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Author Topic: Four strokes  (Read 17461 times)

tobyker

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Four strokes
« on: January 19, 2007, 10:55:55 PM »

Has anyone tried using a four stroke glo engine in a boat? Did you fan or water cool it and if so how? It seems to me that these modern four strokes don't need much cooling, judging by the vestigial fins. I wonder just how little cooling one could get away with. ???
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glennb2006

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Re: Four strokes
« Reply #1 on: January 21, 2007, 01:40:35 AM »

HI there,

many year ago I had a Merco two stroke aero engine which I managed to watercool successfully with two turns of 4 mm (I think) copper tube round the cylinder and held in place with a jubilee clip. Also wrapped a couple of turns around the exhaust header and had no problems with it at all over two years and many hours on it.

Guess the feasibility of this depends largely on the shape of the cylinder etc on the engine you are thinking of water cooling.

May be that the fan turns out to be the better option.

Is there any particular reason that you want to run a four stroke? You are also going to have the hassle of findong (or in my case making) a flywheel to suit as well as the cooling. May be a two stroke water cooled that is available just ready to be dropped into place...
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tobyker

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Re: Four strokes
« Reply #2 on: January 22, 2007, 12:03:05 AM »

I like four strokes; I think they can be silenced better; and I like a challenge.
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glennb2006

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Re: Four strokes
« Reply #3 on: January 22, 2007, 01:33:15 AM »

 :) Ah well, sounds like you are about to start a challenge then.
From memory, OS four strokes have an awkward king of shape to cylinder, (for wrapping copper pipe round!), they are "squared off", and the push rod tubes run in front of the cylinder, so might be good to avoid.

You are right about the noise though, should be reallly quiet in a boat.

Prop size will need thought, as the engine power delivery characteristics will be different to a more conventional two stroke motor.

I (and I am sure lots of others here) will be very interested to see photos of the completed conversion, and to see an update on operational progress.

Good luck and have fun.

Glenn ;)
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Seaspray

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Re: Four strokes
« Reply #4 on: January 22, 2007, 11:06:09 AM »

Not many 4 stroke marine engines about.But did see somewhere O.S. did one. Maybe S.C. does one but not keen on their quality.

Quieter, smoother, lower revs, less fuel, easier to start, no need for a silencer,a little hard to get and dearer but sounds good to me.
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Bunkerbarge

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Re: Four strokes
« Reply #5 on: January 22, 2007, 11:16:14 AM »

Not many 4 stroke marine engines about.But did see somewhere O.S. did one. Maybe S.C. does one but not keen on their quality.

Quieter, smoother, lower revs, less fuel, easier to start, no need for a silencer,a little hard to get and dearer but sounds good to me.

As there are plenty of aircrasft four strokes around is there really much difficulty in using one of these in a boat as long as you can cool it? 
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glennb2006

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Re: Four strokes
« Reply #6 on: January 22, 2007, 01:48:39 PM »

Had a scout about for you and can not find any four stroke marine motors "out of the box". There is a page on the OS site about fitting fans to heli engines for cooling them, so that may be a viable option for you perhaps?

Otherwise looking like copper pipe and jubilee clips.

Glenn
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tobyker

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Re: Four strokes
« Reply #7 on: January 23, 2007, 12:07:39 AM »

Just Engines import the ASP OS look-alikes (but not cost-alikes) and these start at a .30 cu in (5 cc) but as remarked above, there is very little clearance between the pushrods and the cylinder at the flywheel end, and the inlet tract and cylinder at the backplate end. I am very tempted as this looks like a worthwhile project, but I've still got to do a plank-on-edge (1730 rule) schooner and the pop-pop pre-dreadnaught. If no-one else has tried recently, this might push it a bit further up the list, but it is quite a lot of cash to splash if you ruin the engine. Thanks to all for their contributions.
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OneBladeMissing

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Re: Four strokes
« Reply #8 on: January 23, 2007, 12:50:13 PM »

Why not buy a pre-owned engine off ebay to ferkle about with, rather than risk messing up a new one?
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BobF

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Re: Four strokes
« Reply #9 on: January 23, 2007, 01:43:38 PM »

Hi tobyker,

I was looking into this option early last year.  The one thing worth bearing in mind, is the much lower power output of the four stroke motor, so you would require a larger heavier motor.

There were a few on ebay last year, but they went for a lot of money, and I was a bit dubious as to what the mechanical quality may have been. If I ever have money to spare though, I will fit one in a cruiser style boat.
Good luck
Bob
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tobyker

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Re: Four strokes
« Reply #10 on: January 23, 2007, 04:33:59 PM »

I have a copy of a MMI free plan, Ravenna by Jim Pottinger, put by for this project. If i wanted sheer speed, I'd go for a noisy 2T, but I'm thinking of something a bit more gentlemanly.
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glennb2006

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Re: Four strokes
« Reply #11 on: January 25, 2007, 12:56:23 AM »

http://modelgasboats.com/magazine/index.php?option=com_content&task=view&id=119&Itemid=47

Looks like someone else fancies trying it too, although this one is petrol....


Glenn
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Braders

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Re: Four strokes
« Reply #12 on: January 25, 2007, 09:56:26 AM »

Hi gentlemen, just out of interest I had a discussion about this with Martin last year as I was considering building a fairly large scale Riva Aquarama and we concluded that probably one of the better 'shape' motors to water cool would be one from the RCV range. They offer two types, both rotary valve and either type would be suitable for wrapping copper pipe around (with a little fin modification and removal to clear carbs etc) or machining off the fins and fitting a water jacket.

