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Repower

 
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Mark



Joined: 24 Oct 2005
Posts: 30

PostPosted: Tue Aug 07, 2007 5:10 am    Post subject: Repower Reply with quote

We're thinking about repowering and I wanted to ask if anyone has repowered with the 40 hp Yanmar 3JH? I know several of you have gone with the 50hp 4JH and are very happy with it.

I'm asking because one of the guys at the yard suggested that the 3JH might be a better fit for the T37 because it would have to work harder. He thinks the 4JH is probably fine, but that it might not get loaded down as much leading to possibly shorter engine life.

If you have the 4JH are you able to get up to full RPMs? If you have the 3JH have you been happy with it's performance? Do you think it might be underpowered?

Mark Kaynor
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jklewissf



Joined: 26 Feb 2007
Posts: 103
Location: San Francisco, California

PostPosted: Tue Aug 07, 2007 7:01 am    Post subject: Reply with quote

I have a 4JH on my Tayana 37 PH and think the power is about right for the boat.

In dead calm conditions it can drive the boat to hull speed so I have a little reserve for pushing the boat into the wind, and running the alternator. I have also used the engine to pull the boat off when it has run aground. Since it took full throttle once I have to assume I would not have been able to get free if I had a weaker engine.

I don't think the a weaker engine would be appropriate for the way I use my boat.

If you go up to the more powerful engine you will probably need to change your prop as well. You want the prop to allow the engine to run up to its full governed speed while the boat is tied in its slip. If you cant get up to full rpms under those conditions, you have two much prop.
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Tayana 37 PH #581 "Active Transport"
KF6BPU
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FTimmons



Joined: 17 Nov 2005
Posts: 103
Location: Deltaville, VA

PostPosted: Tue Aug 07, 2007 10:56 am    Post subject: Reply with quote

Mark:

As the owner of a marginally underpowered V42 (older model 4JH), I would tell you to put the biggest normally aspirated engine you can fit in the boat. Make sure it is propped right to keep the engine in the fat part of the power curve, and that it can get to max RPM's without overloading.

I wish we had a few more HP's, but the engine is nowhere near replacement.
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Frank Timmons
V42 Magic Dragon
Deltaville, VA
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Kamaloha



Joined: 28 Oct 2005
Posts: 225
Location: Lebanon, NH

PostPosted: Mon Aug 13, 2007 7:08 am    Post subject: Reply with quote

I'm no powerplant expert but I would tend to agree with you. I have a 4JHE rated at 40HP, and I am never able to get it up to high enough RPM's to load it the way the books all say I am supposed to. I get hull speed at 2100 RPM in a calm, which is only 58% of maximum. Since there is a chance I may be looking at repowering soon too (see my other post about nasty noises) I may be inclined to use the 3 cyl you suggest; same horses in a smaller package. I'd like a smaller package since the 4JHE barely fits in the engine compartment, and I'd like enough room to add some sound insulation.

As far as driving in heavy weather, if there is wind, I sail; in six years I've almost never operated the engine if there is wind about.
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Charlie
s/v Kamaloha
1987 T37 #542
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Rollo



Joined: 09 Feb 2006
Posts: 18
Location: San Pedro Ca.

PostPosted: Fri Aug 24, 2007 4:40 pm    Post subject: Repower Reply with quote

Off the Yanmar path abit, however I just repowered with a Volvo D-2-40
from the old MD-17. Had to change the engine bed's, but what a great choice. I considered Yanmar, but after looking at torque curve and HP to RPM comparison, the Volvo was better in all aspects. The 8 degree down angle trans is a big plus, engine isn't running up hill. Fuel economy is fantastic, and it power's the boat quite nicely. And It's cheaper up front cost with dealer network world wide is also a plus. It's small compact design adds lot's of room in the engine bay for access to the bilge area I.E. pump's head hose's replacement ect. and it has a drain plug for oil!
It's way more quite than the old, I would strongly suggest that you make a comparison with all on the market in this HP range and make your choice accordingly. If you would like picture's of the conversion, my E-Mail address is apogee1@cox.net

Rollo
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John Keefe



Joined: 06 Aug 2005
Posts: 127
Location: Youngstown New York

PostPosted: Sat Aug 25, 2007 3:56 pm    Post subject: Reply with quote

Rollo,

I would really like to see the pictures of your Volvo installation. I presently have an MD17c and considering re-powering. If possible please email them to me at:

t37odyssea@roadrunner.com

Thanks very much,

John K.
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John J Keefe
ODYSSEA CT37 No. 63
Youngstown, New York (Lake Ontario)

"We Live In The Land Of The Free Because of the Brave"
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