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Diffuser removal?

Old 01-21-2021, 09:44 AM
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Default Diffuser removal?

Sent my B1 x 24p to BBlades for lab service and diffuser was removed and wondering why. I'm not questioning his talents.
running on 270 Convincor w/496HO

thanks
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Old 01-21-2021, 09:58 AM
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Brett labbed my Bravo 1 years ago and did not remove the diffuser. The Max 5 is a Merc modified and labbed Maximus which does have the diffuser removed. It's my understanding that the diffuser is to help keep exhaust gases from getting into the blades so when we run through transom exhaust it only becomes a hindrance and also creates some transom lift. I'm not a prop expert but that's my take on it.
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Old 01-21-2021, 12:51 PM
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He's tuning it for how much transom lift your boat needs. The shorter or removed diffuser lowers the transom lift, which raises the bow. Every hull type is different. Interested to see how it performs.
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Old 01-21-2021, 02:25 PM
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All started with this and BB stated go with the B1B1 24p vs QIV-X 24p. Both are 4bld both virgin. 2002 Convincor 496HO with normal load, usually 1/2 tank gas or more runs 65, but when the stars and moon align then just over 67. Both GPS. The only difference I notice is that under about 45mph the hydromotive needs more down tabs to prevent porpoise. WOT.. it's a toss up for MPH. That said which prop would be best to rework and what would be estimated results? I usually run with about 30-40gal fuel and WOT RPM is in the range of 4700-5000 depending on the season with spring and fall producing 5K RPM. So 4700 most of the summer here in western PA
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Old 01-21-2021, 03:32 PM
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I couldn't answer that. That's where you gotta trust someone like Brett. I've never messed with a Hydro prop.
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Old 01-21-2021, 10:53 PM
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Originally Posted by PA.WOODCHUCK View Post
Sent my B1 x 24p to BBlades for lab service and diffuser was removed and wondering why. I'm not questioning his talents.
running on 270 Convincor w/496HO

thanks
I agree with most of the answers below. The diffuser helps the boat plane faster, provides stern lift and that means less bow lift, and it creates drag as well. I have a 24P Bravo FS Pro Finished prop (stock) that I use on my Checkmate. The Bravo FS has almost no diffuser and less cup height than the standard Bravo 1. When I tried a 26P Bravo 1 (stock with diffuser) I was surprised that the 26P came on the plane much faster than the 24P FS. Some of that was due to the diffuser. It ran 2 mph slower but the rpm was also a bit too low. The bow lift on the Bravo FS without the diffuser was much better (almost too much). However, like someone said, Brett has probably determined what your boat needs from talking to you and tried his best to give you that.
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Old 01-23-2021, 09:36 AM
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could anyone measure total height so I can then know how much was cut off?

thanks
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Old 01-23-2021, 12:38 PM
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Originally Posted by PA.WOODCHUCK View Post
could anyone measure total height so I can then know how much was cut off?
thanks
Total is 7 1/4 including the turned down part that goes into drive. As in total height of the prop sitting on the bench. How high is yours now?
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Old 01-23-2021, 07:47 PM
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6 5/8 when on bench to top...
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Old 01-23-2021, 08:17 PM
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Why not call Brett and ask him why it was cut off?
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