Heres their site: http://www.rcvengines.com/rcvmodelengines.htm

The 'SP' in line range are also geared down 2:1 by virtue of their design and also has a hexagonal starting dog so would be easy to start and should turn a nice size prop in reasonable fashion, down side is they are mechanically noisy. I have seen these on Ebay for reasonable money second hand so it could be worth a 'play'.

Other engine range is more conventional but not having pushrods to get in the way would mace copper pipe cooling easy to fit, they also have a low profile so should fit below deck better.

Maybe a line to RCV identifying a gap in the market could kick off a range or new ic fourstrokes...who knows....?

Braders.
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Martin [Admin]

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Re: Four strokes
« Reply #13 on: January 25, 2007, 10:49:30 AM »

OS used to make one.....



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Seaspray

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Re: Four strokes
« Reply #14 on: January 25, 2007, 03:49:51 PM »

Seen an O.S. like above on Ebay last year,should have bought it.

Do I remember that there was A Fox 4 stroke engine to mate up with the famous Spearfish Cabin Cruiser.

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tobyker

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Re: Four strokes
« Reply #15 on: January 25, 2007, 05:41:09 PM »

The RCV are very interesting - thanks for pointing me at them. the CD version in particular looks as if it is just waiting to be machined down to take a water Jacket. However, the smallest available is 10cc, and they are a bit pricey. I wonder if they'd do me one cheap, for proof of concept of water-cooled version?
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glennb2006

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Re: Four strokes
« Reply #16 on: February 06, 2007, 11:35:10 AM »

http://cgi.ebay.co.uk/OS-FS-26S-CX-Four-Stroke-Recoil-Start-Car-Engine-New_W0QQitemZ190079578908QQihZ009QQcategoryZ34062QQrdZ1QQcmdZViewItem

Here is a four stroke glow car motor, did not know they made such things but there you are, every day's a school day, my work for your boat OK and no water cooling required, I presume the engine has additional cooling fins on it.

Not sure what size motor you are after, this one is a .26

Glenn
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Seaspray

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Re: Four strokes
« Reply #17 on: February 06, 2007, 03:27:37 PM »

Might need to cool it it by wrapping coil around the body get it from a model shop.  I know that an O.S. 20 was around 3.2cc many years ago.

There some out there keep looking.
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tobyker

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Re: Four strokes
« Reply #18 on: February 06, 2007, 05:52:23 PM »

Thanks Glenn, (and for your PM) I'll have a pop at that. (4.4cc acording to the OS web site) Its interesting that the advt Martin found shows a tiny cooling jacket on the barrel only - I think these things are designed to run pretty hot, and don't need all that much cooling.. Certainly with the 2-stroke car engines with the enlarged fins I reckon you could drill a few holes through the fins, interference fit for some copper tubing and run the water through like that. The car engine might have more finning than the aero ones, it's difficult to see.
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glennb2006

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Re: Four strokes
« Reply #19 on: February 06, 2007, 06:39:22 PM »

You are most welcome. I would be interested to see the results if you get it.

Good luck.

G
 :o
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martno1fan

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Re: Four strokes
« Reply #20 on: February 07, 2007, 05:18:33 PM »

im sure if you wanted to you could make a water jacket yourself if you can weld aluminium? or solder it.just cut some thin sheet to desired length and bend it round then attach a bottom and top and bend another larger circular peice to make a jacket then drill and attach inlet and outlet nipples.ive seen this done on homelite engines(petrol).in fact you may be able to buy a jacket depending on which engine you get.the jacket just slips over the head and cools it but the easyest way is the copper or brass tubing i used this method for my .61 size sc engine for a boat hers a pic i used the zip ties to hold it till i soldered the coils together and it worked great.this pic was before i also attached the new fly wheel from prestwich models.
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tobyker

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Re: Four strokes
« Reply #21 on: February 08, 2007, 11:10:37 AM »

The car engine on e-bay is now up to two thirds of the cost of a new ASP aero 4-stroke. I think I could have more problems fitting a flywheel to the car engine than an aero so I'll let it go, but thanks Glenn for pointing it out to me. Cooling a four stroke is going to be complicated by the proximity of the pushrod tubes to the cylinder but I will keep it on the list of things to do.
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martno1fan

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Re: Four strokes
« Reply #22 on: February 08, 2007, 01:07:39 PM »

can you not get a pull start for the car engine??  Also the car engine wont need water cooling if you run it in an open hatch boat.
  just checked that engine out and it has a pull start so you dont need a fly wheel either, just stick it in a boat thats designed for an open hatch like the one i built !!.it will get more than enough air to cool the engine that way.
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glennb2006

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Re: Four strokes
« Reply #23 on: February 08, 2007, 01:25:40 PM »

If you don't fit a flywheel the motor won't run, no momentum to turn the engine over the non power stroke...   :(

I see your point Tobyker, getting a bit too dear now. Never mind.

G
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martno1fan

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Re: Four strokes
« Reply #24 on: February 08, 2007, 02:42:55 PM »

what i meant was he wont need the usual marine flywheel for the v belt !!it will have a standard fly wheel on wont it?.
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