6BTA 5.9 370 difference 6BTA 5.9 330

[Frank Unsicker]

My 2002 40′ boat has twin 5.9 6BTA 330 engines.  What is the difference between the 330 and the 370? What needs to be updated to convert from 330 to 370?

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[Kyle Routh]

We also have a 40ft 2002 boat (Carver 396 with twin Diamond 370s) and live in Florida so I’ll give you my 2 cents….  😁 Short answer – no, you will not NEED the extra speed. Long answer – My wife and I live aboard and rarely travel over 8mph (7ish knots) – unless the current is in or favor! 🤣  And since it is our home, we try to minimize any unnecessary transient turbulence – including going fast which is much rougher than slogging along at trawler speeds.  Plus our fuel mileage is amazing at the approximate 1100rpm/8mph we run!! We have never had any issues or found the NEED to have to go fast.  Maybe you’re thinking about outrunning or getting away from weather.  Yes – it’s nice to have the option to go fast, but even then we just plan to leave sooner than later. What made you you think you would need to go faster in Florida vs. Texas? Again, just my opinion.  Take care! Kyle

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Frank Unsicker

[Frank Unsicker]

more info

I wanted to add more information.  The prop pitch was lowered from 22 to 20 about 10 years ago and the boat will run at WOT 2950 RPM,  both of the engines have 950 hours.   I plan on moving the boat from a freshwater lake (89,000 acre Lake Texoma) to Florida.  I normally run around 10 knots but every time I have boated in Florida in the past 20 years seems like everyone is going much faster than 10 knots and wonder If  I will need the extra speed. 

[pwrobert]

Considerable

Lots if similarities of course, most external accessories and such but there are a number that are not just easy change-outs. Tony or one of the others can give you a full list but for starters the pistons and rings are different and parts of the fuel system like injectors and maybe pump. Don’t know about heads, valves, cam, etc. <br />Remember that the 370 Diamond designation is a marketing one and not the HP. The 370 is actually 355 HP. 

 

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