Re-power MerCruiser 5.7 Horizon MPI to a Yanmar 4LHA-STE 230hp

[Patrick Presti]

Hi Guys,

Has anyone had any experience re-powering a boat from a MerCruiser 5.7 MPI to a Yanmar 4LHA-STE 230hp? I was curious if there was any performance gains with the re-power…

I have a 27′ H&H lobster boat with a MerCruiser 5.7 MPI with a 2.5:1 ZF63a gearbox, 1.5″ shaft, and a 20″x17″ 4-Blade propeller.

Right now she cruises 14kts at 3400 RPM’s. Ideally, I would like a 17-18kt cruise.

Any insight would be greatly appreciated.

Thanks,

Pat

Topic

[Tony Athens]

Noting that matters–The 230 was an early rating with hotter fuel used in a test cell.. Later on, Yanmar rated the engine in a test cell using colder fuel, hence the engine could make 10 HP more at WOT/3300+ RPM…

Tony

[Patrick Presti]

Tony Athens wrote:

If you can find a really good 4LHA 230/240 and set it up 100% right, then you will be able cruise with that model Yanmar and be within Yanmar’s guide lines at where your “gasser” cruises now ( maybe a tad better) , but at 1/3″ less fuel burn……That may also be an important part of your decision too ??

If you really want to CRUISE at 17-18Kts. then you have to up your available and true “CRUISE HP”.. That means, like Rob said — a 6LPA 315 or a Cummins 6BTA 330 or 370 Diamond..

The 4LHA 230/240 is a really great engine, but it has it limits..

Tony

All great info. Engine wise, what’s the difference between the 230/240 HP models?

Pat

[Tony Athens]

If you can find a really good 4LHA 230/240 and set it up 100% right, then you will be able cruise with that model Yanmar and be within Yanmar’s guide lines at where your “gasser” cruises now ( maybe a tad better) , but at 1/3″ less fuel burn……That may also be an important part of your decision too ??

If you really want to CRUISE at 17-18Kts. then you have to up your available and true “CRUISE HP”.. That means, like Rob said — a 6LPA 315 or a Cummins 6BTA 330 or 370 Diamond..

The 4LHA 230/240 is a really great engine, but it has it limits..

Tony

[Rob Schepis]

Do you already have a line on that Yanmar? Normally the Yanmar 6LP was the engine of choice to replace the small block gasser..

[Author]

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