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Old 22-06-2012, 17:00   #1
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Yamaha 9.9 4 stroke ENGINE as generator

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.
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Old 22-06-2012, 17:15   #2
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Re: Yamaha 9.9 4 stroke ENGINE as generator

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!
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Old 22-06-2012, 17:45   #3
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Re: Yamaha 9.9 4 stroke ENGINE as generator

Quote:
Originally Posted by atoll View Post
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
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Old 22-06-2012, 17:47   #4
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Re: Yamaha 9.9 4 stroke ENGINE as generator

Quote:
Originally Posted by cat man do View Post
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.
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Old 22-06-2012, 17:50   #5
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Re: Yamaha 9.9 4 stroke ENGINE as generator

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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
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Old 22-06-2012, 18:03   #6
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Re: Yamaha 9.9 4 stroke ENGINE as generator

Just Take the prop off?
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Old 22-06-2012, 18:41   #7
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Re: Yamaha 9.9 4 stroke ENGINE as generator

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
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Old 22-06-2012, 18:57   #8
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Re: Yamaha 9.9 4 stroke ENGINE as generator

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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.
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Old 22-06-2012, 19:01   #9
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Re: Yamaha 9.9 4 stroke ENGINE as generator

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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.
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Old 22-06-2012, 20:00   #10
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Re: Yamaha 9.9 4 stroke ENGINE as generator

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.
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