Engine drivetrain dilemma

[northsider]

I have a Hughes Northstar25 I recently purchased a Volvo 3 cylinder diesel with tranny for it but as the engine goes in facing the stern I dont know what I need to hook it up to the shaft. What do I need?

[DeepFrz]

It sounds like you need a V-Drive.

[Mirar]

If it is a new engine /gear that you bought , can you exchange the conventional gear for a v- drive? Like DeepFrz mentioned, you would want a ZF V-drive or something similar. These are not cheap, mine for an 85hp was 2500 U.S. There is the Walter V-drive than is extraneous to the gear, but it adds a lot of bulk and length to the equation.
Good luck on this one, hope you didn't get taken on something you didn't really want.

Greg

[Kokanee]

If you are saying the engine goes in facing the stern, I assume that it is a V-drive gearbox you have bought with the engine.

Knowing the model of the engine & gearbox would help others to help you.



To install the setup you have, you'll likely need to do a lot of preparation work setting up an engine bed & mounts.

Before doing anything, Id suggest taking lots of measurements to determine if this setup can work. Download the drawings for engine & gearbox. Determine the down angle on your prop shaft and on your gearbox. You need to work out exactly where your engine will end up. This is all determined by by the position and angle of your prop shaft coupling.

If you think it will likely fit, I'd suggest is building a wooden model of your engine & gearbox. Basically a box roughly the size of the engine with a gear coupling & engine mounts. The critical points on your model need to be:
1)the gearbox flange angle relative to the engine;
2)position of engine mounts
3) the maximum height and width of your engine

Trial fit this model to see if it will work. Determine how much work it will be to build some engine mounts. Will the prop shaft have to be shortened or lengthened (replaced)? Will the engine be higher than your cockpit floor?
How will it change the centre of gravity of your boat? Generally V-drives mean the engine is higher. This may be a problem.

Best of luck.

[Kokanee]

btw - If your 3 cylinder volvo is an MD17, I've got a good used MS-2 gearbox for sale cheap, if you live in Australia. That would greatly simplify things.

[jimbunyard]

Is this your boat?



If so, it came with an Atomic 4 and, as previously advised, a V-drive.

So the question is, did the Volvo you bought come with a V-drive, and you are wondering about the connecting bits, or did you get a standard transmission (output flange faces aft) and hope to somehow use it?

If you have a standard aft output gear, you'd have to either put the engine in the cabin, a serious engineering challenge, almost certainly upsetting hull balance, or get a v drive like this



at 3500.00 used, a pricey alternative.

If your engine has a gear like this, then all you need to hook it up is an appropriately sized shaft to fit into the dark green coupling shown in the lower part of the above picture. if you don't have that coupling, it should be available from either Volvo or a prop shaft company.

Also, if you don't have a V-drive, be aware that getting a non Volvo V-drive to fit can be done, but it will involve a lot of modification.


Additionally, an engine set up for a V-drive application is usually laid out completely differently from a rear drive engine, with the common maintenance
items on the rear (now front) of the engine...

[northsider]

That indeed is the boat! I just have the standard transmission on the volvo.Thanks for the assistance now all I have to do is find a v drive.

[Mnbear]

Hi I bought a hughs 1500 without engine and v drive. Bought atomic 4 with v drive looked to be the best way to go for me. Good luck

[jimbunyard]

There's one here:


http://www.ebay.com/itm/VOLVO-PENTA-...-/350499914181

but keep in mind there are model specific variations, even though one gear may actually bolt up, there may be differences that are not initially apparent. For instance, on a standard MS2 gear, which looks exactly like the upper part of the gear shown above, and exactly like the upper part of a sail drive, and all will bolt up to the same flywheel housing cover, the aluminum input shaft housing on the saildrive is about an eighth of an inch shorter than the one on the standard gear, allowing the housing of a standard gear to just touch the rubber bonded drive plate and generate just enough heat to debond the plate, an 800.00 mistake. Guess how I figured that one out...


And again V- drive engines are usually set up so the maintenance items like filters, coolant and oil fills are located at the normally rear end of the engine to facilitate access in a reversed engine configuration, the point being that in a 25' boat, engine access is already tight, so make sure you can get at everything. It's a real pain in the ass to have to pull an engine to change the starter...

[gjordan]

Any 3 cylinder motor (Volvo, Yanmar, etc) is much more power and weight than you need in a 25 foot boat. You probably should find out what motor was originaly in the boat, and see if you can find a used running ,exact same model. It is much easier(and cheaper) to replace with the same motor as it is to adapt something. Just my opinion. ______Grant.

[jimbunyard]

Originally Posted by gjordan

Any 3 cylinder motor (Volvo, Yanmar, etc) is much more power and weight than you need in a 25 foot boat. You probably should find out what motor was originaly in the boat, and see if you can find a used running ,exact same model. It is much easier(and cheaper) to replace with the same motor as it is to adapt something. Just my opinion. ______Grant.

Except that this boat came with a 310 lb (without V-drive) Atomic 4 engine. For comparison, my MD2020 weighs 260 lbs.

But I agree that it might be much easier and cheaper to install what was there originally rather than to re-engineer everything, especially a gas to diesel conversion.

And we'll leave the gas/diesel pros and cons discussion out of it.