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Diesel gear ratio

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martylee

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"I have a bravo 2 92 model, do

"I have a bravo 2 92 model, does anyone know what ratios are available and what would be best for d219 170hp diesel pushing a 23ft 2500kg planning hull ? are the gears easy to change ? any special tools needed ?"
 
"Is this a change-out/new inst

"Is this a change-out/new install, or are you looking for a performance change in existing boat configuration?
Gear changes are usually major increment changes to match engine power curve to the design and hull involved. Intermediate performance changes are usually accomplished by varying propeller pitch, design, and/or size.
A little more info may help in getting appropriate responses."
 
"The boat is a 23 ft bertram,

"The boat is a 23 ft bertram, originaly had 351 w with alpha 1. The d219 and bravo 2 came out of a 28ft 5000kg planning hull but was underpowered. it had a 17 3/4 x 21 prop. With this info (I would be guessing) the prop to suit my boat will be more like 24"+. Would it be better to change ratio to bring the pitch back, What is the best way to go about this problem before I start."
 
"If I have right interpretatio

"If I have right interpretation, the diesel setup has been installed and you have the 17 3/4 x 21 prop available, but not yet run in the water?
I do not have a table of all gearing ratios available for that sterndrive unit.

Someone else on here may have better experience in this area, but I think what I would do is make a test run with what you have and collect some data on rpm/speed etc. Then take this data to a good prop shop and get their recommendation on what they can do for you with propellers - since that is the fastest and cheapest way to proceed. If propeller mods cannot get you where you want to be, at least you will have some data to guide gear selection."
 
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