Wrong Prop??

TonyMcbride

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Jul 12, 2019
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I recently purchased a 2002 Sanpan 2500LE with an I/O 4.3 EFI in it.. It came with the Bravo 3 outdrive. I noticed I can only get 3400 RPM at WOT. PLUS, it is a gas hog! I'm wondering if I have too much prop pitch as it has the dual props and 22 pitch. Is that what is causing my problems?? any help would be greatly appreciated, as I am not familiar with this setup!
 

TonyMcbride

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PS..I used one of the online calculators and it recommended I go to a 16-17 Pitch prop..Can this be right?
 

alldodge

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Agree, 16 to 17 would be better if (BIG IF)

If your motor is running good and full HP rating

Have you did a compression ratio test?
Do you know if someone has replaced the drive with a different ratio?
Do you know what the drive ratio is?
 

QBhoy

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Hi
unusual to have a bravo attached to a 4.3. Has either or been replaced ? 22” prop is also quite unusual on the outdrive too. Not impossible but unusual.
 

TonyMcbride

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Thanks for the quick reply, guys! The motor runs great and it has a good takeoff. I'm not positive, but I think this is a factory setup..the other boat I was looking at when I purchased this one had a Volvo Penta outdrive on it. The pontoon I had before this one was WAY better on gas (24 ft. Playbuoy w/ 3.0 4 cyl) and I wonder if I could damage or shorten the life of the 4.3 by having too much prop on it. Also, know of any prop shops that will do an exchange?
How do I tell what the ratio is? is it stamped somewhere on the outdrive? Thanks in advance!
 

TonyMcbride

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PS. The other boat I was looking at to purchase was also Sanpan 2500 LE..
Also forgot to say in first post that the WOT was 23.6 mph by GPS..
 
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jimmbo

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Thanks for the quick reply, guys! The motor runs great and it has a good takeoff. I'm not positive, but I think this is a factory setup..the other boat I was looking at when I purchased this one had a Volvo Penta outdrive on it. The pontoon I had before this one was WAY better on gas (24 ft. Playbuoy w/ 3.0 4 cyl) and I wonder if I could damage or shorten the life of the 4.3 by having too much prop on it. Also, know of any prop shops that will do an exchange?
How do I tell what the ratio is? is it stamped somewhere on the outdrive? Thanks in advance!

Yes, over propping an Engine will shorten it's life

VPs usually have the ratio on a metal tag on the upper gearcase.

With an increase in displacement of about 43%, Fuel consumption is going to to rise
 

jimmbo

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My mistake, you have a Mercrusier. Ratio is in same place



VP = Volvo Penta
 

TonyMcbride

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With an increase in displacement or about 40%, Fuel consumption is going to to rise

??? I don't understand this. Can you explain?
 

TonyMcbride

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Oh, you mean between the 3.0 and the 4.3. I get it now.. I just went to see the drive ratio..found it! It says 2.2 on the tag. Thoughts?
 

TonyMcbride

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I just did a search for props for a Bravo 3..I can only find a 19 P as lowest pitch. (mercruiser site) Does another company make lower pitch for a Bravo 3?? Thanks in advance!
 

TonyMcbride

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Update: I'm narrowing down my problem! I decided to change oil, oil filter and check the engine as much as I could before jumping to a new prop for the pontoon. I ended up putting a new Distributor cap and rotor on it and it sounds MUCH smoother and seems quieter under way! I just did a test and it reached 4400 rpm at WOT and was really scooting along! My only problem now is when I turner around to head back home is under WOT it reached 4000 rpm and quickly started loosing back down to 3400! What gives? Any ideas? I did purchase a new water/fuel separator that I haven't installed yet. Could that be the problem? All guages read normal at the time this occurred. SO glad it isn't the prop!
 

alldodge

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Since it did fine at first and then slowed down I would look into the fuel system.

Pull the separator off and pour contents into a clear container to see if you have anything but clean gas.
When removing the filter do note if it is completely full

Next need to check fuel pressure, and leave gauge on it so it can be seen when running hard
 

TonyMcbride

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Thanks Alldodge, I'll do that today..confused though..can you set me straight as to how it runs perfectly at WOT for over 2 minutes and after that lose rpms?
 
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