Switching Gear Ratios
#1
Geronimo36
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It's been a long time and I have a question regarding prop pitch with gear ratio changes.
Last year I was running 32" Bravo 1's to 51-5200 rpms with a 1.50 gear ratio, with about 20% prop slip.
Over the winter I picked up different drives and the gear ratio is 1.30. In addition to changing the prop pitch I am looking to turn higher RPMS (5600) than last year because of where my motors make peak TQ and HP.
I was thinking Bravo 1's with 28" pitch would do the trick? Anyone??
Last year I was running 32" Bravo 1's to 51-5200 rpms with a 1.50 gear ratio, with about 20% prop slip.
Over the winter I picked up different drives and the gear ratio is 1.30. In addition to changing the prop pitch I am looking to turn higher RPMS (5600) than last year because of where my motors make peak TQ and HP.
I was thinking Bravo 1's with 28" pitch would do the trick? Anyone??
#2
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When going from a 1.5 to a 1.3 you will need to drop the pitch by 10%. That will put you at about 29. If you want to increase your rpm another 400 that's about 2" of less pitch, so that's about a 27.
You are pretty close with the 28's you thought you needed. If you have the 28's they would be a good prop to start with. If you need props to test with give us a call.
Matt
You are pretty close with the 28's you thought you needed. If you have the 28's they would be a good prop to start with. If you need props to test with give us a call.
Matt
#3
Geronimo36
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Originally Posted by SVL4
When going from a 1.5 to a 1.3 you will need to drop the pitch by 10%. That will put you at about 29. If you want to increase your rpm another 400 that's about 2" of less pitch, so that's about a 27.
You are pretty close with the 28's you thought you needed. If you have the 28's they would be a good prop to start with. If you need props to test with give us a call.
Matt
You are pretty close with the 28's you thought you needed. If you have the 28's they would be a good prop to start with. If you need props to test with give us a call.
Matt
Frank
#4
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Sorry, I forgot to log out and back in on the last post.
We are located in St Pete, FL.
Don't hesitate to call or e mail if you have any questions.
Matt
We are located in St Pete, FL.
Don't hesitate to call or e mail if you have any questions.
Matt
#5
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Matt, you have two user names?
Panther, the raise in gear ratio (lower #) is about 2 inches in pitch to maintain the same rpm. So dropping yet another 2 inches of pitch in the Bravo 1 propeller family should put you where you want to be. Sounds like you had it figured out already.
Panther, the raise in gear ratio (lower #) is about 2 inches in pitch to maintain the same rpm. So dropping yet another 2 inches of pitch in the Bravo 1 propeller family should put you where you want to be. Sounds like you had it figured out already.
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Brett Anderson / BBLADES Professional Propellers
920-295-4435 http://www.bblades.com/
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Brett Anderson / BBLADES Professional Propellers
920-295-4435 http://www.bblades.com/
[email protected]
#6
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Panther,
I need a set of 32's and I have a set of 28's. Do you want to swap or whatever ?? I went from 1.36 to 1.50 which is the opposite of what you did.
Call me at 847-902-9702 and let me know.
Smitty
I need a set of 32's and I have a set of 28's. Do you want to swap or whatever ?? I went from 1.36 to 1.50 which is the opposite of what you did.
Call me at 847-902-9702 and let me know.
Smitty
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Want your ECU tuned right?? Call Mark at Precision www.pmefi.com
#7
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Originally Posted by bbladesprops
Matt, you have two user names?
Matt
#8
Geronimo36
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Originally Posted by Smitty
Panther,
I need a set of 32's and I have a set of 28's. Do you want to swap or whatever ?? I went from 1.36 to 1.50 which is the opposite of what you did.
Call me at 847-902-9702 and let me know.
Smitty
I need a set of 32's and I have a set of 28's. Do you want to swap or whatever ?? I went from 1.36 to 1.50 which is the opposite of what you did.
Call me at 847-902-9702 and let me know.
Smitty
I'll give you a call. How old are the props, have then been "worked"?
Frank
#9
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Panther,
They are not virgin. I bought them used from a fellow OSO'r. They appear to have been redone at some point. I would rate them a 9.5 out of 10. They worked well for me but since I have changed ratios I need something else. I'll be available tonight by phone.
Dave
They are not virgin. I bought them used from a fellow OSO'r. They appear to have been redone at some point. I would rate them a 9.5 out of 10. They worked well for me but since I have changed ratios I need something else. I'll be available tonight by phone.
Dave
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Want your ECU tuned right?? Call Mark at Precision www.pmefi.com
Want your ECU tuned right?? Call Mark at Precision www.pmefi.com