617 Turbo into a Boat
 

Let me start off by saying my day job is as a boat mechanic and I have been wanting to do this for some time now. I have an old 17' Hydroswift with a good drive and no engine. The engine the boat came with was a 140 HP mercury 3.0 Liter 4 cylinder. My thought is that the 617 turbo has similar HP output but much more torque which would allow me to run a much more efficient higher pitch prop. Today at the pick and pull i found a 1983 300d with what seems to be a good motor (it will turn by hand and feels just like my SD). I asked the people in the office if i could start the motor before i pull it they said no of course so before i pull this thing I want to do a little more thinking.

I have read many places and seen people mention doing this swap into a boat but no one has ever really ended up with anything. I have a boat and will have an engine so here we go.....

My thought is to use a manual flywheel out of a 240d and attach the splined coupler to the flywheel by drilling and tapping it so that it is center. Mercruiser has a very similar design where they drill and tap the GM manual flywheel and bolt the coupler too it. the next hurdle to get around is the bell housing/rear engine mount. I thought about using and modifying the bell housing that i already have from a GM v8 mercruiser engine and making some sort of adapter plate. My biggest worry is getting everything centered.

The next hurdle to jump is to keep the exhaust/turbo cool as marine engine exhaust is usually cooled by water. I haven't quite figured this one out yet but it will prob involve a fan with a heat exchanger or some sort or find a marine turbo that has the water cooling fittings.

What does everyone think.... Ready go!

A machine shop could get everything machined on center for you. It may be worth the extra expense to make sure you're rotating around the right way.

Sounds like a cool project, post pics if you do it.

Sounds like a pretty sweet project. If you do it, take lots of pictures and post them here!

good question.... the Mercruiser engines are Left hand rotating engines as viewed from the flywheel...(right rotation as viewed from the front). I believe i remember that the 617 is the same way.

If i do this i will definitely post pictures and the boat is green so it would fit well if i run biodiesel in it too!

Would i have to take the engine to a machine shop so they can measure it or does anyone have the technical measurements for the bell housing bolt pattern and Center of the crank on a 617? never really done this so not sure how it works

I've seen pictures of a 616 or 617 in a boat. I'm betting marinized water cooled manifolds are available somewhere.

http://mercedesforum.com/forum/showthread.php?p=135004#post135004

http://www.peachparts.com/shopforum/showthread.php?t=124061

http://www.coastalboatsales.com/jfraley/gallery/scubaboo?page=13

if you drill and tap the flywheel and attach a coupler to it, won't that throw it out of balance? you're going to have to have it balanced after you do that of course. i never heard of anyone doing this to a flywheel before. have you?

Yes as i said Mercruiser (and all other sterndrive manufacturers for that fact) have this basic design. On the coupler i am thinking of using there are three bolts that hold the coupler to the flywheel. they are evenly spaced and as long as the coupler is centered on the flywheel there should be no balance problem.... However, and this is my thinking for using the 240 D flywheel, some people on this forum have said that the 240 D flywheel is too light for the 617, I am hoping that the additional weight of the coupler will help balance out the weight even more.

http://www.rutledgedc.com/8171.JPG

there's no such thing as a flywheel that's too light. haha. i say go for it.

shoot, now that i know that little tidbit, i'd better start asking around to see who has done a 240d flywheel on an auto trans om617 and what the results were

These guys are only cooling the exhaust post turbo which was my original thought..... I may still do this but i would like to keep the turbo cool as well in the engine compartment, as it is quite a small engine compartment.... So i was thinking like a heatsink exchanger that bolts to the turbo and exhaust manifold in some way that has water runing through it.

These guys also did what i was thinking ... they drilled and tapped what appears to be a normal manual flywheel; however, they are using a direct drive setup whereas i am using a sterndrive....but similar.

From what i have read on the manual swaps from the 240 D to the 617 there sometimes is a slight vibration:confused: because the flywheel isn't heavy enough to balance out the 5th cylinder i am assuming:confused: someone that has done a manual swap into thier 123 or 126 back me up on this.

You haven`t heard of some one doing a 4-spd swap into a 617 eng that had a automatic? where have you been? don`t you read the forums to see what people are doing? start doing a search.

www.peachparts.com/shopforum/showthread.php?t=88699

this should keep you busy reading. :D

Charlie

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A lot of the 240D 4 spd swaps into a 123 that was a automatic, does seem to be some problem with some vibrations around 1800 - 2000 RPMs. all depends on each indivual car and swap. could be the 240 fw being about 10# lighter. good luck finding a 617 fw, not many of those around.

As far as a bell housing, the early 123`s used an iron box trans and had a seperate bell housing. maybe one of those might work for you. I think 82 they went to the one piece all aluminium trans case. don`t see them very often, there was one last week at PNP, but think it is gone now.

there is a forum member here that installed 2 617 in his boat. wish i could remember his name.

Charlie

Exactly the info i was looking for.... I just weighed the coupler by itself and its about 9 pound so should be close to spot on. Of course i don't need a perfect condition flywheel cause i have no clutch that needs to ride on a smooth perfect surface so maybe i could fine an old unusable one.