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Old 02-26-2012, 10:02 PM   #1
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Default Signature four by four props on 2800scr

Hi there everyone. I was wondering if anyone has had any experience with the four by four props on a 7.4l bravo iii equipped 2800scr. I am considering get a set to help me plane quicker and maintain a lower cruising rpm. Any info would be greatly appreciated!
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Old 02-26-2012, 10:28 PM   #2
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Do they make a four blade for b-lll?Don't think they do.........

Have you tried dropping your trim tabs down when you take off?l do that on my 3000 and that gets me up and on plane real quick.

Try this before you spend all that money on new props


Roger.
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Old 02-27-2012, 01:02 AM   #3
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Thanks for the input Roger. After doing some research, they do make a set for the bravo III, and we use the trim tabs now, but we put on a new swim platform this winter so we are a little worried about the added weight.... Reviews say they help get on plane quicker and you can cruise at a lower rpm. We also only have a single on our 2800scr. Anyone else use the 4x4 props for the bravo III?
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Old 02-27-2012, 02:41 AM   #4
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Don't have them but read about them and a 4X3 prop, very interested in real world results.
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Old 02-27-2012, 06:19 PM   #5
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Seems a bit like a contradiction. Get on plane faster AND cruise at lower RPM's? Typically a lower pitch will get you on plane faster, but have a lower top speed. Larger pitch gets on plane slower, but has a higher top speed. Larger pitch can also maintain the same speed at slow rpm's. Here you're talking about BOTH faster tim to plane and slower planing speeds. Going from 3 blades to 4 should decrease prop slip. I would expect to get slower cruising speeds on plane, but wouldn't expect faster planing times. I supposed it could be said that less prop slip could be translated to more forward movement, but i'm curious what kind of load you're introducing to the engine.

I also didn't think they made a tue 4 blade prop fo rthe B3. I have read that they have been toying with a 3 blade and a 4 blade combo. It was my understanding that the 4 blade introduced a cavitation problem for the second prop in a dual prop config. I think I recall they used a 3 blade fro the forward prop and a 4 blade for the aft prop to counter this behavior. i could be wrong.

I caution you to be carefula dn aware of what your time to plane is, and you max RPM's at WOT throttle. Make sure your WOT RPM's are within the manufacturers range. below the max. rpm range at WOT is just overloading the engine at that point.
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Old 02-27-2012, 11:34 PM   #6
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Well I do know that they make four by four props for both the front and rear props on the bravo III, I have no experience with them, which is why I was starting this discussion. I also heard using a combination of two different pitch props on the Bravo II was also beneficial for performance. For Instance, you would use a 20p on the outer prop and a 22p on the inner prop, any experience with this setup?
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Old 02-28-2012, 12:05 AM   #7
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All I can say is those props are going to be big $$$$$$$$$

Roger
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Old 02-28-2012, 01:33 PM   #8
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I found this on another forum - was posted in '09:
In 1999, while still employed at Mercury Racing, we began development of a new set of B3 propellers. The reason we did this was Formula began mating 500 EFI engines to B3 drives on their sport cruisers. The second generation B3 props (still a 3/3 set up) was cavitation burning so fast we couldn't get 10 hours on the props before their would be a hole in the front prop blades. The new development produced 2 finalists. One set had a 4 blade front which truth be told was a mis communication accident. However, after much testing it was determined the 4/3 had the better cav. burn resistance and the performance was equally as good as the other new development set. What we found was the 3/3 original set was slightly faster still. However, the new 4/3 burned much less and had a slightly better mid range. We decided to release them under the Mercury Racing logo and it took till 2004-2005 to get it done. This is the time frame slightly after my leaving Mercury Racing. The decision to Hi Polish the props came from the management that took my place. Hi Polish looks pretty but isn't a performance related issue.

If a guy wants low end and mid range specifically, the 4/3 is the better choice. If bow lift and speed are the main concern, working the 3/3 is still the better choice. Unfortunately, I believe the 3/3 is going to go away for good.

Now, as far as the new 4/3 versus the Merc Racing 4/3, there doesn't appear to be much difference other than the finish and a bit of a geometry and cup change. Main line propellers has basically created a new propeller option to continue moving forward with new offerings in the market place. It has a duller finish and is priced to offer the consumer a option. And a Hi Polish price point to match the Racing XR version. The whole thing is kind of goofy in that main line has created a product to directly compete with the Racing product.

We have worked with the XR propellers here at BBLADES. We have yet to work with the main line 4/3.

Again, bottom line, 4/3 for low end, 3/3 for top end. Also, go down 1" of pitch if you go from the 3/3 to the 4/3.

Brett
----------------
Here's some info on the Signature props: http://www.hillmarine.net/Bravo-3-4-...4ds-hpr4cs.htm

And this from Merc: http://www.mercurymarine.com/propell...e/bravo-three/
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