/adamsdock/chopper.html

According to Adams, the later big ear 30s are different from the earlier ones, ie the later big ear 30s really are bigger.

I would also expect that bigger diameter and bigger blades would turn fewer rpms. If that's what you want, you need the later big ear as it has bigger blades

I ran a Chopper 2 big ear 30 on my SS2000 and it was spooky. The bow never stood still. My small ear 30 runs much better. Your application is about the opposite to me - big power twin cat vs underpowered V bottom, so take my advice for what it is - guesswork.

[rev.ronnie]

I will know soon...I have a 14X30 Dunamis coming from Steve Smith that I'm going to try. It is a 14" that is based off an inline chopper..

I will report the results.

[Bayou Native]

Me too......
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