Choosing a Petrol Engine

[Red Admiral]

I would like to fit a larger engine in my 54" cruiser, it currently has a OS .20 nitro engine installed, which pushes it along ok, but it is pretty heavy so top speed is about 6mph!!

I have a heavily pitched prop that came with the boat, but the nitro will not drive it, so I suspect that a petrol engine was fitted once. :cool:

Can I fit an air cooled petrol engine from a strimmer / chainsaw or similar, or is it best to get a water cooled engine? :confused:

If water cooled is best is it possible to get a water cooling kit for an air cooled engine? :confused:

Thanks,
Red Admiral :) :)

[Doubledog]

With the prices of these gas engines now, you can buy a good watercooled Zenoah for around $200 new.

If the boat has enough airflow, you can go a little cheaper with a Zenoah (or similar) aircooled version. The differences from the outside are they're physically larger than their watercooled cousins.

Either version will accept a clutch too. :)

Zenoah 231 or 260 PUM - Watercooled
Zenoah RC230, RC260 - Aircooled
or you can search for the SIKK / Chung Yang (sp) engines too.

Do a google search and see what pops up.

Btw,
Depending on your drive setup (submerged, subsurface, surface) will determine your overall prop size. These will range from roughly 60mm diameter to 75/ 80mm. You'll also need a 1/4 inch (6.35mm) drive shaft to accomodate the power of the stronger engines.

[Red Admiral]

Thank you for your reply Doubledog, She is a semi displacement cruiser, with a keel, so the prop is totally submerged. I have some work to do on the hull, so replacing the drive shaft is no problem :) I like the idea of a clutch! At the moment I have to grab it to stop it!! lol! :)

I was wondering, If I used an air cooled engine, could I wrap copper pipe around the cylinder head for water to run through and cool it, having the water exit with the exhaust, or would this not be sufficient? I am in the UK and water cooled petrol engines for model boat are hard to find, especially second hand, on a budget! lol!! :)

http://img.photobucket.com/albums/v304/mk2_fiesta/Image451.jpg