gene375

I am getting ready to purchase a large gas powered boat, and would like some information regarding a 4 stroke engine vs. a 2 stroke, I am not going to race and do not need excessive speeds. i previously had a 40" .46 that was running 35-38mph. any help would be appreciated. thanks

torpedox

who makes any water cooled four strokes?? i've never really looked into them but power to weight will almost always be on the 2 stroke's side. how big a boat are you looking at?

TERBObob

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Well , not really sure what kind of info you are looking for , but heres a bit of info reguarding the 4 verses the 2 cycle .
First , a 4 does not crank out the RPM's as a 2 does , which in turn , means MUCH slower speeds ( since we use direct drive to the prop from the motor ) , next , the 4's , as stated above , do not come already water cooled and that means you would probably need to make a water jacket . Also , the there is a weight difference .
The 4's have been tried and seems like they failed the test . ( by major engine builders and racers )
I beleive the motors the tried , were the RYBOI and the HONDA , and , like I said , neither one did very good .
Although there was one major advantage over the 2 strokers , they were a LOT quieter .
For the bucks , I would suggest you stick with a 2 stroker.
For the dollars , its still a best bet to get a Zenoah .

ballgunner

My Feedback: (1)

A four stroke could be cooled by wrapping the cylinder with aluminum tubing with water in an out. If you don't intend to race the problem of direct drive and slower speed should not be a problem. The advantage of reduced noise would be an asset at our pond.

Will Sgarlat

Hey BG,
The aluminum tubing to cool the engine is OK for "well behaved" shapes, like electric motors and exhaust. But a 4C cylinder head is kinda lumpy! The engine stands a very good chance of overheating with that approach. A water cooling channel that has more surface contact would be preferable.

ballgunner

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Will you are probably very right. After I posted that idea I looked at my four strokes again, My suggestion would be a bear to implement and is not a sure thing in any case. Just an idea that wasn't too practical. Sorry

yamraptor2cool

Do they make four stroke boat motors?

TERBObob

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Hey YAM ,
Kinda lost here ... was that link to that picture of a 4 wheeler in reference to the size of engine you are talking about ? If so , then what SIZE boat are you talking about ? ( geez , all this time , I thought he was referring to a "normal" size RC boat - 36 to 70 inches - )

pro27

There have been Model 4 strokes for marine in the past. I believe OS had a few. Don't know of the current availability. Displacements were around a .40 I think.

It's true that a 4 stroker does not have the rpms as a 2 stroke, But like other motors, electric included, some types provide more torque, thus able to swing a larger prop.
The same holds true for a diesel, which I have seen in the past.
I see nothing but possibilities for a 4 stroke in a scale type boat, Like a Dumas Cris Craft or something. A mid-size DV hull would be suitable also if it's not speed you are after.

Just came to me.............there are several conversion kits out there in the RC Touring Car world for 4 stroke conversions, one that I remember seeing is for a .26 4 stroke. I believed it was air cooled.

I'll have a look through my mags if you want ,and see what I can come up with?

The possibilities are there

yamraptor2cool

Sorry about that terbobob, I was trying to put a picture of my quad on there but it didn't work!

RcBoatLover

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A friend of mine just built a 50 inch boat with a 4 stroke weed eater engine. He left it air cooled and it runs fine. The engine sits pretty low in the boat with little air moving over the head and it still dosn't over heat.

*** One big problem though!!!*** It is a led sled! Fun play boat for some, but I think most would get tired with the 25mph top speed!

Yes OS made a four stroke marine engine in the past. In fact they made three different ones. They were .40 to .61 in size. I had the .40 New in a box and sold it last year! I know dumb me. I wish I would have kept it!!!

PAINLESS

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http://www.rcuniverse.com/forum/upfi...90923_8380.jpg

Here is a photo of a boat I'm building with a 4 stroke engine. Since his was taken the boat has been finished
exept for radio installation. It is a Magnum .80 engine, it is supposed to turn 12k rpm. As you can see the engine is mostly exposed to the air flow.
I'm going to start with a prather 255 prop and go up or down depending how it runs. This is just for fun, not going to race it, if I can get 40 mph out of it I'll be happy. I can post another photo later if interested.

pro27

Is that the Dumas Miss Unlimited Hull?
I never thought of a 4-stroke for this one.
Considering it is an'old school' hull design, I think you may be surprised how well it will perform with the stroker.

PAINLESS

My Feedback: (19)

Yes it is, I thought the 4 stroke in this old style hydro hull would just sound too cool.

I was hoping to get it finished sooner but some other projects got in the way. Its way to cold here now,
will have to wait for spring.

ChuckAuger

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I have a couple of 4 stroke boat engines. An OS 60 with exposed rockers, and a couple of Gannet gasoline ignition 4 strokes, 15cc. These are all more of a vintage style, not really performance oriented engines

Kmot

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Painless: That shovelnose with the stroker is sweet!!

Chuck: Can I see a picture of the OS.60 four stroke marine engine?

ChuckAuger

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ChuckAuger

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A much rarer example..

TERBObob

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Well , this one won;t be available till next year , made by MTC - twin over head cams and four valves - WOW , but something for you guys to drool over meanwhile That thingy on the side is a water pump ( the item with the clear hose on it going to the top of the engine .
And yes , this IS a 4 stroker BOAT motor . Claims 14,500 RPM's ( forgot what the rated HP was though - sorry )

They also make a two cylinder one as well









( better have DEEP pockets to get one of these babies ! )

Kmot

My Feedback: (24)

Chuck: THANK YOU!

I was really curious to see how OS cooled it. I am planning a project with twin four-stroke's and need to figure out the cooling.

What is that ignition stroker? Looks neat.

Terbo: Yup, seen that new DOHC MTC all over the 'net already. It's a work of CNC art and it will be priced accordingly no doubt!

ChuckAuger

My Feedback: (12)

That is the Gannet I mentioned. They were hand made in England by a "slightly eccentric" fellow in the late '50's, early 60's. Fairly low production and pretty rare in this condition, this one sports the original coupler and exhaust tube. This is a latter production model after the inventor, George A. Nurthen (GAN of GANNET), teamed up with a man named Ivor Morgan who did nickle plating. Talk about an engine that is hard to find anything about...I was lucky enough to be put in contact with a group of English model engine enthusiasts who sent me some magazine articles detailing the collection if these engines...dated from '83! So they are scarce in England, almost non-existant in the states. There is at least one other RCU member who owns one, though. I bought this one off a guy on RCO who is also an RCU member.

I have another in almost as nice condition.

Kmot

My Feedback: (24)

If I won the lottery I would be an engine collector.

Since you are into exotica, here are some intersting examples for sale right now:

3159108596
3159395194
3158422568
3158742719
3159393782

EDIT: It seems RCU doesn't like links to the evil 'bay, so plug in these numbers in their search box.

ChuckAuger

My Feedback: (12)

Man, those are some fine engines..a little out of my league price-wise. I'm like you, if I had the $$$ I'd own them all.

ibstar

why not go the whole hog a get a colney v8 supercharged 8000 us

TERBObob

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That's CONLEY