Yamaha 9.9 4 stroke ENGINE as generator

[cat man do]

As the thread title suggests I have an old yamaha 9.9 4 stroke that is redundant to my needs.

Worthless to sell but I had always thought that if I built the engine into a dedicated ventilated box in the back step/lazarette of the cat with water pickups for cooling, over the side exhaust, key start ignition, throttle etc etc. and then have that connected somehow to a huge alternator so as to have the equivalent of a 10hp genset.

Figuring this should be as reliable as a very expensive diesel genset but with a lot less weight and expense.

Silly idea or not and if not silly, ideas on where to start.

[atoll]

dont mean to be negative,but by the time you have,built a bracket for it,made up systems to handle the cooling and exhaust,bought a 240v alternator found the correct pullys and tenstioner,built a box with flexible mounts etc

you might save a lot of money by looking on ebay for a 2nd hand aircooled diesel genset!

[cat man do]

Originally Posted by atoll

dont mean to be negative,but by the time you have,built a bracket for it,made up systems to handle the cooling and exhaust,bought a 240v alternator found the correct pullys and tenstioner,built a box with flexible mounts etc

you might save a lot of money by looking on ebay for a 2nd hand aircooled diesel genset!

This was my point.
We have ultra reliable, relatively light, water cooled, quiet
Vs
Unknown reliability, heavy, air cooled , noisy.

Upside is the later runs on diesel
Downside could be many

[Factor]

Originally Posted by cat man do

As the thread title suggests I have an old yamaha 9.9 4 stroke that is redundant to my needs.

Worthless to sell but I had always thought that if I built the engine into a dedicated ventilated box in the back step/lazarette of the cat with water pickups for cooling, over the side exhaust, key start ignition, throttle etc etc. and then have that connected somehow to a huge alternator so as to have the equivalent of a 10hp genset.

Figuring this should be as reliable as a very expensive diesel genset but with a lot less weight and expense.

Silly idea or not and if not silly, ideas on where to start.

Dave there was a guy who built a schionning in FNQ who adapted large alternators to his 9.9 outboards. He wrote an article on it - And I am struggling to remember where but I think Multihull World (Aus). He also did a DVD of his build that he was selling as a sort of boat building manual. If I remember any more I will let you know.

[cat man do]

Originally Posted by Factor

Dave there was a guy who built a schionning in FNQ who adapted large alternators to his 9.9 outboards. He wrote an article on it - And I am struggling to remember where but I think Multihull World (Aus). He also did a DVD of his build that he was selling as a sort of boat building manual. If I remember any more I will let you know.

Thanks for that but by the sounds of it he is still using them for propulsion?
I am not wanting that I am after 100% generator from this engine

[Factor]

Just Take the prop off?

[djmarchand]

It might work, but I wouldn't plan on more than 5 hp out of that engine or about 3 kw (50% generator efficiency). Any more and it won't last very long.

David

[cat man do]

Originally Posted by djmarchand

It might work, but I wouldn't plan on more than 5 hp out of that engine or about 3 kw (50% generator efficiency). Any more and it won't last very long.

David

Thanks David,
Is that a real number or a guess? 3 kw = 3.75kva, so more than your zip start honda, but not enough to warrant doing it imho.

A quick google shows that 9.9hp/10hp yamaha generator is the one with a MZ300 engine.

This puts out 5.75kva
Generator House - Gentech 5.7kVA Recoil Start Petrol Generator

If only it was quiet, water cooled and electric start I would more than likely get it which is why I was considering starting with what I have.

[cat man do]

Originally Posted by Factor

Just Take the prop off?

What I was getting at is the guy you speak of has the motor set up for , guessing on numbers here, 95% propulsion and 5% power generation.

I want 0% propulsion and 100% power generation, so a far larger alternator than what you are thinking.

[Florida Mike]

Keep in mind most outboard engines cannot withstand side loads. A while back and Australia (I believe) mounted an alternator on top of an outboard. He made a solid coupling and would basically set the complete alternator on top of the engine. Basically all you would need to do for your version is to cut the bottom of the foot off just under the engine tap into the water inlet and connect to the rest of it as an exhaust. Keep in mind that the water pump is in the foot on most outboard. I would thank that a small side loads of a small pump would not hurt it for an electric pump. Very interesting concept though. Just my two cents, Mike.
PS. You might also consider putting two equal alternators on each side that should cancel out all side loads.